Holy SHIT !!!!!!!!!! :icon_eek: :icon_eek: :icon_eek:
My quest for a high gain dist for metal has just ended.
Just threw in all 5 J201's biased at 4.5V, as is, and after some minor debugging it works. It's my first perfboard built so I forgot a couple of jumpers. Still have to check if all the circuit is correct, but through the oscilloscope it looked more or less OK.
This thing plain rocks. It has everything. Palm mutes sound awesome, has sustain for days, the eq works like a charm, and it has more gain than I will ever use. The basic timbre is dense and silky.
Don't know if this is what a Rectifier is supposed to sound, but man, after so many dist builds, this is something really special.
What is better, it complements perfectly with the BSIAB. The BSIAB is more heavy rock'n'roll and this is heavy metal and beyond.
Obviously I've tested it at low volume and not in the rehearsal with my rig, so I still have to see how it works within a gig situation, but so far........ I got a big smile when I've fired it up for the first time.
Great, great dist pedal. Can't wait to box it up.
... and here I am wasting my time (and money) on an octavia! :) Good to hear that you're liking the Dr. Boogey. I've been meaning to get around to build some of these JFET amp sims, especially the Boogeyman, Dr. Boogie, and Professor Tweed.
Would there be any way you could post some clips?
Quote from: joelap on July 27, 2006, 10:01:46 AM
... and here I am wasting my time (and money) on an octavia! :) Good to hear that you're liking the Dr. Boogey. I've been meaning to get around to build some of these JFET amp sims, especially the Boogeyman, Dr. Boogie, and Professor Tweed.
Would there be any way you could post some clips?
Not at the moment. I still need to buy the enclosure, so I don't expect to have it fully finished in less than a couple of weeks. The clips I've heard so far don't make justice (no pun intended) to this circuit.
I'm also curious about what is the difference with the boogeyman soundwise
Could you guys post a site where to find a dr. boogeyr layout and pcb? And where could I find a dr.tweed??thanks guys!!!
Quote from: Nashtir on July 27, 2006, 10:48:53 AM
Could you guys post a site where to find a dr. boogeyr layout and pcb? And where could I find a dr.tweed??thanks guys!!!
Schematic: http://geocities.com/electrictabs/dr.boogey.png (http://geocities.com/electrictabs/dr.boogey.png)
Bucksear's Layout: http://www.4thlevelmedia.com/DrBoogeyPCB.bmp (http://www.4thlevelmedia.com/DrBoogeyPCB.bmp)
Wiring diagram: http://www.4thlevelmedia.com/DrBoogeyPartsLayout.gif (http://www.4thlevelmedia.com/DrBoogeyPartsLayout.gif)
Quote from: Nashtir on July 27, 2006, 10:48:53 AM
And where could I find a dr.tweed??thanks guys!!!
I think you mean "Professor tweed" www.runoffgroove.com/professor.html
MM.
Xavier, do you have your Perf layout posted? I'm not geared up for etching so I perf everything I attempt. A perf layout of a Dr. Boogie would be awesome.
Thanks,
BT
Great, Xavier. It's probably the nicest distortion box I've ever encountered for that high-gain, palm-chug sound. I can't imagine getting a higher gain sound, which is why I use an MPF102 for Q1.
It's the top-ceiling for me as far as gain goes (don't want more than that), and you're right, the BSIAB II is the perfect compliment to it being a very 'Marshall-y' box. I just need to fill in a few gaps in between: Vox/hot-Vox overdrive, plus a low-gain OD and that would probably do me.
As far as clips go, the ones I put out there do NOT do that box justice.
- Buck
Quote from: bluetubes on July 27, 2006, 11:41:55 AM
Xavier, do you have your Perf layout posted? I'm not geared up for etching so I perf everything I attempt. A perf layout of a Dr. Boogie would be awesome.
Thanks,
BT
Here you go, but be aware. Torchy wisely warned me that this layout was TOO compact. Some caps are tricky to place because of their size, and definitely use vertical mounted trimmers.
Otherwise, it works .
Bucksears, I didn't mean to be harsh about the sound samples. I myself find very difficult to have a good guitar tone direct to DAW
(http://i72.imagethrust.com/i/216795/boogeyperf.gif) (http://www.imagethrust.com)
BTW at low gain settings (which I don't think I'll use that much anyway :icon_mrgreen:), I perceive like an octave-down effect. Anyone else has experienced this? Still needs to be completely checked and debugged though
I find mine a bit on the high-endy side. Does anyone else experience this? I have to keep the treble WAY down on mine.
