GCB-95 Wah Mod's

[Single Coil]

I bought the Dunlop HotPotz 470K pot for my wah and the red fasel inductor. My wah has a bit smoother, better overall sound but now, it's a bit too bright at the upper end of depresseing the pedal.  I'm sure the 470K pot has something to do with that.

I had planned to do the mods that are recommend at www.diyguitarist.com. Now, I'm thinking I may need/want to adjust those mods to attempt to compensate for the extra brightness.

The standard mod for the GCB-95 calls for changing the sweep cap from 0.01uF to 0.022uF. I'm thinking about trying a 0.047 uF since I've got the brighter pot.

I definitely need to increase the midrange now. The recommended changed is to replace the 1.5K resistor between the base of Q2 and the inductor with a 2.2K resistor. What if I were to use a 3.9k resistor there?

What about the 33K resistor that's in parallel with the inductor? Should I go with a 47K?

Finally, should I stay with the 470k resistor at the emitter of Q1? I may leave that the same and use my modded DS-1 in front of the wah if I want more gain.

You guys have any comments or recommendations for these mods?

Thank you.

PS. Paul Marossy did warn me that the 470K pot would likely be too bright. But, I fell victim to the market usage of Jimi Hendrix's name. Dunlop says this 470K pot is the pot they use in their Hendrix wah. They got me....

[lumpymusic]

I bought the Dunlop HotPotz 470K pot for my wah and the red fasel inductor.
My wah has a bit smoother, better overall sound but now, it's a bit too bright
at the upper end of depresseing the pedal. 
I'm sure the 470K pot has something to do with that.

...Paul Marossy did warn me that the 470K pot would likely be too bright....

Add a 100k pot, full size or trimmer, across the 470k HotPot. Then you
should be able to "dial down" the resistance to closer to 100k. Add a
SPST switch to completely remove the new trimmer if you like. There's
so much room inside a typical Wah, it's a great playground. You can
pot/trim every resistor, multi cap every cap, add a cup holder.

Lumpy

[jonathan perez]

I bought the Dunlop HotPotz 470K pot for my wah and the red fasel inductor. My wah has a bit smoother, better overall sound but now, it's a bit too bright at the upper end of depresseing the pedal.  I'm sure the 470K pot has something to do with that.

stick to 100k, it hasnt failed anyone, yet.

The standard mod for the GCB-95 calls for changing the sweep cap from 0.01uF to 0.022uF. I'm thinking about trying a 0.047 uF since I've got the brighter pot.

whoah buddy, way too low. try .022, which is pretty low already, and see how that sounds.

I definitely need to increase the midrange now. The recommended changed is to replace the 1.5K resistor between the base of Q2 and the inductor with a 2.2K resistor. What if I were to use a 3.9k resistor there?

then you would have a whole lotta mids. becareful with that one, as you may lose the sweep of the wah.

What about the 33K resistor that's in parallel with the inductor? Should I go with a 47K?

sure. you can go with 56k, 68k, or 100k. most prefer 100k, for a big QUACK.

Finally, should I stay with the 470k resistor at the emitter of Q1? I may leave that the same and use my modded DS-1 in front of the wah if I want more gain.

i suppose you can, but...i dont know many people who have. try higher gain transistors, like some 2n5089.

You guys have any comments or recommendations for these mods?

thatll do it, i suppose...unless you lower the input 68k resistor to 33k. youll get a bit more OOMPH, but hardly noticable to the common man.

PS. Paul Marossy did warn me that the 470K pot would likely be too bright. But, I fell victim to the market usage of Jimi Hendrix's name. Dunlop says this 470K pot is the pot they use in their Hendrix wah. They got me....

yeah, but theres also a set of capacitors that dull the high end.

[Paul Marossy]

I've been thinbking about that Jimi Hendrix 470K pot thing. I bet that Roger Mayer modded his wah that way. I don't think there ever was a stock wah that came with a 470K pot at that time...

