input cap blend pot options

[mordechai]

I've used Joe Gagan's input cap blend pot with a 100K pot -- but would it be possible to use this with a pot of a lower value like a 50K or even a 10K?  What would be the benefit or detriment of doing this?

[Quackzed]

if youve used a 100k, basically when its at noon, it IS a 50k resistance... so at full clockwise a 100k 50k or 10k will all be 'full on'- zero resistance and sound the same, but the 100k at noon will sound the same as the 50k at full counter clockwise 'off' and a 10 k pot at full off -counter clockwise will sound like the 100k did at 90% clockwise- almost fully 'on'... so the smaller pot you use, the more 'bass' in the fully off position- if you have it wired to be more bassy at full on. 100k at off- much less capacitance and much less bass- 50k at off- a bit less bassy at off- 10k at off -barely less bass at off... basically the smaller the pot value, the less bass you roll off at full counterclockwise on the pot.

[John Lyons]

^Yep
Additionally, using a larger pot will get you a larger range of bass cut.
More specifically the lower cap will have more isolation from the larger cap
which will basically be closer to the low cap's value (with 100K the caps still
add up a bit.)

[Gus]

This is a good place to use a program like LT Spice.  I adjusted a circuit like this for a treble boost using LT Spice You can try different values and tapers and other cap values and graph the results.

http://www.diystompboxes.com/smfforum/index.php?topic=93926.0

[mordechai]

^Yep
Additionally, using a larger pot will get you a larger range of bass cut.
More specifically the lower cap will have more isolation from the larger cap
which will basically be closer to the low cap's value (with 100K the caps still
add up a bit.)

Would the added variable resistor cause problems regarding impedance if it's placed at the front end of the circuit?

[John Lyons]

There is always a path around the resistance, that's how it does what it does.
The impedance may be altered but I don't think it would cause a problem.
It's been used many times in a Fuzz Face type circuit among others.