Perhaps I should do a component check as I've put wrong values in before, and my eyesite seems to get worse by the day now, it's terribly hard for me to see part values these days. Resistors I just have to measure. I fear I'm in need of quadfocals or something horrible like that.
RDV
Quote from: RDV on July 27, 2006, 02:36:48 PM
I find mine a bit on the high-endy side. Does anyone else experience this? I have to keep the treble WAY down on mine.
Perhaps I should do a component check as I've put wrong values in before, and my eyesite seems to get worse by the day now, it's terribly hard for me to see part values these days. Resistors I just have to measure. I fear I'm in need of quadfocals or something horrible like that.
RDV
In fact and after playing through it at a decent volume, I was going to ask how to get MORE treble out of it. It's kinda dark sounding (I'm serious). I like bright pedals :icon_mrgreen:
Has anyone hooked up a dpdt switch and experience sqeul......It is a quad inversion so oscillation is very inheritable...
I would think that maybe the buffer at the end helps ...but I just know if I build this it will squel being of four inversions and such high gain...ANY answers would be nice...
Nice layout Xavier.
Quote from: Xavier on July 27, 2006, 02:55:10 PM
In fact and after playing through it at a decent volume, I was going to ask how to get MORE treble out of it. It's kinda dark sounding (I'm serious). I like bright pedals :icon_mrgreen:
My guess is that either mess with the capacitor on the prescence control, or if that doesn't work, mess around with the tonestack in http://www.duncanamps.com/tsc/
Though the real Mesa ARE dark voiced amps too so I guess thats what the goal was when the pedal was designed..
Is there a variant with a different tonestack? one knob tonestack of some sort, perhaps?
Branimir: You should breadboard it and play with different types of Tone knob configurations. You could take any tone knob from any schem, plug it into that schem and see how it works. You could even just omit it altogether.
Or maybe Mark Hammer's:
http://img.photobucket.com/albums/v474/mhammer/FlexibleMetalEQ.gif (http://img.photobucket.com/albums/v474/mhammer/FlexibleMetalEQ.gif)
Question about the layout:
"VR" is trimpots, right? Also, on the pot wiring k8 is mentioned for 2 leads off of "gain." I assume it's supposed to be L8 for gnd, yes?
I'm a tube guy by trade, and I've been thinking alot about circuits like these, and what's really going on with the tube side of things.
One thing that's been left out, but was addressed here a week or so ago, is the effect of miller capacitance in tubes, and how to sim those in these circuits. If you look at the circuit you'll see a 220k feeding into the 4th stage. When used with a tube that resistor does a couple of things. One is it has an effect on bias shift which is pretty hard to get the jfets to do anyway, but the other is it sets up a filter with a miller cap that has a value around 150pf or so. the value is gain related, and can be calculated if you really want to get picky about it. call it 150p, and you've got a -3db point at about 4800hz.
At the second stage there's also a series 470k resistor, but the real value of what the miller cap would be is around 150p instead of the shown 20. This would give a roll off around 2200hz. again these are average numbers because the real value of the effect is gain dependent, but 150pf is close for common circuits. Also that 1n bright cap is pretty big, and the 150p miller cap helps to offset it's effect.
The 3rd stage is different. It has very little gain, and the miller cap is very low because of that. This circuit is based on the Soldano SLO. The circuit uses a 39k cathode resistor with the 3rd stage. This has a major asym clipping effect with very little gian. The wave shape has a serious chop to the top of the wave form. I think what might work better is to replace the 3rd stage with an asym diode setup. It would give you the hard asym clip while keeping the gain under control going to the 4th stage.
But I've not tried this yet - it's just a thought. PaulC
PaulC, this is interesting stuff that is pretty much over my head. Is there a way to measure/guess what the appropriate miller cap values would be and how to correctly apply them for us dumber DIYers?
Sweet!! Thanks Xavier. I gotta give this one a go. :icon_biggrin:
Hey tcobretti,
Here's a link to a site with some good info about this.
http://www.aikenamps.com/MillerCapacitance.html
This guy really knows his stuff, and he makes some killer amps. There's some great tech articles he's written on his site that you should check out. He's got a great way of getting deep while keeping it simple.
