Here's another rare pedal, the Foxx Guitar Synth (currently 1395$ Buy it Now on Ebay :icon_eek: :icon_eek:);
(http://files.effectsdatabase.com/gear/pics/foxx_guitarsynth_004.jpg)
(http://files.effectsdatabase.com/gear/pics/foxx_guitarsynth-black_003.jpg)
but I've got a question concerning this schematic;
(http://i214.photobucket.com/albums/cc196/digi2t/Foxx20Guitar20Synth20Service20Schematics2_002.jpg)
The upper quad opamp, specifically Z2-3 and Z2-4, the opamp "+" inputs, I'm assuming connect to the lug of the 1M sensitivity pot at the input?
I'm just looking for a second opinion, although it makes sense to me, since the rotary selector will either give you band-pass, or low-pass, from the input.
Sorry if the quality of the image is weak, it's the best I can do.
I think I'm going to try another Vocalizer type ressurection here. This should be interesting :icon_mrgreen:.
Cheers,
Dino
It's a Mutron III with manual sweep.
That's not a criticism, merely an observation.
Not taken as criticism, but as a directional aide :icon_lol:.
Thanks amigo, time to study the Mutron III schem.
I can't even find a sound clip, let alone a video of this puppy (like the Vocalizer, before I built it). It's got my curiousity peaked.
QuoteIt's a Mutron III with manual sweep.
Yup, almost identical. Should be able to fill in any blanks I may face.
Muchos gracias :icon_mrgreen:
One of the small differences between this and the Mu-Tron is that the Mu-Tron adjusts the signal level hitting the filter and envelope follower via a gain adjustment pot on the first stage. The Foxx uses a fixed gain on that stage, with an attenuator pot ahead of it. Same diff, I guess.
As an aside, if you check out the effectsdatabase, you'll see that the basic Mu-Tron circuit was licensed to a LOT of different companies. I used to have one of the Funky Filter pedals, back in the 70's, that I bought...new....for $25, not realizing that it WAS a Mu-Tron, but thinking it was a cheap imitation. Perhaps, Mike Biegel licensed the basic circuit to Foxx too.
Yeah, I've been digging into it today, and you're absolutely correct. I've been spotting this circuit, or variants thereof, can be found in other pedals. If anything, this has been a good "eye-training" exercise.
You know, one thing that's boggling me right now, is the cap on the pot in the picture above. I've been staring at the diagram, and the picture side by side, and I can see where the circuit is going, but I can't seem to spot the cap in the diagram.
I think I've been staring at the forest for so long now, I can't seem to spot the tree. I need a cup of coffee :icon_evil:
I also found on JC Maillet site, that he stuck a Mutron III into a wah as well, using the treadle for the wet/dry control. He also brings up a very good point about using a trimmer on the voltage divider (repalcing the resistors) to fine tune the opamp bias. Interesting...
You're about 6 weeks late. He was over at the house when I had the party for Steve Daniels in late October. Had you either come in to Ottawa, or notified me, we could have brought it up for discussion. :icon_lol:
Here... I'm passing you the salt.... rub it into my wound why don't ya :icon_mrgreen:
I'm going back to looking for my cap (I'm pouting my lips, and connecting my eyebrows) :icon_lol:
I'm beginnig to think that the cap on the pot is actually the 2.2uF electro shown in the diagram, just above the +9v. Since it either swings to ground, or goes direct to -9v, it isolates the positive side?
I've just never seen an electro cap that looks like that, and I have a layout of the PCB, and there is no 2.2uF cap showing. Maybe that's whats messing with my mind. I'm just having trouble seeing how it works placing it on the pot vis a vis the wiring. :icon_rolleyes:
Screw the coffee, I need a Red Bull...
Crikey! Trying to read that schematic is giving me a headache! ;D Interesting though, I like anything that can be built in a wah enclosure.
I'm surprised we haven't seen any threads about how to produce the faux velour fuzzy finish on Foxx enclosures.
Dino, the cap on the pot in the photo is known as a "brown turd" in my country, it is not an electro, but a polyester or mylar type cap, of a later vintage than the caps used in that pedal. I'd say it is a "mod" of some kind, who knows. Do you know exactly what is going on with that DPDT switch at the pot, labeled something like "pedal speed + manual or speed"?
Mark, how about the finish on this pedal?
http://www.ebay.co.uk/itm/ThorpyFX-Clark-Gainster-Clone-Klon-Hoochie-Mamma-overdrive-/110783823254?pt=UK_Guitar_Accessories&hash=item19cb3afd96 (http://www.ebay.co.uk/itm/ThorpyFX-Clark-Gainster-Clone-Klon-Hoochie-Mamma-overdrive-/110783823254?pt=UK_Guitar_Accessories&hash=item19cb3afd96)
Quote from: Ronan on December 10, 2011, 04:44:21 AM
Dino, the cap on the pot in the photo is known as a "brown turd" in my country, it is not an electro, but a polyester or mylar type cap, of a later vintage than the caps used in that pedal. I'd say it is a "mod" of some kind, who knows. Do you know exactly what is going on with that DPDT switch at the pot, labeled something like "pedal speed + manual or speed"?
I was pretty sure that it's some kind of mylar, or metal film, but I was kind of reserving judgement seeing how my experience is rather limited in this field. You folks must have really insulted them with the "brown turd" moniker, I figure that's why they took on colors, and became "tropical fish"? :icon_lol:
That part of the circuit (from what I gather) might control the envelope speed/decay. Either directly, via the pedal (manual?), or by how hard you "strike" the strings (strike?). I reminds me somewhat of the Uglyface sensitivity adjustment in a way. There's also another switch downstream that dictates whether the pedal is simply a wah, or sweeps the envelope. To my untrained eye, the Foxx seems to be using haly of the IC as a CV for the envelope control. As Mark pointed out earlier, this pedal has got "Mutron" written all over it. Maybe this pedal is rare because there was too much going on, or maybe Mutron sued their ass? JC Maillet modded a Mutron III into a wah shell, controlling the decay via the treadle, like this (sorry it's sideways, it's a direct link);
(http://www.lynx.bc.ca/~jc/moddedMutron3.gif)
It's just that the Foxx diagram shows a 2.2uF electro cap on the +9v line (going to IC Z1-1 neg. input), which I think acts as a block when we switch the neg input to -9v. I have a layout of the PCB that came with the schematic, and there is no 2.2uF cap shown. Meanwhile, two different gutshots show this "turd" on the pot.
(http://files.effectsdatabase.com/gear/pics/foxx_guitarsynth_006.jpg)
(http://files.effectsdatabase.com/gear/pics/foxx_guitarsynth-black_003.jpg)
Maybe the schematic was a first draft, and changes were made later in production?
I'm REALLY curious about this one, so it's going on the breadboard this week. I just have a weakness for these rare/obscure/over-priced-on-EBay pedals.
In the meantime, any trained observations are (as always) most welcome. I love going to bed a little less stupid at night :icon_mrgreen:
*edit*:
I copped this from the EBay ad;
Here's a something really cool! It's a Foxx Guitar Synthesizer I, Model 9. No doubt, it is vintage and rare and incredibly cool, I must inform you (if you are not already aware) that it's not really a synthesizer. It's actually a somewhat complex and sophisticated envelope-controlled, phase shifter/wah pedal. The wah/filter circuit uses a Vactrol, similar to the MXR Phase 100, and the effect can be swept with an LFO or you can use the foot pedal to sweep. Also has high/low sweep and you can change the direction of sweep and the direction of the envelope. You can freeze the sweep and just have the envelope control.
I'm going to email them, and ask if they can send me some pics of the guts. Wish me luck....
YYYYYEEEEEEEHHHHHHHAAAAAAAWWWWWWW!!!!!!!!!!!!!!!!!!!!!!!! I got the mother working!! :icon_biggrin: If you like Mutron III's, wahs, autowahs, LFO's, and a bit of flanging (kinda), well, you came to the right place. This sucker is a gas. There are some settings that even remind me of my Gristleizer.
Well, the schematic has some major errors in it, so I'm hesitant to believe that it ever came from the factory. In any case, with guidance from Mark Hammer, R.G. Keen, and J.C. Maillet (big FAT thanks guys!), their words of wisdom, and websites, put me on the right path. What we've got here is a Mutron III copy, with an LFO built in. Like the Mutron, it's got the LP/BP/HP filtering, gain control, lo/hi filter, up/down sweep, and so on. Unlike the Mutron, it doesn't have the resonance control, but does offer some psuedo flanging type effect. The resonance control easily added (I have it on the breadboard). The treadle is either a filter sweep control, LFO speed control, or is bypassed in autowah mode.