[Single Coil]

I bought the Dunlop HotPotz 470K pot for my wah and the red fasel inductor. My wah has a bit smoother, better overall sound but now, it's a bit too bright at the upper end of depresseing the pedal.  I'm sure the 470K pot has something to do with that.

stick to 100k, it hasnt failed anyone, yet.
I already installed this 470K pot, and I can't return it. Surely, I can't make this one work. But your right, if I had to do it again, I'd stick with the 100K. Silly me.

The standard mod for the GCB-95 calls for changing the sweep cap from 0.01uF to 0.022uF. I'm thinking about trying a 0.047 uF since I've got the brighter pot.

whoah buddy, way too low. try .022, which is pretty low already, and see how that sounds.

OK, I'll try the 0.022.

I definitely need to increase the midrange now. The recommended changed is to replace the 1.5K resistor between the base of Q2 and the inductor with a 2.2K resistor. What if I were to use a 3.9k resistor there?

then you would have a whole lotta mids. becareful with that one, as you may lose the sweep of the wah.

Ok, Then, I'll stick with the 2.2K.

What about the 33K resistor that's in parallel with the inductor? Should I go with a 47K?

sure. you can go with 56k, 68k, or 100k. most prefer 100k, for a big QUACK.

I'd like a bit more quack...Maybe I'll try the 68K, first. But, this may be a really good spot for a trim pot.

Finally, should I stay with the 470k resistor at the emitter of Q1? I may leave that the same and use my modded DS-1 in front of the wah if I want more gain.

i suppose you can, but...i dont know many people who have. try higher gain transistors, like some 2n5089.

I'd need to take mine apart, What transistor is stock in the GCB-95?

You guys have any comments or recommendations for these mods?

thatll do it, i suppose...unless you lower the input 68k resistor to 33k. youll get a bit more OOMPH, but hardly noticable to the common man.

PS. Paul Marossy did warn me that the 470K pot would likely be too bright. But, I fell victim to the market usage of Jimi Hendrix's name. Dunlop says this 470K pot is the pot they use in their Hendrix wah. They got me....

yeah, but theres also a set of capacitors that dull the high end. I guess I was hoping you guys might be able to help me figure this out.

[Single Coil]

I bought the Dunlop HotPotz 470K pot for my wah and the red fasel inductor.
My wah has a bit smoother, better overall sound but now, it's a bit too bright
at the upper end of depresseing the pedal. 
I'm sure the 470K pot has something to do with that.

...Paul Marossy did warn me that the 470K pot would likely be too bright....

Add a 100k pot, full size or trimmer, across the 470k HotPot. Then you
should be able to "dial down" the resistance to closer to 100k. Add a
SPST switch to completely remove the new trimmer if you like. There's
so much room inside a typical Wah, it's a great playground. You can
pot/trim every resistor, multi cap every cap, add a cup holder.

Lumpy

Thanks, cup holder! I'd love a cup holder mod...thanks for the suggestion. I'll give the trim pot idea some consideration...good idea.

[jonathan perez]

the stock transistors vary...i think theyre using mpsa18, right?

i will try one of those pots...maybe there be mojo in them pots.

try using a .022 first, and see if it helps.

[Single Coil]

Earlier tonight I was jamming with this wah and I was just using it as a overdrive. I left the pedal about half or a little less pressed from toe towards the full toe position. This wah was sounding great as is...I still plan to do the mod's discussed earlier, but what a great variable tone overdrive unit a wah is. That worked on Money for Nothing...and at the moment it's working for me. I can really see/hear now how these can be modded into tube screamer style pedals.

...in the full toe position, I do still think it's very bright... but with a cranked tube amp it's still a useable tone for something brightly different. I'll still work to tame those highs a bit. Just because I'm really itching to do some soldering. Hopefully I can get by Radio Shack soon.

As far as changing the transistor on the GCB-95 from the online pictures of the circuit board, it looks like there are 3 of them. Which one should I change or do all three need to be changed if I want more gain? There's one just below the output jack, one below and slightly right of center of the stock inductor, and then there is one below and left of the stock inductor.

