I love synthy-sounding pedals, and I've been messing with the Shocktave to that end, on and off for a while now. This is a souped up and tweaked version based on Joe Davisson's super cool Shocktave circuit, to achieve that kind of sound. I came back to a simple version I had build a while ago that I recently felt I could improve, and developed this. It's nothing drastic, but I think I've tweaked it as much as I'm currently capable of, so I thought I'd offer it here for others to try, and dare I say, for others to continue to improve....
Here's a link to a schematic: http://sites.google.com/site/teaandfiction/_/rsrc/1247755172710/Home/synthboxschem/Synthbox.jpg (http://sites.google.com/site/teaandfiction/_/rsrc/1247755172710/Home/synthboxschem/Synthbox.jpg)
It's tweaked to work with bridge pickup without a tone roll off, as there's 3 stages of identical filtering built-in post-buffer. It's uses the bleepy, sqare-ish octave down and shapes it a bit to get a sound I find like a modern and 'aggressive' synth sound.
It tracks fairly well, but is of course is not perfect. As always, picking technique (both pickstroke and rest) should be even, timbre should still be as warm-toned as possible (fingers or with picks near neck pickup) for best results. Glitchy playing = glitchy octave. :) Playing more in the middle of the neck on up is favored, as first five frets are most likely to cause it to 'skip' an octave up after a few seconds, but that can be mitigated for the most part. Lower strings will always sustain more than high strings, but you should be able to play notes solidly, even above the 12th fret E string, with a fair amount of sustain time. The decay on the octave side of the shocktave, to me, was fairly odd and glitchy; I think I've improved it, but it still fades a bit oddly on occasion though less so, and more so just 'gates out' if you try and hold a note endlessly. It loves bends and staccato playing...
Careful on the schematic around the 1N4148--the program I used is limited and made it difficult to draw that and the flip flop section; do reference the original shocktave for more visual clarity on the schematic.
Matching' transistors as closely as possible, and using the .22uF/220nF caps really seemed to help the tracking significantly, though .1uF could be used (or put in parallel) if thats all you have. The resistor and cap feeding that section seems to make the 'octave' ultra dry, and removes remnants of the 'straight' signal that comes through. The value of that cap affected the decay quite a bit; 68nF seemed optimal, though 100nF works too, though maybe not as well to my ears....
While using electrolytics is not ideal for most, but it seems the cumulative affect of using smaller(even .1uF) caps was more than tonal--it affected tracking a bit. Use whatever reasonably sized electrolytics you have around for the caps labeled as 2.2uF - I'm using random values that I rarely use otherwise. Do avoid going below 2.2uF for best tracking, to my ears. The 'bass' DPDT at the end then gives you the option to for huge low end or filtering through the .01 which is still HUGE-sounding, but may 'cut' better live, especially with already bass-heavy rigs.
Most importantly, this thing is tons of fun with some reverb and/or a little echo! Enjoy!
nice work
any chance of some clips?
My "recording rig" is really awful -- an old $5 computer mic into my generic soundcard...but I'll see if I can manage something over the weekend as I imagine more people will be interested once I do. :D
The schematic had some errors and a thing or two missing, so I updated it:
http://sites.google.com/site/liquidselectronics/synthbox (http://sites.google.com/site/liquidselectronics/synthbox)
I found that the first link only goes to the original version, which will be removed. This link should stay updated to whatever is the most recent version, if I ever do work on the schematic. Once you're there, clicking on the image should isolate the page to view the image only, and make it clearer.
I did record a long sound sample as per Derringer's request, but I need to whittle it down a bit; that should be coming soon, for those who are interested! :D
Sound sample montage is here: http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+Demo.mp3.html (http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+Demo.mp3.html)
I recorded a bunch of stuff and chopped it down to what I though was most useful for a sound sample. Most of it has a fair amount of reverb, and a tad of delay right into the amp. Here's a play by play of what is happening...
Phrase played cleanly :00-:04
Phrase played through my Foxrox Octron for comparison; octave down only :04-:08
Phrase played though Synthbox with 'shape' knob up, showing range of notes low to high :20-:30
Synthbox improv with tone knob up :08-:20
Phrases with shape knob down :30-:48
Phrases with 'shape' knob down demonstrating sustain and decay characteristics, no reverb :48-1:00
Improv with 'shape' knob down and a little extra delay for a little nintendo 'lead' sound :) 1:00-1:10
Sounds really good! Much more synth-like than most octave effects I have heard.
Cool!
Quote from: Top Top on July 17, 2009, 10:54:53 PM
Sounds really good! Much more synth-like than most octave effects I have heard.
Yeah, I thought so too. As you can hear, it's not synth-like in that that it's a satisfying moog copy. Nothing ever will be, in my opinion, though it's fun trying and getting close. There is no filter here on purpose, which is a key aspect of 'convincing' synth sounds, though you could add one and it's fun. More so this sounds 'synthesized' to me, something 'from outer space,' yet the feel when playing it is controllable enough to have fun playing through it. I've tried a fair number of 'synth-like' pedal configurations (boss synth pedals over the years, multi octaves+various filters, good digital, etc, etc). I have an EH microsynth, which is amazing, and to me a pinnacle of analog synth imitations and non-guitar sounds with straight guitar. It's huge, and I love it, but like the rest, it's more borders on a fun toy than something to put in the average guitar rig. I want(ed) to be able to cop even one moog-like synth sound, but in the end, live, I always ended up saying that if I need a true synth sound, we should get a real one! :D
I liked this because it made single notes sound rather unlike a guitar, but is relatively consistent; it can have an aggressive tone that cuts for leads. For example, the concept of a 'clean octave up' is interesting, but what makes octavia sounds cool is that they can cut through a mix, since they're clipped and squared, to some degree, and fairly aggressive about it. This one likewise has a unique tonal quality I like a lot, but happens to be a very fat octave down. So like an octavia it is less something that is trying to imitate a sound, more so the interest factor is that it makes a sound that you hear and say, "what the heck IS that!" :)
I love the escobedo Simple Square Wave Shaper Made Simpler and the PWM, and I have tweaked those out a bit to similar effect. They have counterpoint tonal qualities worth exploring, though they don't octave. Those have gone on the back burner for me like this one did, and I ended up coming back to this one first and being satisfied with the result. I still need to do a vero layout, though! :icon_lol:
Was this clip made with the Synthbox on breadboard or have you created some kind of layout? I noticed you said that you still need to do a vero layout... just wondering if you've created one on other formats.
Brilliant work - I love a to see a quest for the holy grail take a substantial step forward!
-chris
yes, vero layout please.
really cool modifications to an already fun circuit.
Almost saxophone-like at the end there... :o
Quote from: cpnyc23 on July 18, 2009, 09:43:57 AM
Was this clip made with the Synthbox on breadboard or have you created some kind of layout? I noticed you said that you still need to do a vero layout... just wondering if you've created one on other formats.
Yeah, that was with my breadboard 'rig.' :)
Quote from: mantella on July 18, 2009, 09:52:56 AM
yes, vero layout please. really cool modifications to an already fun circuit.
Thanks! I'm painfully slow with creating vero layouts. I tend to make ones that are fairly tight and not so pretty as the spacious layouts I've seen in the gallery, with all the pot wiring coming off the end of strips, etc. Lots of people on here are fast with them, though, so maybe one will show up soon. When I finish one I'll post it, but hopefully someone will beat me to it. :)
That sounds great.
I would build this right away if there was a layout... even a breadboard layout.
It sounds very synth-like - sounds like a raw synth waveform sound before the filter.
Would be cool to combine this with some filters and PWM effect.
[EDIT: sorry, removed comment about schematic link not working]
i've been looking for a new project to do. i think i just found it. this thing sounds right up my alley.
That sounds great...nice work
Awesome soundclip.
Found an error, the output seems to be taken from 9v instead of the emitter. Also looks like one side of the shape control is not connected?
Your right that it should be from the emitter side. Good catch :icon_redface:
The shape pot is just a variable resistance, a tone control like a rat, but after a buffer so that is correct. The 'tracking' trimmer is wired the same way, though I should state that you can make that any value you want, within reason. I tried it with a brighter guitar and found that a little more range is not bad, though too much and you lose the highest notes on the guitar.
The tone pot with only two terminals wired up as a variable resistor and in conjunction with the buffer stage means it can go from having no audible effect on the tone, to cutting off some amount of the highest highs. It, at most, adds about 11k resistance on the output if you leave it stock, so it's fairly minimal. 'The third terminal' should not be connected to ground. It could be connected to the same point as the second terminal.
Realistically, that whole part could be omitted and you could tap straight off a cap (or via the DPDT switch) from the emitter if you prefer the sound of the 'earlier' clips where it is more aggressive, rather than the smoother sounds with the 'shape' knob down. You could also wire it as a SWTC, if you prefer, I imagine.
Quote from: liquids on July 17, 2009, 12:20:13 PM
The schematic had some errors and a thing or two missing, so I updated it:
http://sites.google.com/site/liquidselectronics/synthbox (http://sites.google.com/site/liquidselectronics/synthbox)
I found that the first link only goes to the original version, which will be removed. This link should stay updated to whatever is the most recent version, if I ever do work on the schematic. Once you're there, clicking on the image should isolate the page to view the image only, and make it clearer.
I did record a long sound sample as per Derringer's request, but I need to whittle it down a bit; that should be coming soon, for those who are interested! :D
is this verified shematic? http://sites.google.com/site/liquidselectronics/synthbox (http://sites.google.com/site/liquidselectronics/synthbox)
No....the schematic actually has a error as mentioned above, that needs correction, but I update it later at some point, when I have access to edit those files...my computer had a meltdown this weekend, so that may not be right away, but hopefully will be soon. I'll post here to make it clear when I've updated it.
Quote from: liquids on July 20, 2009, 11:19:26 AM
No....the schematic actually has a error as mentioned above, that needs correction, but I update it later at some point, when I have access to edit those files...my computer had a meltdown this weekend, so that may not be right away, but hopefully will be soon. I'll post here to make it clear when I've updated it.
thanks for reply! Coz I am really interested of this and I'm hoping your update schematic.
It sounds fabulous....congratulations!
It's great hearing that people like how it sounds! I didn't expect this much response or interest at all. Of course the credit goes to Joe Davisson, all I've done it tweak and experiment like the curious amateur DIY hack I am. :D
I've corrected the errors on the schematic that were noted above. Good catch Joe, thanks again! :)
Has anyone breadboarded (etc) this yet? I'm curious as to what people who are adventurous enough to try it sans a vero layout think of it in their own hands, if their results are consistent with mine, etc. The buffer stages and low pass filtering is based on the filters in the Microsynth schematic, with a little flexibility (Added the tracking knob to control the last filter stage a bit, to each's personal taste). But I did design it with my own rig, needs, and priorities in mind, so I'd love to hear about how it goes in other people's hands, and with other people's setups.
It really sounds great! I am planning to breadboard this and eventually perf it. I recently finished a mod of Nocto Loco, but this one sounds less chaotic, and closer to what I was looking for :)
By the way, are the transistors critical? Can I use BC109, BC549 or 2SC1815 instead?
cheers
I love the sound of this thing! Great job. Looking forward to the corrected schematic and possible layout.
sounds awesome man ... nice work!
Quote from: isildur100 on July 21, 2009, 09:34:57 AM
By the way, are the transistors critical? Can I use BC109, BC549 or 2SC1815 instead?
It's worth a try, but 2N5089 and MPSA18 are cheap transistors that should be on any bench. I would lean toward the BC549s if I had to pick one of the ones you mentioned. But it's probably good that I explain some of the parts choices for those who are experimenting themselves--which is a good thing--rather than going direct from schematic to build.
MPSA18s are there for their low noise operation as input and output buffers, high hfe to keep the gain of the stage close to 1. This may be overkill as, when the effect is not being played, it's kind of 'gated' silence anyway. You could
probably use darlingtons, or 2N5089s, or basically any NPN transistor I imagine without experiencing much difference. Possibly any silicon transistor that you listed will be fine, if they're NPN.
2nd and 3rdtransistors - I chose 2N5089s since are low noise, high HFE, cheap, relatively consistent, common, and
I have them in abundance. The second transistor is acting kind of like a buffer, but also is responsible for some of the 'gating' as its base is biased at ~2 volts above ground. Likewise feeds a voltage to the base of the third transistor. I'd pick any old BC549 for this stage out of the three types you listed, but again, the differences may be negligible, and BC109, 2N5088, 2N3094 will work probably quite similarly. Don't quote me though. :) The third transistors from the input is the one that is responsible for most of the gain/fuzzing, and so the higher hfe's are preferable, if I recall. Again, of the three, BC549 is definitely best option you have as the others are lower hfe range, I think.
The 4th transistor in there with the 1N4148/1N914 diode...I don't think I did much swapping with, come to think of it; I did mess with the diode, and the type chosen (1N4148/1N914) had the 'best' tracking I could find. Germanium type diodes screwed up tracking, etc, and for whatever reason, 1N4001 was noticeably worse in tracking than the 1N4148, so stick with that if you aren't experimenting yourself. That type are fairly common.
The flip flip is the most critical part. I remember that I found that mismatching the caps affected tracking and tone, and in some cases eliminated the octaving. Mismatching transistors (2n3904 for one and 2N5088 in the other spot) really screwed with tracking and the octave, I found. This made me think, "maybe if I match transistors, I'll get better tracking" and sure enough, it did. I vaguely recall MPSA18 and darlingtons not working as well here for whatever reason, but I may be mistaken. 2N5089 have high hfe and were the easiest to match from the few I tried. 2N3904s do seem pretty consistent though, and I don't recall what the difference would have been here, actually.... 2N5088s should work well too, but they are lower HFE (may not be an issue) and seemed harder to get two as close as with the 2N5089. Note that the resistors should be the best you have, too. On the breadboard I have 5% carbon films and that worked as you heard, but off values will likewise screw up the tracking or octave altogether. If you can get 1% resistors, it surely wont hurt, closer is better.
If you are experimenting with transistors, set your DMM to test hfe across a batch of a certain kind of transistor. For the flip flop, first pick two of the same kind (say 2N5089) that are the closest. Than pick two of the same type transistor again from the said batch, but one with highest hfe in your batch and one with the lowest hfe in your batch. Listen to the tracking differences between these two pairs--I happened to find it significant enough to note it on the schematic, as I wanted the best tracking I could muster. I think you will too will that a matched pair will do better than 'any old' pair in the flip flop, if all else is in place for good tracking.
So in short, your transistors may work just fine, but it depends on 'where' in the circuit, and it will affect the circuit, anywhere from dramatically to negligibly.
Ok thanks for all that information!
It seems tricky to fine tune but it looks like it is worth the trouble. Out of the 3 transistors I mentioned, the 2SC1815 has the lowest noise and highest hfe.
Anyways, I will experiment following your guidelines. Thanks again!
I noticed that you made quite a few changes to the frequency-to-voltage converter section. Is it just for additional lowpass filtering, or something else?
Quote from: earthtonesaudio on July 21, 2009, 01:20:06 PM
I noticed that you made quite a few changes to the frequency-to-voltage converter section. Is it just for additional lowpass filtering, or something else?
I thought the F-to-V was the section with the diode and transistor combo? Be more specific, if you can..I'm just a hack. :)
If you mean what I you mean, my schematic should in effect be the same as the shocktave, with the only difference in that area being an added 10k and the 68nF cap. The DIYlc program I used to draw that schematic doesn't allow (or I haven't figured out how) to flip transistor symbols around, or how to more clearly indicate that lines crossing do not in reality intersect, etc. It's not that clear even to me on the schem, and as I said early on, the shocktave schematic should be referenced for clarity, especially in this area; it's much nicer looking.
I noticed that Joe calls the section I've been calling the 'flip flop' (and I don't even know why) the 'oscillator.' He also says "the oscillator is tuned so that it can only keep up with every other cycle, resulting in the octave-down effect." This is useful information.
That added R-C started as an idea for further filtering to help tracking. I think that is most of what it does. It seems rather extreme, and it's interesting to tap the audio at this junction. you'd think that no sound would get through...but it works somehow. Most of what I added, other than the buffers, is a lot of filtering for tracking. It still happens to sound good and aggressive despite that.
With the steep roll off, it filters out any sound of the 'unoctaved' signal well, to boot, so it sounds more synthesized as well as tracking better and having better decay characteristics. The Roll off corner for 10k/.068uF is 234hz or lower! I was baffled it even works...
Originally I added no resistor and just put a .1uF cap in there, and that worked to some degree. With the 10k resistor in and a .1uF cap, everything works fine, until notes on the E string around 12th fret seem to be unable to 'keep up.' Yet rather than making no sound, it tracks those notes as '2 octaves down.' AS counterpoint, too much filtering early on more so makes those notes inaudible or far too short in decay (so be careful with the tracking trim). The bigger you make that cap, the more you get that affect of not being able to keep up with the high notes and reading them as 2 octaves down. This sounds good, but it quickly becomes becomes a monotone bleep bleep bleep no matter what note you play. OH yeah, If you want two octaves down, you can run two in series, or an octaver into this circuit. I had an old prototype and ran it into this, and it indeed octaved 2 down. I find 2 octaves down impractical, but to each their own. :)
I digress. In my mind, I only understand this part as lowpass filtering, but it may affect the 'oscillator' section too--I don't understand that part at all, so I'm not one to say. This is certainly an area that could potentially be improved, by someone who understands what is happening more than I do--that is, someone who understands it at all. :D
I wanted to replace the flip-flop with something that would divide by an adjustable amount, in hopes of using a rotary switch to select harmonies. If anyone has any ideas for that, I'm all ears.
You've inspired me to give this one another try.
I tried to build a Shocktave once using an LM3086. This is a transistor array on a 14 pin dip. I thought it might work well since the transistors are matched. This would be good for the two that form the VCO that generates the octave. Not too mention it might make for a nice build since one part would replace all 5 transistors.
It didn't work on the breadboard so I gave up. It could have been that the transistors on the chip might not have enough gain for this application or just an error on my part.
Looking at the datasheet for the LM3086, the hfe is only around 100, which is probably too low for this circuit. This could explain your problems.