Ronan, that "brown turd" is the LFO speed range cap. The schem says 2.2uF electro, but you can use different caps to increase/decrease the range. One thing I found though, I am getting some faint ticking bleeding of the LFO into the audio. I'm hopeing that it's because of the lack of shielding, but I'll cross that bridge when I get to it.
OK, here's a video of the sucker on the breadboard. Since I had some VTL5C3's on hand, that's what I'm using. Needless to say, I had to stray from the schematics to compensate for the response of these Vactrols, so lucky for me I had lots of trimmers on hand. I recently ordered some LDR's for the EH Talking Pedal project, and I'm going to try them instead when they get here, since then I'll only need to run one LED. When I do build this, the resonance control, output mix control (thanks J.C.), and maybe a speed range selector for the LFO will go into this. Also, since this pedal requires +9v and -9v, I'm running it on a MAX1044. I'm using two LM324's, leftovers from the Mr. Multi build. They seem to have brought their good mojo with them. Or, maybe the fact that I just got some TL074's in, scared the crap out of them into working well. Who knows... :icon_mrgreen:
Here's what I have to date;
Once I get the schematic finalized, I'll whip up a vero for it. Once again, big thanks to all those who chipped in with guidance. I'm soooo glad I took this one on. :icon_biggrin:
Great stuff, very interesting!
More fine tuning....
LFO ticking bleed when in envelope mode is fixed. Since you can either be in "pedal" mode, or "envelope" mode, the "pedal/envelope" footswitch will be converted from a SPDT to a DPDT. The line going to feed -9v to the LFO will now detour to the "pedal/envelope" footswitch, and then go back to it's pole on the pedal footswitch.
I had noticed that if I was in "pedal" mode, with the LFO on, if I switched to "envelope" mode, the ticking was bleeding through. Although the pedal is disabled now, that would mean that I would have still have to click the pedal as well to kill the LFO. That's when it dawned on me, I'll give the "pedal/envelope" switch a double duty. Shielding or not, this will ensure quiet operation.
If you switch out of "pedal" mode, then it will also kill any power going to the LFO. After all, it's a moot point having power going there if the treadle is disabled. This way, if you're in "pedal" mode, and switch out to "envelope" mode, you won't get any ticking, and you can simply switch back to where you were before. No double switching. :icon_mrgreen:
I A/B'd the IC's again, and I found the TL074 sound a touch better, and a tiny bit quieter. The LM324's are now sulking in their drawer. On the the Foxx diagram, they show a 20K, and 220K resistor going to ground from pins 10 and 12 of the IC, whereas these pins go to ground on the Mutron. I tried both, and straight to ground is better. Envelope sounds, well, "wonkier" for lack of a better term. Score 1 for the Mutron.
I've got the VTL5C3's tuned to the point where they sound pretty damn good, so I guess I'll keep them. This also means a different resistor/trimmer to ground combo, in this case, a 270 ohm resistor below a 25K trimmer. This combo put me in the right range to dial in the sweet spot for these Vactrols that's useful for all the filter modes. I initial used a 100K direct to ground. I set it to the max 100K, and then started dialing back slowly. The danger here is that you don't have a resistor as a safety to prevent you from hitting ground directly, so be warned. I should have used a 1K, or a 560 ohm at the very least, as a backup, but I winged it this time. When I was satisfied with the sound, I pulled out the trimmer, and it gave me 10K on the meter. I settled on a 270 ohm resistor to ground, with a 25K trimmer on top. It gives me all the range I need.
The UP/DOWN balance was driving me nut for a while, because I was getting a different decay rate between the two. I installed a 250K trimmer as a voltage divider, to balance between the UP and DOWN modes, and I just couldn't find a happy medium between envelope, and LFO mode. I get one down, and the other one would go off. Then I spotted the problem... on the Mutron both resistors on the UP or DOWN poles are 22K. On the Foxx drawing, one is a 12K, and the other a 22K. That's what I breadboarded. When I realized the difference, I replaced the 12K with a 22K, and it made a world of difference. The decay between modes, or LFO mode is really nice now, being fairly even on either side. Funny enough, R.G. "Neutron" also uses the 12K/22K combo, but it just doesn't line up for me :icon_confused:. I'm not quite sure what's going on here, but Hey!, if it works... I see that J.C. used a 330K for the divider, but the 250K is working fine here, besides, I can't find a 330K multi-turn. Either way, score 2 for the Mutron.
Another dilemma is the cap just before the envelope detector. The 10uF is just too much, making the whole thing very bass sensitive. 2.2uF a la Mutron is nice, and I tried J.C.'s 0.1uF idea as well. Both worked well, but for me, a 1.0uF works nice to my ears, especially in high pass mode. This is going to be one of those "season to taste" thingys, to each his/her own. *edit* I tried a bunch of different diodes here as well, germanium, silicon, and LED's, but the best response I got was with 1N4148's. As per R.G. "Neutron" work alike. He shoots, he scores. It was kinda cool though with the LED's. They flash as you play. :icon_lol:
And, in case you're wondering (maybe not, but I'll tell you anyway), the UP/DOWN switch also reverses the sweep on the pedal, if so desired. NOW HOW LOOC IS TAHT!! If you're "wahslexic" (dyslexic using a wah), it can accomodate you as well.
I made another video, this time with all the above mentioned mods. I'm blasting through all the different setting, so you can get a of this thing, in better tune;
I'm going to draw up a new schematic, incorporating all the new tidbits and corrections, and post it in the next few days. Once I try a proper UP/DOWN trimmer (I'm using a pot, not precise enough), then I'll start a vero. IMHO, this is a really cool wah, that never got a fair shake. Maybe Foxx tried something, but didn't want to get bitch-slapped by Mutron, I dunno, but it could be a really great tool on the pedalboard with the right tweaks. As my bro Jimi would say, I'm going to "ressurect it's ass", and make sure it doesn't cost anyone 1400 smackers in the process. I think I'm going to rename this sucker "The Foxxtron", or maybe the "Mufoxx". :icon_mrgreen:
Stay tuned.....
I have one of these that needs some repair... :-\
Quote from: Mark Hammer on December 09, 2011, 04:24:05 PM
I'm surprised we haven't seen any threads about how to produce the faux velour fuzzy finish on Foxx enclosures.
I think it's described in AnalogMan's Guide To Vintage Effects. It was something electrostatic and there was a high rate of failure, so they had to remove that layer and try again.
Quote from: DiscoFreq on December 14, 2011, 02:43:34 PM
I have one of these that needs some repair... :-\
What's wrong with it?
Some time back, at the dawn of recorded history, I made an EPFM-I Super Tone Control and installed it into a wah shell. The EPFM STC is also a fairly standard variable state filter, like that used in the Mu-Tron and all its cousins, with switch selectable hi/lo/bandpass filters and notch. I wired it up so that it could be used in wah/anti-wah fashion. That ended up being particularly useful for the hi-pass setting, where the sound would be thinnest in heel-down, and fullest in toe-down. There was no envelope control in the one I built, but when EPFM II came out, Craig Anderton recommended using the stand-alone envelope-follower module to auto-sweep the STC.
I guess what this thread needs to do next is generate a standardized mod for Mu-Tron/Neutron/Q-Tron users that will permit foot control, and over-ride the envelope control.
Quote from: digi2t on December 14, 2011, 03:15:06 PM
Quote from: DiscoFreq on December 14, 2011, 02:43:34 PM
I have one of these that needs some repair... :-\
What's wrong with it?
I think it was a problem with some of the settings (LFO/envelope/...) not sweeping the filter as they should, but I should check again, it's already 2 years since I tried it...
Well Mark, it's a shame that the pedal pot is being held in a vise for the time being, and not inside a wah pedal. I think being able to reverse the sweep would be a hoot, apart from all the other bells and whistles on this puppy.
As for a Mutron foot control mod, using the Foxx and Mutron schematics, we can see that we can graft the pedal and LFO part in fairly easily to the Mutron. Maybe a jack in the side of the Mutron, and a rebuilt wah with the extra circuitry on a small board that plugs in? I think, Plug n Play of sorts. Am I out to lunch here?
This thing has really sent my imagination on a magic carpet ride :icon_mrgreen:.
I already have the empty wah shell ready for it (move over Ludwig Phase II build :icon_evil:). As soon as I finalize everything on the board, it'll be vero and build time again.
The wah-antiwah thing is relative to how one intends to "express" with a given filter type. Certainly bandpass works "best" with forward providing the most emphasis, since that's where all the harmonic content lives. Lowpass tends to work a bit betterwith foot-forward opening up the filter, though closing the filter with foot-forward is useful too. Personally, I found that sweeping the cutoff downward with foot forward worked better in hipass mode, since that would result in the guitar having "more balls" the more bandwidth you gave it, and more bandwidth meant flipping the sweep in the other direction.
