2. amps-preamps
  3. 1098390944

Hum or buzz through speakers

I just turned over my system from all B&K to Audio research and McCormack. I was running the Audio Research through the B&K until Monday when I put the McCormack DNA-1 in place. I am hearing a hum or buzz through my Vandersteen's audible from three feet away. Preamp is ARC SP9MK2. Tubes are 6922 Golden Dragons which I am going to change over to some Amperex 7308 USN-CEP. Would this be tube noise that perhaps the McCormack is picking up where the B&K did not or is there something in the McCormack amp that would cause this.

Eagleman
eagleman6722

Showing 3 responses by newbee

newbee
4,751 posts
 
Sounds like a 60 cycle hum - a grounding problem most likely. Try floating the ground at your amp and see what happens. Usually it will go away. This is usually not tube noise but tubes do have a residual noise typically heard as a hiss sound. If your amp has a high input sensitivity and your speakers are very effieient you could well be hearing tube noise. If so, be careful buying NOS tubes, many are not all that quiet.
newbee
4,751 posts
 
Did you try putting a cheater plug on the amp PC. Only costs a couple of bucks at the local hardware store and is usually quite effective. That is what I meant by "floating the ground" as the cheater plug removes the ground from the circuit. This is not really a major safety issue if the pre amp has its ground intact, and even then...... Try it.
newbee
4,751 posts
 
If the input sensitivity of the McCormack is higher than the B&K it is quite possible that, as Steve Mc said, you are now hearing the noise floor of your pre-amp a bit more than before, although usually this is more hiss than buzz. See what happens when you change tubes, I suspect you will like the tone of the Amperex's much more (assuming that they are low noise tubes.) At least you can't hear it from more than 3ft away...........:-)
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