Hi,
Ive breadboarded this yesterday and I can confirm the schematics. It works like a charm. I love the sound and it tracks very nice. I just saw that I misread the 68nF value for 68pF (which I did not have, so I put in 51pF). I'll swap it tonight and see if the tracking/sustain gets better as you say. I did not find the tracking pot to be very useful, I set it to 0k for the best tracking. I was going to do a vero for this, but the component count is just a bit to high for vero, it will be a big board.
Now how about adding a mu-doubler in parallel, so we get into micro POG territory?
I'm definately going to play around with this and then box it up for a friend who will love this for sure.
Wow this thing sounds neato to the max. I've gotta put this on my list of pedals to build when I get better at all this stuff.
Quote from: liquids on July 17, 2009, 12:20:13 PM
The schematic had some errors and a thing or two missing, so I updated it:
http://sites.google.com/site/liquidselectronics/synthbox (http://sites.google.com/site/liquidselectronics/synthbox)
I found that the first link only goes to the original version, which will be removed. This link should stay updated to whatever is the most recent version, if I ever do work on the schematic. Once you're there, clicking on the image should isolate the page to view the image only, and make it clearer.
I did record a long sound sample as per Derringer's request, but I need to whittle it down a bit; that should be coming soon, for those who are interested! :D
Hi
Really nice sound in this one. What about morph this one with the oct up/down capability a 4024 an a 4070. To take the signal from "Volume" then mix it with the oct UP and/or oct down like in the Slacktave MK II.
http://www.diystompboxes.com/smfforum/index.php?topic=76695.0 (http://www.diystompboxes.com/smfforum/index.php?topic=76695.0)
Quote from: Joe on July 21, 2009, 09:29:17 PM
I wanted to replace the flip-flop with something that would divide by an adjustable amount, in hopes of using a rotary switch to select harmonies. If anyone has any ideas for that, I'm all ears.
The main route to do this analog is with PLLs. Recently Nelson put up an unverified schematic for his "Glitchshifter" which might help you with ideas.
Quote from: ~arph on July 24, 2009, 03:52:28 AM
Ive breadboarded this yesterday and I can confirm the schematics. It works like a charm.
Great! This helps my credibility. :D Isn't breadboarding great? :) (had to sneak that in there).
Quote from: ~arph on July 24, 2009, 03:52:28 AM
I love the sound and it tracks very nice. I just saw that I misread the 68nF value for 68pF (which I did not have, so I put in 51pF). I'll swap it tonight and see if the tracking/sustain gets better as you say.
You may find you don't need any cap there if you liked the tracking with '51pf' instead of 68uF and satisfied. Feel free to experiment. :) Very easy with a breadboard! If you don't find need that R-C filter stage, pull out that resistor, too. I'm very interested to see what your findings are here. How do you compare the decay/trail off compared to the same I recorded right now? Is it more glitchy and more 'arpegiating' at the end of note decay/gate, or about the same?
Quote from: ~arph on July 24, 2009, 03:52:28 AM
I did not find the tracking pot to be very useful, I set it to 0k for the best tracking. I was going to do a vero for this, but the component count is just a bit to high for vero, it will be a big board.
Did you use the 5k? 0k as in not there, or full up? I originally designed it without the tracking pot. The values are based on the low pass filter design in the microsynth, based on the frequency of roll off, rather than exactly imitate the values. I wanted to likewise keep the resistor values fairly low, and shoot for no more than 10k total out of the buffer, hence the three x 3.3k which worked rightly with .022uF; the roll off corner is around 2200hz.
As I edited the schematic, I though to add a the tracking pot for others, realizing some people might not play so cleanly, and/or have brighter guitars than I do, and might need more high end roll off for better tracking. I play this mostly with a bridge humbuckers, so it needs quite a bit of harmonic filtering--switch to a neck position and it's pretty effortless and easier to design around, but that was part of the fun.
I worked it a bit more and found 10k to have a better range, as the 5K was still very subtle (there are 3 stages of filtering as it is!), but that is coming from someone who didn't need it in there anyway. Anyone could just unsolder or socket that third 3.3k resistor on a final build anyhow and replace it with what tehy prefer--it's mostly set it and forget it pot. I may just leave the tracking trim out of mine, since I did design it with my rig in mind, without the tracking pot. :) I did try it as a 25k pot on the breadboard for the heck of it (I had no 10k on hand that second), and it compromised the high notes when turned up near and past halfway (10Kish) which is starting to roll off around 800 or 400hz if I recall...but it was otherwise subtle, and not necessary for me since I was getting fine tracking before. The only benefit was the decay on the lower strings on the lower frets did smooth out and glitch less at the end, but losing the highest notes played was a compromise. If you remove the trimmer, it will be a smaller board on vero. :)
I started a rough vero middle of the week, and it's very tight, but I should be able to get it on a very messy 15/30 veroboard, or smaller...but it's going to take a few revisions, and time is limited in the coming weeks...ah well. Maybe someone can do a small run of PCBs? I'd even buy one! :)
Quote from: ~arph on July 24, 2009, 03:52:28 AM
Now how about adding a mu-doubler in parallel, so we get into micro POG territory?
I personally have no interest, especially since my Octron and microsynth have that octave down/straight/octave up mix. So that is beyond the sound I'm going for with this particular design; that would also only make this design that much bigger, but go ahead! that is what DIY is all about. :)
Quote from: ~arph on July 24, 2009, 03:52:28 AM
I'm definitely going to play around with this and then box it up for a friend who will love this for sure.
Cheers to that! One more - how did you find the 'shape'/tone control? Too drastic, too subtle, or good?
Great to hear from people who have given it a try hands on...keep it coming!
I'll do some more testing this weekend. Yesterday was late so I can't recall all my exact settings.
I haven't really tried the shape control, I stuck a fixed 2k2 in there. Sounded the best. Not too sharp and not too dull.
Currently the decay is a bit more glitchy as in your sound sample. I'll do some testing around the tracking pt. BTW I used Single coils to test this, (mostly neck p/u) but my pu's are on the hot side (Lindy Fralin Vintage Hot's)
2 questions: Why 2 series (coupling) caps in the filter section (the 2.2ufs)? And did you find any difference between MSA18 and 2n5089, that you chose to use the MPSA18 in the input stage followed by the 2N5089s? I always thought they were pretty much interchangeable types in terms of hfe, noise, etc.
Anyway, nice work--the clip sounds great.
Quote from: Ben N on July 24, 2009, 10:31:02 AM
2 questions: Why 2 series (coupling) caps in the filter section (the 2.2ufs)?
Because I'm an sophomoric hack. :) No, really, I am. I'm not sure it matters. I thought I needed to block DC out of the transistor before the filters, and then needed another cap to isolate the bias voltage on the next resistor. I was being extra cautious, but it may not need both. I'm not sure. Someone like Gus, R.G. and the like may have better insight into it being 'good design' (which it probably isn't) vs totally uncessary to have two caps.
Quote from: Ben N on July 24, 2009, 10:31:02 AM
And did you find any difference between MSA18 and 2n5089, that you chose to use the MPSA18 in the input stage followed by the 2N5089s? I always thought they were pretty much interchangeable types in terms of hfe, noise, etc.
Anyway, nice work--the clip sounds great.
The difference is likely negligible for those sections (buffers), especially in this circuit. I labeled those as MPSA18 as an ideal, for a buffer stage. It has slightly lower noise specs than the 2N5089. So it's 'better' as a buffer on paper, but in reality may be negligible. My memory sucks, but I dare say MPSA18s have higher hfe, though on paper the datasheets make that unclear--the 2N5089 has a higher 'maximum' with MPSA18 having the higher minium hfe, so it's more sensible to talk to 'trends' and one actual transistor vs another, meaning they're pretty close. I dare say the MPSA18 is higher from minimum experience, as I've not found a 2N5089 beyond 999 hfe with my DMM, but if I recall correctly, a few and/or most of the handful of MPSA18s I have read beyond 1000 (i.e. they are unreadable on my DMM).
To be honest I no longer even recall what I actually have in there on the breadboard ;) Possibly 2N5089s, since I have them in abundance currently.
Quote from: Ben N on July 24, 2009, 10:31:02 AM
2 questions: Why 2 series (coupling) caps in the filter section (the 2.2ufs)?
Keeps DC off the volume control, preventing scratchy noises when that control is adjusted.
Concerning Vero, here's a vero I did for the Shocktave as designed by Joe ... change the values of a few components and you have the shocktave section of your synthbox ... so if anyone needs to, go ahead and use this vero for that part
http://www.diystompboxes.com/smfforum/index.php?topic=76966.0
Big update!
That 'noiseless biasing' arrangement for the Vref at the base in and out of the buffers also works better in theory than in practice. I'm looking to get about .7v above 1/2 the voltage at the base. On the breadboard I had 1M from +9.4v (one spot) to base and 2.2M from base to ground to get it about there in theory. Checking the voltage, even that wasn't working as planned.
Switching over to using the Vref on the current schematic with a 4.7k/10k arrangement, I was getting about 3-4 volts, which is not ideal. Trying to make it a little stiffer I tried 47k/100k, but with the same voltage reading. it too 4.7k/15k pair to get me to about 5.6 V (1/2 x 9.4=4.7) which is good. At that point, just running 1M resistor from the 9v to base with nothing to ground was not much different, though is 'bad design' in TAoE, so I'll stick with the 4.7k 15k for now.
Here comes the embarrassing part. :-\ I changed this all, only to notice I was getting a slightly different sound with notably less decay than I was getting before. Since I was messing with these changes on the breadboard, parts got moved around and I re-seeded them. The soudn was different, but I couldn't figure out what. I even swapped all the caps in fear I tried one, with little luck.
I don't know how I came to it, but this morning after a new look, I realized that I was witing the second transistor (on my schematic) all wrong. The schematic and shocktave indicate a buffer arrangement with the 220k resistor from emitter to ground on this transistor, with a 10k reistor feeding from the emitter to the 3rd transistors base. That is how I wired it up this time, causing the slightly less ustaining sound...
I don't know how I went back to it, possibly by the same slight of eye putting the lead in the wrong hole, but it seems I originally I had the 10k feeding from the base of the 2nd transistor to the base of the third, which is 'incorrect'. Believe it or not, this is a BETTER sound (and what you heard on the samples), though I don't know what would be happening in that stage now.... This is another indication that this could definitely be improved. I'm back to the breadboard working on stuff. Anyone with insight, please chime in. I'll leave the schematic as is. It works that way, just not as sustainy and edgy. :icon_redface:
Quote from: liquids on July 25, 2009, 10:09:03 AM
it seems I originally I had the 10k feeding from the base of the 2nd transistor to the base of the third, which is 'incorrect'. Believe it or not, this is a BETTER sound
Does that mean the second transistor was actually bypassed? Or is it that it made 2 signal paths going to that third transistor?
Been fiddling around with the circuit a bit. I took out the tracking pot.
Replaced my misinterpreted 51pF with a 47nF and now it sounds more synthy even.
I came up with a three parts mod that will give you, ring modulation and two octaves down :icon_mrgreen:
Do this:
At the 10k/68nF junction after Q4 (the part that is feeding the oscillator) put another 10k into a 100k pot an then into a 10uF electro into the base of the last mpsa18.
This mod works best with the volume up 100% so one might want to move the volume pot to the end of the circuit.
One side of the pot rotation gives you the normal sound (1 oct down) the other side of the rotation gives you two octaves down.. and in between is where it gets interesting.. 8)
EDIT: I tried the transistor bypass mentioned above, but found the sound better using the schematic as is.
Wow, I love circuits like this! Thanks for sharing.
Quote from: ~arph on July 25, 2009, 03:41:59 PM
Been fiddling around with the circuit a bit. I took out the tracking pot.
Replaced my misinterpreted 51pF with a 47nF and now it sounds more synthy even.
I came up with a three parts mod that will give you, ring modulation and two octaves down :icon_mrgreen:
Do this:
At the 10k/68nF junction after Q4 (the part that is feeding the oscillator) put another 10k into a 100k pot an then into a 10uF electro into the base of the last mpsa18.
This mod works best with the volume up 100% so one might want to move the volume pot to the end of the circuit.
One side of the pot rotation gives you the normal sound (1 oct down) the other side of the rotation gives you two octaves down.. and in between is where it gets interesting.. 8)
EDIT: I tried the transistor bypass mentioned above, but found the sound better using the schematic as is.
I greatly appreciate your feedback! Seems like you are enjoying it as much as I am!
Quote from: isildur100 on July 25, 2009, 12:44:46 PM
Does that mean the second transistor was actually bypassed? Or is it that it made 2 signal paths going to that third transistor?
I've done further work and experimenting, and yes, it seems that for all intensive purposes signal was havling little to do with the 2nd transistor. I suspected that, but wanted to make sure. In the shocktave, that stage is mostly functioning as a buffer, however it also importantly feds a base bias voltage to the transistor that followes it, which is why you cant just bypass that stage altogether, as in elminate it. There need be compensation.
So, the main difference in sound between feeding the boost stage off that stages emitter vs or straight off the base was the voltage difference between the two. The slightly more positive voltage at the base happened to sound 'better' to my ears as is, it turns out, what I tweaked it around; with signal tapping off the emitter, it gated a bit sooner, due to a slightly lower voltage.
Since I have a buffer stage in there already, it's probably not needed and can be worked around. The base of the transistor providing the 'boost' could be biased on it's own, similarly, by feeding it the 2.2M/1M or something similar. By eliminating the second transistor stage, I used a voltage divider (pot) to get down to exactly what voltage the base wants to see. it's really in optimal range in the area around 3V (with a 9.4v supply). I was surprised, but it won't bias at all above 4v or below 2V, roughly speaking.
Since I was back at the drawing board with a renewed interest in improving it, I'm working on the filtering amongst other things. I may even add a buffer stage after the booster stage, with some more filtering, before the frequency-to-voltage and oscillator sections...
The circuit works with the schematic posted as-is, and still rather similarly to the sound samples, as ~arph has confirmed. That being said, I'll definitely post here when I've updated it with further revisions.
Thanks for this update!
cheers
The schematic has been updated. A few tweaks in there, but I mostly just removed the second transistor stage and biased the base of the 'boost' stage directly. I also tweaked the voltage divider to bias the base(s) of the emitter follower stages more optimally.
I worked on the filtering a bit while I was at it, eased up on the pre-boost filtering to make the trimmer's range more 'usable,' but also added a little more filtering after the booster stage.
Overall, the circuit can always be tweaked and modded to your personal needs if you are so inclined, from Joe's original circuit on up. I am always tweaking and experimenting, but I definitely think this 'corrected' version is a great build with no mods required, so to speak. So I'm going to try to leave the schematic as is from here on out. :)
I am back to working on a reasonable sized vero layout, which may be more practical now that I've eliminated the 'unnecessary' transistor stage. I will post an update about that when I've finished and boxed one up for myself, whenever that is! :D
Vero update please!
:)
Nothing final to speak of. For me, i'd say it would be a months time till I really got to it and finished a vero at the soonest, (http://soonest,) FYI, probably more, and it doesn't seem like anyone else is working on a vero layout so far.
I talked to John Lyons about doing a 'run' of PCBs a few weeks ago. How much interest would there in that? The disadvantage is it's obviously costlier than doing it on vero.
If there were enough people interested in buying a PCB for the circuit from him, the time/cost might be worth it, and it would get the circuit in hands far sooner.
Maybe PM me, or post here if you think you'd buy a PCB from John if he he designed one for us. Otherwise, be very, very patient, grasshopper. :)
I'll buy a PCB.
A vero for this would be very large. I started on one, but it got too big too fast.
I would buy a pcb.
Possibly 2 so I could make one for my bassist buddy.
I think this circuit sounds freakin fantastic
The soundclips inspired me to draw up this, based on the schematic from page 1 ... at least I found a use for my insomnia, right? ;D
(http://img40.imageshack.us/img40/3503/synthboxlayout2.jpg)
... not verified, but it looks ok AFAIK.
Here is my effort at making a perf layout for this fine effect ;) If you see any errors, please tell me and I will update it.
(http://www.polygraphx.com/synthboxPerf.png)
cheers
Isildur...you listed the resistors following Q1 as 33k, but they should be 3k3 / 3.3k, FYI.
Thanks, I just corrected the layout, refresh the page if you still see them as 33k.
cheers
Quote from: Naz Nomad on August 13, 2009, 06:03:13 AM
The soundclips inspired me to draw up this, based on the schematic from page 1 ... at least I found a use for my insomnia, right? ;D
.........................................................................................
... not verified, but it looks ok AFAIK.
Very nice your work...thx for sharing it!
Can you post the PCB, too?
awesome job Isildur100. Thanks!
Looking forward to this one...
Any replacement transistors? Or do I have to order those exact ones?
Quote from: kristoffereide on August 14, 2009, 12:00:52 PM
Any replacement transistors? Or do I have to order those exact ones?
Please read the whole thread.
oh now I found it :D
Quote from: gigimarga on August 13, 2009, 03:00:19 PM
Very nice your work...thx for sharing it!
Can you post the PCB, too?
LINK TO PnP DRAWING (http://img268.imageshack.us/img268/8657/synthboxpcb.jpg)Print size ... 2.7" x 2" ... 600 dpi (I think ... lol)
I realise now that I've left 2 pads for the trimpot, thinking it was an offboard pot.
I'm sure it'll still fit on the board with no problems, but there's only holes for the 2 legs that are used. ::)
For the record, this is what I did to the schem so I could draw the PCB ... The layout mimics the schem pretty closely, so should be easy to follow ...
(http://img27.imageshack.us/img27/64/synthbox.jpg)
That's one of the hardest to follow schematics that I've ever seen.
Naaah, it's easier to folow than the original if you take it as 2 separate schems ... the top half is one, the bottom half is another ... it's just that the bottom half was flipped to join the grounds together and make the board more square, instead of 6 inches long. ;D
Thanks a lot Naz! I should have all parts on hand to build this on PCB... can't wait!!
By the way, if anybody needs a board I can do it while I'm etching mine within the next couple of days... drop me a PM.