If you like this design then that's all that matters. There's no reason to try and nail the soldano/boogie. But if that's really the goal I believe you'd end up with a circuit that looked pretty different. If I was really wanting to make nailing it a goal I'd start off by building the actually tube preamp first, and then using that as a ref that I could hear/scope out. If only we had 36 hour days...
PaulC
Well fellows, I was so unhappy with my DB I just jumped on that PaulC advice. I used 100pF caps cause I didn't have 150s. I replaced the 22pF I had in the 2nd stage with a 100pF and liked the tone a bit better.
So...
I thought why not do the thing on the 4th Fet as well. I just had to add it on the back of the PCB.
Now I really like it. I can control the tone with the tone controls now. It really seems more amp-like in it's response now.
TRY IT!!
RDV
I just read that Aiken article and it's funny because exactly what you're trying to avoid and or compensate for in tube amp design is what I'm looking to add to the DB so it will react more like the amp in question.
RDV
Quotejust read that Aiken article and it's funny because exactly what you're trying to avoid and or compensate for in tube amp design is what I'm looking to add to the DB so it will react more like the amp in question.
Well in the case of the boogie, and it's father the soldano, those roll-offs are planned. It's just something that you wouldn't see if you didn't know about the miller effect. There is another reason though for having those large series resistances in the tube amps. It has to do with bias shifts and things like blocking distortions. A large series resistance is always asking for noise problems though, and since you don't have those issues needing the large values with jfets you can scale the values down a bunch to help cut the noise back a little. Scale it all by 10 and you might notice a slight reduction in noise.
Jfets are effected by Mr. Miller to. The thing to do would be to figure out the miller value for the jfet you're using, and then add what's needed to get the tube values. Or just go by that average of 150pf and then tweak by ear.
Look into the asym diode thing to replace the 3rd stage when you have time. In the amp that stage isn't ment to add gain - it's ment to chop the top off of the wave. It's a perfect use for diodes in this circuit since they could do the job as well as a gain stage could, and the diodes wouldn't be adding the noise of a gain stage.
Later, PaulC
Thanks Paul , interesting read :D .... wierd thing is that I added a diode to ground arrangement onto
my little "G3 Distortion" from last week , as a "final stage" ( 4th ) and it does make quite a difference
I guess "lopping off" the waveform a bit, lost a tiny bit of level but not much ( 3mmLED's )
I think it's time for the "perfect" amp sim, take into account IDSS of fets , Miller capacitance etc etc.
The new Fetzer valve setup is also a good read, seems like there could be a VERY exact and repeatable
amp sim waiting to emerge .....
MM.
The diode thing would probably make the circuit smaller and quieter but since I've got it on PCB I probably won't be doing that one.
Adding the caps however seems to have really brought mine under control.
The way it was before I had very little control with the tonestack. With everything at dead zero I still had a ton of fizz.
Now, with everything at dead zero it's very dull(as it should be) and then there is plenty of treble and mids and bass to be had by rolling up the tonestack. It's still nice even after sleeping so I know it's a good thing.
I may experiment with values a bit but the caps are staying.
RDV
Quote from: RDV on July 28, 2006, 10:47:41 AM
The diode thing would probably make the circuit smaller and quieter but since I've got it on PCB I probably won't be doing that one.
Adding the caps however seems to have really brought mine under control.
The way it was before I had very little control with the tonestack. With everything at dead zero I still had a ton of fizz.
Now, with everything at dead zero it's very dull(as it should be) and then there is plenty of treble and mids and bass to be had by rolling up the tonestack. It's still nice even after sleeping so I know it's a good thing.
I may experiment with values a bit but the caps are staying.
RDV
What caps have you added and where? It's not very clear to me after reading the post , sorry for my ignorance.....
Quote from: Xavier on July 28, 2006, 12:26:18 PM
Quote from: RDV on July 28, 2006, 10:47:41 AM
The diode thing would probably make the circuit smaller and quieter but since I've got it on PCB I probably won't be doing that one.
Adding the caps however seems to have really brought mine under control.
The way it was before I had very little control with the tonestack. With everything at dead zero I still had a ton of fizz.
Now, with everything at dead zero it's very dull(as it should be) and then there is plenty of treble and mids and bass to be had by rolling up the tonestack. It's still nice even after sleeping so I know it's a good thing.
