Crybaby mod question - power bypass.

[Steelystan]

Hi guys

Just finished modding a CBG95 for true bypass and the vocal Q resistor mod.  I also took out the input buffer circuit.  Its all worked fine despite the appaling quality of the PCB and the flimsy cable block connector.

Buzzing out the board i find 8.5v in a number of places regardless of the on/off state of the pedal, so I assume the mod does not disengage power in the off postion.  I can see how I could use the same switch pins, recommended for fitting an LED, as a power switch when the pedal is turned on but will this cause a significant glitch in the signal as the circuit powers up or will it be quick enough to be effectively instant?

I know removing the input cable disconnects the battery but the pedal is in a pretty tight space on my pedal board and even with a pancake cable its fiddly to pull the cable out.

Cheers

Stan

[thermionix]

Almost all pedals are done the same.  If you cut power during bypass, there will be a loud pop, or a lag, or both.

One thing you can do is put a separate toggle in to cut the power when you're done playing for a while, so you don't have to unplug.

[Steelystan]

As I expected.  Thanks.

Yes, I think I'll put a little switch on the side, although I suppose I should just run it off the same power block my other pedals are on.  I've dithered on that because of the dastardly recessed power socket which needs a longer power plug.  Ordinary "boss" style ones can't quite reach.

Cheers

[drummer4gc]

If you're already going to drill for a switch, might as well drill out the hole for the power jack and replace it with a jack that accepts a standard plug so you can stop using batteries.

[Elijah-Baley]

[...]
Just finished modding a CBG95 for true bypass and the vocal Q resistor mod.
[...]

How do you find the Vocal mod? I tried to replace that 33k resistor with a 100k pot for a wide range, but (except when the pot was really close to the low set where I got no wah effect) I couldn't hear any difference in the wah. Indeed I excludede from my package mod.

[Steelystan]

At first I thought the vocal Q mod was a bit overrated.  I replaced the stock resistor with a 68k and found the resonance to be more peaky but also a bit narrow.  Effectively I had the same sound at either end of the pedals travel and a strong resonant hump in the middle.  I was going to reverse the mod, or try a pot. 

But in the process of performing the true bypass mod I removed the input buffer circuit and between that and the Q mod I suddenly got a really good sound.  So I'm going with it for now.

Next thing is to make a light plate for it.  Ive ordered some blue LEDs but I'm considering designing a circuit that changes the light colour from red to blue or green according to where the pedal us %^&*ed.  Might be cool.

[thermionix]

Yeah that input buffer is a dog.  Don't know why Dunlop did that instead of true bypass.  It would have been cheaper and better to just change the switch to a DPDT.

OTOH an output buffer can be very useful, enables the wah to work in front of a fuzz face.  I have mine wired to a 3PDT toggle so I can true bypass it and cut the power to it when not in use (switch while the wah is in bypass to avoid the pop!).

[zombiwoof]

I've always wondered if there is a way to use the section of the board that has the input buffer components to install an output buffer there.  Has anyone tried that?.
Al

[Elijah-Baley]

I bypassed the input buffer (without to desolder any components) and I added a Foxrox Retofit board in the output.

[thermionix]

I used (a clone of) the FoxRox as well.  It has a dip-8 opamp, so couldn't be mounted in the place of a GCB-95 input buffer, which uses a single transistor.