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Help me solve another speaker hum thread :)

My dealer recently installed a set of Sonus Faber Aida’s with 2x McIntosh MC901 monoblocks. I also have 4x dedicated lines.

The problem is I have have hum in both speakers (hum in the midrange only. The tweeter makes a different noise but I read that’s more normal?) One speaker is louder than the other. Neither changes with volume. The louder one can be heard at about 6 inches away, the quieter one needs my ear as close as possible to faintly hear anything. Sound from both is 50hz maybe 60hz hum. Both monoblocks also make a slight mechanical buzz that can be heard about 6 inches away.

If I have only one speaker, speaker cables, and monoblock powered (nothing else connected, powered, or even plugged in), it still makes the hum.

I have tried using a cheater plug for possible ground loop, also a DC blocker. Neither made any difference. What do you guys think the issue could be? Bad tubes?

Do I need to send the amps back? Or just live with it? I don’t hear from listening position or anything. Thanks in advance.

battbot

Showing 1 response by femoore12

femoore12's avatar
femoore12
683 posts
 

The only time I ever got a hum out of my system (horns and McIntosh tube amps) is when one of my interconnect cables went loose at the plug. Just the slightest adjustment on the cable at the plug at the amp and the hum would appear or disappear. It was still under warranty so I returned it for repair. Now it’s back in my system and no more hum.

Those amplifiers shouldn’t be making any hum or hiss at all. It’s possible the amps are picking up interference from your electrical system. Have you removed the speaker cable from the amps and then powered on the amps to see if it still makes the hum? If they do it is your electrical feed or the amps themselves. 

 

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