I may experiment with values a bit but the caps are staying.
RDV
What caps have you added and where? It's not very clear to me after reading the post , sorry for my ignorance.....
I replaced the 22pF from gate to ground I had in the 2nd stage with a 100pF and liked the tone a bit better.
I placed a 100pF to ground where the 220k resistor attaches to the 4th Fet's gate as well. I just had to add it on the back of the PCB.
They just filter some of the scritch that was causing me some headaches with the super-high feedback and stuff, though I've still plenty of highs on hand. It just seems a little more controlled to me. 100pF was what I had on hand, so other values could be tryed as well.
RDV
QuoteWhat caps have you added and where? It's not very clear to me after reading the post , sorry for my ignorance.....
There's an "invisible" cap not shown in the circuits that are a part of the way tubes run. An average value for normal types of 12ax7 biasing is about 150pf. It depends on the how the gain is set up for the tube, but this is a good average. Just add it from gate to ground on your Jfets. Include it on the input fet. It sets up a filter with the 68kinput resistor rolling back highs at about 15khz.
Without this cap being added those large series resistors are not doing the voicing things with the jfets that they do with the tubes. If you're trying to capture the eq curves that go on between each tube stage then you need to add these caps.
Later, PaulC
Using that bit of advice, I'll draw up (just a section) of how I think it should be with that. Then you can tell me if I'm wrong :D
Boy I'm tired from the gig, but I just had to give a report on this thing. It was amazing!
I used my newly modded DB at a gig that was supposed to be a duo thing as far as I knew, but the singer had set up a set of electronic drums and a bass amp. I'm thinking "oh GOD! no amp(I play through my RP12 into the P.A. on the duo gigs). I was just gonna try out the DB and play clean most of the night, or so I thought.
So me & the little singer do our little singer/songwriter thing for a set, then these guys come in to play(including another guitarist who brought in a half-stack.
So I turn on the DB and crank it a bit to equalise the level to my clean sound and cannot believe my earholes! This thing is sounding like an amp through the PA, people were flipping out wondering where I'd hidden the Dual Rectifier Head!
This has been one of the few times where people really wanted to know how I was doing that!
ADD THE CAPS PEOPLE.
RDV
Also in Q5? Q5 doesn't have anything to ground.
So my guess is:
Q1 is clear to me, there's not any cap so I just have to add it in parallel to the resistor
Q2, make the stock 20pf 150pF
Q3 is also clear, as there's nothing neither
Q4, there's already a 1uF electro to ground. Do I have to add anything here?
So if I'm not wrong we need 3 caps for Q1, Q2 and Q3?
I might redraw the perf layout to include the cap change.....
I only did Q2 & Q4 because those filter frequencies are within human hearing range. I'm not too worried about 15khz, though I may add the cap to Q1 just as an anti-fizz.
QuoteQ4, there's already a 1uF electro to ground. Do I have to add anything here?
Paul is refering to caps from gate to ground.
RDV
so that's all there is to this cap adding? Add the cap going to ground, not inbetween/instead of something?
Hey RDV And PaulC, this looks really good. The bsiab has an input cap to ground also to simulate the roll off. The only difference is that RDV put his cap from drain to ground...and Paul advice was putting it from gate to ground. I'll try this on the recentely built Dr Boogey, and let you know my results...i only have acces to BF245A, so maybe it's a different beast, but anyways, a change is going o be notice in my case also. Thanks a lot!
No no, I put mine from gate to ground on both Q2 & Q4. I just edited my post from earlier to try to make that clear.
I've drawn up my changes on the original schematic but I'm not posting it out of respect to Electrotabs(unless he's interested in seeing it).
RDV
Hey PaulC...is it possible to do the assymetric stuff with fets?. How high do you think i can go on the source resistor? I was thinking on getting less gain on that stage, by means of a higher resistor, and maybe adding the diodes as suggested.
Hey swt,
The 3rd tube stage used a 39k cathode resistor which gave a massive chop to the positive side of the wave form. You've never seen a more asym clipped signal! It also had very low gain. Only a couple of dB vs around 35db or so for a 12ax7 biased with standard values. Because of the headroom issues with the jfets you've got more than enough signal to replace that 3rd stage with a diode clipper to do the same job. Again - I've not built this. Just looking at it I'd think it would give you better results at nailing down what the slo/boogie circuits are trying to do. What I'd do is set it up so Q4 clips first with good symmetry, and then have the diode in place of the 3rd stage kick in after you've got a good clip on Q4. Then after you've got the diode clipping I'd have Q2 clip a little behind it. Play around with voltage dividers and the threshold of the diode to time the clipping between the stages.
