EzraplaysEzra wrote:Capacitors are much like batteries in their construction and contain an oil or a thin film as the dielectric between the two conductors. In time, usually decades they "dry out" and need to be replaced through out the circuit.
Tiny amendment: electrolytic capacitors (the big ones, usually can-shaped and blue) are the ones that contain a gel and can (among other things) dry out. The smaller ones you'll find in a tone circuit (generally disc or drop shaped, not blue) most often use mylar or ceramic/mica and should last as long as anything (it is possible to blow them up, but you have to try).
Smaller capacitors on the board also use oils, particularly older ones and higher end reproductions. And I really wasn't endorsing a wholesale recap. I was trying to give him a heads up as to what he might experience in the life of an amp. Any tech worth a salt would diagnose issues and short comings and replace components. To be clear, tone caps in the first stage in general tend burn out sooner than other chiclet and waffers, but filter caps usually have a shelf life much shorter than that of the rest of the amp.
And I completely agree, changing filter caps requires the same care as working on the service in your home and both can be done safely by my wife after reading an article or two.