Quote from: Naz Nomad on August 14, 2009, 05:11:15 PM
Quote from: gigimarga on August 13, 2009, 03:00:19 PM
Very nice your work...thx for sharing it!
Can you post the PCB, too?
LINK TO PnP DRAWING (http://img268.imageshack.us/img268/8657/synthboxpcb.jpg)
Print size ... 2.7" x 2" ... 600 dpi (I think ... lol)
I realise now that I've left 2 pads for the trimpot, thinking it was an offboard pot.
I'm sure it'll still fit on the board with no problems, but there's only holes for the 2 legs that are used. ::)
Thx a lot Naz...you're great!
Hi,
I'm new around these parts!
I'm in the middle of doing this on perf. What would you guys recommend for the non electrolytic caps? Metallised Poly film or multilayered ceramic? Looking at the perf layout I'm following it looks like ceramic is the way forward. Would using one make a noticeable difference to tracking/sound?
Sorry if this is obvious but I am new to all this!
Thanks for your time,
Jimi
I used poly on the breadboard and that worked fine.. I don't think the difference will be that big.
I've just finished it using BC549C for all transistors...it works poor, far from the soundclip...can somebody to post some good voltages?
Thx a lot all!
You need transistors with higher gain. The BC549 is typically 270, the 2N5089 is around 800.
Thx ~arph for your answer!
All the BC549C that I used had the gain over 600 and instead of MPSA18 I used two with gains around 700.
Anyway, I will try to found some MPSA18 here.
Are you using a power supply? Check your battery for one...
This is one circuit where I think that an audio probe will be far more useful than measuring voltages. Your transistors should be fine, by the way.
Describe what you mean by 'it works poor,' that might help...as I've messed with this quite a bit. :)
Do be sure to read this entire thread. It has some useful bits.
That being said, from my recollection, using a 9.43v supply:
The first and last transistor are buffers, and base of each should be around 5-6v. Following, the emitter will be a silicon diode drop (.7 volts) below the voltage you get there, and the collectors should read whatever voltage your voltage source is. Easy enough, but if not, something is wrong.
The second stage, the base should be about 3.3ish volts, if I remember correctly. Audio probe at the collector, though, and you should get a fairly loud and overdriven/fuzzy sound.
Measuring voltages at the next transistor--in conjunction with the diode, you should find, will actually be somewhat akin to measuring the voltage of an envelope signal at some points (base and emitter?), and vary according to input signal...that much I remember.
The oscillator transistors, I don't recall ever checking their voltages...hmm.
I'm sorry I don't have more exact voltages, but even so, I do believe this is one where audio probing and careful checking of your values will be far more helpful in solving the problem. And as I said in posts previously, be careful looking at the schematic on the bottom half, around the 'third' transistor and the oscillator (two transistors with emitters to ground). Check out the 'original' Joe Davisson's schematic which is the springboard and which I find is a clearer visually for this part of the schematic, due in part to the limitations of what I used to draw my schematic: http://www.diystompboxes.com/analogalchemy/sch/shocktave.html (http://www.diystompboxes.com/analogalchemy/sch/shocktave.html).
Thx a lot liquids for your answer!
I will check the voltages as you indicated above.
By "it works poor" I understand that it sounds farty and unclear (I can't hear the octave), as opposite in your demo where it sounds metal-ish and very sharp!
The trimpot seems to do nothing, but the other pots works OK.
Thx again!
From that description it sounds like something is wrong in the frequency to voltage or oscillator sections....oftentime it won't octave due to a bad connection there, a missing connection there, or having mismatched values in caps, etc...
Also, note that the trim is for improved tracking - it shouldn't make much difference to the tone, more so to compensate for how you play and maybe assist a very bright guitar and/or bridge pickup to have cleaner tracking.
Thx a lot liquids!
Hi all
First, TNX:s for sharing this Liquids. I fell in love with the sound and had to test it.
Her is a bread board template if any one wants to test before doing it on PCB or vero etc.
Its kind of tight but verified (at least it worked for me).
I did not, How ever, get any where near that sound in the post earlier. It migt be that I did not have the specified transistors. I used 2N3904 for Q1 and Q 6. The rest is BC547C they are 470 hfe. Maybe to low. I matched Q4 and Q5. (469 and 470)
Any one have tried some other ones with a good result?
(http://solderman.fatabur.se/Future%20project/synthbox.gif)
http://solderman.fatabur.se/Future%20project/Synthbox-bom.txt (http://solderman.fatabur.se/Future%20project/Synthbox-bom.txt)
I'm surprised that people are having such trouble. Except that I find wiring the shocktave was difficult to wrap my mind around at first.
But if you've done a shocktave than this should be intuitive - if not, than you might want to build a shocktave first, minus the clean blend. I'll repeat that the schematic I drew is better when referenced with the clearer layout of the shocktave. The shocktave uses all 2n5089s and those should be fine, as should 2N5088s just to get it fired up.
If/once you can get a shocktave to work, from there, just swap some components with the values I've changed.
And from there, all you are doing is adding some filtering and two buffers....think building blocks. All it is is a shocktave with some optimized tweaks, if you look at it critically. I'm bummed that such a small percentage of people have had success. :-\
I have breadboarded this three times, but not build one yet. Somehow I keep coming back to it.
I tried driving the frequency to voltage converter with an LM386 and plain opamp boosts. Still the transistor version tracks the best.
I found some great sounding mods that give you octave up and down as well. I'm sure I'll do a vero for this and one for the mods I have. because as I said..
this thing sounds so cool I keep getting back to it. I have to build one..
My Synthbox it's still dead, but I hope I will have some time next week to try to tweak it :)
Quote from: gigimarga on September 30, 2009, 04:28:22 PM
My Synthbox it's still dead, but I hope I will have some time next week to try to tweak it :)
Might be a good idea to ask the the designer of the pcb (Naz Nomad) if it's verified and working. I was REALLY anxious to get one built when the artwork was posted, but got too distracted with other projects to build it myself.
Regardless,this one looks best to tweak on the breadboard before committing to pcb/vero it seems.
Quote from: liquids on September 30, 2009, 03:24:21 PM
I'm surprised that people are having such trouble. Except that I find wiring the shocktave was difficult to wrap my mind around at first.
But if you've done a shocktave than this should be intuitive - if not, than you might want to build a shocktave first, minus the clean blend. I'll repeat that the schematic I drew is better when referenced with the clearer layout of the shocktave. The shocktave uses all 2n5089s and those should be fine, as should 2N5088s just to get it fired up.
If/once you can get a shocktave to work, from there, just swap some components with the values I've changed.
And from there, all you are doing is adding some filtering and two buffers....think building blocks. All it is is a shocktave with some optimized tweaks, if you look at it critically. I'm bummed that such a small percentage of people have had success. :-\
Hi
I did not find this one hard to build. More like standard. Many breadboard errors have made me a wiser man so now I always do a bread boar template before the bread boar sees some action when it comes to +10 components. This way I don't need to trouble shoot my sloppy "from the schematics builds" as I did before.
Sound vise. I thing the Q1 and Q6 can be any low noise transistor. Q2 and Q4 probably needs 7-900 hfe (2N5089 is 1200 max) and mine was 470. The sound I got from them was quite OK between the to choppy and octave jumping sound and the tacking was too jumpy and the decay sounded to buuzzz. I'll gonna change Q2-Q3 to 2N5089 as soon as I find some( or equal in gain) and test with different gain for Q4-Q5 as long as they at matched. I'll get back with the results.
So in the end I confident that Liquids design sounds good and I'm gonna get there as well.
Cheers
Allright here is an idea I have..
In order to have better tracking we filter out frequencies above ~2200Hz which also removes the harmonics for frequencies above 1100Hz.
If we filter at a lower frequency we affect the playable range of the circuit as we will be cutting frequencies of playable notes. (1100 Hz ~C# 6th oct. 21st fret on high e string)
The tracking problems mostly occur in the low frequency range. Say low E to low A which is 80 - 110 Hz. tracking above that seems pretty stable. Now what if we also apply a not so deep notch filter at the 1st harmonic of the center of the problem frequencies. In this case at 190 Hz (=2x 95 Hz). Will this give us better tracking? or will it become problematic around the notch frequency?
Also are higher order harmonics going to be a problem? ( I assume that the first order harmonic usually has the largest amplitude)
In that case we can add another notch filter at 380 Hz.
Does anyone see any errors in my assumptions?
Quote from: bluesdevil on October 01, 2009, 01:29:47 AM
Quote from: gigimarga on September 30, 2009, 04:28:22 PM
My Synthbox it's still dead, but I hope I will have some time next week to try to tweak it :)
Might be a good idea to ask the the designer of the pcb (Naz Nomad) if it's verified and working. I was REALLY anxious to get one built when the artwork was posted, but got too distracted with other projects to build it myself.
Regardless,this one looks best to tweak on the breadboard before committing to pcb/vero it seems.
Not verified but
gigimarga built it using different trannies and had problems ... I haven't tried it myself.
Very good news: after 2-3 hours of debugging I found the best solder joint that I ever made (exasperated, I've begun to measure the voltages and I saw that the emitter and the base of one of the transistors of the oscillator are at 0V...after 15 minutes I found the solder joint)!!!
So, now it's working fabulous!!!
Instead of 2N5089 I used BC549C that had the gain over 600 and instead of MPSA18 I used two BC549C with gains around 700.
Thx a lot liquids for the schematic and Naz Nomad for the PCB!!!
I have only two observations to make:
1. it's not very clear that lug 1 of the Shape pot is not connected
2. the 10nF cap from the Bass switch seems too low: the sound is thin and lifeless...I will try higher values instead
THX A LOT ALL OF YOU AGAIN!
Good news!
I hope you like it. Ho wis the tracking with those transistors?
Quote from: ~arph on October 02, 2009, 06:30:00 AM
Good news!
I hope you like it. Ho wis the tracking with those transistors?
Seems to be good to very good, but I must to tweak the trimpot more.
Sweeet ... glad you got it sorted.
I always try to quadruple-check my layouts but you can never be reeeealllly sure until someone builds a working version. ;D
... just need someone to cobble together a parts list and we got ourselves a project. 8)
Quote from: gigimarga on October 02, 2009, 05:51:05 AM
Very good news: after 2-3 hours of debugging I found the best solder joint that I ever made (exasperated, I've begun to measure the voltages and I saw that the emitter and the base of one of the transistors of the oscillator are at 0V...after 15 minutes I found the solder joint)!!!
So, now it's working fabulous!!!
Instead of 2N5089 I used BC549C that had the gain over 600 and instead of MPSA18 I used two BC549C with gains around 700.
This
is fantastic news. And congrats for completing what is...well, seeming to be a difficult build for some. :) Your report is great in that it's excellent for others to know that a variety of transistors will indeed work just fine--so long as the gains are not low and inconsistent, as I've hopefully made clear in the past. And that tracking can be considered 'good.'
Quote from: gigimarga on October 02, 2009, 05:51:05 AM
I have only two observations to make:
1. it's not very clear that lug 1 of the Shape pot is not connected
2. the 10nF cap from the Bass switch seems too low: the sound is thin and lifeless...I will try higher values instead
I truly appreciate your input and observations.
Re: 1) I looked back, and looking at the schem, I agree about your observation. I wonder if this has confused others. I will change the schematic so the shape pot looks more like the 'tracking' pot. Even better would be someone who is good with schematic drawing programs to re-draw it to make it clearer! Please? Anyone? ;D
Re: 2) Interesting assessment. Are you certain you used .01uF/103 and not 102 (.001uF)?
The 10n should definitely sound tighter, not thin by any means, but it may depend on your amp. I do have a pretty bass-heavy amp, so to those who don't, a 22nF might be a better option, if one is needed at all.
But if you'd double check your values and let me know what amp (and speaker config) you are using, I'd appreciate it. If this is a common complaint, I'll mod the schematic again for others to have a better starting point.
The 1uF sounds good on it's own and has no calculated roll off (1.6hz), but could easily be subbed for 100n probably, even, without audible change (16hz). Now, I thought I tried the 10n and liked it...and the R-C calculator I used estimates the the roll off point for the 10nf and the 100k should be about 159hz...but my memory of all this is getting dim.
The switch is because I felt an option for something with a little trimming of the bass would be good 'in the mix' live or otherwise, but the cap value should be 'to taste.' If indeed 10nF is too think, 22nF should do. If not, than maybe just eliminate the switch completely, as, on paper the differences shouldn't be that significant audible between 47n and 100n...which is why I want to confirm you are using 10n/103.
Anyhow, enjoy experimenting! Now that you have it working, mod away ;D Last note - many people have commented on finding the tracking pot subtle, or having no audible effect. This is, to me, in some ways a good thing (a compliment to the EHX-based filter), as it means that the other stages probably do well enough on their own that the minor tweak of high frequencies at the input is a minimal tweak...but if you find it to make a difference in tracking, especially with a bridge pickup, please let me know.
Quote from: liquids on October 02, 2009, 09:20:26 AM
Re: 1) I looked back, and looking at the schem, I agree about your observation. I wonder if this has confused others. I will change the schematic so the shape pot looks more like the 'tracking' pot. Even better would be someone who is good with schematic drawing programs to re-draw it to make it clearer! Please? Anyone? ;D
When I've finished it I wired the lug 1 to the ground :D...but it was easy to find the mistake because it had acted like a second volume pot :)
Quote from: liquids on October 02, 2009, 09:20:26 AM
Re: 2) Interesting assessment. Are you certain you used .01uF/103 and not 102 (.001uF)?
I am very sure that it's a 10nF because it's very easy: I use only some MKT yellow capacitors on which is written very clear his value :)
I forgot to mention that it's a big volume drop when I switch to 10nF...I think I must to test the switch, too.
Quote from: liquids on October 02, 2009, 09:20:26 AM
But if you'd double check your values and let me know what amp (and speaker config) you are using, I'd appreciate it. If this is a common complaint, I'll mod the schematic again for others to have a better starting point.
My amp it's a 20W full-tube romanian old amp which (with a no-name speaker) was modified by a friend of mine to be more fenderish (he modified the tonestack adding a mid pot and a bright switch). It has only one clean channel, but I am very happy with it. I play only at home, for fun, so it's enough. Anyway, it has enough bass :)
Quote from: liquids on October 02, 2009, 09:20:26 AM
Anyhow, enjoy experimenting! Now that you have it working, mod away ;D Last note - many people have commented on finding the tracking pot subtle, or having no audible effect. This is, to me, in some ways a good thing (a compliment to the EHX-based filter), as it means that the other stages probably do well enough on their own that the minor tweak of high frequencies at the input is a minimal tweak...but if you find it to make a difference in tracking, especially with a bridge pickup, please let me know.
Yes, the tracking pot has no audible effect because it tweak the tracking. I have no time to tweak it seriously, but when I rotated it, I heard a better tracking (but not perfect, yet).
Thx a lot!
Quote from: gigimarga on October 02, 2009, 10:54:53 AM
I am very sure that it's a 10nF because it's very easy: I use only some MKT yellow capacitors on which is written very clear his value :)
I forgot to mention that it's a big volume drop when I switch to 10nF...I think I must to test the switch, too.
Fair enough. You will loose 'volume' with a bass roll off of any kind, so that is not unusual, the switch is probably fine.
One thing that you or others might want to do is get to know the R-C cutoff and frequency of what you experiment with: http://www.muzique.com/schem/filter.htm (http://www.muzique.com/schem/filter.htm)
There's lots of possibilities. Those caps work in conjunction with the 100k resistor for high pass filtering. The 100k may be too small to some anyhow, so I'm considering increasing it on the schematic once I get back to it (someday I will hopefully soon... :-\), in conjunction with tweaking cap values, especially since 1uF caps are typically electrolytic or physically large, so using a 100n might be a better option.
You can see that making the 100k resistor ~200k will do the same thing as swapping the 10nf with a 22nF cap. The side affect would be that the 1uF would likewise be the equivalent of modding it to a 2uF. So off the top of my head, leaving the 10n in there, but making the 100k to 220k, and 1uF to 100n might be a better starting point. Then you can mod the resistor (increase) the value for your preferred frequency response rather than mod the caps. So long as you only make the resistor larger than the current 100k (for more bass) the 100n cap side of the switch will keep it's humongous bass response and have the same response into the sub-audio range.
At least, I think that's how it works... :)
I have almost no theoretically knowledges in electronics, but I am curious if it possible to obtain something like an octave up from Synthbox (or Shocktave)?
More clearly, it's possible to change the caps in the oscillator to do what I want?
Read the full thread...this has been discussed. :)
Quote from: liquids on October 04, 2009, 04:48:14 PM
Read the full thread...this has been discussed. :)
OK...thx!
I've read all the thread, but I didn't found the answer...:(
Quote from: gigimarga on October 05, 2009, 11:19:06 AM
I've read all the thread, but I didn't found the answer...:(
PM'ed.
Thx a lot liquids!
I've read all that you send to me and I understood that's not possible to change only the caps from the oscillator to obtain an octave up.
Anyway, it's a very good soundinf effect....thx again for it!
News: I've finally updated my version of the the schematic per gigimarga's suggestions. Still no vero layout for it. Maybe someday. :)
I've learned a bit even since I first worked on this project. I've finally gotten to reading up and experimenting with the basics of op amps (basics only). Now I understanding that the Microsynths early filtering is active and the advantages of that etc, which is what finally brought me back to working with this project. I still haven't built one myself other than whats been on the breadboard! :o Anyhow, duplicating and tweaking around the microsynths ACTIVE filter more accurately afforded some other little tweaks, which have all yielded a little better tracking.
I'm also toying with the idea using your basic active EQ filtering at the end (likely based on what's on the LM833 datasheet) using a second dual op amp instead of the passive filtering options, and eliminating the BJT buffers for op amps.... It's still a work in progress. And if/when I get that version of the circuit where like it I'll probably post a schematic of that version, too. :)
Quote from: liquids on October 27, 2009, 12:43:40 PM
News: I've finally updated my version of the the schematic per gigimarga's suggestions. Still no vero layout for it. Maybe someday. :)
I've learned a bit even since I first worked on this project. I've finally gotten to reading up and experimenting with the basics of op amps (basics only). Now I understanding that the Microsynths early filtering is active and the advantages of that etc, which is what finally brought me back to working with this project. I still haven't built one myself other than whats been on the breadboard! :o Anyhow, duplicating and tweaking around the microsynths ACTIVE filter more accurately afforded some other little tweaks, which have all yielded a little better tracking.
