Q On Anderton's "Volume Pedal Descratcher"

[Paul Marossy]

I built this circuit per this schematic: http://www.diyguitarist.com/PDF_Files/vpr.pdf

Because I have been using my DOD FX17 volume pedal for a while, I haven't been using the volume pedal that has this circuit installed in it for quite a while and I "brought it outta storage" recently. I noticed that I used a 4.7uF cap installed on the output (C4) instead of the 2.2uF as specified. So my question is this: what affect does the cap size here have on the circuit? Does it simultaneously increase gain and the bass response, or? I ask because it seems to be distorting a little bit, so it seems to me that the gain might be too high...

[cd]

Shouldn't make any difference.  A 2u2 is passing everything below audio range anyway.  The cap doesn't affect gain at all.  Try increasing R9.

[Paul Marossy]

Adjust R9... I think that's what Anderton's article suggests as well if there is too much gain. I'll take a second look at that section of his book tonight. Replacing R9 with a 330K might do the trick, or maybe even a trimpot.
I suppose that the battery voltage will have some effect on that as well. But, I ramble.

Thanks.  

[Paul Marossy]

Just for the record, in Anderton's book, he suggests decreasing the size of R4 until any distortion is no longer present. He also suggests using a 100K trimpot in series with a 1K resistor in place of R4 if you anticipate using guitars with varying outputs. A nice mod might be to have a "full size" 100K pot instead of the trimpot to adjust this on the fly.

Just thought I would pass it along...