8-lugged pot? (RV-3 hi-cut mod)

[spacelordmother]

Found some information on FSB about how to do this mod -- seems easy: "put a 47nF cap over the two outer lugs of the balance pot, one is ground and the other is the one from the repeats."

But when I opened it up the balance pot looks like this:



Here's the schematic, specifically looking at VR Board 2/2 in the upper right:

NSFW: show

I tried to find a data sheet, but came up with nothing. Probably user error. Thanks for any info, happy to post more pics as needed.

[crochambeau]

Pull a datasheet for a dual gang 100K with center tap for a nice visual reference of what's going on there.

According to the schematic the center tap is giving a ground reference at mid point of the 100K sweep, and so is the wiper. So the pins would read left to right CCW (high), wiper (common), CW (high), CT (common).

If the mod is tying one "high" leg to ground through a small cap (47nf is pretty huge as shunt caps go) and they do not specify WHICH ONE (as in after R11, 12, 13, or 14), I'd connect one side of the cap to ground and probe each of the four high pins to determine what sounds best.

[spacelordmother]

Good info!

A quick lunchtime test reveals that the third pin from the top left cuts the highs on the dry signal, and first pin on the bottom left cuts highs on the repeats. It's actually really subtle -- I need to play around with some different cap values to see the results.

[spacelordmother]

I ended up sticking with the .047uf -- after playing with other values and listening more intently it seemed to be the best sounding and most usable. Thanks again for the help, Croc!

[crochambeau]

Happy to help!