I'm also toying with the idea using your basic active EQ filtering at the end (likely based on what's on the LM833 datasheet) using a second dual op amp instead of the passive filtering options, and eliminating the BJT buffers for op amps.... It's still a work in progress. And if/when I get that version of the circuit where like it I'll probably post a schematic of that version, too. :)
I'm feeling very honoured to be mentioned here (you're very kindly liquids, because I think that my contribution is almost zero...) and I'm very glad to hear that you will try to improve it (and impatient!).
Best regards!
Hi guys,
I finally found some time to put this on my breadboard :P I've been playing around with it for almost a week now. Here are my observations.
First, I built it exactly like the schem (the version I made a perf layout for). Unfortunately, I was not able to obtain any good sounds mainly because of bad tracking. The octave down could only be heard once in a while. The tracking trim pot did not change anything for me so I removed it. I did use the transistors recommended and tried different 2N5089's for finding the best match possible for the oscillator section. The matching made a difference but not enough to be satisfying.
Also, like gigmarga, I found the switchable 10nf cap at the end sounded very thin, so I left it with a fixed 1uf cap. But that's my taste ;)
Just as I was going to quit on it I decided to try a bit of tweaking :) Here's an interesting tweak I found:
I was able to make it track almost perfectly by changing the biasing at the base of the second transistor (the 680k and 330k voltage divider). This solved it !!
At first I replaced the 2 resistors with a 1M pot and and found where the sweet spot was. There is a range of around 100k in there that is track-able and depending if you want to play very low notes or higher notes, you can set it where it tracks better at those note frequencies. So I replaced the 1M pot with a 100k pot in between resistors in order to map the usable bias range to the full range of the pot. It looks like this:
(http://www.polygraphx.com/bias.png)
The resistor values look strange but that's what it took to properly spread the usable bias range on the 100k pot. What is really cool is that you can obtain different sound textures when turning that pot.
Also, I found that it tracks better when using more than 9V. I used a 9v wall wart outputing around 14v and it sounded better than when I used a 9v battery...
Anyways, I thought I might share my experience and give hope to those having tracking problems with this cool effect. :)
cheers
Cool, will try this too.. I'll start with wiring up a voltage doubler 8)
Isildur - your mods are interesting and make a lot of sense in some way. Thanks for your input! You're right that the base biasing of that BJT stage is critical to the tracking, gating, etc. It works heavily in conjunction with the collector and emitter biasing, keep in mind. While I like the 680k/330k (2:1), which is in the range of what you are doing, for us tweakers who don't mind trimpots even on sizable builds(!), why not? But it could be improved....
However, I've breadboarded my schematic quite a few times over, and had none of the issues mentioned. The octave down not sounding sounds like an issue in the oscillator section, though it could be the gain section, as your fix would indicate. Still, check your connections and values. You shouldn't have that issue even slightly, matched parts or not so long as you have the same parts and values, so keep with it....the trimpot may help and even improve things, but it shouldn't be 'needed' to fix the issues you mentioned.
I also find the 680k/330k to have had the best tracking after lots of resistor swaps, (or 820k/390k or 560k/270k much the same) though your trimpot is a nice addition to get it perfect by ear. The original ratio is (by ratio) within the trimpots range. However, you may want to 'double all your values' if nothing else. That is, the input impedance of that stage is affected by these values. With the schematic it is already low (lets say it's 200k now). With a 73k (?) resistor, the impedance is probably ~50k, which means you are probably losing a fair amount of signal at that end of the trimpot...combined withh the 20-30k of resistance feeding it = no good.
Maybe make your 74k resistor ~330k again, and do the rest of the math from there...something like 1M, 330k, and 500k trimpot, or 470k/220k and 250k at lowest. Worry less about the extremes end of the trimpot range functioning exactly correctly...it's all about compromise. :) At that point, maybe a pot is even merrited on your build...try and see. Just some thought.
Along with that, I tried it with higher voltages myself. I didn't notice any significant difference - in fact I noticed it was a bit worse, because the higher voltage makes the BJT stage drive the rest harder.... You need a fair amount of gain to drive the F-V and oscillator, however, too much and it goes wacky. Note that you may have liked the higher voltage either because of a weakened battery by comparison, or because of lack of designed amount of gain, in one or multiple places...as mentioned above.
So the need for the trimpot and prefering higher voltage leads me to believe that your issues may come surrounding the gain stage, if not more... Be sure the emitter bypass cap (47uF) is connected and properly sized (at least 22uF or biffer).
Last but not least, the bass trim. I tried it again and found 10n a subtle change...but my amp is bass heavy...and there may be other factors. I think that was bad design anyhow. A better place for a cap switch would be between the oscillator and last buffer - far more effective. Or none at all...
That being said,if you're up for it, I've found following the circuit with an op amp buffer feeding a Baxandall like this (http://sound.westhost.com/dwopa2.htm#baxandall (http://sound.westhost.com/dwopa2.htm#baxandall)), which would give more interactive control over boosting/cutting both sub bass and treble than passive treble cut controls and a 2 position bass switch. Give it a shot....
All that said, again, thanks for your input! I'll tinker with your ideas in short time I'm sure. :) And more great tweaks coming! Arnoud (~arph) is helping me out....and I found another synthy TRUMPET sound in here...to be continued! ;D
Hi liquids,
Quote from: liquids on October 29, 2009, 10:09:22 AM
I also find the 680k/330k to have had the best tracking after lots of resistor swaps, (or 820k/390k or 560k/270k much the same) though your trimpot is a nice addition to get it perfect by ear. The original ratio is (by ratio) within the trimpots range. However, you may want to 'double all your values' if nothing else. That is, the input impedance of that stage is affected by these values. With the schematic it is already low (lets say it's 200k now). With a 73k (?) resistor, the impedance is probably ~50k, which means you are probably losing a fair amount of signal at that end of the trimpot...combined withh the 20-30k of resistance feeding it = no good.
Maybe make your 74k resistor ~330k again, and do the rest of the math from there...something like 1M, 330k, and 500k trimpot, or 470k/220k and 250k at lowest. Worry less about the extremes end of the trimpot range functioning exactly correctly...it's all about compromise. :) At that point, maybe a pot is even merrited on your build...try and see. Just some thought.
In fact I am using a real pot, not a trim pot. I like to be able to play with that pot because it lets me choose different sound textures and adjust tracking depending on the pickups I am using. I have tried at first with a 1M pot, then with a 500K pot with resistors, then with a 100k pot with different combinations of resistors. To my ears, the best sounds were obtained with the values I mentioned in the previous post. It may be lowering the input impedance, I don't know but it just tracked better like that. :) I was able to get very long sustain on the low E when adjusting this pot to the sweet spot ;D
Quote from: liquids on October 29, 2009, 10:09:22 AM
Along with that, I tried it with higher voltages myself. I didn't notice any significant difference - in fact I noticed it was a bit worse, because the higher voltage makes the BJT stage drive the rest harder.... You need a fair amount of gain to drive the F-V and oscillator, however, too much and it goes wacky. Note that you may have liked the higher voltage either because of a weakened battery by comparison, or because of lack of designed amount of gain, in one or multiple places...as mentioned above.
When using different voltages, the bias pot really comes in handy. I had to adjust the pot depending on the input voltage. For me, that's another reason to keep it as a pot instead of a fixed v divider.
Quote from: liquids on October 29, 2009, 10:09:22 AM
So the need for the trimpot and prefering higher voltage leads me to believe that your issues may come surrounding the gain stage, if not more... Be sure the emitter bypass cap (47uF) is connected and properly sized (at least 22uF or biffer).
I had this set up correctly :)
Quote from: liquids on October 29, 2009, 10:09:22 AM
That being said,if you're up for it, I've found following the circuit with an op amp buffer feeding a Baxandall like this (http://sound.westhost.com/dwopa2.htm#baxandall (http://sound.westhost.com/dwopa2.htm#baxandall)), which would give more interactive control over boosting/cutting both sub bass and treble than passive treble cut controls and a 2 position bass switch. Give it a shot....
All that said, again, thanks for your input! I'll tinker with your ideas in short time I'm sure. :) And more great tweaks coming! Arnoud (~arph) is helping me out....and I found another synthy TRUMPET sound in here...to be continued! ;D
I plan on keeping the synthbox on my breadboard for a little while. I will try to post some sound samples so we can compare with real results. It will give you an idea of the sound differences when adjusting the bias pot (which I now call the tracking pot) :)
I can't wait to hear your trumpet sound!
I will keep in touch!
cheers
I'm waiting for the trumpet...COOOOOOOOOOOOL!!!
it sounds like a sax allready.
LOL
Sound samples please!!! ;D
I was able to get a somewhat trumpet-like sound by putting a 4.7n cap across the base and the emitter of the third transistor (where the diode is (leaving the diode there)). Again it could be adjusted just right with the bias pot I talked about.
I also tried it before my superfuzz and man, massively heavy sounds! :icon_biggrin:
This thing is quite a different animal in comparison to all of the other octave-type effects I've heard/owned/built. And it's pretty simple too! Definitely going to build this one... Possibly tonight.
Okay, here's the schematic for the op amp version. http://sites.google.com/site/liquidselectronics/synthbox-2 (http://sites.google.com/site/liquidselectronics/synthbox-2)
It adds an active EQ and some tweaks for filtering, in addition to some new sounds via the "attack" pot. The attack pot offers the more 'trumpet like' sounds, but don't take this too literally...with the sound clips of the synthbox as its base sound, the above schematic can get more 'trumpet like' in terms of the attack of the note. It does offer a cool variation on the tonality of the original sound in my opinion, with subtle shades of blending between the two in between with the added attack pot...the 100nF is crucial, for whatever reason this will not happen with the stock 'shocktave' schematics 1uF cap in there.
I'm hopefully done tweaking it! Other people may tweak it to their liking. I tried biasing the base of the first BJT per isildur's concept, and twisted the pot to hear the range it offered, then set it to the place I liked it best by ear. Then I measured it with a DMM for voltage at the base and the resistance values, only to find it exactly where the 330k/680k resistors bias it. :) I also didn't find it that useful, so I'm leaving the biasing as is since I find it optimal.
Note that if you breadboard this up, you can actually get even more interesting sounds, like a 'pure' trumpet-type sound...though bare in mind, it's more like a cheap guitar synth trying to 'imitate' a trumpet sound...but very cool nonetheless. I found it a bit too much of a novelty and too much trouble to merrit all the controls necessary to add it to the design, and some of tim escobedo's circuit snippets could probably be tweaked similarly.... For those who like that sound may find it merits a completely separate build with filtering designed around that sound. If you breadboard it and are interested in hearing it, try this: starting with the above version (you'd have to tweak values a bit if you start with the original version), break the connection between 9V and the collector of the transistor that is fed by the new 'attack' pot/10k. This would leave the collector of that transistor with only the 100nF cap connected to ground. This will now make the tone 'sweet and smooth,' and remove all agressiveness from the sound. But it will be very dark and muffled. You will then want to remove, or greatly reduce the 68n capacitor that comes after 'B' and the 10k resistor to something like 2.2n.
Tracking is a non issue when you break that 9v connection as mentioned above, so the 68n is not needed, though it's pretty key to good tracking with the stock synthbox sounds along the range of the attack pot. Likewise, some of the other filtering stages may beg tweaking for the best sounds when you break that connection, even after removing the 68n cap.
Eventually I'll get someone to do a PCB of the op amp version for me and build it--I don't know that I have the patience or room to work out a vero for this one! And if you want sound clips of the new sounds available...well, breadboard it. :) Enjoy!
Hi liquids,
Congrats for the new design! :icon_razz:
It would be nice if you could put some sound samples just so we see how different it sounds from the first version.
As for the biasing question, the thing is that your fixed setup may be good for the voltage and guitar pickups you have but someone else with another guitar, different setup etc it will not necessarily have it tracked perfectly like you. It's only my opinion but I think that having the possibility to adjust that is a plus :) And I don't know if you experienced the same thing but I find there are more than one sweet spots offering different sounds and better tracking for playing higher or lower notes.
I will definitely try your "attack" pot with the version I have on the breadboard.
cheers
Finally 'finished' the vero layout for the 'first' All BJT version. I simplified it via removing the tracking pot so that it would all fit on 15x30 piece of vero. I also updated some of the component values.
If you search for synthbox in the layout gallery, you'll find both the vero and the schematic that more closely matches it. I needs some other eyes to look at it before anyone should build it, since it may have errors....I can only look at it so much.
Since it is unverified, and rather than load it as a huge image, and since there are so many cuts and so many components, I just loaded it as a working file to be downloaded and opened in DIYlc. This way, you can save it yourself, and also 'remove' all the components just to see the board and cuts, invert the image how you like, and drill properly, since there are so many cuts under components.
I like to cut almost everywhere that traces aren't needed. It takes more time, but I find it easier in the long run...since there are more places to drill than not, I just need to know the where NOT to drill rather than count off the trace breaks. Then, when I'm inserting components or soldering, I'm less likely to make an error with most component's placement or bridge a trace....however, you can remove all but the essential trace breaks if you like, after you download the file. Since I imagine there will be many, PM me if you have questions about the layout, corrects, etc, and I'll fix anything that needs clarification or correction. Good luck!
Anyone else try the circuit, successfully or unsuccessfully with single coils? My experience, testing, etc for this is mostly (if not completely) limited to humbuckers. I've been working with isildur, and I'm now wondering if some of the different results and complications we've had are due to pickup differences. Any experience and feedback about that (via PM, ideally) would be appreciated.
if so, and it's simply a matter of a way to boost the signal, a simple gain control (as a mod to the input buffer, or in addition to it) could probably be implemented. I may experiment with that one myself, as a matter of fact...
Hi,
Yes I did put it on breadboard, also without the tone section, but with an opamp buffer at the end.
I had far worse tracking on the opamp version over the original transistor version. I am using the same guitar, high output single coils (lindy fralin vintage hot's). Tracking seems to be the best at a certain input level, not too loud ,and not too soft. This leads me to the conclusion that to make this thing really good we have to ensure a constant input for the f-v section. I am currently experimenting with a NE571 in front. Still looking where to place this, before or after filtering the signal.
Also I found that the filtering after the 5089 right before the F-V converter has no noticable effect on the tracking (I both versions of the synthbox)
Still playing around with this.
I'll report back.
I've got the circuit working but I've only tried it with single coils. I have a guitar with a humbucker as well so as soon as I get a chance I'll try that as well.
So far the circuit sounds pretty close to "correct" but I don't always get the octave down. I am going to try some of the suggestions in this thread WRT that problem but I haven't had time to get back to it yet. Based on what others are saying maybe I'll try to get it working with the humbucker-equipped guitar first and then move back to the single coils...
Sorry to continue an older thread, but I'm having some issues with my build. I followed the perfboard layout by isildur, and I am getting ticking from the oscillator. The gate doesn't seem to be working properly. I used 2n5088s where the 2n5089s were listed in the schematic, and MPSa18s where they were supposed to be. Any thoughts on this one?
No problem reviving this...it's still a 'work in progress.' I may even have a 3rd version which is mostly op amp, and more user friendly in the near future.
Ticking? There is no LFO so I'm not sure I understand you....do you mean, when you aren't playing it is still 'making a note?' If so, that should be fairly easy to resolve.
Following the layout, Check your traces for any stray solder connections especially around Q3. Get your voltages on Q3. Either the base or the emitter - I can't recall which right now, but one of them should mostly be variable as you play a note. The 'no note playing' voltage should be below .6 volts, which is a key part of the 'gating' and 'decay.' Examine this area carefully, I suspect that is where the problem is. Audio probe carefully here as well...it may give you clues.
Also, the electrolytic cap that feeds that stage, right before the diode and Q3...you may want to reverse it.....and if you get it working, try replacing the 1uF and 47k pair with .1uF and 10k, you may like it better (maybe not!)
Good luck, let us know what you find.
Quote from: thedefog on December 19, 2009, 11:41:41 PM
...
I used 2n5088s where the 2n5089s were listed in the schematic, and MPSa18s where they were supposed to be.
I've built it using BC549C and it works like charm, so I don't think that transistors are the cause of the problem.
Anyway, if I'm remebering right, 2N5089 is the same as 2N5088, but with lower noise.
Build Confirmed. Tracks great, sounds great. Mine seems to sound a little more octave like than synth like. PLease listen and tell me what you think. The only thing I changed was to use a BC239 (Hfe=500) for the last buffer and I replaced 1N4148 with a 1N4517 which did improve tracking. Blows away the shocktave and is better than Rocktave.
http://www.aronnelson.com/DIYFiles/up/synth_box.mp3 (http://www.aronnelson.com/DIYFiles/up/synth_box.mp3)
Quote from: igor12 on December 20, 2009, 06:02:34 PM
Build Confirmed. Tracks great, sounds great. Mine seems to sound a little more octave like than synth like. PLease listen and tell me what you think. The only thing I changed was to use a BC239 (Hfe=500) for the last buffer and I replaced 1N4148 with a 1N4517 which did improve tracking. Blows away the shocktave and is better than Rocktave
Cool sound clip! :)
Quote from: igor12 on December 20, 2009, 06:02:34 PM
Build Confirmed. Tracks great, sounds great. Mine seems to sound a little more octave like than synth like. PLease listen and tell me what you think. The only thing I changed was to use a BC239 (Hfe=500) for the last buffer and I replaced 1N4148 with a 1N4517 which did improve tracking. Blows away the shocktave and is better than Rocktave.
http://www.aronnelson.com/DIYFiles/up/synth_box.mp3 (http://www.aronnelson.com/DIYFiles/up/synth_box.mp3)
That definitely sounds more synthy than octave-y to me!
Like a blue box on steroids.
Quote from: igor12 on December 20, 2009, 06:02:34 PM
I replaced 1N4148 with a 1N4517 which did improve tracking.