One more thing, I read something were David Gilmour used a reverse wah, he would plug his guitar into the output and run the input to the amp. I tried that...but it didn't work. What's up with that?

[lacto]

I was going to chime in on this earlier with an obvious suggestion, but I was sure someone else would beat me to it. The first line of attack for overly brightness or shrillness in the toe down position, before you do any soldering, is to adjust the toothed rack that contacts the pot gear. Loosen up that plastic holder that presses against the rack so you can move it up or down, pay attention to where you start and try adjusting it by one or two teeth even three at most to limit the range of the toe down position, thus reducing the brightness. Based on what you said about liking it set near the middle of the sweep, this adjustment alone may take care of it for you. At least do this, and then you have a baseline of where to start swapping out components.

[Dai H.]

I've been thinbking about that Jimi Hendrix 470K pot thing. I bet that Roger Mayer modded his wah that way. I don't think there ever was a stock wah that came with a 470K pot at that time...

does 470k sound closer (if you've tried it)? FWIW, my RM 9090A kit that was touted as giving Jimi sound came with a 100kA Bourns cond.plastic pot (but my confidence on it's "Jimi-ness" is not very high, however).

[powerplayj]

The wah is sort of the enigma of all pedal mods for me. Seems like when I change one component I make one thing better better while something else in the tone suffers.  If you don't do anything else, make sure you only change one component at a time.  For starters, I would put the stock pot back in and see where that gets you.  Also, the pads on those Dunlop boards seem to come off easy (for me anyway).  You may want to get some sockets and install them everywhere you intend to swap caps or resistors.  Make sure the sockets are soldered well as they have a tendency to not hold in place as well (must be the metal type???)  I have tinkered with many wah components to get "that sound" and have come to realize that the guitar, amp, adjacent pedal and player have a huge role.  Good luck and don't let it consume you too much.

[Paul Marossy]

I have tinkered with many wah components to get "that sound" and have come to realize that the guitar, amp, adjacent pedal and player have a huge role.

Yep, there's a huge amount of factors involved. The wah pedal is just a small part of it. You could try changing the sweep cap from 0.01uF to 0.015uF or even a 0.022uF to try amp compensate for the brightness. Might even make for a nice combo between the 470K pot and the right sweep cap.

[jonathan perez]

...in the full toe position, I do still think it's very bright... but with a cranked tube amp it's still a useable tone for something brightly different. I'll still work to tame those highs a bit. Just because I'm really itching to do some soldering. Hopefully I can get by Radio Shack soon.

yes, adjust the range of the pot. that may work, for now.

As far as changing the transistor on the GCB-95 from the online pictures of the circuit board, it looks like there are 3 of them. Which one should I change or do all three need to be changed if I want more gain? There's one just below the output jack, one below and slightly right of center of the stock inductor, and then there is one below and left of the stock inductor.

since were all tone wizards, you may want to truebypass it. heres a page that invloves that. http://www.stinkfoot.se/andreas/diy/mods/dunlop.htm the one on the far left is apart of the output buffer. the two on the bottom are the trannies. swap them both for 2n5089 for higher, if not highest, gain. people often use bc109, bc239, or bc256 transistors, but i find them to be thin sounding unless used in an old clyde. youre not going to get TONS more gain, after all it is a WAH pedal.

One more thing, I read something were David Gilmour used a reverse wah, he would plug his guitar into the output and run the input to the amp. I tried that...but it didn't work. What's up with that?

my assumption is that he may have had a wah that had reversed jacks, like the older Boomerangs.

[Single Coil]

I was going to chime in on this earlier with an obvious suggestion, but I was sure someone else would beat me to it. The first line of attack for overly brightness or shrillness in the toe down position, before you do any soldering, is to adjust the toothed rack that contacts the pot gear. Loosen up that plastic holder that presses against the rack so you can move it up or down, pay attention to where you start and try adjusting it by one or two teeth even three at most to limit the range of the toe down position, thus reducing the brightness. Based on what you said about liking it set near the middle of the sweep, this adjustment alone may take care of it for you. At least do this, and then you have a baseline of where to start swapping out components.

