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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
sutts OP
701 posts
 
Gentlemen- I will add one note below- an exciting new finding for me... (by the way, no one is going to convince me about that the Mosfet haze doesn't exist- I know what I heard on my reasonably high-efficiency speakers).

I recently auditioned a remarkably uncoloured, yet also extremely communicative set of SS monoblocks. They are the Audiosector 'Patek' SE (the 6Moons guy raved about them I believe). I believed they would be termed a 'gainclone'. The low parts count and superb contruction stunned me, really superb and obviously meticulous build quality- perhaps this translates to the purity of sound I experienced??

I see big potential here- in fact, I compared them to the other 'new technology kid on the block'- digital switching power supply amps, in this case, a set of Bel Canto Ref 1000 monos. The BC's were interesting- but almost TOO quiet between the notes, as if in a vacuum... I found more 'life' in the Pateks...
kalan
185 posts
 
I wonder if some of Sutts' "haze" impression of the GamuT D200 could have been mitigated by adjusting the internal dip switches that govern gain (and input sensitivity).

Matching with the pre-amp and speakers contributes a lot to the over all performance of a given amp. Lots of break in, careful cabling choices and gain-matching of the GamuT could make or break the impression, IMHO.

The GamuT could have been adjusted for less gain to mate up with the 97-dB sensitive Coincident Victories. I think the manual advises this with high output sources; so, I would imagine some aspect of the same principle would apply for sensitive speakers.

With the First Sound 4.0-Paramount Plus pre-amp, the Gamut amp happens to sound very clear with no gain attenuation--in other words .77 V input sensitivity or 35 dB of gain. (Speakers are Coincident Super Eclipse III's in this case, 14-Ohm, 92dB.) The Gamut amp needs about 300 hours of run-in time to kick in. The dealer's demo unit may not have had enough time on it and could have had its setting not optimized for Sutts' surrounding gear.
jtgofish's avatar
jtgofish
515 posts
 
Hazy is how the vast majority of SS amps sound.Compressed too.Efficient speakers just highlight it more.
The one exception seems to be chip amps that can sound amazingly clear and fresh on sensitive speakers.
aball
2,018 posts
 
The Kora Aries MOSFET hybrids will knock your socks off. They have a clarity that is unmatched by any BJT or tube amps I have ever had in my system.
sutts OP
701 posts
 
Kalan- those are all good points- did not realize the Gamut was 'adjustable' in that way... Hey- a fellow Coincident owner huh? The SEIII's are cool, and in fact more flexible in that I have found a wider variety of amps that can sound good through them. I recently had the Victory's updated to 'II' status at Izzy's place (he lives 15 minutes from me here in Toronto, which is handy!)- increased resolution, yet not in any harsh way, in fact the greater inner detail was immediately apparent.

Jtgofish- sounds like we are on the same wavelength with SS amps- agreed on the chips- they could be the way of the future, however equally likely seems these 'digital switching power supply' amps like the Bel Cantos I tried. In fact, if you can believe this, when I plugged the BC's into the BPT line conditioner, all of a sudden my Accuphase fm tuner went all staticky- sp?? also- my television (also plugged into the same line conditioner) had snowy lines through the picture on certain stations!! Those digital nasties from the amps are definitely not for me- maybe they would work for someone in an all-digital, audio only system with very careful electrical isolation...
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