1N4517 returned no results on mouser. Do you mean 1N5817?
Quote from: liquids on December 20, 2009, 07:36:47 AM
No problem reviving this...it's still a 'work in progress.' I may even have a 3rd version which is mostly op amp, and more user friendly in the near future.
Ticking? There is no LFO so I'm not sure I understand you....do you mean, when you aren't playing it is still 'making a note?' If so, that should be fairly easy to resolve.
Following the layout, Check your traces for any stray solder connections especially around Q3. Get your voltages on Q3. Either the base or the emitter - I can't recall which right now, but one of them should mostly be variable as you play a note. The 'no note playing' voltage should be below .6 volts, which is a key part of the 'gating' and 'decay.' Examine this area carefully, I suspect that is where the problem is. Audio probe carefully here as well...it may give you clues.
Also, the electrolytic cap that feeds that stage, right before the diode and Q3...you may want to reverse it.....and if you get it working, try replacing the 1uF and 47k pair with .1uF and 10k, you may like it better (maybe not!)
Good luck, let us know what you find.
Hey Liquids,
Thanks for the help. I'm going to try that out now. I have no clue why I said LFO. What I meant was that the oscillation kept going when not playing. I was a little drunk when I wrote that last night, so that explains that. ;D
I meant 1N457, sorry.
Quote from: thedefog on December 20, 2009, 09:32:24 PM
Quote from: liquids on December 20, 2009, 07:36:47 AM
No problem reviving this...it's still a 'work in progress.' I may even have a 3rd version which is mostly op amp, and more user friendly in the near future.
Ticking? There is no LFO so I'm not sure I understand you....do you mean, when you aren't playing it is still 'making a note?' If so, that should be fairly easy to resolve.
Following the layout, Check your traces for any stray solder connections especially around Q3. Get your voltages on Q3. Either the base or the emitter - I can't recall which right now, but one of them should mostly be variable as you play a note. The 'no note playing' voltage should be below .6 volts, which is a key part of the 'gating' and 'decay.' Examine this area carefully, I suspect that is where the problem is. Audio probe carefully here as well...it may give you clues.
Also, the electrolytic cap that feeds that stage, right before the diode and Q3...you may want to reverse it.....and if you get it working, try replacing the 1uF and 47k pair with .1uF and 10k, you may like it better (maybe not!)
Good luck, let us know what you find.
Hey Liquids,
Thanks for the help. I'm going to try that out now. I have no clue why I said LFO. What I meant was that the oscillation kept going when not playing. I was a little drunk when I wrote that last night, so that explains that. ;D
I reversed the cap as you suggested, but it unfortunately made no difference. When it is powered on, even with nothing connected to the input, it sounds like a race car in pole position (which isn't a terrible thing, but not what I hoped for).
I guess I could try a different transistor for Q3. I have more MPSa18s laying around. I used alligator clips to probe at it, and before Q3 it just sounds like a fuzzy distortion, but the base and collector on Q3 has that race car sound coming off of it. Audio probe on the stages after that point still have it as well, just filtered differently and boosted. I checked all my components and soldering work, and I see no bridging or anything. The only thing I can think of is that I have the wrong resistor value somewhere in there. Voltages were variable on the base of Q3 when I checked that when I played notes (If I remember correctly, higher voltages around 6.8v when playing and drooping back down to like 4v when not).
Quote from: thedefog on December 20, 2009, 10:41:27 PM
I reversed the cap as you suggested, but it unfortunately made no difference. When it is powered on, even with nothing connected to the input, it sounds like a race car in pole position (which isn't a terrible thing, but not what I hoped for).
I guess I could try a different transistor for Q3. I have more MPSa18s laying around. I used alligator clips to probe at it, and before Q3 it just sounds like a fuzzy distortion, but the base and collector on Q3 has that race car sound coming off of it. Audio probe on the stages after that point still have it as well, just filtered differently and boosted. I checked all my components and soldering work, and I see no bridging or anything. The only thing I can think of is that I have the wrong resistor value somewhere in there. Voltages were variable on the base of Q3 when I checked that when I played notes (If I remember correctly, higher voltages around 6.8v when playing and drooping back down to like 4v when not).
Yeah, it's all right there. You got it, even though you didn't 'get it'. I just tested mine, and when rigged off a 9v (one spot = 9.4v) supply, the emitter/base hover around .2v, and when I play a note it gets up to about 2.5v. Q4 and Q5 also seem variable voltage with note played (?) but stay pretty low, from a quick look - below a volt even?
That transistor stage crates a voltage which acts in one way or another like a gate, in response to the 'note signal' of which the oscillator responds to. Any voltage above the diode drop (.6v) = the gate is open. Likewise, I don't totally understand it, but if there is enough voltage, it somehow triggers the oscillator to create a frequency - how or what frequency is determined, I don't know, but that little bit I know. Hey, I'm still just an amateur hack, as I've said many times. ;D
Following the layout you said you are using: first off, make sure there is no voltage on those 1K resistors. everything should be very close to ground between the 2.2uF capacitor off of Q2 and to the 'inside' of the following 2.2uF capacitor. This ensures that the Q3 is not being fed any DC from the previous stage.
At that point, make sure Q3 is what it says it is, and that it's oriented properly. Again, you should be at or below .6v , where you reading 4v (the emitter), to keep the oscillator from ringing. Check this whole area around and after that very closely with your DMM and find out where the voltage is coming in. Since nothing outside of the collector of Q3 (which should read about the voltage of the power supply) has much voltage on it, you should be able to track down where the 'stray voltage' is coming into play around Q3 or afterward pretty clearly....you may even be 'backfeeding' from Q6 if there is a bad cap somewhere...
Hope this helps!
I believe 89 is higer gain too.. EDIT: ??? where did the post go that I replied this too??
I've had some oscillations too during the experimentation phase. This is the flipflop arrrangement oscillating. This means it is getting the wrong voltage from the frequency to voltage converter.
OK, I tried with all 3904 and it works fine. Just match the gain in the flip flop section. This opens up the choices if you want to use a transistor-array IC. I also tried setting Vref to 4.5v using 2 15k resistors and that works fine also. Now how can I get second octave? Cascading 2 synth-boxes? I still can't figure out the theory behind the F-V and flip-flop section. But I will.
http://www.diystompboxes.com/analogalchemy/sch/shocktave.html (http://www.diystompboxes.com/analogalchemy/sch/shocktave.html)
"The circuit consists of a high-gain preamp stage, followed by a frequency-to-voltage convertor, which in turn drives an oscillator. The oscillator is tuned so that it can only keep up with every other cycle, resulting in the octave-down effect..."
Quote from: liquids on December 23, 2009, 03:29:19 PM
http://www.diystompboxes.com/analogalchemy/sch/shocktave.html (http://www.diystompboxes.com/analogalchemy/sch/shocktave.html)
"The circuit consists of a high-gain preamp stage, followed by a frequency-to-voltage convertor, which in turn drives an oscillator. The oscillator is tuned so that it can only keep up with every other cycle, resulting in the octave-down effect..."
This part still eludes me.
igor, the sound clips are very cool!
what type of guitar pickups are you using, humbuckers or single coil?
Quote from: earthtonesaudio on December 23, 2009, 03:59:20 PM
Quote from: liquids on December 23, 2009, 03:29:19 PM
http://www.diystompboxes.com/analogalchemy/sch/shocktave.html (http://www.diystompboxes.com/analogalchemy/sch/shocktave.html)
"The circuit consists of a high-gain preamp stage, followed by a frequency-to-voltage convertor, which in turn drives an oscillator. The oscillator is tuned so that it can only keep up with every other cycle, resulting in the octave-down effect..."
This part still eludes me.
If you use your DMM at the base/emitter of the transistor paired with the diode...you see that as you pluck a note, voltage varys...so I'm assuming thats the f-v part. How it works? NO idea...
humbucker, neck pickup. IBANEZ LR110 (ES335 Copy)
Quote from: liquids on December 20, 2009, 11:17:18 PM
Quote from: thedefog on December 20, 2009, 10:41:27 PM
I reversed the cap as you suggested, but it unfortunately made no difference. When it is powered on, even with nothing connected to the input, it sounds like a race car in pole position (which isn't a terrible thing, but not what I hoped for).
I guess I could try a different transistor for Q3. I have more MPSa18s laying around. I used alligator clips to probe at it, and before Q3 it just sounds like a fuzzy distortion, but the base and collector on Q3 has that race car sound coming off of it. Audio probe on the stages after that point still have it as well, just filtered differently and boosted. I checked all my components and soldering work, and I see no bridging or anything. The only thing I can think of is that I have the wrong resistor value somewhere in there. Voltages were variable on the base of Q3 when I checked that when I played notes (If I remember correctly, higher voltages around 6.8v when playing and drooping back down to like 4v when not).
Hey Liquids,
Thanks for your help. I really appreciate it. I'm going to take another look at it tonight.
Yeah, it's all right there. You got it, even though you didn't 'get it'. I just tested mine, and when rigged off a 9v (one spot = 9.4v) supply, the emitter/base hover around .2v, and when I play a note it gets up to about 2.5v. Q4 and Q5 also seem variable voltage with note played (?) but stay pretty low, from a quick look - below a volt even?
That transistor stage crates a voltage which acts in one way or another like a gate, in response to the 'note signal' of which the oscillator responds to. Any voltage above the diode drop (.6v) = the gate is open. Likewise, I don't totally understand it, but if there is enough voltage, it somehow triggers the oscillator to create a frequency - how or what frequency is determined, I don't know, but that little bit I know. Hey, I'm still just an amateur hack, as I've said many times. ;D
Following the layout you said you are using: first off, make sure there is no voltage on those 1K resistors. everything should be very close to ground between the 2.2uF capacitor off of Q2 and to the 'inside' of the following 2.2uF capacitor. This ensures that the Q3 is not being fed any DC from the previous stage.
At that point, make sure Q3 is what it says it is, and that it's oriented properly. Again, you should be at or below .6v , where you reading 4v (the emitter), to keep the oscillator from ringing. Check this whole area around and after that very closely with your DMM and find out where the voltage is coming in. Since nothing outside of the collector of Q3 (which should read about the voltage of the power supply) has much voltage on it, you should be able to track down where the 'stray voltage' is coming into play around Q3 or afterward pretty clearly....you may even be 'backfeeding' from Q6 if there is a bad cap somewhere...
Hope this helps!
I did a major overhaul to the op amp version that I've been working on again recently I wanted something that might offer a little more consistency and flexibility in terms of input signals and other users, and more so, more ideal filtering for myself.
The links for the 'op amp' or synthbox 2 will show this new schematic, the original version which used all transistors, so to speak, is still up since there are projects that people occasionally seem to be building and working on with the original version.
http://sites.google.com/site/liquidselectronics/synthbox-2 (http://sites.google.com/site/liquidselectronics/synthbox-2)
While the output sound is nearly identical with this version, I think this one is by far the best one to build for anyone interested. The op amps offer consistency in impedance, gain, and filtering, while the active filter at the end offers some cool tonal flexibility.
I didn't originally work on this design with filters in mind, so it stands alone, but I've been expirimenting with using it with envelope filters. I do plan on integrating it/housing it with other builds, in particular an envelope filter that will probably be a modified version of the MFOS EF. With the synthboxes active treble boost filtering in particular, when it is combined with an EF, it gets some of the best synthy filter sounds I've heard yet, and gets a sound that rivals my favorite setting of my my Microsynth! Cheers!
Hey that's cool!
I need some clarifications. What are the mosfets models used (Q1, Q2)?
What voltage is it run on, +- 9V ?
Are the "grey" grounds the negative voltage or they are the ground?
There seems to be only one V- connection (in blue). You should show where V- is to be connected elsewhere too, if any.
thanks
Quote from: isildur100 on January 09, 2010, 03:07:04 PM
I need some clarifications. What are the mosfets models used (Q1, Q2)?
Use whatever mosfet you like, but follow the datasheet and this site: http://www.muzique.com/lab/zenmos.htm (http://www.muzique.com/lab/zenmos.htm)
Both BS170 and 2N7000 have worked for me. Zeners and LEDS can work too...tweak away. The schematic is a bit open ended in some places on purpose....
Quote from: isildur100 on January 09, 2010, 03:07:04 PM
What voltage is it run on, +- 9V ?
Any bipolar supply from any charge pump should work about the same for this circuit, but I've currently used something close to +/- 9v from a one spot PS and a LT1054 charge pump, currently. V+ and V- can be whatever pubolar supply you like outside of the the limitations of the parts you use, most likely.
Quote from: isildur100 on January 09, 2010, 03:07:04 PM
Are the "grey" grounds the negative voltage or they are the ground?
The ground connects are ground, and ground is typically identified with something like this symbol (http://people.sinclair.edu/nickreeder/EET114/PageArt/symbolGround.gif) Power is listed as generated of a bipolar supply (which can be gotten via a charge pump or otherwise).
Quote from: isildur100 on January 09, 2010, 03:07:04 PM
There seems to be only one V- connection (in blue). You should show where V- is to be connected elsewhere too, if any.
The only other thing that connects to the rails of the bipolar power that isn't shown, are the op amps. I'm under the impression, from some recent reading, that typically that power connections for op amps are not included on most schematics, especially with a bipolar supply? I'm going to leave that as is. The only thing outside of the op amps connected to power is liste -- the red arrow is shown as connecting to V+ and the blue arrow as connected to V-. Again, it is left a bit open ended on purpose.
Ok that's what I figured but just wanted to make sure, thanks!
SOUND CLIPS PLEASE!!!
Ok, I will give this a go as far as designing a PCB for it.
Let me try to fit it in a 1590B ;D
Question, what is the value of the resistor coming of the positive input to ground on the last opamp stage (ic 1b)?
My guess is 1M-3.3M, but I thought I'd better verify.
Quote from: ~arph on January 12, 2010, 03:53:59 AM
Question, what is the value of the resistor coming of the positive input to ground on the last opamp stage (ic 1b)?
My guess is 1M-3.3M, but I thought I'd better verify.
I'm not in front of the breadboard, but if I recall, right now I have it connected right to ground with no resistor. I'm pretty sure that, since it's off a bipolar supply, it doesn't matter. ...?
I don't have my op amp book in front of me, but the last thing I
think I read, said that the value in these situations is generally negligible, something small will do. But hopefully someone more savvy can chime in.
And, why is that particular op amp stage labeled 1b? :D Yes, the schematic is not only bare bones, it
is a bit rough. I do things as time permits. :)
Any luck breadboarding it?
Ah yes, I was just tracing the circuit into eagle without paying a lot of attention. It seems it is a normal non inverting stage so a straight ground connection seems like the right thing as we're on a dual power supply.
Haven't breadboarded it, but I can't spot any mistakes after completely redrawing this into eagle. I think I might be taking the bold route and build this from PCB directly.. It's about time I made one for real.
This looks rather interesting and I'm adding the necessary parts in my current Mouser order to have a go with this!
But I was wondering: is it possible to feed various types of oscillators? I like doing synthy sounds (I play in a rock cover band, but we do some dance and techno songs for fun) and I'd like to be able to do sawtooth waves as well, perhaps square waves too. I don't care if the pedal has to be huge.
And mostly I'd like to add a high-resonance variable low-pass filter controlled with a wah-type pedal (I love that effect).
I'm not looking for someone to feed me a nice schematic, but rather maybe brainstorm with me on how to implement this kind of stuff, or perhaps point me to a DIY resource that deals with analog synth filters and oscillators?
And mostly, I still have trouble wrapping my head around this one, but from what I understand, what comes out at the output of the pedal is really an oscillator that is pitch-controlled by the input signal. Is that correct?
If that is correct, am I correct in thinking I can feed various types of oscillators? (Octave effect not always required, but appreciated)
Or perhaps just run the signal through an extra circuit node that would reshape it? I can build a tube amp no problem, but I have no idea how analog synths work!
Thanks
Yannick
Help!!!!!
I've just finished building this on Perfboard using the layout by isildur100. When switched on all I get is a sort of pulsating sound. Kind of machine gun sound. The bypassed signal is fine, the volume pot works fine and controls the level of machine gun, the bass switch also thins or thickens the sound so thats working. The shape pot does seem to make it a bit thinner and hissier.
This is only the 6th pedal I've built and so far they've all worked first time so I'm new to the de bugging lark.
I'm going to make an audio probe tomorrow but for now I've checked all transistors are correct, the right way round and have I've also tried different transistors.
The voltage on the trannies are as follows
E B C
Q1 5.60 5.69 8.78
Q2 2.06 2.60 4.41
Q3 0.25 0.46 8.74
Q4 0 0.26 0.18
Q5 0 0.43 0.61
Q6 5.59 5.69 8.78
The power supply is a soundlab GO25M and is kicking out 8.78 V
Is there anything obvious to anyone? I'm pretty clueless, I just follow other peoples layouts at the mo!
Thanks for your time guys,
Jimi
Hi,
The best thing to do is to use an audio probe. That way you will see up to where the signal starts to act funny. Basically you should have a very loud signal right after Q2.
Did you match Q4 and Q5? What trannies did you use exactly?
It's not quite so simple to audio probe due to what happens in the circuit as compared to most distortions and fuzzes, but audio probing does help, to a degree. Some of the voltages need to be variable when notes are played, etc. And There's other places in the circuit to compare voltages than just the transistor pins as well. I believe I have posted some info about voltages in this thread a way back.
You should indicate if playing notes has any affect on the 'machine gun' better known as the oscillator triggering- or at least that is what I call it.... Anyhow, it sounds like playing doesn't 'override' the machine gun, which is one problem if so.
Here's some quick help: Audio probe at the capacitor before the diode/Q3, around where the 22n caps go to ground. It should sound like a semi-muffled, distorted fuzz type tone without too much gating if any. If that is all good, than you are good up to there (at least for this issue). If not, stop right there and audio probe where the signal dies from the input to this point. Up to Q3 it's just a filtered fuzz.
