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SS amp mosfet 'haze' - ever experienced this?

Tried a new amp in my system on the weekend: the well-reviewed Gamut D200 mkIII (partly based on HP's great review), a single-mosfet SS design. At the dealers' place, it sounded great (speakers were Wilson Benesch Discovery, an isobarak, lower-efficiency design). I can't use a tube amp right now (unfortunately!) due to pending child and the system is on a LOT (2-ch/HT mix), so am looking for the most full-bodied SS amp I can find (prefer fully balanced design to match my modded SF Line 3 pre).

Well, to my surprise, the amp did NOT work out as well at my place. My speakers are 97db Coincident Total Victory. Yes, it was full-bodied, but I was definitely aware of this haze, or veiling around each note. I have a friend who designs amplifiers, and he said that this is inherent of mosfet designs. I called Israel (Coincident) and he was not surprised that I only heard this once I got back to my place, due to the high resolution abilities of my speaker vs the speakers at the dealer's. I guess I will be sticking with my Sim Audio W-3, as it is much 'cleaner' on my system (given that I must stay with SS). Too bad, 'cause my Sim W-3 definitely has the edge in clarity, but the Gamut was a touch more full-bodied.

Has anyone else experienced this 'haze' with a mosfet-based design? I admit, those with higher-efficiency speakers like mine (97db/14ohm) probably are NOT using higher-powered mosfet designs anyways, but I would like to know how others feel about mosfet designs and this issue I had.
sutts
kalan
185 posts
 
I have found the GamuT D-200 III to require at least 250 hours of playing time to sound truly open and transparent. It also likes to be turned on and left on. Other folks have mentioned the break in factor and also the role power cords can play with this amp.

I use the 92 dB, 14-Ohm Coincident Super Eclipse III's with the D200. While I think some tube amps are more "audiophile" impressive with midrange transparency and sound staging, the GamuT D-200 III sounds complete and integrated from top to bottom to me. It's the best SS amp I have ever used in my own system: Plinius SA102 MkII, Goldmund M28, BAT VK500, MF kW500, Spectral DM80, 47 Labs Gaincard S, and Sunfire amp.
sutts OP
701 posts
 
Wow- a response almost a year later on my original thread- thanks Kalan! OK- you might have something with the Super E/Gamut- interesting observation- what preamp; interconnects; and speaker cables though??
undertow
1,033 posts
 
I always liked Bi-polar designs over mosfet.. Don't know why but they are more organic sounding, mosfets have a more envelope sound to them and sometimes sharp, basically Mosfets were all the rage I remember with big name audio companies in the 90's and I tried a bunch out, it was kinda a trend like the Class D stuff etc.. going on right now, I find the new Digital designs to sound similar to the Mosfet designs to be honest, so its kinda a new twist on that sound, Cars sound best with mosfet in my opinion, at least the bulk of the designs I heard in the 1000.00 to 6000.00 range of amps.

There are a few big designers still using mosfet stuff, but honestly if you look around at the more expensive and discrete hi-end stuff its exclusivley bi-polar I believe.. I could be wrong but anyway thats what I see for the most part. Companies like boulder, gryphon, Mcintosh, Belles, McCormack, Odyssey etc.. that are the most mentioned and respected amps all seem to use bi-polars.
weez
14 posts
 
Interesting read...missed it first time around.

A mosfet operates more like a valve (tube) so it is no wonder that many have claimed they sound more 'tube like' than bipolar's. And they do- most of the time.

The 'haze' or 'mist' isn't a characteristic of the mosfet; it's a characteristic of the implementation. I think it was Sam Tellig that coined the phrase 'mosfet mist'. This from a guy who raved about the Unison gear that uses tubes and mosfets. Go figure.

By the way, Belles uses mosfets in the 150A Hotrod. John Hillig uses mosfets exclusively; as does Frank Van Alstine. None of these amps sound 'hazey'.

WEEZ
kalan
185 posts
 
Sutts: Yes, I took a chance on answering a thread that had not had activity for a year. Interesting topic, though. You asked, "...what preamp; interconnects; and speaker cables though??"

Pre-amp = First Sound 4.0/Paramout Plus upgrade
Interconnects from CDP (Ayre CX-7) to pre' and to power amp = Shunyata Altair.
IC's from TT rig (TNT 3.5/SME V/Benz LP) to phono stage (modified Luckaschek PP-1) = Audience Au24.
Speaker wire = Shunyata Andromeda

BTW, the First Sound/GamuT combo is fantastic. I expect a pair of Gamut M200 monos to arrive any day now.
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