Direction reversal for autosweep is an entirely diffeerent thing than foot sweep, because there is a sort of "psychic link" between verbal expressive intent (and wahs/filters are always a translation of what you want to do with your mouth into something done with your foot) and how you want to move your foot. EXpressive intensity is inextricably linked to moving forward, not backward. Or at least that's how MY brain/foot works.
The downside to having switchable wah/anti-wah sweep is that the pot MUST be linear, or else you end up with a whack job taper trying to go in the other direction. Gotta sweep the same way i the one direction as the other. That may not work for everyone's tastes, although I suspect that the sonic difference between a state-variable filter and the oddball bandpass of a Cry-baby obliterates any memory of taper preference in a wah.
Don't forget to give yourself a notch-filter setting (HP+LP), in addition to a variable Resonance control. The schematic shows a two-position setting for Q, using a 100k and parallel 22k resistor. NO reason why that can't be a 15k in series with a 100k pot.
Quote from: Mark Hammer on December 14, 2011, 06:49:46 PM
Don't forget to give yourself a notch-filter setting (HP+LP), in addition to a variable Resonance control. The schematic shows a two-position setting for Q, using a 100k and parallel 22k resistor. NO reason why that can't be a 15k in series with a 100k pot.
Thanks for the heads up Mark. It's already there on the board, the hi/lo, and the Q. The Q is a 12K resistor with a 100K pot. I figured why have a switch, when I can have a pot instead. According to R.G.'s Neutron article, he states that the Mutron had a 150K pot. He recommend using a dual gang 100K in series, but I found 200K pots on EBay, so I'm going with that. I must say though, the 100K does a nice job. They will be part of the finished product, for sure.
As for the voltage divider to balance the up and down modes, the 250K is OK, but it's still out a touch. I have a 500K trimmer, so I might try to cheat. A pair of 470K resistors across the lugs will give about 326K. I'll see if it does the trick.
I keep reminding folks that upward and downward sweeps on autowahs are not simply the direct opposite of each other. The feel and starting/ending points of each generally need to be a little different for the most "musical" sounds. All the Mu-Tron derivatives tend to acknowledge this by adjusting the start point for downward sweep a bit. Of course, that doesn't mean the adjustment suits our individual tastes.
Do you have a copy of either EPFM 1 or 2 or the Super Tone Control project? I can scan it for you if need be.
The notch setting produces something functionally equivalent to a Phase 45, so with the LFO moving it around, you get yourself a simple phaser for free.
Finally, the über-version would have either a send/receive loop between the input stage and filter, so you could sense the envelope prior to external processing, or a dedicated clipping circuit to feed the filter something more harmonically rich....just like the Q-Tron+ does
QuoteDo you have a copy of either EPFM 1 or 2 or the Super Tone Control project? I can scan it for you if need be.
No, and yes please.
QuoteFinally, the über-version would have either a send/receive loop between the input stage and filter, so you could sense the envelope prior to external processing, or a dedicated clipping circuit to feed the filter something more harmonically rich....just like the Q-Tron+ does
Funny you bring that up. Today I found an article by Beigel and Randall on Envelope Controlled Filters, and lo and behold, there's a section on adding a loop. Very well written for the noob like me. I'm sold on the loop.
I did try J.C. sensitivity control tonight, but it didn't really blow my skirt up. The effective range was very small, and nearly all at the end to the dial. I'll stick to the resistors. Speaking of which, I err'd when I said previously that the Mutron had two 22K's next to the up/down switch. It's a 12K and 22K, like the Foxx. My copy of the Mutron diagram wasn't the cleanest, and I found a cleaner one today, showing up my erroneous statement. My apologies.
The "cheated" trimmer works better than the 250K, or 500K. A 500K, with two 470K resistors across the lugs, does the job better. It seems to dial in a more balanced response down versus up. I'm assuming because the resistances on either side of the center lug are closer to the original specs than before. I've got it at 235K/65K, versus the 150K/82K spec'd, but it sounds very good. 330K trimmers are available, but not in multi-turn Bourns, which I prefer. I'll just add the resistors to the vero when I get there. I just have to decide on where I like my sweep right now. It seems that every day I tweak that damn trimmer a bit. I'm just trying to spread the love between the HP and LP I guess.
I'm going to try the loop next. Afterall, I have to shoe horn this puppy into a Crybaby. Besides, like the Skyripper, I prefer to have the option of what I want to plug into the loop. Good for people who get bored easily :icon_lol:. If that works well, then I'm drawing this puppy up, and building it. I'm putting a fuzz box on the tarmac :icon_mrgreen:.
If you run out of space in the chassis, you can simply do what so many mixers do: use a single stereo phone jack for both send and return, like a sort of "mini-snake".
Alternatively, just use a single op-amp stage where the loop would go, and plunk a Distortion+ type circuit in there. Realistically, once the filtering is applied, the "character" of whatever is placed in there won't really shine through all that much, so there's no sense in driving yourself crazy about picking the "right" on-board source of extra harmonic content. Really what you're looking for is a simple clipping stage to intensify the filtering effect that you can toggle in and out. A Dist+ with a trimpot for adjusting gain and another to yield clip/no-clip volume balance, is pretty much all you really need.
Quotethere's no sense in driving yourself crazy about picking the "right" on-board source of extra harmonic content.
:icon_lol:
I get the feeling that you're starting to get to know me. I think that's why I'm leaving it somewhat open ended by going with a loop.
The mini snake idea reminds me of some pictures of older Schaller wah pedals that i came across recently. It wasn't for stereo or anything like that, they just had a jack, and a cable for the in/out. I don't think it was very practical though, if one wanted the pedal further away from the amp or instrument. It intrigued me for the longest time as to why my Schaller had a hole in the casing, right next to the switch. I thought it was a manufacturing thing, but I found out why recently when I saw the pictures.
Well, I decided to put down what I have so far. I also "modernized", including the MAX1044 that I'm using, the trimmer to balance the up/down modes, and the use of VTL5C3 Vactrols. The "Pedal/Envelope" switch is modded now to a DPDT to kill the +9 volts to the oscillator, effectively doing away with any possibility of ticking in the audio. I did not use the 20K and 220K resistors in the filter section as per the Foxx. Instead, I went with the Mutron diagram, and sent these two pins to ground.
This makes things a lot clearer than that other "chicken scratch" diagram.
(http://i214.photobucket.com/albums/cc196/digi2t/Foxxguitarsynthschem_1.jpg)
I haven't added the effect loop yet, but I haven't tested that yet, and I can just update this diagram later. This drawing will give you a working effect though. It sounds pretty good on the breadboard. I forgot to mark down what my trimmers are reading though. I'll put that down when I update, since it will give a good starting point for tuning if anyone else decides to build this.
I'm testing the effect loop tomorrow, and from what I read in the Beigel/Randall article, I think I should be splicing it in between the buffer and the VCF. I just not sure if it should be all before, or after the 4.7K resistor. Or, if "IN" should be before the resistor, and "OUT" after the resistor. I guess testing will tell.
I am debating whether I should make this true bypass, or just leave it as is. I don't know how it will "play" with other effects right now, so I'll leave it in stock trim for the time being. It's easy enough to convert to T.B. if need be.
*edit* - After a good nights sleep, I thought of looking at the Meatball circuit. Shows very clearly where the effects "send/return" should be. :icon_cool:
well done again, dino...
are you gonna do a vero of this one, too? i hope? :icon_redface:
OK, version 2...
(http://i214.photobucket.com/albums/cc196/digi2t/Foxxguitarsynthschem_2_2.jpg)
This one has the effects loop, and the output volume as well. I figured the volume may come in handy if you're using the effects loop, to match up with any other effect one might decide to use. Also changed the 3.3uF cap to 4.7uF tantalum, since that's what is on my board. 3.3uF works fine as well, but at the time, I didn't have any. I'm sticking with the 4.7uF. Also, the 10uF cap going to the detector is now a 1uF.
It was kind of bugging me that I had these open ended connections insofar as the loop is concerned, but I don't seem to be picking up any noise when nothing is plugged in. Besides, I lifted this from the Meat Sphere, which seems to have an overdrive in it already. Since the Foxx doesn't, it doesn't really have anything to loop around. Then I thought about the Skyripper, and I noticed that if you're not in Ripper mode, with nothing in the loop, the connections are open ended, so it should be fine. I'm speculating here, so, Mark, you can chirp in anytime now :icon_mrgreen:
All in all, the loop works fine. I tried it with a Geiger Counter, and an Uglyface. The result was quite satisfactory. The filter really goes to work on the signal. The 10K resistor fits in nicely to keep the loop, and the filter, at more or less even gain when bypassing the external effect. There is a slight loss of "wonkiness" (in the higher frequencies) when the effect in the loop is bypassed, but I can live with it. Nature of the beast, I guess.
