Weird MC2000 issue

[McInosh]

I have lost bass out of one channel in my MC2000

Thought it might be one of my Amati's, but switched cables and the lost bass switched to the other speaker.

Tried a new speaker cable, no change.

Before I carry it to the car for repair, any ideas on losing just the bass? There may be less volume overall but it's hard to tell with nothing is coming out of my woofers.

Can old tubes cause this type of thing. They are the original tubes and get heckuva lot of use.

[Cohibaman]

Originally Posted by McInosh

I have lost bass out of one channel in my MC2000 Thought it might be one of my Amati's, but switched cables and the lost bass switched to the other speaker. Tried a new speaker cable, no change. Before I carry it to the car for repair, any ideas on losing just the bass? There may be less volume overall but it's hard to tell with nothing is coming out of my woofers. Can old tubes cause this type of thing. They are the original tubes and get heckuva lot of use.

Swap source cables then preamp cables and see if it follows....

[McInosh]

Already tried that too.

The meters on my pre show equal but the meters on the amp definitely show much less "power" on the right channel. Significantly less.

[Cohibaman]

Originally Posted by McInosh

Already tried that too. The meters on my pre show equal but the meters on the amp definitely show much less "power" on the right channel. Significantly less.

So the amp meter is showing lower volume regardless of cable swapping?

[McInosh]

Correct

[Cohibaman]

Swap tubes...all from left to right & visa versa.

[McInosh]

Power, input or all of them? I'll need to re bias if I swap the KT88's correct?

[Cohibaman]

Originally Posted by McInosh

Power, input or all of them? I'll need to re bias if I swap the KT88's correct?

One at a time would be tedious, but it will tell you exactly which tube is the culprit.

[McInosh]

Except there are 4 KT88's per channel. Swap them one at a time to see if a single tube is the culprit?

[Cohibaman]

Originally Posted by McInosh

Except there are 4 KT88's per channel. Swap them one at a time to see if a single tube is the culprit?

Yup