Revox help

[miner]

My B-I-L has a Revox integrated amp (45w/ch) that he bought new in 1984. He has develpoed a problem that I can not diagnose. He seems to have a 'crackling' in one of the channels, or so we thought. When he reversed the channels (amp has a reverse channel function knob) the crackling was coming from the same speaker (right speaker 'A' pair {ADS L-710}). Ah ha, so it is the speaker you say. Problem is it is also making the crackling sound from his 'B' pair right speaker, even with the 'A' pair off. Since it is not channel-relevant or speaker-relevant what could it be? I am baffled.

Interconnects would indicate channel-relevant as would speaker cable.

[Karma]

HI,
Rather than using the switch to reverse channels, physically change them on the rear of the amp. Indication so far is the problem is in the reversing switch or relay.

Sparky

[miner]

HI,
Rather than using the switch to reverse channels, physically change them on the rear of the amp. Indication so far is the problem is in the reversing switch or relay.

Sparky

OK, update. When he listens to his tuner the 'noise' is not there. He has told me he is using high-dollar ICs. I was beginning to think it may be a bad voice coil in his speaker (ADS L810). But even when he has these off the noise is in his right 'B' speaker. We are both dumbfounded even more now.