On to vero-land now :icon_smile:
great job! will build this very soon
thanks for sharing
Dino, there might be a typo on Z2-2, both inputs are tied together. Another thing that has me baffled is how the flange outputs are any different to the HP and LP outputs, except for the series resistors 47K and 68K. Other than that, looks like you got it sorted. From the vids you did, I think there will be some really nice fat rich wah sounds come out of this one! Very tempting.
Good catch Ian. I also spotted that, plus a mistake above Z2-3, with an extra line between the diodes. I've corrected it. I'm removing the other schematic as well, it had the same errors. Besides, the v.2 drawing has most all the elements of the original drawing, plus some added goodies. If anyone wants to build a Foxx in stock trim (or an upgraded Mutron?), it's an easy retro-grade.
BTW, I'm convinced, that "brown turd" on the pot is the 2.2uF capacitor. I did a bit of research, and they are available in metal film, box and axial form. I'm not sure whether it being non-polar really makes a difference in this case (for the LFO), but I do know that the metal film has a tighter tolerance at 5%. Going to bed less stupid, again :icon_mrgreen:.
As for the "flanging", I'm only using the term that's on the original diagram. It ain't no flanger. It's more useful in LFO mode. I think the resistors are cutting back a bit on the filtering, so more of the guitar signal cuts through. More like a background shimmer of sorts. The bigger resistor on the LP makes sense, since the bottom end cuts through more than the HP. Personally, I debated keeping this, but I didn't want to massacre the original circuit either. I prefer to keep the idiosyncrasies that made these pedals special, "ahead of their time", or just plain stupid, for their day. That's the mojo factor I guess, it reminds us from whence we came.
Back to the vero board... and more head busting. I've got to fit this into a Crybaby :icon_eek:
The "flanging" (cough, cough) setting is simply the notch produced when highpass and lowpass outputs are combined. The Anderton Super Tone Control does this. While it certainly can be used in foot-control mode, it tends not to be as noticeable an effect as the other 3 modes, simply because it retains much more than it filters out. If you feed it a very harmonically rich source, it becomes more noticeable, though. Used in LFO mode, it is functionally equivalent to a Phase 45, that produces a single notch.
The notch that IS produced occurs because of the manner in which the highpass and lowpass functions are produced. because neither of those are particularly steep, and they don't overlap, they leave a small zone where stuff falls below the corner frequency of the highpass, but above the corner frequency of the lowpass, producing a moving midscoop.
I draw your collective attention to the difference between the Mu-tron and Meatball with respect to how the two variable resistances in the filter are swept. The Meatball uses a 120k fixed resistor in parallel with the LDR in the first section and the standard 220k for the second. I remember a discussion way back when we were trying to decipher the Meatball, where someone noted that this tended to produce a sweeter, more musical, change at the highest points in the sweep. Never tried it myself, but iof you still have it on the breadboard...
Finally, why is the return in the loop brought back to the inverting input in the re-draw? One would think that the send/receive loop would interrupt the 4k7 path to the second op-amp. I can see why one might be interested in futzing with sum/difference things, but the loop is intended to provide a pre-processed signal that doesn't interfere with envelope detection.
QuoteFinally, why is the return in the loop brought back to the inverting input in the re-draw?
Hmmm... major brain fart (or too many night shifts!) on my part. As I mentioned before, I was looking at the Meat-Sphere, and the blinders went on :icon_redface:. As the old adage goes about assuming... don't! Thank God guys like you are around to spank us out of our temporary stupor :icon_lol:. I did find that it sounds better with the loop behind the resistor, especially with high gain devices like an Uglyface. I tried all the different configurations (pre, mid, post), and what is on the drawing worked best for me. Redraw, coming up!
(http://i214.photobucket.com/albums/cc196/digi2t/Foxxguitarsynthschem_2_3.jpg)
As for the variable resistances, it so happens that it's still on the breadboard, and I was using 500K trimmers sub'd in for the 220K resistors on both LDR's. I went on a hunch early on that this might be a place to fool around with the circuit. I did try the Meatball settings, along with a slew of different combinations, but in the end, they always found their way back to 220K. It especially didn't produce any positive results with a high gain device in the loop, I was getting some howling in the sweep when trying lower resistance levels.
Here's a short video of the effects loop in action;
Sorry about the sound quality, I should have turned the amp down a touch. I only used the H.P. and B.P., resonance at about 50%, but the filtering really pops the dirt right in the Chicklets. I like. I keep.
Alrighty then... here's a vero. If anyone would like to peruse it for errors, I'd greatly welcome it. I'm still going over it myself, but sometimes, things get blurry after a while :icon_biggrin:
(http://i214.photobucket.com/albums/cc196/digi2t/Foxxguitarsynthlayout1_1.jpg)
Although it's a bit big, it can still comfortably reside inside a Crybaby, sideways. If anyone can see a way to shrink it more, please pipe up, but 2 Vactrols take up board space.
There are off-board connections, but I didn't put them on the layout just yet. The schematic fills in those blanks. Once the vero is verified, I'll add them to the layout, to consolidate things.
I also changed the name to the "Muttoxx", seeing how Foxx is back in business. Besides, there's more Mutron than Foxx in this thing anyway. Hence, a "mutt". Other name recommendations are heartily welcomed. God know there are people out ther with a lot more imagination (or time) than me :icon_mrgreen:.
*EDIT* - Just spotted a missing cut under R23. Noted, and corrected on future issue.
Hi Dino, just doing a check on the vero, and you may have already found it, but it looks like pins 9 and 10, and 11 and 12 are mixed up on the upper TL074. (10 and 12 should go to gnd, not 9 and 13). I can't find the second 10uF cap on the MAX1044. The ENV. SENS POT 2 at the top left needs to move down one row. I ordered some TL074, will try it with discrete LED's and LDR's instead of vactrols, and see how it goes.
Edit: oh yeah, its boxing day over here now, hope y'all have a great Christmas day!
Quote from: Ronan on December 25, 2011, 06:04:12 PM
Hi Dino, just doing a check on the vero, and you may have already found it, but it looks like pins 9 and 10, and 11 and 12 are mixed up on the upper TL074. (10 and 12 should go to gnd, not 9 and 13). I can't find the second 10uF cap on the MAX1044. The ENV. SENS POT 2 at the top left needs to move down one row. I ordered some TL074, will try it with discrete LED's and LDR's instead of vactrols, and see how it goes.
Edit: oh yeah, its boxing day over here now, hope y'all have a great Christmas day!
Thanks a bunch Ian. Nice of you to take a look. At some point, I can't see the forest for the tree, so it's nice to have an objective eye. The second cap for the MAX is located more towards the center of the board, to the right of the chip. Your observations have been duly noted (and greatly appreciated!), and I'll make the necessary corrections.
I'm going to try and put together 2 LDR's, and an LED, into a package. I gutted an FRN type fuse, cutting the ends off. It's a nice, 3/8" diameter, black fiberglass tube body, which I'll encapsulate the LED and LDR's inside. That way I'll save the Vactrols for something else. I'll take pics of the process, if it works out, I'll post them.
All the best wishes to you and your family this holiday season.
Cheers,
Dino
The loop may not be working well for you because of what isn't in front of Z2-2. Seems pretty sparse to me. You probably want an RC network in there. Alternatively, take a look at the Colorsound Vocalizer and the EHX Talking pedal. Note that they feed the input to a clean gain stage and a diode clipping op-amp stage, with their respective outputs fed to the outside lugs of a panpot. That permits for continuous variation of how much harmonic emphasis you want to add.
http://www.freeinfosociety.com/media/pdf/4101.pdf
Quote from: Mark Hammer on December 26, 2011, 09:00:15 PM
The loop may not be working well for you because of what isn't in front of Z2-2. Seems pretty sparse to me. You probably want an RC network in there. Alternatively, take a look at the Colorsound Vocalizer and the EHX Talking pedal. Note that they feed the input to a clean gain stage and a diode clipping op-amp stage, with their respective outputs fed to the outside lugs of a panpot. That permits for continuous variation of how much harmonic emphasis you want to add.
http://www.freeinfosociety.com/media/pdf/4101.pdf
Hi Mark,
First off, best wishes to you and your family this holiday season. All the very best.
My first time around with the loop wasn't so great, because I wasn't injecting the return into the right spot. As you mentioned earlier, I should have simply interupted the path where the 4.7K resistor is, this worked much better. Rather, I simply copy/pasted the circuit from the Meat-sphere, and incorrectly returned to the inverting input of the op-amp. I really would like to stick to the loop idea, leaving the pedal open for "outside influences".
