Noise from MM Input - C2600 Preamp

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hikerneil

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Feb 8, 2020
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Carlsbad
I have a McIntosh C2600 and I am having problems with noise from one speaker when I listen to albums. At first I thought the noise was coming from my Turntable but I disconnected the turntable and the noise is still coming from my Left Speaker.

Here are my symptoms:
- Noise only comes from left speaker
- Noise only comes when I dial Input to the MM input (not other sources)
- Noise is present, even if I disconnect all wires and cables from the MM inputs on the back of the preamp

I am guessing I need to replace some tubes??

Have others had this issue?

Thanks.
 
Welcome to Audio Shark.

I would think if it was a tube the noise would happen no matter the input. Sounds like an issue specific to the phono preamp section.
 
According the the C2600 manual the left two tubes are specifically for MM phono, with the leftmost one for the left channel and to its right the right channel. So if the noise is only on heard with the MM input selected and only in the left channel the source is likely the leftmost tube. It's common though to replace the pair of MM tubes to keep them matched. If you have a spare 12AX7A tube you could try just swapping the leftmost tube to see if the noise is eliminated in order to troubleshoot the problem. If so you can then consider replacing the pair of MM tubes. Hope that helps!
 
This is all new to me - but studying the design of the tube layout for the C2600 it sure seems logical that it would be the tube(s) that audio.bill mentions. I have emailed the retail store where I bought the unit to see if they do this work. I am very tempted to order two new 12AX7A Gold Lion tubes and try replacing them myself. I am very mechanically inclined and capable of learning new skills from YouTube videos, BUT I also don't want to damage my C2600 baby.

Is the tube replacement relatively straight forward??

Thanks.
 
Tube changing is very easy, make sure the unit is fully powered down and you can even unplug it from the AC to be sure. Then once you have access to the tubes they will lift gently out of the sockets, then you orient the new tube pins so they're lined up with the holes in the tube socket and gently insert to seat the tubes securely. Close up the unit and that should be it, but you can check with your dealer to get their go ahead before proceeding. Good luck!
 
hikerneil said:
This is all new to me - but studying the design of the tube layout for the C2600 it sure seems logical that it would be the tube(s) that audio.bill mentions. I have emailed the retail store where I bought the unit to see if they do this work. I am very tempted to order two new 12AX7A Gold Lion tubes and try replacing them myself. I am very mechanically inclined and capable of learning new skills from YouTube videos, BUT I also don't want to damage my C2600 baby.

Is the tube replacement relatively straight forward??

Thanks.
Click to expand...

Yes. Easy peasy. Just do it. Yourself! :)

If you are not using the MC input then swap the two tubes from that input section into the MM section. Put the tubes from the MM section back into the MC section. Done. Hardest part will be taking the cover off.

That will get you going for now and you can decide what to buy at your leisure. Noise in a tube can be a precursor to failure so I wouldn’t wait forever. I use Gold Lion re-issues on my C2300 - they perform well to my ears.
 
I AM VERY HAPPY TO REPORT A HAPPY ENDING TO THIS STORY:

After getting input from several on this forum, and after speaking to the retail store where I bought the C2600 - I took the plunge and ordered two new Gold Lion 12AX7 tubes. The tubes arrived today (I was so excited when the box arrived!).

I opened my McIntosh C2600 by removing the glass top (6 screws) and then I removed one black metal crossbar that helps hold the tubes in place (2 more screws). I carefully removed the tubes on the MM circuit and installed the two new tubes. I closed everything up, and turned the preamp on. I was happy to see the tubes turn from gold to green, and then I put on one of my favorite albums, then another, then another, then another - the system sounds better than ever!!!!

My wife still doesn't understand why this little thing made me so happy. It's a great day.

Tube.jpg
Old tubes.
 
Glad all is well.

hikerneil said:
I AM VERY HAPPY TO REPORT A HAPPY ENDING TO THIS STORY:

After getting input from several on this forum, and after speaking to the retail store where I bought the C2600 - I took the plunge and ordered two new Gold Lion 12AX7 tubes. The tubes arrived today (I was so excited when the box arrived!).

I opened my McIntosh C2600 by removing the glass top (6 screws) and then I removed one black metal crossbar that helps hold the tubes in place (2 more screws). I carefully removed the tubes on the MM circuit and installed the two new tubes. I closed everything up, and turned the preamp on. I was happy to see the tubes turn from gold to green, and then I put on one of my favorite albums, then another, then another, then another - the system sounds better than ever!!!!

My wife still doesn't understand why this little thing made me so happy. It's a great day.

View attachment 33197
Old tubes.
Click to expand...
 
Very glad it worked for you. I would have given McIntosh a quick call. They answer their phones are amazingly helpful! I am sure they would have told you the same thing. Knowing them they might have surprised with a new set of tubes.

Personally, when I was using tube gear, I loved the Gold Lions. If it were me, I would probably replace all of the McIntosh tubes with Gold Lions :).
 
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