Adcom preamp not sounding good

[mars_volta]

I've been using an Adcom GFP-565, GFA-555 and an Adcom CD player for quite a while. They sound fantastic but I've noticed sometimes the right channel isn't at bright as the left. I recapped the amps input board already. I kept telling myself its my imagination then finally I bypassed the poly switches on the Polks, tried my Parasound CD player, switched all the RCA cables, tried all the outputs on the pre, different switches on the Adcom speaker switch. Nothing. Still bugs me.

I brought in the BT butler 140 amp and Pro-5 preamp from the cold garage last week and got a chance to hook it up today. Sounds great and there's that right side high end I've been missing!!! Great combo there. Really sweet sounding. I went back to the Adcom 555 amp with the BK Pro 5 preamp. Still sounds great so I'm thinking that Adcom GFP-565 probably needs some work.

Anyone else have issues with the GFP? I've got another Adcom pre with the tuner built in. I'll try that later.

 

[avionic]

They sound fantastic but I've noticed sometimes the right channel isn't at bright as the left

Dirty switches or controls ?

 

[dr*audio]

Did you try the Bypass outputs on the preamp?

 

[mars_volta]

I don't think its controls. I've never had problems with them on that box. I usually run it in bypass mode so most of that is out of circuit.

Come to think of it, I wonder if its the CD input? I dont think I've noticed it listening to vinyls. Hmm I'll have to do some swapping.

 

[mars_volta]

I've been rocking the GTP-400 today it sounds great!

 

[dr*audio]

The only thing I can suggest is cleaning the controls on the preamp. The bypass switch could be dirty.

 

[ScooterMcTav]

Agree with controls - I've had weak channels caused by no less than 4 or 5 different switches or knobs on a pre or integrated.

Worse case scenario, you have clean controls at the end. And one of the worst offenders I had was an old JVC RS-7 where the input selection knob was causing the problem. Mind you, I had weak channel due to a selector on a Marantz 2252B. Oh and also a NAD 7400 (one of many problems). Oh, and my Pio SX950.