As for an RC network, I don't have any experience in the concept, so I guess I'm going to have to get up to speed on that as well. If you have the time to give me some of your wisdom, I'd appreciate it. In the meantime, I'm hitting the net on this one. More to learn.... yyyaaaaaaaaa :icon_mrgreen:
As for the vero, I found a bunch of errors, due to the fact that I managed to find a bum pinout diagram of the TL074. That sucker lead me completely astray, :icon_mad: :icon_mad: :icon_mad:. Thanks to Ian for initially pointing out the tip of the iceberg. Owe you one brother.
I adjusted the vero to the correct pinouts, tweaked some switch numbers, plus added some other stuff that was missing (filter cap, and pot). Posting it for verification purposes only. I'm going to trace it again tomorrow.... very carefully (it's personal now!). I also updated the schematic to add the filter cap.
(http://i214.photobucket.com/albums/cc196/digi2t/Foxxguitarsynthschem_2_5.jpg)
(http://i214.photobucket.com/albums/cc196/digi2t/Foxxguitarsynthlayout1_4.jpg)
Off to bed now...
OK, one tiny error with R21, but it's corrected now. All the pinouts line up, as does the rest of the circuit. I'm comfortable enough now to go to vero.
I made sure to throw out that damn stupid pinout abortion that I printed the other day :icon_evil:. That taught me to verify, verify, verify.
Mark, if you'd like me to try something funky here (well... not TOO funky) with the loop, let me know. I don't mind being the guinea pig :icon_mrgreen:. Going to read up on RC networks today.
One of the better uses of such a loop is filtering a synthesized octave-down. Because those tend to be finicky with respect to triggering, and also tend to provide a rather non-dynamic signal, it is usually best to extract an envelope before feeding one. Of course, because they generally produce square-wave outputs, they provide a nice harmonically rich signal for filtering. Sticking something like a Blue=Box, or similar, in the loop is a natural combinations, liked pie and ice cream.
Just wondering out loud here...
Would a VTL5C3/2 work here? Use the center (common) pin of the LDR side to connect to pins 7 and 8 of the IC. Then one leg to 9 (one LDR), and the other to 13 (the other LDR)?
Hmmm, I have some. Time to try it while it's still on the breadboard :icon_mrgreen:
I went over the latest vero revision, just a minor error, D1 and D2 appear to have the band at the wrong end. All else looks fine.
On the shematic, C10 on the MAX1044 shows reverse polarity, and the option for T2/VR2 shows a short circuit from 9V to ground.
I think you got it pretty well nailed now Dino :)
Quote from: Ronan on December 27, 2011, 05:32:39 PM
I went over the latest vero revision, just a minor error, D1 and D2 appear to have the band at the wrong end. All else looks fine.
On the shematic, C10 on the MAX1044 shows reverse polarity, and the option for T2/VR2 shows a short circuit from 9V to ground.
I think you got it pretty well nailed now Dino :)
D1 and D2 fixed. C10 was backwards on both, corrected. T2 corrected as well.
I don't know why this sucker has been so problematic. To much X-mas cheer maybe :icon_mrgreen:.
Please... don't drink and draw.
Thank you sir.
Quote from: digi2t on December 27, 2011, 03:39:26 PM
Just wondering out loud here...
Would a VTL5C3/2 work here? Use the center (common) pin of the LDR side to connect to pins 7 and 8 of the IC. Then one leg to 9 (one LDR), and the other to 13 (the other LDR)?
Hmmm, I have some. Time to try it while it's still on the breadboard :icon_mrgreen:
OK... I went, I tried, I got my ass kicked. It doesn't work. Guess I'll try doing the custom Vactrol job.
Here's a video of the custom Vactrol results. the build report for the Vactrol are here; http://www.diystompboxes.com/smfforum/index.php?topic=95269.0 (http://www.diystompboxes.com/smfforum/index.php?topic=95269.0)
This baby will be going into the build, rather than the twin VTL's. It sounds better, and is cheaper than the VTL's. The dynamics are much better, especially in BP, and LP mode. I was never completely happy with the LP mode, thinking it a bit muddy for my liking. Much cleaner now.
One note though, the 25K trimmer for tuning the range, had to be changed to a 500K. This Vactrol is running around 116K for the LED, whereas the twin Vactrols were down around 19K. You can use a 250K as well, but I didn't have any, so a 500K was pressed into duty. I retained the 270 Ohm resistor as the backup to ground.
Thanks to Ian for pointing me towards the LDR's. They were meant for the Talking Pedal, but work beautifully here as well. The LED is a 5mm clear bright white, available at Mammoth Electronics.
Thanks also to R.G. for his recommendation of black gelcoat tint, mixed with the 5 minute epoxy, to cap the ends of the tube after everything is set. Sheer brilliance.
I've reworked the drawings to accomodate anyone who wishes to roll their own Vactrol like mine. The nice part with the custom Vactrol is that it takes up less room on the vero, thus reducing the footprint. The vero should fit both ways into a Crybaby now. I've also included an updated schematic, that reflects the vero.
(http://i214.photobucket.com/albums/cc196/digi2t/Foxxsynth1Vactrollayout1_2.jpg)
(http://i214.photobucket.com/albums/cc196/digi2t/Foxxsynth1Vactrolschem1_1.jpg)
This is the layout I'll be using to verify the build.
If anyone is going with the dual VTL5C3 build, please let me know how it works out, so I may stamp a verified on it.
gonna be a while bro, but eventually i wanna build it!
great job all around, keep it up, and happy new years my brother!!
;)
Thanks bro. Here's a pic of the board just about populated. I'm missing the 220K resistors, they're in the mail :icon_sad:
(http://i214.photobucket.com/albums/cc196/digi2t/PICT0140.jpg)
The off board wiring is gonna be real spagetti :icon_mrgreen:.
Yeeee Haaaw, it works!!!
I discovered two small errors, which I corrected on the vero and the schematic, and are reflected above. They tuckered out my troubleshooting hamster today, but perseverance prevailed. I've marked them as verified as well. I'll be uploading the updated versions to the gallery as well.
Video will be posted tomorrow.
:icon_biggrin: :icon_biggrin: :icon_biggrin:
this thread is awesome. my first time delving into it. dino , you are a legend in the making.
Quote from: joegagan on February 23, 2012, 11:54:27 PM
this thread is awesome. my first time delving into it. dino , you are a legend in the making.
Thanks Joe! I'm very honored by your praise, since there are a bunch of you "pedal Jedi's" that I look up to, you among them. Thanks for throwing another shovel of coal into my fire.
Well, as promised, pics and and a vid.
I was lucky to come across this behemoth, the EXR Projector. It was marketed back in the 80's as a sort of "aural enhancer". In reality, was a fancy volume pedal, really crap weak wah ,slash paper weight. The latter, being it's best trait. But, casing wise, this thing is hoooooge, dwarfing a Crybaby. Also, it's SOLID cast aluminium, I mean heavy. No... I mean cave-somebodies-skull-in heavy. Keep this baby next to the night table, in case of a home invasion. You can subdue the perp, and in a pinch, this baby will take a bullet or two. Anywho, for a real "switch n' knob" monster like this project... perfect! I was lucky enough to find two, here is an unmolested one, next to a Crybaby, for size reference.
(http://i214.photobucket.com/albums/cc196/digi2t/Muttroxx/DSCF0703.jpg)
I proceeded to gut the casing, but since the switches, and pedal were PCB mounted, I decided to keep the parts of the boards that I would require to use for the Muttroxx. The real bonus was that there was a fourth switch, hidden inside. Since the original pedal ran on 120vac, the hidden switch served to switch the tranny over to 220vac if required. Lucky again, I could flip the switch around, drill a hole in the casing, and viola!, I have my UP/DOWN switch. There is also a segmented LED section, which on the original served as an output level meter. I used this as well, blacking out alternating LED's, and now it's a filter selection indicator. 3 green LED's for the pass filters, and the last 2 yellow for the flanging. From left to right; Pedal/Envelope selector switch, Resonance pot, Hi/Lo range toggle, Output volume, Bypass switch.
(http://i214.photobucket.com/albums/cc196/digi2t/Muttroxx/DSCF0707.jpg)
On the right side, the Wah/Speed selector switch, and the Filter selector rotary switch.
(http://i214.photobucket.com/albums/cc196/digi2t/Muttroxx/DSCF0709.jpg)
On the left side, the Envelope sensitivity pot, and the Up/Down selector switch (this was the hidden one inside). I actually had to use a counter-boring bit, to take down the thickness of the casing for the pot. I was way above the threads here. Like I said before, this thing is "built like Russian tank Comrade"!
(http://i214.photobucket.com/albums/cc196/digi2t/Muttroxx/DSCF0708.jpg)
On the front, power jack, and effects loop jacks.
(http://i214.photobucket.com/albums/cc196/digi2t/Muttroxx/DSCF0705.jpg)
Now the guts. Like I said before, I recycled the boards from the original. Mouser and Digikey still stock the exact type of switches and slider pots as well. Even the little chrome tops for the switches! Here are the part numbers, in case anyone decides to take on this adventure;
Slider pot - Mouser P/N = 312-9201F-1M
Pushbutton switches - Digikey P/N = 401-1226-ND
Chrome switch caps - Digikey P/N = EG1099-ND (These come in colors as well)
I swapped out all the switches for new 4PDT's, and the pot had to be replaced, since the original was 10K, and this calls for a 1M. I stripped the two boards of all components, cut all the traces that may have conflicted, and chopped out a section of the main board, for access to my new board.
(http://i214.photobucket.com/albums/cc196/digi2t/Muttroxx/DSCF0712.jpg)
This is a wiring monster. Not for the faint of heart. My Mr. Multi build was good training for this sucker. Good fat harness in here brother! Unfortunately, the harness is hiding the custom vactrol I made for this project. Info on the custom vactrol construction is here; http://www.diystompboxes.com/smfforum/index.php?topic=95269.0 (http://www.diystompboxes.com/smfforum/index.php?topic=95269.0) . The off-board wiring is taken from the schematic, since my vero layout is already pretty heavy. What I recommend before starting, is to highlight all the lines on the schematic that represents wiring. It will be easier to progress through it when you get to that point.
(http://i214.photobucket.com/albums/cc196/digi2t/Muttroxx/DSCF0713.jpg)
Here is a shot of the secondary board, which the pot, and some of the switches and LED's are mounted on.
(http://i214.photobucket.com/albums/cc196/digi2t/Muttroxx/DSCF0714.jpg)
And a close up of the pot workings. Pretty simple, just a silicone tube, in an eye hook, and the slider actuator fits snuggly into it.
(http://i214.photobucket.com/albums/cc196/digi2t/Muttroxx/DSCF0710.jpg)
Now the meat and taters. The different filter selections, along with the Hi/Lo selector give you a great range of filtering. In it's essence, this is a Mutron III ripoff, with a wah or LFO speed selection added. That's why I renamed it the Muttroxx; Half Mutron, half Foxx. A mutt! The added trimmer for balancing the Up mode against the down mode works quite well, once set up. The Envelope sensitivity can be tweaked to give you just the right WAHP (or PHAW :icon_lol: in down mode). Basically, one could really tweak this to get along with just about any input.
Once again, I have to thank Mark Hammer here for the effects loop idea. You can plug in your fav dirt pedal, or get crazy with a delay, whatever your heart desires. So, without further ado, the customary video. Unfortunately, I don't have the camera charisma (or chops!) of say, a pinkjimiphoton, but hey...what's a guy to do. :icon_lol: Gives a general overview of what the clone sounds like.
By far, one of my most complex builds, but very satisfying when things come together. I'd never fork out 1300$ for original, but I would recommend building one, if you've got a hankering for an auto-wah.
Another step in preparation for the Ludwig Phase II clone build. I'm hoping to use the second EXR for the Ludwig.
Many thanks again to the forum, and all who helped out with info and encouragement. Rock on brothers!
Cheers,
Dino
*EDIT* - Just had to add a mod here. In Envelope mode, I was getting a high pitch whine, that I managed to trace down to the LFO section bleeding into the audio path. I then found that I would only hear it if the Pedal Mode switch was in the Speed control setting. In Wah setting, it would disappear. Looking at the diagram, I realized that the pot was going to ground in Wah mode, so it would kill the LFO whine. In this case, the Pedal/Envelope switch has to be a 3PDT (with a ground and +9 going to this switch, you can still power LED's if desired). Use the spare pole on the switch to ground pole 2 on the pot when in Envelope mode. This will kill the LFO completely, no matter what the pedal position, and eliminate any possibility of noise from the LFO section. I had already modded the original circuit by cutting the +9v to the LFO, to get rid of the ticking. Unfortunately, it wasn't until I packaged the deal that this problem popped up. Anyway, problem solved. I've updated the schematic accordingly.
Time to rest my hampster.... again :icon_mrgreen:
I have one of those EXR's too, but I think I still have to test it (didn't have a 220v to 110v converter when it arrived a few years ago). You're right, it's VERY heavy :icon_mrgreen:
Quote from: DiscoFreq on February 24, 2012, 12:12:30 PM
I have one of those EXR's too, but I think I still have to test it (didn't have a 220v to 110v converter when it arrived a few years ago). You're right, it's VERY heavy :icon_mrgreen:
Yeah... if this pedal was a ship, then it's the USS Missouri :icon_lol:
Excellent job there Dino! Wonderful bit of engineering gone into that "battleship".
I have a build under way today. It's going into an Aria wah shell, with a simplified user panel (read less bells and whistles), but it will have the mandatory send and return jacks for using a dirt pedal in ENV mode :)
here's a pic (http://dl.dropbox.com/u/61170900/Muttrox%20build1.JPG)
If the jumpers on the PCB and the home-grown Vactrol look familiar, its because Dino graciously gave me a nice pre-prepared vero PCB! Thanks mate, looking forward to seeing how this turns out.
Quote from: Ronan on February 25, 2012, 12:29:42 AM
Excellent job there Dino! Wonderful bit of engineering gone into that "battleship".
I have a build under way today. It's going into an Aria wah shell, with a simplified user panel (read less bells and whistles), but it will have the mandatory send and return jacks for using a dirt pedal in ENV mode :)
here's a pic (http://dl.dropbox.com/u/61170900/Muttrox%20build1.JPG)
If the jumpers on the PCB and the home-grown Vactrol look familiar, its because Dino graciously gave me a nice pre-prepared vero PCB! Thanks mate, looking forward to seeing how this turns out.
Your very welcome friend! One good deed ALWAYS deserves another :icon_wink:
BTW, I noticed that you don't have the latest version of the schematic there. I've updated it since, and explained why in my edit, at the end of the build report above. Basically have to add another wire, and a switch type change, but very important to the operation. The problem didn't manifest itself on the bread board, but once you pack everything together, it bleeds into the audio. I'm very surprised that the original didn't deal with the LFO noise. Then again, maybe that's why they never made a big splash.
You may want to test that vactrol, to be sure that it's working properly. When I was making it, once I put it together, for some reason the LED failed. Luckily, the epoxy was still soft enough for me to open it up, and change it. I tested it again before I sent it to you, but if you could validate it's operation, it'll remove a little black cloud hanging over my head. It's funny, I never had a problem with mine. Guess I laid my hand on a weak LED at the time.
I've been fiddling with the trimmers mine, and I think I've got it just about to my liking. Once I'm satisfied, I'll take some readings, and pass them on to you.
No worries, the vactrol is tested and working. I forgot to refresh the browser, hence the older schematic. I'm thinking of going without the LFO, so will be using the Pedal (without speed) and Envelope modes. Got a few holes to drill today...better get moving on it :)
Edit: a quick question, do we really need a volume pot on the outside or would an internal trimpot suffice?
Quote from: Ronan on February 25, 2012, 04:44:53 PM
No worries, the vactrol is tested and working. I forgot to refresh the browser, hence the older schematic. I'm thinking of going without the LFO, so will be using the Pedal (without speed) and Envelope modes. Got a few holes to drill today...better get moving on it :)
Edit: a quick question, do we really need a volume pot on the outside or would an internal trimpot suffice?
Hmmm, that all depends on your set up I guess. Since I run all my effects through a midi matrix router, it means that I can mix and match my effects chain and order any way I want. I've found that it's useful for me to have a volume on each effect for balancing when creating a particular chain. It really depends on whether your needs really require an external pot. If you're using a set order of pedals, then yes, an internal trimmer would be fine. Set it, and forget it. I would drill a hole in the cover plate though, so I could just use a trimmer driver to make an adjustment if necessary.
Looking at the vero, you've got a spot just below the 15uF cap for the trimmer. You should be able to shoe-horn it in there.
Now this is interesting, the Mutron III and the Neutron (RG's version) have one end of the sensitivity or gain pot unconnected. I think it is done like that so that the gain of the first stage is adjustable by the ratio of the 120K resistor and the variable resistance of the 1M gain pot. But the original schem of the Foxx synth wah on page one of this thread shows one end of the gain pot going to ground. Something to try.
Quote from: Ronan on February 25, 2012, 07:00:07 PM
Now this is interesting, the Mutron III and the Neutron (RG's version) have one end of the sensitivity or gain pot unconnected. I think it is done like that so that the gain of the first stage is adjustable by the ratio of the 120K resistor and the variable resistance of the 1M gain pot. But the original schem of the Foxx synth wah on page one of this thread shows one end of the gain pot going to ground. Something to try.
Dude, that one completely blew by me :icon_eek:. I've got to look into that one as well.
There is also the difference of input caps between the two, 10uF versus 4.7uF. I did experiment here, and I found that to my ears, splitting the difference at 6.8uF was good for me. You might want to fool around with the values here as well. Season to taste :icon_lol:
Another place you might want to play with is the cap going into the detector, 1uF on my schematic. Between the Mutron and the Foxx diagrams, it varies between 2.2uF to 10uF. Personally, I had a bit of a hard time picking up the higher register with the 10uF. There wasn't much difference between the 1uF and 2.2uF, but I went with the 1uF, because I could just tweak the Sensitivity to zone in the detector. No biggy.
Cut the ground on the Sens. pot.... hmmm....Hang on....
OK, better with the ground off. Not that you'll ever go that low on the Gain, Sensitivity, whatever you prefer, but if you do, at least you don't lose your signal completely. Left mine disconneted, and tye-wrapped it to the harness.
One other thing I just discovered (still exploring this sucker :icon_mrgreen:), in the high range, in pedal mode, if you go into speed control mode, you get the LFO ticking coming through the audio. Only in high range. If you go to low range, it's inaudible. It reminds me a bit of the fuzz percussion on the Ludwig Phase II. It seems that I read Mark Hammer's info on using a seperate op amp for the LFO too late in the game :icon_lol:. Oh well, personally it doesn't really bother me because to date, I've found that I'm on the low range most of the time. Maybe for fun, I'll try an RC network on the V+ side of the chip, or I could just redraw the vero to use two dual opamps, instead of a quad here. We'll see.
OK, tried the RC network, but no dice. Tock, tock, tock... Like I said, only in high range, and most prominant in low pass, less so in band pass, almost inaudible in high pass. In low range it's fine, in all filter ranges. Two seperate op amps should be de rigeur here, if one wishes completely tick-free operation.
*EDIT* - Been doing some reading, and came across a deticking strategy used in the Boss BF-2 flanger, again by a post by Mark Hammer, at the bottom of this thread; http://music-electronics-forum.com/t1073/ (http://music-electronics-forum.com/t1073/) . Man, that guy is golden! Anyway, looking at the BF-2 schematic, the strategy seems fairly easy to implement, so I'm going to try rigging this temporarily, and see if it does anything.
Thanks for checking that out. I finished the PCB last night, but found some unexpected engineering challenges today with the wah shell, so I probably won't get it wired up and running until next weekend. But all is well and looking very good at this stage.
Quote from: Ronan on February 25, 2012, 10:47:41 PM
Thanks for checking that out. I finished the PCB last night, but found some unexpected engineering challenges today with the wah shell, so I probably won't get it wired up and running until next weekend. But all is well and looking very good at this stage.
Is the Aria shell comparable to a Crybaby? If so, I found that the best pots for app's like this is PEC. He's a shot of my Mr. Multi clone, with a PEC pot (1M also);
(http://i214.photobucket.com/albums/cc196/digi2t/PICT0114.jpg)
Fits perfect, and is military grade. They also come with a long shaft (2" I believe) so you can cut it to length. They're a bit pricey though, at 9$ Can. a pop, but good for life though. You can order them from ABRA electronics. http://www.abra-electronics.com/categories/Potentiometers/P2W-Series%252d-2-Watt-Linear-Taper%252d-Long-Shaft/ (http://www.abra-electronics.com/categories/Potentiometers/P2W-Series%252d-2-Watt-Linear-Taper%252d-Long-Shaft/)
OK, that PEC pot is a good idea, I'm a bit new on wah setups, well, lots of things actually pedal-related. Abra has a large minimum foreign order, but there is one on ebay, looks good.
The Aria looks very close to the Crybaby, but I think it might be made in China and they fitted a steel L-bracket to mount the original 24mm Alpha pot, and didn't use the big lugs cast into the housing for a standard larger pot. This arrangement is a bit rough as the rack and pinion is operating a long way from the pot, causing undue stress on the bush inside the pot. Also it left me no room to mount a SPDT switch where I wanted to. I wanted to mount the new 24mm Alpha pot I bought in the large lugs, or cut the lugs out and use the angle bracket but move it closer to the rack to make room for the SPDT switch. The solution I found in my stash was in the form of a small lamp holder, which has a bezel that screws into the front of it so you can change the color of the bezel if you want. This lamp holder is like a bushing that has an internal thread and an external thread. It just happens the inside diameter and thread of the lamp housing fit the thread of the new 24mm Alpha pot I intended to use, and the outside diameter allowed the pot to fit nicely in the lugs, and the extra length allowed me to be actually able to mount the pot also, as the original threaded shaft was too short to get a nut onto it. Here's a close up shot of the arrangement. (http://dl.dropbox.com/u/61170900/Mutt%20pot.JPG)
With that sorted, and all the holes drilled, you can see I ended up with some sort of symmetry, (http://dl.dropbox.com/u/61170900/Mutt%20guts%20no%20wires.JPG) and here's a pic from above. (http://dl.dropbox.com/u/61170900/Mutt%20top%20view.JPG) As you can see I went for minimal options at this stage, pedal/env, BP/LP, sens and res pots, and send and return jacks. The caps are bent over at one end of the PCB since there is not enough vertical clearance inside the housing unless I grind off some cast bosses that were used to mount the original wah PCB. I can do that at work if required, I'll just see how it goes. Now the new apprentice at work needs some soldering and wiring skills so the pedal is going to work to hopefully be completed under my watchful eye. It will be a good learning experience for him, plus he expressed an interest in all things music and especially in wiring up a pedal. Hmmm.
QuoteIt just happens the inside diameter and thread of the lamp housing fit the thread of the new 24mm Alpha pot I intended to use, and the outside diameter allowed the pot to fit nicely in the lugs, and the extra length allowed me to be actually able to mount the pot also, as the original threaded shaft was too short to get a nut onto it.
Wow, that looks good. I've run into that problem before, but this is the first time that I've seen those bushings. Thanks for the heads up Ian! Going to hit my hardware store today, and maybe get a few to keep handy. The lay of the land looks very nice. Great work to date. Just one tiny thing though, I've found that it's better to mount the in/out LED on the side, just below the heel. It's much more visible there, especially if the pedal is an a heel down position, and you're looking at it from an angle. At the top, below the toe, it'll tend to disappear from view at times.
As for the the PEC pot, if ever you see anything you might need on this side of the pond, PM me. We can take a look at it, and if it's financially advantageous, I don't mind picking it up for you here, and posting it to you. You can just Paypal me instead. Sometimes, the cost, shipping, and/or conditions domestically are much better. ABRA for instance, has a store about 10 minutes from where my girlfriend works :icon_wink:.
Again though, NICE catch on that bushing! Killer man.
I got the envelope section running and tuned the caps. I Really like it! The filter works well, will try to do a sound clip later.
Great news!!! :icon_biggrin:
Looking forward to soundbytes. Maybe a video? :icon_mrgreen: I'm happy it works.
P.S. Let me know what you settle on for caps. Just out of curiousity. Thanks.
Sound clip, be warned its 6 mins long, 6 meg, 128 kb/s mp3, just noodling. If it gets boring, try 3:00 manual pedal with dirt, 4:20 manual pedal clean, 5:15 envelope clean. I used a marshall guvnor clone in the send/return for dirt. I'm using 6n8 ceramic caps in the filters, and I think the whole clip is with Low Pass selected. On this unit here, band pass will cut some bottom end and give some more top end, read "treble boost". Because I went with simple options, it turned out more complex. I left out the LFO, but then had to knock up a different voltage feed to the pedal pot to get it to work right, which it does well now. I can post that circuit later if anyone is curious.
sound clip (http://dl.dropbox.com/u/61170900/610%20clip.mp3)
EXCELLENT!!! Really nice. Sounds just like mine. Really helps validate the custom vactrol build as well.
It would be cool to post your circuit as well, since maybe someone would want build a stripped down version as well. I could upload it into the gallery as well, into my Muttroxx folder.
More knowledge = more power :icon_mrgreen:
Really nice Ian. Have fun with it buddy!
I'm just wondering if it wouldn't be easier just to put the five LFO parts in, but I can't work out what the output of the LFO opamp would be in WAH mode. I'm only using about 1.5V across the 1M wah pot. Dino, would you be able to measure the voltage at pin 1 of the LFO opamp, with the pedal in WAH mode?