As for the cause of the machine gun sound, my though is you have a problem around Q3, possibly Q4/Q5. Something is causing stray voltage in this area that is causing the oscillator to remain open, and respond to the voltage like a note....otherwise your Q3 E and base would be resting above the diode drop....other have suggested using other types of diodes, but if you have a germanium or schottky diode there, use a silicon for now until you get this resolved...I prefer it anyhow. The silicon diode drop/silicon transistor (.6v to turn on or so) helps it gate so that at your said voltages (.25 E .46 B) it reads 'no signal' and gates off. I don't have voltages for Q4/5 but I find it odd that Q5 C is at about .6v....
Also check your values, correct part types, make sure you've got everything correctly oriented, crossed traces, etc. Look it over with a magnifying glass. You'll learn a good amount from the debug. It's usually something small and embarrassing if you had so much success in the past. Good luck.
Quote from: igor12 on January 10, 2010, 11:51:07 AM
SOUND CLIPS PLEASE!!!
With all the building blocks this is a fragile monster that spans 4 breadboards currently, and over 10 pots! But I finally got back to the workbench this week, and got it all working again on the board. I'm tinkering still, and sorry for the delay, but I did record some sloppy clips for you.
Also, my original Synthbox demo was (as noted in that post) recorded with a poor setup involving an awful recording program and a cheap computer mic, put at a distance to avoid distortion. It definitely colored the tonality of the recording a bit....
These samples should be a bit more realistic, as now I've got Audacity, a SM57 in front of the amp with a cable that goes from xlr->1/8", all that into the same cheesy sound card. So I recorded a short snippet of the 'current' Synthbox '2' on the breadboard (but with the active EQ disconnected), and also a few sloppy phrases of the synthbox-->rather modified MFOS envelope filter. But The envelope is generated using a buffered, high passed-filtered version of my clean signal as the 'trigger.' See these dead threads for some of the basics, if you happen to be interested in that part:
http://www.diystompboxes.com/smfforum/index.php?topic=81140.msg671699#msg671699 (http://www.diystompboxes.com/smfforum/index.php?topic=81140.msg671699#msg671699)
http://www.diystompboxes.com/smfforum/index.php?topic=78325.msg671598#msg671598 (http://www.diystompboxes.com/smfforum/index.php?topic=78325.msg671598#msg671598)
So, the new clips are in the gallery. I may eventually remove the old clips...Enjoy!
Brief demo of the Synthbox 2 in the same vein as the original clip: http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+2+Demo.mp3.html (http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+2+Demo.mp3.html)
Some sloppy phrases of synthbox-->down sweep envelope filter: http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+with+Filter.mp3.html (http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+with+Filter.mp3.html)
Nice that sounds really neat!
I still intend to do a PCB layout for the latest version, but time is not on my side.
You could also try to run this into a Snow White autowah (schem at the other forum)
That looks a bit like the MFOS. Just a bit simpler I believe.
I've tried to download the vero layout file a few times, and it always tries to save as an Adobe After Effects file. Is there a straight-up image file (jpg) of that vero?
And has anyone built the vero layout yet?
Thanks!
As far as I am aware there is no vero layout for this?
Can you give me a reply# in this thread where I can find the file you're trying to save?
The Adobe Effect problem is probably a setting on you personal computer. Adobe must heve registered image file extensions to Adobe Effects.
(I currently endure the same problem but then it wants to open in adobe image ready, which su#ks)
Regards,
Arnoud
Thanks for the help guys, it's very much appreciated! I didn't get much time lastnight to do much but I did make some progress!
Firstly I've confirmed the transistors are MPSA18 for 1 and 6 the rest are 2N5089s. Qs 4 and 5 are perfectly matched 2N5089s and they are all oreintated as per the layout with Ll the emitters going to ground.
I've made an audio probe and after finding a dodgy solder joint on Q2 (looked fine but slightly on the lean side) after checking components around it. After I'd resoldered that I am now getting the correct synth sound but the machine gun/oscillation is still present. The pots and bass switch all do as they should.
I carried on probing and it does seem to start at Q2 very quietly where the 2.2 cap meets the collector. Its more of a flutter here than machine gun. This carries on until the diode where it dramatically increases in volume. I replaced the diode with another 1N4148 and it's not cured it. The strong noise starts where the diode meets Q3.
Reading your previous posts it seems that I have a voltage on the 1k resistors after the 2.2 cap that comes off the collector of Q2. You mention these should be close to ground voltage. Mine start around 2.6 and slowly decrease untill you play a note and they hit 2.6 again. I've replaced this cap and it's still the same. The - side of the cap is connected to the resistors and the + to Q2 collector. I've also changed the 2.2 before the diode and the diode itself.
Any more clues as to what could be causing this?
Must say that I think I'm gonna love this pedal, sounds great (from what I can hear!) and also tracks well with my 67 SG Special with P90's just a shame it sounds like Im jamming with a machine gun!
Thanks again for your help guys, I'm trying my best to absorb all the info and learn, so hopefully I won't be pestering you too much in the future.
Jimi :icon_idea:
Some of what you are saying seems odd, but it would indicate that the stray voltage is most likely coming into the signal after Q2...it may be that some is 'feeding back' into that area, but not where it starts, since there is no aplification going on between Q2's collector and the diode.
Theoretically, there should be no voltage between the cap coming off Q2 and the cap that connects to Q3/Diode as those caps are there to take DC off that whole section, so that DC stops at the Q2 collector, and likewise does not 'feedback' from the voltages on the diode/Q3. Hence t that whole resistor-capacitor network in between should be very close to ground.
Check and or replace both of those caps if it's reasonable, to ensure they are not faulty. I'd suspect the one closest to Q3 is the cuplrit, of the two. Also, it may help to reverse the orientation of that 'second' cap anyhow since it's presumably electrolytic and polarized. The side that is facing the Q3/diode junction will have some level of varying voltage on it (positive), while the other should not have much or any voltage (negative)....
These are semi-informed shots in the dark, but keep trying, you're getting there, and learning a bit about debugging in the process!
here's the link I was referring to:
http://www.aronnelson.com/gallery/main.php/v/liquids/SynthboxLayout_diy.html
maybe there was a layout there at one time?
EDIT: ah, just had to download the DIY Layout Creator (http://www.softpedia.com/get/Others/Home-Education/DIY-Layout-Creator.shtml) to get the download to work.
Hi,
Well this evening I have replaced 7 Caps and its still doing it! Grrrrr!!!!!!
I've replaced the 2.2 polarised cap before Q2, the 3 polarised caps between Q2 and Q3 and also the 2 non polarised caps between Q2 and Q3. I reversed the 2.2 just before the diode too. I also changed the 1 u polarised cap that goes from the Q3 Collector to ground.
I've also triple checked all joints for solder bridges and have scored between each 'close' joint with a small screwdriver to confirm that they are not touching.
If the DC was bleeding back, how far could it bleed back from?
I'm thinking about just scrapping this and starting again, it'd probably be quicker!....no..... its doing me good to learn about debugging and looking into what is actually happening in the circuit, I'm not really in the right frame of mind tonight though!
Any thoughts guys?
Cheers once more,
Jimi
Has anyone built the op amp version? If so what op amp did you use?
Nothing special needed here. Common Jfet input types should work quite well here if not best--such as TL072, LF353. Standard 4558 type should work well too.
I have the opamp version on my breadboard right now. It works pretty good. I used TL072 for the opamps and a max1044 to obtain +/- 9V.
The tracking seems to be better than with the original version. The only thing is that I had to replace the 100nf cap with a 10uf cap where that transistor and diode section is. Doing that gave a lot more sustain which helped the tracking at the same time.
I also used the tone stack at the end which is not bad at all. However, I had to change a 10k resistor to a 15k value for the treble because with a 10k, when the treble was maxed I had a loud squeal. The 15k got rid of the problem.
Oh, and there is a resistor with no value in the tone stack going from the + input of the opamp to ground. I put a 470k there but I don't know what value should be there optimally.
All in all, I really like this circuit. I will try to make sound clips very soon.
cheers
John
I've breadboarded both incarnations, and while both sound quite cool, to my ears the discrete version sounds noticeably more "synthy" and seems to track better than the opamp version. Anyone else notice this?
Ok here is a soundclip of the opamp version I have on the breadboard.
http://www.upload-mp3.com/files/153980_htl9t/synthbox2soundclip.mp3 (http://www.upload-mp3.com/files/153980_htl9t/synthbox2soundclip.mp3)
I added a bit of stereo reverb to the mix but nothing else. This circuit sounds really good when putting a chorus or flanger after it. It really becomes synthy.
I was playing with my fingers (like a bass player) on a strat, neck pickup noise canceling single coil. That's the way I obtained the best tracking, with the fingers.
Enjoy! :icon_mrgreen:
John
Wow, that sounds pretty sweet...I'll have to poke around my boarded opamp version and see if i messed something up somewhere- sounds more like a fuzz octave...good, but not like yours. Thanks fer the clip!
Hey all-
Not sure if anyone's done a perf layout for the opamp version (Synthbox 2), but for those interested, mine is here:
http://www.aronnelson.com/gallery/main.php/v/jdub/synthbox+2+project.png.html (http://www.aronnelson.com/gallery/main.php/v/jdub/synthbox+2+project.png.html)
Not the best layout, but works well. The trickiest parts were the jumpers (green wires) feeding the -9v to opamps 1&2- they run partially under the IC sockets on the component side of the board. I used a MAX1044 for the bipolar supply (onboard), but didn't find the need for R.G.'s transistor jack switching (but this could be added if desired using a little daughter board). I also included a function for same-octave sound by switching the caps in the oscillator section (.22 to .047)- it's a little glitchy tracking-wise, but sounds pretty cool when normal guitar sound is blended in via the attack pot. The caps are mounted on the switch- I used a footswitch, but a toggle could be used. Also, the .047s could be varied (.01 for example)- these just worked best for me. The only other thing I noticed is that the treble and bass pots tend to crap out a bit at the very extremes, but most of the range works fine. I used TL072s for opamps 1-3 and an LF353 for the active filter section.
This is built and verified- fits comfortably in a 1590BB, but the layout could probably be condensed even further if resistors were mounted upright. Sounds great, with a nice variety of tones. If anyone would like the .diy file to fiddle with, PM me and I'll be glad to send it.
Props to Liquids & Isildur100 for all the work on this fine box, and of course to Joe D for the Shocktave. Enjoy!
some questions about synthbox2 perf layout
there is some E B C spots in there, is it suppose to be transistors there? if so, should it be MPSA18s or something else?
c14 is a 10uF non polarized cap, right? but is there any alternative here as i having trouble finding a big non polarized cap like that?
sorry if those are stupid questions :icon_redface:
Not stupid at all- actually, it's my bad :-\. I use sockets for all the trannies, and DIYLC doesn't have an image for sockets, so I fudged it a bit- and forgot that the transistor types won't show up in the BOM when doing that. So I forgot to list them :icon_redface:. Anyway, all trannies are 2N5089s except for the one for the attack pot, for which I used an MPSA18. I should also mention that the 5089s for the oscillator (right side of board) should be matched as closely as possible. I'll fix the layout when I get a chance.
As for the 10uF nonpolar, I used a monolithic multilayer ceramic from Mouser- they're very compact. Here's the link: http://www.mouser.com/ProductDetail/TDK/FK22X7R1E106M/?qs=sGAEpiMZZMuAYrNc52CMZNINJMxZfzHjfBZIDGnSImg%3d (http://www.mouser.com/ProductDetail/TDK/FK22X7R1E106M/?qs=sGAEpiMZZMuAYrNc52CMZNINJMxZfzHjfBZIDGnSImg%3d). A 10uF mylar would be huge, so you kinda hafta use a ceramic.
Sorry for the omissions- hope this helps.
Liquids, your Google page is keeping me out. ???
The 10uf cap can be a normal electrolytic polarized cap (that's what I used). No need to try to find a non polarized 10uf cap, I think it was an omission. The + side should be connected to the op amp output.
The transistors can all be 2n5089 except for the mosfets which are bs170.
John
Oooops, forgot to mention the BS170s. Boy, I'm really batting a thousand here, ain't I... :icon_redface:
OK, perf layout is now revised: http://www.aronnelson.com/gallery/main.php/v/jdub/synthbox+2+project.png.html (http://www.aronnelson.com/gallery/main.php/v/jdub/synthbox+2+project.png.html)
Without thinking, I had notated bipolar leads (EBC) where the MOSFETs should be in the gain section. These are now corrected & I added some notes regarding the trannies, etc. Lemme know if I forgot anything... :P
Hi jdub,
I think you forgot to connect the 2.2uf caps. The one from the mosfets and the other for the tone section. I don't see the 1k resistor going from the mosfet to the 2.2uf.
John
Hey man-
Actually, the 2.2uF cap for the tone section is there, mounted on the bass pot (C17). As for the MOSFET 2.2uF & 1k: aw, crap :-[. I was working from a rough layout and the schem when I built the box, so those components are in my build, but I did the DIYLC layout after the fact & forgot 'em. Thanks fer the heads-up; looks like another revision for me... :icon_cry: Apologies- I'll try to get a(nother) fixed one up after work...
Where's the schematic for this? Google pages are gone.
I took the site down. But minus the values in the Baxandall (tweak that as you like), I've loaded the schem as I last had it and put it on Aron's gallery.
http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+Op+Amp.JPG.html (http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+Op+Amp.JPG.html)
thx!
What kind of op amps and MOSFETs are you using? The sound clips sound pretty cool. :icon_cool:
I made mine with TL072's and BS170's. I guess any of the popular opamps can do the job.
Trannies were 2N5089.
cheers
This box is still on my to do list.. especially trying to improve the tracking on those first frets on the low E.
ordered the parts needed for this now. I hope I manage to build this, haven't built anything this complex before but I love the sound of it so I just have to give it a go
thanx for the help btw :icon_biggrin:
OK, I think I got it now... the new final revised updated ;) perf layout for the Synthbox 2:
http://www.aronnelson.com/gallery/main.php/v/jdub/synthbox+2+project.png.html?g2_imageViewsIndex=1 (http://www.aronnelson.com/gallery/main.php/v/jdub/synthbox+2+project.png.html?g2_imageViewsIndex=1). Hopefully I remembered everything this time... ::)
Enjoy!
I'm really digging this project, but I was wondering how tracking was with quicker licks? When I get the time and money I am definitely going to build this. I love synth sounds from guitar but find when playing faster leads things tend to get a bit messy.
As with most octave down pedals, the tracking issues are more with the lowest notes. Playing fast licks on higher frets will track ok. Anyways, it depends on what you mean by fast :) If you accidentally hit more than one string it will surely mess with the tracking.
i think the caps on the DPDT is mounted wrong on your pref layout jdub
it should be like this
(http://img441.imageshack.us/img441/9632/dpdt.th.jpg) (http://img441.imageshack.us/i/dpdt.jpg/)
i can be wrong but i don't understand how it would work in any other way
It works- that method was copped from a Mark Hammer post, and operates by shunting. When the common lug of the switch is connected internally to one of the outside lugs, current essentially takes the path of least resistance (i.e. the internal contact) and bypasses the cap mounted between those lugs. So in the layout, for example, if current enters the switch through C1a, if the common is connected internally to that outside lug, the cap between C1a and the common (C19) will be shunted (or bypassed) and the current will pass through the cap C21. If the switch is pressed, and the internal contact is now between the common and the other lug, C19 will become the effective cap and C21 will be bypassed. I didn't get it at first either, but then I used that method for Univibe mods to a Phase 90, and it worked like a charm; makes sense to me know. At any rate, that's how I have it wired on my Synthbox and it does work, even if it's a bit puzzling at first. It's cool, though, because it allows the caps to be mounted compactly on the switch with a minimum of flying leads... 8)
ok, thanks, now it makes sense :)
ok I have built this circuit now but it doesn't work properly :icon_sad:
first it made no sound at all then i removed the max1044 and the thing started to work... well not actually work because it sounds far from the sound-sample
it sounds like the octave is missing and the pots doesn't seem to do much either
the sound is kind of swelly and after being on for a couple of minutes it started to hum
I'm going to look through my soldering again but i thought it was strange that it worked without the charge-pump but not with
maybe i should mention that i used mpsa18 for all the npn transistors and LM833N for all the op-amps, is it crucial to use those specific op-amps TL072 and LF353?
