Power supply filtering

[Mr.Curwen]

I've heard that using bigger filter caps on your classic amp will effect the sound. How exactly?

What are the exact changes that take place tonewise when you for example change some 22µF filter caps to 47µF?

What is the theory behind this change, what does it do to the amp?

[ckpop]

Using a bigger filter cap value can make your amp tighter and thick and have more punch but there is a drawback. Your amp may not sound as open and colorful in my opinion. Bumping up the filter is more for high gain more modern type sound and would never do this to any amp outside the high gain stuff or the vintage vibe is gone.

[KT66]

Lower notes need more current to amplify them optimally, so if you have more on tap with bigger filter caps, the bass will be more pronounced and less mushy. In some cases raising the filtering will reduce hum caused by AC ripple. I read in a Gerald Weber article a while back that the low amount of PS filtering in a vintage AC30 can make certain notes sound out of tune and this can be heard in some Beatles songs.

The cap that makes the most difference is the first one in the chain, try raising that one in your amp and see if you like it. I worked on an old single ended Airline recently that I raised the first cap to 30U ( stock was 20u ) and my customer liked it alot. here's a video I made to show him where we were at : http://www.youtube.com/watch?v=Pihy4RYd8X4. Please forgive sloppy playing, audio quality, and monotony !

[Structo]

You can piggy back a new cap on top of the existing one to see if it helps.
I would choose one that is half the value with the same voltage rating.
Connect it in parallel, plus to plus and negative to negative.

[tubeswell]

Even if you double the reservoir cap value, it will only increase the B+ by a handful of volts, but it does tighten-up the amp/reduce some flab, which is particularly noticeable with low powered amps (like the tweed champ). If you are doing this to a 'vintage'-style (or even a vintage amp) with tube rectifier(s), be aware that there is a maximum recommended reservoir capacitance printed on the (rectifier) datasheet. Increasing the reservoir capacitance is progressively harder on the rectifier's anodes.

[Buddha's Guitar Tech]

i've had a number of problems with a champ build (yes it's me again) and i think it's the relationship between the rectifier, the filter caps, the B+ and the screen grid. i've burned through more than a fair share of caps.
after working with and building a couple of 50W 6L6 amps, i'm learning that some tolerances shouldn't be ignored.

Too much of anything can be a bad thing.