When adding the miller caps to the circuits you'd have them on Q1,2,4. Since the gain of the 3rd stage is so low it suffers very little from the miller effect, and Q5 is a source follower (or cathode folloer in the tube circuit) which does not suffer from miller effects.
The Slo had a 68k grid stopper resistor on it's input that set up a filter with the miller cap of the input tube (Q1) to roll off the highs at about 15k. This helped keep the radios out, and can also help with osc problems. The only problem with this cap is it will interact with your guitar volume pot making things darker as you roll back the volume.
But like I said - these are just thoughts from looking at the circuit. I've not built it.
Later, PaulC
well PaulC...i did built it, and so RDV, so thanks a lot for all the help and advices. i'm going to fool a bit with the concept and let you know. one thing i'm planning to try is...i'll use a low drain resistor, maybe 6k8, and 2k2 source to get it biased, just as a small 2x boost, transparent, and use a 100n cap, with a diode and a small series resistor, between drain and gate, to create assymetric clipping. or maybe a back to back pair of diodes, with a resistor in one for the assymetry. i can also try a bound back to back pair to ground...but i think it will over compress, and maybe make it sound a little rough...what do you guys think??
Thanks PaulC and RDV - I built a Dr Boogie first without then with your observations/tweaks and it does sound great - like a RAT with real tone, very heavy.
I added an extra set of pads for each of the FETs in the PCB layout for the Miller capacitance to go from G to S (not necessarily ground - although in a lot of cases it does not matter). Other things I added to this build:
- I used an MPS102 for Q1 and a 150pF Miller (G-S) cap
- Took RDV's advice on the 100pF in for the 20pF (Q2) cap and added a 100pF Miller cap to Q4
- Added back in the 68k resistor on the input (in place of the jumper) for a 15kHz roll off
- On Q1's source, I used a .47uF + 47k resistor for the AC bypass (in place of the 1uF cap)
+This input stage is now more like on the Original Mesa Dual Rec schematic
+This added more control to the gain
Now, this sounds great - very amp-like, palm-mutes are unreal great!! - but I'm still tweaking.
QuoteOn Q1's source, I used a .47uF + 47k resistor for the AC bypass (in place of the 1uF cap)
Hey Mojo,
Having the 47k in series with the cap will remove the cap from the circuit. It's there to lift the cap out of the circuit when you're in the clean mode. When you're in the overdrive mode the LDR shorts it out bringing the cap in for a hotter front end. This is used on all three high gain stages to tame them down for the clean channel. If you're going for the gain stuff you'd leave off the 47k.
Also if you don't get splats try to set up the drain voltage on Q3 to around 7 or 8 volts. This will give you the hard asym saturation clip that the tube stage does instead of the cut off clip.
I keep going back to the SLO when thinking about this circuit, but I did dig out my schematics for this amp the other day (I used to be an authorized service guy for boogie). I'd forgotten about that 20pf cap on the second stage. So really that would push the value of the miller cap closer to 170pf or so for an even greater roll off than the 100pf you used will do. The 100pf will give a -3db at about 3400Hz while the 170pf will be at about 2kHz
Later, PaulC
Quote from: PaulC on August 13, 2006, 11:31:59 AM
... Having the 47k in series with the cap will remove the cap from the circuit. It's there to lift the cap out of the circuit when you're in the clean mode....
Yikes! :icon_redface: what was I thinking - of course.... that's one of those 'can't see the forest for the trees' things...
Although, I do like the sound the way it is - that would be - without the cap... :icon_lol:
Quote from: PaulC on August 13, 2006, 11:31:59 AM
Also if you don't get splats try to set up the drain voltage on Q3 to around 7 or 8 volts. This will give you the hard asym saturation clip that the tube stage does instead of the cut off clip.
I keep going back to the SLO when thinking about this circuit, but I did dig out my schematics for this amp the other day (I used to be an authorized service guy for boogie). I'd forgotten about that 20pf cap on the second stage. So really that would push the value of the miller cap closer to 170pf or so for an even greater roll off than the 100pf you used will do. The 100pf will give a -3db at about 3400Hz while the 170pf will be at about 2kHz
Yep - I will try these - THanks!
