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Gamut M250 MK3

I got a pair of Gamut M250 Mk3 mono-blocks that went in place of a D200 mk3. They were installed yesterday, and worked fine for a day. This morning I turned on the amps to warm up. A bit later I went back to the listening room and heard a very loud hum. First I looked out the window for a garbage truck; then put my ears against the speakers. Nothing there. It was coming from the amps. Power-cycle of both amps confirmed that both were making that noise, though one was louder than the other. About 10 minutes later the noise was gone. I have a feeling that this might be one of those intermittent problems that's difficult to track down, but I do want to get to the bottom of it while they're in warranty. To other owners of the M250, have you ever experience such a problem?
ping2357
ngjockey
1,042 posts
 
http://www.psaudio.com/articles/hum.asp

Before you throw money at it, the source of DC might be the house.
ping2357 OP
10 posts
 
Granted that there might be DC in electrical network, but there it has never cause any amp to hum this much. I've live in this house for 10+ years. The D200 was connected via the same AC cords to the same outlets for 1+ year. I am trying to determine if there's a problem with the M250. Maybe the transformer came loose during shipping? or there's a faulty cap? It was a very loud mechanical hum that made me look outside the window for a garbage truck or motocycle.
g_m_c
443 posts
 
boths amps acting up at the same time?
Ag insider logo xs@2x
drubin
3,275 posts
 
Funny coincidence, I've been having the same (or a similar) symptom with my D200 when it's plugged into a PS Audio PP Premier. But it sounds great with the Premier and is otherwise operating perfectly.
ping2357 OP
10 posts
 
yes both amps made that noise, though one was louder. it's been 2 days since that incident. each morning when i turn on the amps, i could hear the same kind of hum, but at a very low level. i had to be right next to the racks to hear it. as the amps warmed up the noise went away. Other than that, the amps sound great. The Strads are much happier with the added power.
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