Any dual opamp will work; I just used those cuz I had 'em. As for the transistors, I'm not certain what effect using MPSA18s would have- what confuses me is the MAX1044 situation. Since the opamps are running off a bipolar supply, removing the 1044 removes the -9V supply which should render the opamps inoperable. Are you sure you have the -9V going to the right places? Is the MAX1044 even producing the negative voltage as it should? Also, be sure the MAX1044 isn't toasted- it has a max supply voltage of 10v. If you can take some voltage measurements (with the 1044 in place) for the opamps and transistors & post 'em, and verify that the MAX1044 is putting out + and -9V, I'll check the voltages on mine as soon as I get a chance & we'll see if we can get it happenin'... ;D
i did some voltage tests not completely certain haw and witch pins that should be tested but i got these results and the max1044 seams to operate properly
+Vcc +9V
-Vee approximately -9V (-8.65V)
on all op-amps
Q1 & Q2 drain +0.5V
Q3 collector +9V
Q4 & Q5 collector between +0.2 and +0.1 V (volume-knob set to max)
I have looked through my soldering searching for mistakes but havent find any but thers probbably a verry good chanse there is some error hiding there
Best to check all pins of all opamps and all leads of all trannies. Check out the debugging thread here:
http://www.diystompboxes.com/smfforum/index.php?topic=29816.0 (http://www.diystompboxes.com/smfforum/index.php?topic=29816.0) for detailed intructions, if you've never done this before. Follow the method & post the results- best way to find the problem. ;)
I'm using a power-supply because the cheap 9v batteries I have measure about 7v
Q1
D = +3-0 *
G = +3-0 *
S = 0
Q2
D = +3-0 *
G = +3-0 *
S = 0
*(started at about 3v and then dropped to 0)
Q3
E = 0
B = +0.2 **
C = +9
Q4
E = 0
B = +0.42
C = +0.42
Q5
E = 0
B = +0.42
C = +0.42
D1
A = 0
K = +0.2 **
**(started at a higher value but dropped to +0.2)
IC1
P1 = +9
P2 = +4.45
P3 = 0
P4 = -4.36
P5 = -8.65
P6 = +4.45 (not connected)
P7 = +6.67 (not connected)
P8 = +9
IC2
P1 = +0.86
P2 = +0.86
P3 = +0.65
P4 = -8.65
P5 = +0.86
P6 = +0.87
P7 = +0.87
P8 = +9
IC3
P1 = -0.05
P2 = -0.05
P3 = +0.87
P4 = -8.65
P5 = +0.6
P6 = 0
P7 = 0
P8 = +9
IC4
P1 = +0.14
P2 = +0.14
P3 = +0.13
P4 = -8.65
P5 = 0
P6 = 0
P7 = -0.93
P8 = +9
thats the values i got but some of them where tricky to read because of the changing values
edited the values now in proper order , i hope
OK, I'm a bit puzzled- are you numbering the pins of the ICs in standard fashion (e.g. looking top of IC, notch at top, pins 1-4 on left from top down, pins 5-8 on right from bottom up)? If so, something is way off. It seems that you may have your pin numbering reversed- are you calling the tip pin on the right pin 1? That's the only way +9V across pin 1 and -9V across pin 5 of ICs 2-4 makes sense... ???
well i was a bit unsure about how they are numbered but i went in this order
- 1 - 8 -
- 2 - 7 -
- 3 - 6 -
- 4 - 5 -
but now i see that i reversed it :icon_redface:
remeasured everything and edited the list
OK, checked my voltages and they are pretty much in line with yours (my battery is only putting out about 8 volts, but voltages are relative to yours). You may wanna check closely for solder bridges (it's kind of a snug layout) and/or check the circuit with an audioprobe. Is it still not working with the 1044? Did you try it with 5089s & TL072s?
the problem remains and I get no sound at all with the 1044 in place, I thought, but actually there is some oscillation sounds or something in some knob-configurations
it seems likely to be a soldering-bridge somewhere but when I tried to get some information on the LM833N I read that people had oscillation-problem with it so I'll get new op-amps on my next order end see if it solves the problem
I suggest you build it on a breadboard and make it work there first. It is not a very complex circuit to breadboard and it will be a lot easier to debug.
John
+1. I had mine on the breadboard for a couple weeks before I perfed it, especially since I had never played around with bipolar supplies before.
Sorry about the zombie thread, but I want to build this on pcb. The pcb layout on the thread is for the transistor version, and the link to that schematic is dead. Anyone have the old, transistor-based schem, or a pcb layout for the opamp version? Liquids?
Man, I gotta learn to do my own layouts...
Search the gallery.
Ah! That reminds me, I did a layout for this a while back, forgot all about it. It's unbuilt, untested, unverified. I haven't added the component values yet, but it's based on Naz's layout, just more compact, so most of the values should be obvious. If anyone's interested I'll revisit it and add the values. It really needs checking over by someone before being built though:
(http://dl.dropbox.com/u/967492/Nanotron%20PCB.gif)
(http://dl.dropbox.com/u/967492/Nanotron%20PnP.gif)
Keep in mind that the transistor version works, for some, but it's primitive compared to the op amp versions. It's more complex, less consistent/controllable results, less precise filtering, slightly less idiot-proof, and I dare say more trouble to build than an op amp version, if you're going through the trouble of building one...
I'd probably even continue updating the op amp version to be honest - the tone controls are especially screwy, but I keep learning... http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+Op+Amp.JPG.html (http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+Op+Amp.JPG.html)
The thing is really amazing if I do say so myself...I don't know how I've not housed one yet. In addition to my 'ADD,' I keep wanting to perfect an envelope filter to joint house it with...haha. Yeah, that is, when the planets align! :)
I must have said this before in this thread. But no I actually have a diy roctave divider on my bench ( did not make it myself) but that has the NE750 trick in so one half is used as a compressor, then that halve also outputs the envelope on one of the pins, that is used with the other half to restore the envelope on the octave signal. Works great!
Thanks liquids. I actually searched the gallery before posting, I just missed the little button that shows ALL results, so I thought it wasn't there. As far as the opamp version, I'd like to build it, but I didn't see a pcb layout (hope I didn't miss that too) and I haven't learned to make them yet.
Thanks for the fast response to an old thread!
this has been on my 'definately to do list' for ages...sounds great, i would love to rip a few licks with one of these....
the one with the filter was very cool....nice.... :icon_cool:
QuoteAs far as the opamp version, I'd like to build it, but I didn't see a pcb layout
I've started foolin' around with PCB layouts lately, so maybe I can fiddle with my perf layout for the opamp version and make it more PCB-ish. I'll see if I can get it up by the end of the week.
This really is a great circuit- I use mine all the time. It can be a little touchy tracking-wise sometimes, but some compression before it as well as the standard neck-pickup, tone-rolled-back octave setting on the guitar and can usually compensate. I highly recommend it.
Quote from: jdub on February 20, 2011, 01:33:13 PM
This really is a great circuit- I use mine all the time. It can be a little touchy tracking-wise sometimes, but some compression before it as well as the standard neck-pickup, tone-rolled-back octave setting on the guitar and can usually compensate. I highly recommend it.
Cool! Yeah, I do still think the filtering can be improved. My knowledge is sophomoric so the projects (and most of my mods/designs) continue to morph as I learn and understand more...
Quote from: jdub on February 20, 2011, 01:33:13 PM
I've started foolin' around with PCB layouts lately, so maybe I can fiddle with my perf layout for the opamp version and make it more PCB-ish. I'll see if I can get it up by the end of the week.
That would be great! I've been attempting to do a layout for the last few days, but it's my first one and likely to be pretty rough.
OK, managed to adapt the perf layout for the Synthbox 2 (opamp version) to PCB (although can be used for either):
Project image w/component values is here: http://www.aronnelson.com/gallery/main.php/v/jdub/synthbox+2+project.png.html (http://www.aronnelson.com/gallery/main.php/v/jdub/synthbox+2+project.png.html)
And here's the PCB transfer image (will need resized, o' course):
http://www.aronnelson.com/gallery/main.php/v/jdub/synthbox2+opamp+pcb.png.html (http://www.aronnelson.com/gallery/main.php/v/jdub/synthbox2+opamp+pcb.png.html)
In retrospect, my original perf layout was pretty crappy, so I modified it as much as I could without redoing the entire thing. This version is not verified by build, but I checked all connections so it should be good to go.
Note that this layout has a mod involving a DPDT with caps mounted on it for switching between the stock octave down and a synth-like same-octave sound. If this is not wanted, simply use the stock caps (.22), one between pads C1a & C1b, the other between pads C2a and C2b. If you do use the switch, I recommend using multilayer ceramics, simply because the smaller size is easier to mount. You can also play around with the values for C21 & C22 on the switch- the .01s worked best for me.
Also, be sure to mount the jumper from -9V that runs under IC3 before installing the socket. If there are any questions, or if you'd like the .diy to fiddle with, lemme know & I'll send it to you. Enjoy!
Couldn't get the images to post before, but I figured it out ;D:
Layout/values:
(http://farm6.static.flickr.com/5096/5479145529_a6f3731f93.jpg)
PCB transfer:
(http://farm6.static.flickr.com/5019/5479745460_0b764d23b4.jpg)
Quote from: jdub on February 26, 2011, 10:06:56 PM
Couldn't get the images to post before, but I figured it out ;D:
Layout/values:
(http://farm6.static.flickr.com/5096/5479145529_a6f3731f93.jpg)
PCB transfer:
(http://farm6.static.flickr.com/5019/5479745460_0b764d23b4.jpg)
Lovely! Great job with the layout. I built the transistor version a year ago, but never got it to work entirely and scrapped it for parts. I'm thinking this is next on the bench! Thanks.
Awesome, thanks jdub! This is my next build for sure. I'll post here once it's done, but it'll be a few weeks at least.
I just put this on the breadboard. After mistakenly building it with 2N5087s in the oscillator (which resulted in a bad fuzz) I got it right on the second try. While I had it on the board, I tried a few of the suggestions posted in this thread:
Quote from: isildur100 on February 15, 2010, 11:54:14 AM
I had to replace the 100nf cap with a 10uf cap where that transistor and diode section is. Doing that gave a lot more sustain which helped the tracking at the same time.
I found this to be no improvement - in fact it made the tracking and sustain both worse in my build.
Quote from: isildur100 on February 15, 2010, 11:54:14 AM
However, I had to change a 10k resistor to a 15k value for the treble because with a 10k, when the treble was maxed I had a loud squeal. The 15k got rid of the problem.
I had a similar problem, but with the treble pot all the way down. Your fix worked like a charm. :)
I also tried jdub's mod for synthy same-octave sound, using .01uF caps in place of the .22s. It worked, but the tracking on the attack of each note was glitchy for me. Values from .0047 on down worked, but exhibited a buzzy quality I didn't like. Using .0068s yielded an effect which I liked a great deal. It's basically a tracking glitch that is consistent and predictable, giving an interesting sound to the attack of each note. I will use this value when I box up the circuit, switchable with the stock caps.
Also, I jumpered the input of the last opamp section to ground, leaving out the unlabeled resistor. For the rest of the unlabeled values in the schematic, I used those suggested in jdub's build file in the gallery. I tested it with a guitar loaded up with an assortment of Seymour Duncans. It has a Duckbucker (supposed to be a Strat sound) in the neck, a Hot Stack rail pickup in the middle, and a Custom 5 humbucker in the bridge. The circuit reacted similarly to all three of these very dissimilar pickups.
Before I take this off the breadboard, I want to see if I can make it work for bass. It seems like this should be possible with some tweaks to the filtering. The problem is, I know nothing about filters. Suggestions would be appreciated!
I found a couple of errors in the PCB layout. There is a pad missing for R22 on the trace between gain pot pin 1 and IC3 pin 2. Also, the trace connecting R5 & C11 on the vero layout was moved, and now incorrectly connects to C5 as well, causing the opamp to short. So far, the only other issue I've found with it is that the lead for pin 2 of the bass pot moved from its spot on the vero layout, but it's not hard to figure out where to attach it on the PCB.
I'm planning to correct these problems with a marker and etch another board to finish my build, so hopefully I can verify the rest of the layout by the end of the week. Wish me luck!
In other news, the box worked better than I expected for bass when I had it on the breadboard, so I made no changes to the filtering. I did, however, change the 47k resistor in the clipping stage to 10k, which enabled me to get some lower-gain settings (which seemed to track a bit better on bass) without sacrificing much gain when the pot is maxed. I also changed the capacitor to ground in that feedback loop from 2.2uF to 100uF. While I was still testing with guitar, this seemed to improve tracking on the lowest notes by a small amount. Values higher than this yielded no change on either guitar or bass.
Nice work, Keppy. Are you going to post any final schematic or layout as well?
No, the schematic is liquids' and the layout is jdub's. I just wanted to build one myself and thought I'd share what I found since it's still an evolving project.
Dudes, sorry about the biff on the PCB. :-[ The connections I checked were on the layout; when I rendered the PCB I musta moved some stuff. Anyway, here's a corrected version: http://www.aronnelson.com/gallery/main.php/v/jdub/synthbox2+opamp+pcb.png.html (http://www.aronnelson.com/gallery/main.php/v/jdub/synthbox2+opamp+pcb.png.html)
Keppy, I'm sorry if my errors messed with your build. :-\
BTW, does anyone know how to correct images in old posts? ???
Quote from: jdub on March 27, 2011, 10:28:58 PM
BTW, does anyone know how to correct images in old posts? ???
You need to replace the old image with your modified one having exactly the same name and link address.
That's what I figured. Can this be done in Flickr? That's where the original image is stored- tried to change it last night but couldn't see how to replace the image with a new one without changing the link address...
Good work guys, like Rob, I've been looking at this for a very long time. Maybe with the layouts all done and tested I'll finally get off my arse and build it. Thanks
Sorry I'm taking so long with this. I (mostly) built this back in March, but noob that I am I didn't plan my enclosure well, and every time I try and assemble the thing something shorts. When I fire it up outside the enclosure, though, it works except for one thing: When I turn the treble knob below about halfway, there's a pop followed by noise. The noise does not go away if I turn the knob back up. It does go away when I bypass the pedal and unbypass it again, but only if the knob is above halfway. Any ideas what could be causing this? Other than this issue, I can verify that jdub's pcb layout works.
I'm just now getting ready to build the op amp version, so I'm no experienced expert on this one, but sounds like a capacitor problem. Should be a non-polar 10uf connected to 2nd lug of treble pot. did you use proper cap there? Or maybe another cap near there is bad?
Actually, I think I found the problem. I failed to notice a damaged trace connecting pin 3 of the treble pot, resulting in the cap from the previous opamp stage being completely disconnected. I'll fix that and see how it goes. Figures that after weeks of wondering I find the problem a few hours after I finally ask for help!
Incidentally, previous posts said it was fine to use a polarized cap on the output, which I can confirm as the components in my build all worked fine on the breadboard.
Finally got this thing to work all boxed up, so jdub's pcb layout is now totally verified!
Glad to hear it! ;D
I'd definitely note that the active EQ section in whatever version that is is wonky.
At the time I mistakenly believed that I could get unique cut/boost frequency response by using unequal value caps, while keeping the eq 'flat' in the middle. Not so, that just tilts the EQ in a wacky way and the 'core' un-EQed sound is lost. The Active EQ is good but if you're not familiar with tinkering with active EQ, just use values something like you'd find in the Xotic pedals or Boss FA-1 instead. It will be more normal sounding and possibly less problematic. As ususal with circuits, I'd do it differently today than I did it than...and will do so, when I myself finally build one! ;D
Yeah, I'm kinda getting that vibe from the EQ. I fixed the treble pot problem, but when I boxed it up last night it reappeared but was less severe. Today it's gone again. I might re-do the pedal someday anyway. It was one of my first attempts to etch and solder a whole circuit board, and two months later I find myself embarrased by how it turned out. It still works, but the traces and solder joints are awful, much less clean than the ones I've done since. I might tinker with it someday when I feel like making a new board for it. It's still an awesome effect, though, so thanks for the design!
I breadboarded various input stages to feed the Joe Davisson shocktave, it really is a cool idea using it to get synth-like sounds. I couldn't get any sounds as nice as liquids sax type sound, but I don't have the correct transistors which I ordered tonight. Tracking is a lot better than I expected. The Davisson circuit needs a lot of gain to drive it, and doesn't like any load after it. In the end I just used a dual opamp, one side to drive it, with mega-gain, and the other side as a buffer and simple treble cut control.
If anyone breadboards the circuit, a simple way to test the oscillator is disconnect it from the preceeding tranny stage with diode, and connect it straight to 9V, you should get a steady note. I discovered I can get some original guitar signal mixed in with the oscillator by disconnecting the 1uF cap from the preceeding diode/transistor stage. This makes it more of a straight octave pedal and it sounds good. When I build this into a box I will fit a switch to give the 2 options.
Just thought I'd post this to encourage others who may be sitting on the fence. It's a useable, but wild, and unique effect, thanks liquids, Davisson, and all who contributed. ;D
This looks very interesting. Haven't had the chance to hear the clips yet, but I'll probably omit the EQ, perhaps add the resonant LP filter from the Drone Lab instead. Also, what is the benefit of using MOSFETs in the feedback loop?
EQ needs tweaking...I'd do it all quite a bit differently now, but the op-amp based circuit works well.
Mosfets in the loop as pictured create a squared signal with greater swing than two/four diodes or even Red LEDs, if I recall (it's been a while), and cliped somewhat less harshly than the other options to my ears, which may help tracking. Orman has a good page on various clipping options and their results (this is taken right from there); select zeners properly arranged would do just as well I suspect.
Use what you have (multiple diodes in series, etc) but I found that, to a degree, you want as large a squared-off peak to peak swing as possible, mosfets were a two-component solution on the breadboard, and I was into messing with them at the time I did that revision, and have a lot of them laying around. There are more than half a dozen ways to accomplish the goal of soft square-ish large swing clipping.
Are there any specific parameters that I should be looking for when picking the MOSFETs?
Quote from: egasimus on August 03, 2011, 09:39:32 AM
Are there any specific parameters that I should be looking for when picking the MOSFETs?
Make sure you like how they sound & work on the breadboard? ;)
Played some more with it today. Came up with a simpler/lower component count. This is quite giggable and consistent. Love it, thanks liquids and Davisson again. The first opamp section has a low input impedance and this probably helps roll off the highs from the guitar. I tried a more "correct" way of doing it but got a lot of glitches and worse quality sound. The tracking is great. To a large extent I used values on hand, so a lot of this circuit and the opamps is not or may not be theory correct. 2SC2547 and BC550C seem to work OK, 2N5089 in the mail to try. This is a circuit that really needs to be breadboarded first to make it suit your guitar (and taste). The oscillator needs to be tweaked to suit the range you want, by changing the 2 x 0.1uF caps to 0.068/0.047 or whatever you like. I think the 100K resistor pair in the oscillator could be replaced with a dual pot and fixed resistors to fine tune the range required. The oscillator will only cover so much range without shifting an octave up/down when it reaches its lower/upper limits. I can get clean notes from low E string fret 5 to high E string fret 19. Shame I'm 50 and don't gig any more, but my fingertips are sore from playing/testing/tweaking this circuit, I couldn't stop playing it, I'm smiling. I would have killed to have this up my sleeve 20 years ago ;D Probably only use it in 2 songs all night but the "fark!" factor would be worth it :icon_mrgreen:
Here's the schem I'm using (http://i198.photobucket.com/albums/aa160/birdy81260/SynthboxDavissonvariant1.gif) at the moment.
This sounds amazing! Well done.
I have a question about the bipolar power though... How would I power it? For example, I would be running it from a DC multi-out brick and not batteries so I'd need some sort of bipolar power charge pump like this (http://www.generalguitargadgets.com/component/virtuemart/?page=shop.product_details&flypage=shop.flypage&product_id=103&category_id=23)?
Would I hook this up in the same box as the Synthbox or in it's own separate enclosure?
Here's (http://www.generalguitargadgets.com/pdf/ggg_ps_cpbp_lo.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a) a link to the layout.
Cheers.
Is there a current clip of this (v2) out there?
