wah circuit

[burksguitar]

Hey guys, I built this http://www.turretboard.org/?p=1845 and have it working. Wired it for true bypassand led. I used a 100k hot pots wah pot.

I have 2 problems.

 There is a noticeable volume loss when engaged, was thinking of putting a buffer in not sure if the buffer should go before or after the effect though.

The other problem is there is very little tonal change in the sweep. I tried moving the pot so it engages in different parts of the pots range but that has little effect.

Also, according to this layout the in and out on the inductor falls on the same trace, which doesn't work. I moved the inductor so that it goes from one trace to another and it works so if you spot that in the layout I've already fixed that.

Any other tips to get more range from it? I figure changing resistance somewhere should give more of a tonal range but where? I just don't have the experience to mod it on my own.

[jtn191]

There's a few things you can do...
*First check the layout against the schematic!
Next, that vox wah follows the same basic schem as the Cry Baby wah (as most wahs do)
-You could decrease that 68k resistor to another value--wire in a pot temporarily to find the exact unity volume. Try between 33k and 47k. This resistor limits the amount of signal going into the circuit
-next you could try different transistors. These seem like they affect the high frequency response and "modern-ness" of the wah. Go with low hfe's for a vintage sound and higher for modern. which transistors did you use? There's a fair chance you've got the pinout flipped around or Q2 (the right most transistor) has too low of HFE.
-If you reduce the 470R resistor, you'll get more volume, more low end, thickness, and growl. This can increase the intensity too.
-Make sure your 100k cap between the pins on the inductor is 100k, this should give it a pretty pronounced effect. stock cry baby is 33k and upwards makes the filter steeper

schem: http://www.freeinfosociety.com/electronics/schemview.php?id=350
Info: http://www.geofex.com/article_folders/wahpedl/wahped.htm

[burksguitar]

Thanks very good info. I think the transistor was to blame. I tried a couple and did notice a difference, but still had the volume loss. If I had read your post I might have salvaged the circuit but I ended up building the Colorsound wah, which is pretty nice. I may go back at some point and see if I can get some better results with it but now I'm thinking I may try to reverse engineer my Wilson Wah.