Thank you. I'll try that simple adjustment. I was wondering if anyone would suggest that one. The original pot was fairly scratchy...I'm set on keeping this pot in it. I think we'll figure out how to get along with one another.

[Single Coil]

The wah is sort of the enigma of all pedal mods for me. Seems like when I change one component I make one thing better better while something else in the tone suffers.  If you don't do anything else, make sure you only change one component at a time.  For starters, I would put the stock pot back in and see where that gets you.  Also, the pads on those Dunlop boards seem to come off easy (for me anyway).  You may want to get some sockets and install them everywhere you intend to swap caps or resistors.  Make sure the sockets are soldered well as they have a tendency to not hold in place as well (must be the metal type???)  I have tinkered with many wah components to get "that sound" and have come to realize that the guitar, amp, adjacent pedal and player have a huge role.  Good luck and don't let it consume you too much.

Thanks for the heads up to careful with the PCB...I like the socketing idea. and the reminder to change one component at a time. Wise advice. I totally agree with you...the wah is just a part of the signal chain total sound package...I do worry about over tweaking to the point where all mojo is lost. I don't want that. Thank you.

...in the full toe position, I do still think it's very bright... but with a cranked tube amp it's still a useable tone for something brightly different. I'll still work to tame those highs a bit. Just because I'm really itching to do some soldering. Hopefully I can get by Radio Shack soon.

yes, adjust the range of the pot. that may work, for now.

As far as changing the transistor on the GCB-95 from the online pictures of the circuit board, it looks like there are 3 of them. Which one should I change or do all three need to be changed if I want more gain? There's one just below the output jack, one below and slightly right of center of the stock inductor, and then there is one below and left of the stock inductor.

since were all tone wizards, you may want to truebypass it. heres a page that invloves that. http://www.stinkfoot.se/andreas/diy/mods/dunlop.htm the one on the far left is apart of the output buffer. the two on the bottom are the trannies. swap them both for 2n5089 for higher, if not highest, gain. people often use bc109, bc239, or bc256 transistors, but i find them to be thin sounding unless used in an old clyde. youre not going to get TONS more gain, after all it is a WAH pedal.

I may be very content with the level of gain I'm getting from it at the moment. It really sounds gooood. I may change the sweep cap and whatever resister would be most likely the fatten up the tone a bit. I think that base of Q2 where DIYguitarist.com recommends a 2.2K may be the change.

[Paul Marossy]

Yeah, that's a good point. Be very careful desoldering stuff off of those GCB-95 boards. It's not hard at all to damage them.

[Single Coil]

I would like to add one of those really sweet blue led on/off lights...do those come in a 2.2K resistance value?

[Single Coil]

The original inductor in my wah had 4 pins, and the replacement uses only two of the four pins. I've seen the mod where you can install a red and yellow and switch between them. This make be a little crazy, but would it be possible to run two red's simulaneously, whether it would be in series or parallel? Can you run two inductors at once?

Surely some has already tried that...what is the result?

[Paul Marossy]

The original inductor in my wah had 4 pins, and the replacement uses only two of the four pins. I've seen the mod where you can install a red and yellow and switch between them.

Two of those four pins are not doing anything electronically - they are just for mounting purposes. You can switch between two different inductors, you just need a SPDT switch connected one end of the pair of inductors. The other end of the inductors would be connected to the PCB.

[alderbody]

I've been thinking about that Jimi Hendrix 470K pot thing. I bet that Roger Mayer modded his wah that way. I don't think there ever was a stock wah that came with a 470K pot at that time...

As history has taught us, Jimi played with ultra-long and "treble eating" curly cables.

I think RM needed something to enhance treble to his Wah, hence the unique 470K pot...

just a guess.