Is there an advantage to equal filter values?

[iknowjohnny]

What i mean to ask is whether there is some sort of advantage to having all preamp filters be the same value? Say you have a PI cap and 2 others split between preamp stages. Is there any advantage to keeping them all of the same value rather than do what i've been doing for a while now and putting whatever value seems to sound/feel best for each stage?

[Cliff Schecht]

To each their own, if you cook up some nice cocktail of signal caps that happen to have the sonic effect you're after then good on ya. I tend to use the smallest value possible to pass the desired bass frequencies (seems obvious but that's really the goal 99% of the time). In the first stage you can really limit this value to prevent blocking distortion when pushing the first few stages hard. If you want a really mid-heavy amp then you can use smaller caps everywhere to knock out some bass or use "excessively" large values to make the amp a guitar/bass amp.

But also you can just use your ears and develop a feel for what changing capacitor "X" does to the sound. Not the most scientific method but another means to an end..

[iknowjohnny]

I fully understand the effect they have, as i have spent a lot of time choosing values i thought worked best for each stage. I'm just wondering if there is some reason that it's best to have them all the same value. Main reason i'm curious is there seem to be no amps like that which leads me to think something negative comes from using different values or i would think some amps would do this too.

[vibratoking]

There are so many things to consider that I don't think you can simplify it down to a rule that is so straightforward. I don't think there is a single reason to have caps of the same value because of the different impedances associated with each stage. All the caps might not be the same value if the target is to match all the cutoff frequencies, for instance.

[iknowjohnny]

I'm talking about PSU (filter) caps.

[John_P_WI]

Regarding the PSU caps being similar I would believe that historical design precedence, lethargy, and minimizing inventory are the driving factors.

[vibratoking]

There are plenty of individual builders here that use unequal filtering.

[iknowjohnny]

Thanks all, i see now.