Op amp version or otherwise.
Interested to hear it, thanks.
John
I'm planning to do a clip once I fix mine and maybe revise the tone stack. So, if you can't find one, there's one forthcoming.
I would be interested too Keppy the only clip I've heard is this one here (http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+Demo.mp3.html) which I believe is liquids' opamp version. The simplified circuit I am playing with does not sound as good as that clip. Are you getting that sax-type sound from your build Keppy?
Ivan, if you build jdub's layout on page 11 the charge pump is already in place on the pcb.
Ahaaa. Thanks a million. I can't wait to make this now!
There are so many great pedals on this site, I feel like I've been bitten by the bug... quite addictive.
Quote from: Keppy on August 04, 2011, 06:28:26 PM
I'm planning to do a clip once I fix mine and maybe revise the tone stack. So, if you can't find one, there's one forthcoming.
Great! Thanks.
Is there a thorough explanation of how this circuit actually works somewhere in the thread?
And can anyone comment on Ronan's (single-supply!) schematic?
QuoteI'm planning to do a clip once I fix mine and maybe revise the tone stack. So, if you can't find one, there's one forthcoming.
If I get some time in the next couple of days, I'll see if I can get a clip or two up as well...shoulda done so a long time ago but didn't have the recording capability until recently... :P
Hi ! I don't find where is C23 on the layout. I think it is between pin 6 ans 7 of the IC1, is that right?. I will use an ICL7660S to replace max1044. I think it should work. For C17, I want to use an 2.2uf film cap, does it ok?
Hi Jerem- Yeah, C23 is the electrolytic coming off of pin 6 of IC1 & connecting (positive side) to R22 (pin 2 of IC3). Sorry, it's hard to read the labeling. As for the ICL7660, should work. ;D
Hi, just wanted to chime in and say that I've been following this thread and can't wait to build it!
I loved the sound samples (from version 1). It's exactly what I'd been looking for.
They sound kinda reminded me of the awesome synth in this classic Tom and Jerry Cartoon (Chuck Jones Era):
Tom and Jerry - "Cannery Rodent"
The synth starts at about 1:00
;D ;D
I've been playing with this circuit for a while, I found out accidentally that by hooking up the transistor wrongly, I got a different sound, a bit like what liquids sound clip sounds like, and similar to that synth sound in the cartoon. I found I then didn't need the associated cap and diode. How it works now, I have no idea, because it really doesn't look right. I have checked, double-checked, and quad-checked the orientation of the transistor. It worked great 2 weeks ago (on breadboard) and worked great yesterday (still on breadboard). Today I put it through an envelope filter and distortion box, all is well. Schem is here (http://i198.photobucket.com/albums/aa160/birdy81260/SynthboxDavissonvariant2.gif) to show the transistor variation, and the circuit I am using it in. I couldn't get "the sound" with the transistor orientated correctly and with the cap and diode. I got "a sound" but not "the sound". Some of the values in the circuit might look unusual but I used what was on hand, for example, the 330uF electro on the 4.5V supply. One can never have too many spare parts laying around...
Quote from: liquids on July 16, 2009, 12:22:37 PM
My "recording rig" is really awful -- an old $5 computer mic into my generic soundcard...but I'll see if I can manage something over the weekend as I imagine more people will be interested once I do. :D
Note the date above...
Quote from: Zero on August 25, 2011, 06:14:58 AM
I loved the sound samples (from version 1).
I think the preference for the 'version 1' discrete sound (http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+Demo.mp3.html (http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+Demo.mp3.html)) stems mostly from those samples being recorded:
1) by a cheap omnidirectional computer mic
2) with the mic as far away from the speaker as the $5 computer mic's cord would go, to avoid the digital clipping I kept getting
3) in a small room
4) and eventually edited a 70 second collage of phrases and lines gathered from dozens of minutes of playing once I got the levels clean.
Quite simply, the elusive mojo of V1 is in the recording...in the room it didn't exactly sound midrangy, pure sax-like, fundamental-focused etc...the 'Synthbox 2' has same tone as the first version in my hands, plus or minus active (wonky) filtering and more consistent TRACKING.
I don't know what if any active EQ was used on the second recording anymore (http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+2+Demo.mp3.html (http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+2+Demo.mp3.html)), but
I'd venture to say the major difference is that the 'v2' clips were instead close-miced with an SM57 as stated in the notes for that recording, and hence probably closer to reality...
Somehow V1 has become a discrete component-sensitive mojo-tone because of that sample...
So to those of you who prefer the lo-fi tones better, maybe the better tweak would be buy a lo-fi amp like a sears silvertone to play the synthbox through....
Hi guys! I made SynthBox 2, and faced with the problem. The transistors I used 2N5088. I matched them as indicated. The sound is very dirty and "jumps". What are your ideas?
Quote from: MAK on August 28, 2011, 03:10:22 PM
Hi guys! I made SynthBox 2, and faced with the problem. The transistors I used 2N5088. I matched them as indicated. The sound is very dirty and "jumps". What are your ideas?
Have you heard the sound samples? Would you call them clean?
It only tracks well if you play cleanly.
No, not like on the sample. My unit sounds very dirty, the sound skips and does not keep a constant tone. The problem arises when the cascade transistors.
Are you using the neck pickup? Another thing is to set the input level high enough to sustain a note, but not too high that the circuit makes noise when you are not playing. It should be silent when not playing. If it is skipping octave up/octave down, try making the 2 capacitors bigger (or smaller) in the oscillator section, these are the 2 caps connected to the transistor collectors. And only play one note at a time.
QuoteAre you using the neck pickup? Another thing is to set the input level high enough to sustain a note, but not too high that the circuit makes noise when you are not playing. It should be silent when not playing. If it is skipping octave up/octave down, try making the 2 capacitors bigger (or smaller) in the oscillator section, these are the 2 caps connected to the transistor collectors. And only play one note at a time.
Well said; +1 to all these. Can also try rolling back the tone control while using neck pickup.
Thank for your precedent answer jdub. Can you confirm me that is R19 wich is under IC4 and R18 on is right?
Quote from: MAK on August 28, 2011, 03:35:29 PM
No, not like on the sample. My unit sounds very dirty, the sound skips and does not keep a constant tone.
The samples sound pretty dirty to me.
@Jeremy- Yep, R19 is under the opamp and R18 is to the right :)
http://www.diystompboxes.com/smfforum/index.php?topic=93508
Here's my layout for Ronan's no-nonsense version. Anyone have some spare time to etch and verify? Cuz I have none...
That there's a good-lookin layout :o I'm gonna have to try this one...and the list grows longer... ;D
I just have finished my synthbox op version. All is ok, the switch selection work good and bass/treeble filter sound good. My only problem come from the gain pot and the attack pot. Nothing working. I believe we have to solder together pin 1 and 2 of these pot?
Thank for your layout jdub, I like the sound of this stompbox !
Quote from: Jerem on September 14, 2011, 12:59:50 PM
I just have finished my synthbox op version. All is ok, the switch selection work good and bass/treeble filter sound good. My only problem come from the gain pot and the attack pot. Nothing working. I believe we have to solder together pin 1 and 2 of these pot?
Thank for your layout jdub, I like the sound of this stompbox !
Nah, just use 2 lugs. Don't worry about joining any together.
If you are looking at the back of the pot (no shaft) with the lugs on the bottom, they go 3-2-1 left to right. Use 1 & 2. It doesn't matter which is which, since they're just variable resistors in this design.
On the layout I did I only showed connections for lugs 1 and 3 of the gain and attack pots, so following that you would have to connect the wiper to one of the outside lugs (I connected 2 & 3). But Keppy is right, it's probably easier to just use lugs 1 & 2. I did it that way just as a personal preference to not have hanging lugs. But either way is perfectly valid. :)
Glad the layout is useful to you, but liquids especially deserves the thanks for for this (as well as Isildur100, Gigimarga and all the other cats who helped develop this killer circuit). And of course the illustrious Joe Davisson for the Shocktave! Hats off to you, dudes!
i havent tried this variation, but indeed the shocktave was one circuit that had great potential! the frist time i got it working i remember the smile on my face. :D definately a new experience playing through that thing. iirc, shorting one of the flip flop caps to ground gave another tpe of sound... not octave down , but synthy same-octave similar tone... something to try...
On a similar note... check out the colorsound octivider. and there is a thread at FSB with a vero layout..
http://www.mtcom.jp/~schematic/effects/colorsound_octivider_v11.gif (http://www.mtcom.jp/~schematic/effects/colorsound_octivider_v11.gif)
There are some youtube vids too..
Sounds great!
Minimal to no difference from the (well regarded) shin-ei?
Not sure, I saw that schematic today for the first time, looked like the same to me. I briefly glanced over the input filter and trigger section and noticed the same values.
Now that I have a scope AND know how to use it, I've seen the waveshape of the synthbox....explains it's unique sound. Hoping to o-scope and take a picture next time I am tinkering with it on the breadboard so people can see...but if anyone else happens to be able to do that easily and quickly, please do, It would be much appreciated.
Cool, I'm interested.
I suspect some PWM action.. as the transistors act like schmitt triggers.
Btw, have you tried modulating the original signal with the output of the synthbox?
should give you octave sounds while retaining attack/decay
Quote from: ~arph on March 27, 2012, 11:31:26 AM
Cool, I'm interested.
I suspect some PWM action.. as the transistors act like schmitt triggers.
Btw, have you tried modulating the original signal with the output of the synthbox?
should give you octave sounds while retaining attack/decay
I'm not certain I understand what you mean by 'modulating the original signal with the output of the synthbox?
In my mind, I'm thinking you mean that the synthbox has no dynamics (true), but you are looking to 'return' some of the dynamics of the plucked note to the synthbox's output.
This could be done by using the guitar to create an envelope, and using that envelope to create a VCA...so that the synthbox sound has the decay characteristics of an uncompressed plucked note...
I mean just like a tremolo, check the colrsound octivider :)
Hmmm......http://www.aronnelson.com/gallery/main.php/v/Martys-layouts-and-photos/colorsound_octivider_v11.gif.html?g2_imageViewsIndex=1 (http://www.aronnelson.com/gallery/main.php/v/Martys-layouts-and-photos/colorsound_octivider_v11.gif.html?g2_imageViewsIndex=1)
I see that it may sort of works like the boss octave / subtractive synthesis (there is an article out there somewhere far more articulate than I) in that by some means the sub-octave generated is fed through a diode/fet/etc with the 'straight' signal...?
I'm all but sure it could be done. Might be interesting to try.
Most of those pedals utilize filtering since the sub-octave generated is harmonic-laden (this being no exception) yet a cleaner/filtered octave is the goal...but thiat approach, with or without the filtering, it might add another element of interest, with or without the post-filtering used in those schematics.
But I think I might be misunderstanding you since I don't see any common ground shared with a tremolo....
Well I mean instead of mixing in the sub octave sound, you mute the original signal at the rate of the sub octave. (that's why I called it tremolo) This shoudl give you an octave down sound while keeping the original envelope.
I built one of these the other day and while I love the sounds coming out of it I liken it more to a fuzz box with an option to toggle the octave up or down. It has a synthy-ness to it's sound but I am not getting the synthy sounds I heard from the clips... The gain knob also seems to do almost nothing (it doesn't seem to decrease the amount of gain in the pedal, which is considerable) and I can't tell what the attack knob does really. The knobs that work best for me are the volume, bass & treble knobs... I play through a Gretsch 5120 with HS filtertrons so you know.
For those who have made this pedal, do you have any thoughts as to why I am not getting the organ/sax like sounds? I can post sound clips if need be.
***Update. I figured it out, i missed the post on the previous page where someonehad the same issue with the attack/gain pot. I used lugs 1&3 originally on each and I switched it to lugs 1&2, i also opted to use matched BC550B's and wow, this thing is wicked!!!! Straight to the pedal board and permanently. This makes solos sound crazy and power chords demented... simply fantastic work guys*****
Thanks for the update.....matched 550b's , huh. What were the gain on those?
bc550b hfe i used was around 525...
has anyone else noticed that this pedal is insanely loud? unity gain for me is 9:00 on the volume knob, but the effect doesn't really start opening up until around 12:00.... is there a good way to hush this puppy?
I used TL072's as my opamps...
I don't recall how loud mine is. I need to hook it up tonight and revisit it. I wasn't satisfied with the octave on mine as compared to the shocktave, so it's been set off to the sidelines.
is there a revised/final schemo for this?..
i now have an empty breadboard.. ;)
I'm going to post my contest entry now.. so that might do.
ahhh the cats out of the bag... :icon_eek:
cool look forward to hearing/seeing it...nice one . 8)
I will say that the octave on mine tracks amazing and it chunky as hell. I had in the past used a Pog2 and a fuzz pedal for a heavy low end sound, but if i can get the unity gain fixed on the synthbox i think i may end up using that instead... it is wicked.
I built mine with a PCB layout instead of vero, it was much easier...
So...did you use the synth box v2 pcb layout?
That's what I built mine from, opamp version..
Quote from: dulcetpine on August 14, 2013, 08:05:58 AM
has anyone else noticed that this pedal is insanely loud? unity gain for me is 9:00 on the volume knob, but the effect doesn't really start opening up until around 12:00.... is there a good way to hush this puppy?
This thing uses a flip-flip that swings almost from rail to rail as the output wave. So yeah, crazy loud. Put a large resistor inline just ahead of the volume pot to knock it down. Also, make sure you're using an audio taper volume pot, not linear.
Quote from: ch1naski on August 14, 2013, 05:43:54 PM
So...did you use the synth box v2 pcb layout?
That's what I built mine from, opamp version..
Yeah, the v2 pcb layout.
Quote from: Keppy on August 14, 2013, 10:46:12 PM
Quote from: dulcetpine on August 14, 2013, 08:05:58 AM
has anyone else noticed that this pedal is insanely loud? unity gain for me is 9:00 on the volume knob, but the effect doesn't really start opening up until around 12:00.... is there a good way to hush this puppy?
This thing uses a flip-flip that swings almost from rail to rail as the output wave. So yeah, crazy loud. Put a large resistor inline just ahead of the volume pot to knock it down. Also, make sure you're using an audio taper volume pot, not linear.
I put a 4.7m resister on lug 3 and it got it down to a respectable volume but robbed all the high frequencies...
Try scaling down to a 470k resistor and a 50k pot. That will get you the same size signal while preserving the original pot's resistance (pretty much).
Quote from: Keppy on August 15, 2013, 09:57:08 PM
Try scaling down to a 470k resistor and a 50k pot. That will get you the same size signal while preserving the original pot's resistance (pretty much).
Tried this. Had the same effect of muffling and killing dynamics.
This pedal is rad sounding but as of now it is purely for recording only given the difference in volume... too bad.
Quote from: dulcetpine on August 28, 2013, 04:01:17 PM
Quote from: Keppy on August 15, 2013, 09:57:08 PM
Try scaling down to a 470k resistor and a 50k pot. That will get you the same size signal while preserving the original pot's resistance (pretty much).
Tried this. Had the same effect of muffling and killing dynamics.
This pedal is rad sounding but as of now it is purely for recording only given the difference in volume... too bad.
Just put an lpb 1 after it
Or a simple FET boost, like a SHO.
ok, i finally have an empty breadboard to try this synthbox out..
ive been meaning to try this for ages..
however most lnks are down now ::)
anyone have the schematic discrete versions?..
edit: found the schemo...but not with the added filter
the one with the filter... 8)
http://www.aronnelson.com/gallery/main.php/v/liquids/Synth/Synthbox+with+Filter.mp3.html
well i have it working on breadboard, worked first go, ...man this thing is sick.. 8) 8) 8)
clip:
i was switching between caps (the 68n)
47n and 100pf..
https://dl.dropboxusercontent.com/u/7464107/synthbox1.mp3
well worth breadboarding and tinkering with... 8)
i think i may try the octup circuit with it.. :icon_idea:
the filter liquids had on his sounded really nice, anyone have the addon schematic?.
Quote from: deadastronaut on March 26, 2014, 11:59:13 AM
clip:
i was switching between caps (the 68n)
47n and 100pf..
https://dl.dropboxusercontent.com/u/7464107/synthbox1.mp3
well worth breadboarding and tinkering with... 8)
i think i may try the octup circuit with it.. :icon_idea:
the filter liquids had on his sounded really nice, anyone have the addon schematic?.
Is that all guitar?
yep... 8)
edit:
a question..
if i added tim escobedo's octup...would i get normal octave too, or is the octup a 12 fret only type octave?.
the sound of this pedal is great !
is it combined to your 4pt delay pedal or reverb or both ?
concerning the synthbox circuit, which schematic did you consider for this test ?
hi, i was just using this schematic in liquids gallery, he has some interesting stuff in there...
still looking for the same filter he was using though....calling liquids :icon_surprised:
http://www.aronnelson.com/gallery/main.php/v/liquids/Synth/?g2_page=2
the delay was in my mixer for ease, but the 4pt delay will do the same...no problem.
i used 5088's btw,
After a couple of days I finally got this thread read! 8)
First of all congratulation to all you guys working on this project, from the audio demos available I can say that it sounds very interesting and definitely gonna breadboard it. I have a couple of questions though:
1. Liquids: Why did you use a bipolar power supply? Did you try a version with a unipolar one?
2. I know this thing gives you an synthy octave down of the note you're playing. Is it posible to get the normal octave also? From what i understand the "oscilator" part is what gives you the octave down. Have anyone tried to get the signal before that stage? By doing that would it loose all the mojo?
3. Any difference between the v2 (Opamp) and Ronan's version?
Quotehere's a neat easy shocktave mod... you can connect q4's collector and it's base for a synthy same octave sound... i couldn't get at my oscillator caps to experiment with changing the values so i did some circuitbending p.s. you can alternately do the same thing to q5 either q4 or q5 and see which sound you like better...
q4 and q5 that i mention here are the 2 flip flop trannies ,..
So you say that shorting the collector and the base of either one of the oscillator transistor's (Q4 or Q5) gives you the normal octave? When I build it, I'm gonna try this.
Anybody gOt a link to a 'good' schematic?
4 posts up.. ;)
reply 289.
Funny how that works. ..