Volume knob on Crybaby wah

[WholeLottaDimitri]

I recently made a couple mods to my GCB-95 Crybaby
It made the volume louder / it boosted the signal
I like the boosted sound in some cases, but for others it would be nice to have it at unity gain
I'd like to know where in the signal chain do I put the volume pot
I know I'd have to break the output wire and put in it between the output jack and the circuit
But I'm not sure where to do this modification
Also what size pot would work?
Any help would be nice

[petemoore]

  You could try 500k across outside lugs of the wah pot, it's wiper to output.
  putting a 100k across there would reduce the 100k wah pot total resistance in 1/2 of course.
  I've had wahs work' with pots ranging lower than 100k and up to 200k.
  Not sure if you might want to cut the output wire [before the switch], insert a DC blocking capacitor, then put a VRD [volume pot] there, wiper to output, other end to ground.
  The DC is blocked by two caps before the wah pot, a somewhat uncommon setup, often there's 1 DC blocking right at the output.
  Not sure whether to mention buffered output, I understand wah outputs are easily loaded down.

[joegagan]

anywhere you put it, it affects the circuit.

everything affects everything else. if you replace the 68k input r as a 100k pot, you may or may not have the sweep or freq range you like where the volume is where you like it.

out buffers affect the tone too. doesn't matter what type, they all do something to the tone. ditto with input buffers. best wah tones i have found have no buffers.

for volume, the best solution i have found is actually 3 fold: replace 68k R gain with a 100k trim ( series), control Q1 e bias with a  1k trim , and a 250k trim or pot wired like a guitar vol ahead of everything else.

by balancing all three of the above carefully you can ( almost completely ) retain the actual tone and range of the wah AND control the volume.

[petemoore]

 Thanks Joe, those trimpots could then be measured and replaced with fixed resistors.

[joegagan]

true pete, but i think the ability to change guitars and maybe need to change the settings a little might be good also.

the order for setting the 3 above  ( suggested )

1. set 100k  input trim & 250k in vol to  middle,  then set proper or desired level of lows and or growl using the 1k trim on Q1.

2. set the 100k to further get growl and or lows dialed in

3. final setting is the 250k for vol.

only slightly related, take a look at the various mods here, this was not necessarily a volume control setup more of a ' body ' control. the wah sounded great, the customer loved it - was a mod to a dunlop jerry cantrell wah.

[ManuVel]

Hey, I recently did this on my GCB-95 wah. You want to put it across the blue wire. like so



I used a 500k POT. I also had a 100k resistor in series so you can't turn the volume all the way down, but this is optional.

The highest volume stayed the same, and I was able to move it down.

Also make sure you know which way it goes!

[soupbone]

true pete, but i think the ability to change guitars and maybe need to change the settings a little might be good also.

the order for setting the 3 above  ( suggested )

1. set 100k  input trim & 250k in vol to  middle,  then set proper or desired level of lows and or growl using the 1k trim on Q1.

2. set the 100k to further get growl and or lows dialed in

3. final setting is the 250k for vol.

only slightly related, take a look at the various mods here, this was not necessarily a volume control setup more of a ' body ' control. the wah sounded great, the customer loved it - was a mod to a dunlop jerry cantrell wah.

Hey Joe.The "Volume Control" mod you talked about,which resistor on the gcb-95 board are you changing?I was going to try this to one of my gcb-95's.Can I use a 250k Audio taper?

[petemoore]

 Lookup the 95's schematic !
audio taper is 'curved wedge', the thick part [where R rises or falls fast past where you want it with small rotation/movement of the wiper near the 'thin end' of the tapered shape resistance wafer]
re one end of the resistive wafer being thicker [audio or logorythmic or A pot are the same thing].
250k pots range from 0.0k to about 250k [measure R with meter to find exact wafer value].
The taper of an audio pot, when oriented so fine control falls where you want fine control allows fine tuning easily, the other end will be very touchy and jump past the sweet spot...try reversing the pot which of course reverses the taper, or use the linear if it comes into view first, try that.
  Sometimes easier to figure out ''where it falls'' by testing a pot on ''it'' to see how well it tunes the value ''it'' wants. ''It'' is the subcontext of the application, example would be the audio taper, dual ganged 100k pot [+ the stop resistors...the 47k in series with 'dual A' and the 5k stop on 'Dual B'] in this case the homework has been done and the final test complete.
For results to be similar at all at this rather particular application [dual ganged pot simulataneously and sympathetically adjusting input and output], start with what the schematic shows: Dual 250k A pot [+ the stop resistors, it looks like maybe they were there stock] and use that taper 'n those values as a starting point.

[espinete]

for volume, the best solution i have found is actually 3 fold: replace 68k R gain with a 100k trim ( series), control Q1 e bias with a  1k trim , and a 250k trim or pot wired like a guitar vol ahead of everything else.

I don't know exactly how to wire the 250k pot. My gcb95 is truebypass.

*  I unsoldered the violet wire placed in the circuit just in the output positive jack. It comes from the switch. I put it in the 1st lug .

*2nd lug(middle lug) to the output jack positive ( where the violet wire was in the circuit )

*3rd lug ( right one ) to ground.

The issue is that it works also when wah pedal is off. So, it looks good but it's totally useless

[espinete]

I think i got it. Thanks anyway