Earlier, I was going for exactly what others had tried. As there's a 470pF cap not in the Dr Boogie (between Q2 and Q3) - that's in the DR between stage 2 and stage 3 - I was taking things iteratively working my way through several changes - one at a time. Bumping up the Miller Caps is on the list of things to try.
Hi guys, building my THIRD boogey board so far :icon_cry:. This time with the Miller caps in Q1, Q2 and Q3.
Just one question. These caps are from gate to ground, or from gate to source? I've seen both things when searching through the forum.
When I finish this damn circuit I'll call it quits for a while......
Quote from: Xavier on October 17, 2006, 01:26:05 PM
Hi guys, building my THIRD boogey board so far :icon_cry:. This time with the Miller caps in Q1, Q2 and Q3.
Just one question. These caps are from gate to ground, or from gate to source? I've seen both things when searching through the forum.
When I finish this damn circuit I'll call it quits for a while......
On Q1 and Q2 - you can go from gate to source as you have a source bypass that is much larger then the 200-100pF Miller cap. I would not worry about Q3, from my experience it's not going to produce that much gain. But, on Q3 if you wanted to put a cap in there I would make it a smaller one (<100pf) and make it gate to ground, because the Miller cap is really 1-3pF multiplied by the gain of that stage. I had planned on doing more homework on this but from what my simulating/experimenting with this leads me to think is that if you always go gate to source with a small cap, on a circuit like this, in a common-source stage with 150-200pF you can cover the parasitic loss (normally in a triode as grid to plate) by coupling some hi-end signal to the source and achieve the marginal parasitic loss via degenerative effects of reducing the V
gs voltage difference for hi-freq signals that are shunted from gate-source; which reduces the gain for that part of the signal. So, I have been going gate to source on this and I think works best because by doing that you scale the affect of the Miller cap with the gain of the circuit - even if it is not a lot of gain. Someone (and be nice please :icon_biggrin:) set me straight if that's not the case.
Hey Mojo, thanks for the explanation. I'm building it from scratch (again) but this time I'll check every step with both the oscilloscope and the tester. I'm using 100pF's throughout.
I hope this time it works.
Quote from: Xavier on October 17, 2006, 04:34:21 PM
Hey Mojo, thanks for the explanation. I'm building it from scratch (again) but this time I'll check every step with both the oscilloscope and the tester. I'm using 100pF's throughout.
I hope this time it works.
Let me know how that works, I went with 220pF caps (all gate to source) on the Dr B and it sounded great and still had plenty of high end. It helped with some of the squeal, but I still have some issues after doing a fairly good job at isolating leads from eachother. I was going to try a choke on the supply voltage as well as redo my leads a bit. On the other hand, I can get it up to about 70% of the max gain without any oscillation and that's more than enough for me anyway - the Dr B sounds awesome!
What layout are you using?
Quote from: mojotron on October 17, 2006, 05:46:31 PM
Quote from: Xavier on October 17, 2006, 04:34:21 PM
Hey Mojo, thanks for the explanation. I'm building it from scratch (again) but this time I'll check every step with both the oscilloscope and the tester. I'm using 100pF's throughout.
I hope this time it works.
Let me know how that works, I went with 220pF caps (all gate to source) on the Dr B and it sounded great and still had plenty of high end. It helped with some of the squeal, but I still have some issues after doing a fairly good job at isolating leads from eachother. I was going to try a choke on the supply voltage as well as redo my leads a bit. On the other hand, I can get it up to about 70% of the max gain without any oscillation and that's more than enough for me anyway - the Dr B sounds awesome!
What layout are you using?
My own perf layout again. I tried the small 22x7 stripboard but everything was so packed that was very hard to find the bugs. This build needs a bigger board.
OK, built it again and now it works. I've been testing every step so now I know where the problems come from. Basically the wiring is the problem, I'll explain.
I have been following the signal with the oscilloscope and a probe, everything is OK. I have a very clean sinus wave at the input, and an almost perfect square-ish wave at the source of the last J201
Then I have wired the final eq section and voilá!! oscillations and what's worse, it even appears at the input jack (how can that happen????).
This means new wiring for sure, so now I have to particular questions about the wiring.