Quote from: Ronan on March 02, 2012, 08:36:36 PM
I'm just wondering if it wouldn't be easier just to put the five LFO parts in, but I can't work out what the output of the LFO opamp would be in WAH mode. I'm only using about 1.5V across the 1M wah pot. Dino, would you be able to measure the voltage at pin 1 of the LFO opamp, with the pedal in WAH mode?
In wah mode, I'm getting a steady 8.47vdc to ground at pin 1. My power supply voltage is 9.14vdc.
I decided to add a 330K tapering resistor across the pot poles on the schematic. Like the Mr.Multi, it helps center the taper of the sweep in wah mode. Otherwise, it's too bunched up at one end. You can also use a 500K trimmer as well, for a bit more adjustment flexibility.
I've uploaded the updated schematic to the gallery, under "Dino's Stuff".
I'll give that 330K resistor a go Dino, I didn't get any pedal stuff done today except for a brief blast through this one, I am really appreciating the difference between pedal sweep and envelope-driven sweep, they are more different than I would have thought, I still need to play this pedal more to learn it. I really like the seeming slow attack in env mode when not pushing the envelope very hard, like a bowed effect, you can hear that in the last few seconds of that clip I did. The other discovery was hitting a chord in pedal (wah) mode with the filter closed and slowly opening it up (with dirt running for sustain of course). This filter starts off deeper than my amp can go (read a low rumble) and then opens up into a chord or whatever I just played, very nice, I don't have anything else that can do that.
QuoteThis filter starts off deeper than my amp can go (read a low rumble) and then opens up into a chord or whatever I just played, very nice, I don't have anything else that can do that.
Oh yeah, it can get pretty low, all depending where you set your range. Don't forget, this is a direct cop of the Mutron III circuit, which has been used on everything from guitar, bass, keyboards, and anything in between. It's very tunable to play nice with other instruments, high or low. :icon_cool:
Dear Sirs,
I have my friends Foxx Gtr Synth that does not work. There were a few wires unhooked. We are not sure where the one battery ground goes. We have one battery + connected to the middle upper terminal of the on/off and the negative goes ???? We have the other battery negative connected to the middle lower terminal of the on/off and the positive goes the the pin 2 of the circuit board with the orange wire. There were a couple of wire loose off of the circuit board. Does anyone know the color code/pinout of the circuit board. PLEASE HELP. Peace and God bless.
Quote from: Tony Bach on May 06, 2012, 06:42:00 PM
Dear Sirs,
I have my friends Foxx Gtr Synth that does not work. There were a few wires unhooked. We are not sure where the one battery ground goes. We have one battery + connected to the middle upper terminal of the on/off and the negative goes ???? We have the other battery negative connected to the middle lower terminal of the on/off and the positive goes the the pin 2 of the circuit board with the orange wire. There were a couple of wire loose off of the circuit board. Does anyone know the color code/pinout of the circuit board. PLEASE HELP. Peace and God bless.
The best I can do is to email you a pdf service manual. Please PM me your email address. It's not the greatest though, the layout image doesn't show the wiring, so the schematic is the only way to go.
If you're not comfortable with this type of circuit tracing, I recommend that you leave it to someone with some experience. Worse case senario, I don't mind doing it for you, but I will ask that you cover the shipping back and forth. That's it. Again, PM me if need be.
Cheers,
Dino
dino,
looky here!!
http://www.ebay.com/itm/1970s-Foxx-Guitar-Synthesizer-I-Studio-Model-9-Project-Broken-Vintage-Pedal-/280986112462?pt=Guitar_Accessories&hash=item416c13d1ce
Hmmm, veeeery intereeesting. Put it in my watch list, and see where it goes. If it stays low, maybe, but I doubt it will. I did download the pics though. Got a great look at the dual LDR setup, all exposed.
Thanks bro!
i'm watching it too bro, hope we don't end up in a bidding war. i will conceed in that case. ;)
just thought it interesting...i think it's the guy that posted here asking about how to re-wire the battery snap.
i downloaded your layout, i gotta find a BOM... i may try and build one...while the eyes aren't bugged out.
it WOULD be cool to add to the collection, tho, huh? ;)
Quotei downloaded your layout, i gotta find a BOM
If you downloaded my layout, you should have the BOM. It's on the layout. You are talking about this one?
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=47111&g2_serialNumber=1)
You'll need the schematic for the wiring though, it's a real Medusa. It's in my Gallery.
If you need me to roll you a custom Vactrol, just say the word. The layout was designed around it. Or, you can use two VTL5C3's, wiring the LED's together in series. I've tried that, and it works as well, though my Vactrol has more... WHONK, to it.
i am BRIAN dead i think...
yah, i got it on my desktop...thanks for the tips bro!! ;)
I should warn you right now, for the most part, great circuit. But...
Since the LFO is part of a quad opamp, it's prone to ticking in some modes. Especially bad in HI mode (think Ludwig Fuzz Percussion!). I've thought about a redraw, to divorce the LFO section from all this, but since I use the envelope and wah aspect of it for 99.9% of the time, I didn't bother.
Wouldn't surprise me if the original is plagued by the same problem. I'm not sure if a resistor/cap reserve on the +9 pins of the IC's would help either. I have to try it I guess.
diggit, thanks for the heads-up...maybe separating the grounds with a cap would work?
seems to me, i'd probably use it the same way you do anyways, lol!!
great minds and all... ;)
well, not quite, but you know what i mean. :icon_mrgreen:
if it's got yoy.... ;)
MAJOR UPDATE!!!After having had the opportunity of exploring an original Foxx Guitar Synth in the flesh, I discovered an error in the wiring for the Arpeggio Hi/Lo function. This was partly due to the, um... vagueness :icon_rolleyes:, of the original schematic. The error pertains to what is called "flange" in the schematic, but is more accurately an arpeggio function. In reality, there is no flanging going on here, but rather, a sort of arpeggio "cascade of notes" effect.
This section of the effect is meant to be used with the LFO engaged, or else it does not do anything. Quite cool actually. Very cool to be honest. Blew my mind when I heard it.
Here is the updated schematic;
(http://i214.photobucket.com/albums/cc196/digi2t/Foxxguitarsynthschem_2_6.jpg)
In the original unit, the rotary selector switch is a DP5T. In Arpeggio mode, the second deck handles routing the signal either through a 22K resistor for HI, or a 100K for LO. In my unit, I have the J.C. Maillet resonance pot mod, so the Hi/Lo selection deck is not required, since I can sweep through the Hi/Lo range with the pot.
If you're using the original resistor setup, then use a DP5T, and use the second deck to switch between resistors. If you're going with the resonance pot and 12K resistor, then you can use a SP4T, and bring the "Flange Hi" and "Flange Lo" wires from the board to a single pole on the rotary switch. Then you can use the resonance pot to dial in the arpeggio range. Personally, I like this better, it's more flexible. If you're going original, use the DP5T, and use the 22K and 100K resistors, with their connected ends going to the B.P. line (imagine the 200K pot replaced by a stright line).
Just an added bonus, I used a DP4T anyway, using the second deck to power my LED's for the mode indication.
I also added the 0.1uF cap on the pedal pot, which is on the original, but at the time of first drawing, I only had pictures to go on and I couldn't make out what value it was. It's a lame attempt to detick the circuit in Arpeggio mode on the original, so I also added a 1uF electro cap on the pedal pot to ground. On mine, the 1uF does an excellent job of deticking the circuit in all modes. It's dead quiet now.
The vero remains unchanged. I just need to update the wiring, since it adds an important dimension to this pedal. Here is a short video demo of the Arpeggio function.
Vero and schematic are in the Gallery as well. I can now stick a fork in this one, it's DONE!! :icon_cool:
always wanted to at least hear one of these . never cease to amaze sir . hats off !
props dino!!
i still haven't got to it yet, trying to give poor gineen a break for a little while, actually cleaned up the dining room... ;)
i have to build a superfuzz for my bud mike out in AZ, (i bought 50 828's off fleabay) but this is definitely on the list of must have stuff.
still gotta get the stuff together for cousin ludvig, too...ayyyy ;)
Ok, (hopefully) resurrecting a very old topic.
I started building this to try to eventually make my own version of the Frogg Compusound. I have a strong suspicion it was based on this.
Pretty much all of it works great.
But I can't figure out the Flanger/Arpeggio mode.
I hooked it up like this (I tried writing it down but this is probably easier to understand):
(https://i.postimg.cc/zbSFWzst/arpeggio.jpg) (https://postimg.cc/zbSFWzst)
(and that goes to the switch that's connected to the output (15µF +side) I should say)
It sounds good, but I'm getting very low output. What am I doing wrong?
And thank you so much for sharing this! It's been a lot of fun to build!!