Of course different designers have different opinions on this but a good place to start is to bypass with a value 1/100th of the big cap. You can bypass again with another cap 1/100th of the smaller and see if that does anything.
example, original electrolytic 4700 uF bypassed by a 47 uF film cap and a .47 uF film cap.
The best thing is to get rid of the electrolytics but the alternatives are expensive and physically very large. For solid state amps using thousands of uF it is pretty much impossible to get away from electrolytics.
check out http://www.percyaudio.com/ to see a variety of film caps to choose from, some quite expensive in relative terms.
DIY HiFi Supply also has a selection.
example, original electrolytic 4700 uF bypassed by a 47 uF film cap and a .47 uF film cap.
The best thing is to get rid of the electrolytics but the alternatives are expensive and physically very large. For solid state amps using thousands of uF it is pretty much impossible to get away from electrolytics.
check out http://www.percyaudio.com/ to see a variety of film caps to choose from, some quite expensive in relative terms.
DIY HiFi Supply also has a selection.