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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 2 responses by james633

james633
1,052 posts
 

I have found this type of hum is often in the power supply. Do you have another amp to try?
 

When my subs are connected between my pre-amp and amp (internal highpass) I get a faint 60hz buzz. I found no work around and will replace the subs at some point. I use a McIntosh MC462 and it has a hair of hiss with my ear by the tweeter and when the subs are in line a 60hz buzz. I have also had my system pick up my Xbox or computers power supply. 

james633
1,052 posts
 

Ok interesting, sounds like an amp issue. One thing is the electrical buzz you hear when you put your ear to the amp is normal for McIntosh. They all have a bit of buzz in the box (no idea what it is).

 

Hopefully you get it sorted. Those are complicate amps and it only take one little thing to go wrong. 

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