2. amps-preamps
  3. 173415-7783

Help with McIntosh Repair Facility

My MC452 is having an issue with the right channel that's a little weaker than the left.  Not by much but definitely noticeable.  Have been trying to diagnose the issue and everything so far points to the amp. I'm using XLR and have changed ICs , preamp tubes, cleaned amp inputs, etc.. but the head scratcher is if I switch the right and left IC inputs on the amp the sound or output is balanced. The meters are in alignment as they should be. The only issue is of course the right and left channels are opposite now.   I've spoken with an authorized repair center and bench testing is $350 and worse case scenario the board needs replacing plus labor can hit $2500 which in my opinion is ridiculous.  Has anyone experienced this issue or have any ideas or know of a reputable or more cost effective repair facility? I'm in Lexington KY.  Thanks in advance.  

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aniwolfe
760 posts
 

@samzx12 

Try Sanford and Son or maybe Dan Aykroyd?

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samzx12 OP
1,220 posts
 

@aniwolfe Lamont is taking it to the local Watts electronics repair shop lol. 

j_damon
388 posts
 

OP, it sounds like when you switch cables at all is good except r&l channels are reversed, did you try to leave that,and change pre end also, that would fix channel reversal 

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samzx12 OP
1,220 posts
 

No because there is an issue to begin with and I want to get it resolved.  I did switch the speaker cables for both channels at the amp and the problem follows from the right to the left.  Measured the dB levels using a test tone and there is a 8-9db difference.  Two sources have told me they think it's the bias but we'll see hopefully very soon.  

 

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samzx12 OP
1,220 posts
 

I want to thank everyone who contributed to this thread (even aniwolfe haha)  Much appreciated :)  With the help of Monty a fellow audiogoner he hooked me up with a retired McIntosh repair guru and we took my amp to him this past Friday. He bench tested and found the bias was a little off and also calibrated the meters.  He found the left channel meter was reading high of all things.  This shocked me but hey they both read the same now and both channels are healthy and putting out equal power. Listened to the amp over the weekend and so far all is well.  It's also a good piece of mind that the amp was serviced by a professional and he gave it a clean bill of health. 

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