Promethium distortion cap swap

[GORP]

Wondering if I could swap the 1.5uf cap at c16 for a 1uf? Taking a look at the schematic I’m not sure what kind or how much of an effect it would have coming out of that ic and into the bass control. Any guidance is appreciated

 

[benny_profane]

You could, but you’d change the behavior of the LOW control.

The stock setting is a band pass filter with a center frequency of 86.8Hz. With a 1uF cap, you’d change it to 106.3Hz.

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[GORP]

Gotcha, assumed that was the case. Thanks for the info

 

[BuddytheReow]

If you want some Swedish chainsaw, keep the 1.5u cap.

 

[benny_profane]

If you make changes to other components to hit the same frequency target, you’ll alter the Q of the filter. Try a 1uF and 470nF cap in parallel to get you there if you don’t have a 1u5 cap.

 

[derevaun]

I swapped it to 1uF on an HM2 build, also changing R25 to 470R. The difference works out to be around 89 Hz with Q=3.8, vs stock 87Hz with Q=3.7. That's roughly a semitone difference for each. Those changes have other (small) implications to that part of the circuit. But, I can't detect the difference between it and a build using the stock values. This was on HM2 Cult Chainsaw boards, where space is tight at that cap.

I wouldn't mess with the mid and high values, but it worked out OK for the low band. Still, if this were my only chainsaw build, I'd try to squeeze in some parallel caps. FWIW, film caps will work in that spot.