2. amps-preamps
  3. 1223066652

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

Showing 8 responses by ping2357

ping2357 OP
10 posts
 
Samtse, I am using First Sound Presence Deluxe 4.0 Mk II. I am hoping to upgrade their higher end 3 box preamp.
ping2357 OP
10 posts
 
I hate to send them back, but I may have to do that. When I was listening to the cello suite late last night, in between the notes I could hear the transformer hum. My listening position was 12+' away. Sound meter on top of the mono-block chassis measured 55db. On top of other components, it measured nothing(<50db). I turned off the system in disgust.
ping2357 OP
10 posts
 
Psjulian, Thanks for the confirmation. I hooked up the D200 again and it had no hum unless I put my ear on the amp.
ping2357 OP
10 posts
 
Hi Nico_g. Nothing wrong with PASS, but in my system, I just love the Gamut sound. I am using tube preamp with the Gamut. The PASS, even with paired with PASS pre-amp, sounded like ordinary electronics. Yes, the M250 is better than the D200 in all areas. The Strads have 2 12" woofers which need more power. I don't know anything about the Tannoy GRF. Like Samtse said, M250s are a keeper.
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.
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.
ping2357 OP
10 posts
 
shortly after my last post, the amps started making that loud noise again, though not as loud as last friday morning. i put a sound level meter on top of the amps. it measured a constant 61db on one, 59db on another. it sounds like the transformers. the noise eventually went away. so far the noise varies with amount of warm up time.
ping2357 OP
10 posts
 
I tried Pass (X350?) with my Sonus Faber Stradivari. It wasn't for me. I love the Gamut sound. In spite of their sensitivity ratings, the Strads needed that much power to sing. Better channel separation is NICE! Save the technical issue at hand, which will be worked out eventually, it was well worth the upgrade. I wouldn't go back to the D200 as long as I have the Strads.
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