Marantz PM711AV


2010-01-17 11:12 am

I am having a problem to detect some form of distortion in this amp. When I play music thru this amp, there is some sort of high frequency distortion heard more clearly thru the tweeter. It sounds like, if you connect a speaker with a torn diaphragm, you hear some kind of breaking sound. When I reduce the AC mains voltage from 240V to about 120V, the interference disappears. I suspected it may be AC ripple present in the audio signal, so I replaced both the filter caps(8200uf, 56V) but its still the same. Can someone please advice what can cause this jittering sound.