- What is the correct way for wiring it? Should I use shielded cable throughout? Should they be arranged in a certain way?
- The high frequency content varies A LOT depending on how the 1M master volume is set. At 25% the treble content is perfect, but it gets muddier as you turn it up. At 50% sure you have output, but even with both the treble and presence pots maxxed, all I have is high mids. Any trick in order to solve this?
UPDATE:
I have just built the voltage regulator that a forumite has suggested some threads below, and it works woohoo !! :icon_biggrin:
The noise when the effect was bypassed has disappeared, along with the hum. I have rebiased again now that I had a clean 9,2V and it sounds even better.
The only problem I have now is that it still oscillates BUT only when there's nothing connected at the input. As soon as I plug the guitar in all oscillations disappear, even with everything maxxed. As this is meant to be played :icon_mrgreen: it's going to stay like this.
Worth the build, but what a challenge !!!!!
I gotta tell you, other than noise when the effect is engaged (and the gain is at 50% or higher), my Dr. Boogey works fine. It's the original one that I built over a year ago, but all the knobs work correctly, no excessive squealing or anything. I may try shielded leads to/from the board, but that's about it.
Quote from: Xavier on October 19, 2006, 12:43:44 PM
UPDATE:
I have just built the voltage regulator that a forumite has suggested some threads below, and it works woohoo !! :icon_biggrin:
The noise when the effect was bypassed has disappeared, along with the hum. I have rebiased again now that I had a clean 9,2V and it sounds even better.
The only problem I have now is that it still oscillates BUT only when there's nothing connected at the input. As soon as I plug the guitar in all oscillations disappear, even with everything maxxed. As this is meant to be played :icon_mrgreen: it's going to stay like this.
Worth the build, but what a challenge !!!!!
You mean the choke idea worked, I had not tried that yet. So, if I understand this, you had immense squealing at higher gain settings, you put a choke in series with the supply voltage, and then the squealing went away?
If so, what kind of choke did you use?
Or can you point me to the voltage regulator thread.
Also, you can ground the input in situations where the plug is not plugged in the connector... Are you using the 3 connector switchcrafts for the input?
Quote from: mojotron on October 19, 2006, 02:32:58 PM
Quote from: Xavier on October 19, 2006, 12:43:44 PM
UPDATE:
I have just built the voltage regulator that a forumite has suggested some threads below, and it works woohoo !! :icon_biggrin:
The noise when the effect was bypassed has disappeared, along with the hum. I have rebiased again now that I had a clean 9,2V and it sounds even better.
The only problem I have now is that it still oscillates BUT only when there's nothing connected at the input. As soon as I plug the guitar in all oscillations disappear, even with everything maxxed. As this is meant to be played :icon_mrgreen: it's going to stay like this.
Worth the build, but what a challenge !!!!!
You mean the choke idea worked...
Also, you can ground the input in situations where the plug is not plugged in the connector... Are you using the 3 connector switchcrafts for the input?
Ahh, I see - you were refering to the 'Topic: Power supply filtering, some advice please.....' thread.
Thanks!
Quote from: mojotron on October 19, 2006, 02:32:58 PM
Quote from: Xavier on October 19, 2006, 12:43:44 PM
UPDATE:
I have just built the voltage regulator that a forumite has suggested some threads below, and it works woohoo !! :icon_biggrin:
The noise when the effect was bypassed has disappeared, along with the hum. I have rebiased again now that I had a clean 9,2V and it sounds even better.
The only problem I have now is that it still oscillates BUT only when there's nothing connected at the input. As soon as I plug the guitar in all oscillations disappear, even with everything maxxed. As this is meant to be played :icon_mrgreen: it's going to stay like this.
Worth the build, but what a challenge !!!!!
You mean the choke idea worked, I had not tried that yet. So, if I understand this, you had immense squealing at higher gain settings, you put a choke in series with the supply voltage, and then the squealing went away?
If so, what kind of choke did you use?
Or can you point me to the voltage regulator thread.
Also, you can ground the input in situations where the plug is not plugged in the connector... Are you using the 3 connector switchcrafts for the input?
No, I'm using a two connector Switchcraft since I'm not using a battery, but I could try your suggestion. How do I wire it?
Regarding this matter I also built a small buffer and placed it between the footswitch and the board input, but it didn't solve the problem.
Your idea seems stupidly simple but effective. :icon_biggrin: