Cap in parallel with diodes

[antonis]

With the 100R 1uF pair I get around 1200 times gain above 1.5kHz and a still at most 200 for the other frequencies.
Doing the logarithms, stock has an 11 dB boost above 1.5kHz and the mod has 8 dB of boost.

I'm confused a bit with stock and modified values but definitely a gain of 1200 corresponds to 61.58dB..

P.S.
A quick and dirty way to check your dB magnitude calculations (concerning voltage gain) is the number of zeros (0) after the 1^st digit..

[Christoper]

Either way my math was wrong, but what I meant was relative to the other frequencies:

Stock = 2300 times gain above 1500 Hz, 200 times gain beneath 1500 Hz (upon the incorrect assumption the filter is linear). This makes the high frequencies get a voltage gain of roughly 20 dB compared to the bass frequencies.

100R 1uF = 1200 times gain above 1500 Hz, 200 times gain below 1500 Hz. This makes the highs 15.5 dB louder than the bass.

Don't know where I got 11 and 8 from.

[Christoper]

Also, @GGBB, when you recommended:

My personal recommendation as a permanent mod to the 560R leg would be 180R and 15uF which is equivalent to about 3. On the 47R leg that would be about 120R and 860nF which reduces the gain pot to the equivalent of about 39k. You could stretch that to 150R-680nF for a more easily available cap value which pushes the gain pot down to 32k equivalent.

These were a "one or the other" mod such that raising the 47R resistor lowered the gain of those frequencies, and lowering the value of the 560R raised the gain of those frequencies, and then obviously the caps were changed to maintain the same corner. It took a second for it to click that raising the gain on one was mostly the same as lowering the gain on the other. I'm now reaching the turnover point where I understand the circuit rather than relying on other peoples anecdotes about what changes what. The 560R leg mod would change the gain the least because the smaller resistor makes a bigger difference in parallel calculations

I'm considering increasing the gain a touch on the 560R leg as well, but I will have to play around with what I have now before I make that decision. This would be in an attempt to curb the sub 60 Hz range a little bit more, but it's no big deal if I find it makes the 47R mod less obvious

[Christoper]

**acidentally quoted myself instead of editing above post**