VOX wah - true bypass with signal loss

Archived from groups: rec.audio.pro (More info?)

Locsmándi Bence wrote:
> Hi!
>
> In an earlier thread I asked your help with losing signal with cables.
> Now I know that the "wrong" object in the chain was my VOX wah.
> It has a true bypass feature, if I take out the battery and switch it off
> the signal passes through. But, strangely, it loses some high end and punch.
> My Marshall head doesn't seem to react this head but if I use my MESA/BOOGIE
> preamp all can be heard.
> As you would suspect I need at least 2 cables for this operation. I have
> this 2 cables and if I route my KORG CMP-1 compressor stomp box instead of
> the wah everything works fine.
> My wah is in good condition. Fastened the In and Out jacks to the case, but
> no improvement. All the solderings seem to be fine.
> Strange situation. Have any of you heard about something like this? Any
> solution?
> Thanks a lot.


The bypass switch just connects the output jack back to the input
connection (as opposed to the output) without disconnecting them from
the circuit's input, so bypassing leaves the wah input still loading the
signal. Basically, the wah still wahs but the output goes nowhere when
it's bypassed (if nobody is there to hear it, does it still wah). This
makes it (I guess) a "cheap" bypass rather than a true bypass.

You would need to replace the bypass switch with a DPDT type that
switches the input OFF the wah's input while it switches the output off
the wah's output. This is not hard to modify. One side of the switch
does exactly what the old single switch did, and input gets wired similarly.

Here's what you have, SPDT (single pole double throw):

wah input and input jack ---O
bypass
output jack ----------------O
normal
wah output -----------------O


You need a DPDT (double pole double throw):


O--O just a piece of wire for the bypass

O O--- input jack

O O--- wah input


On the left side the output connections stay the same as for SPDT.