Resistance question...?

Pete Finney · From: Nashville Tn.

I have a Vox wah-wah pedal, for a certain application I need to pad the output significantly and want to modify it. I thought about just retrofitting a volume pot to the side but don't really need to be able to vary it. Is there any reason not to just solder a resistor "in line" somehow? And if not, what size (ohm) resistor would correspond to turning a pot down about a quarter of the way, and where would be the best place to put it in the circuit to least affect the actual tone? I would experiment before hard-wiring it but would like to know where to start; I'm sure this is an elementary question to many of you, your help would be much appreciated...!

[This message was edited by Pete Finney on 28 March 2006 at 06:58 AM.]

Donny Hinson · From: Glen Burnie, Md. U.S.A.

I'd just use a small trimpot, which is a small variable resistor with a screw adjustment. Be aware that along with changing the volume, this type of mod could also alter the tone slightly. How much it would effect the tone would be hard to predict until you tried it.

John Billings · From: Ohio, USA

Donny, isn't there some sort of simple tank circuit that could be used on the trimpot to make it not effect tone?

Joseph Meditz · From: Sierra Vista, AZ

Hi Pete,

Yes, but you'll need two resistors for this, one in line on the Tip and the other across the Tip and Ring.

T ---- R1 ------- To Amp
...........|
...........R2
...........|
R ---------------

(Ignore the dots. I just edited the diagram it and put them there because the spaces were being ignored.)

You can try R1 = 100k and R2 = 100k which will provide 6 dB of attenuation. If you need more attenuation keep R1 at 100k and just decrease the value of R2. With R2 = 33k you'll get 12 dB of attenuation.

Joe

[This message was edited by Joseph Meditz on 28 March 2006 at 09:17 AM.]

Pete Finney · From: Nashville Tn.

Thanks everyone,

After I posted I started thinking a small variable trimpot might be the answer... any suggestions on the best place in the circuit to put it?

Thanks again for all the info...

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