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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
tvad
9,467 posts
 

08-22-06: Muralman1
I had the advantage of replacing my Supersymmetry monos directly with a "chip" amp, same system. Everything became instantly clearer. I could see much deeper into the recording. Thee bass was much more pronounced and tighter.
...as I have also mentioned above regarding chip amps versus SS. However, I am doubtful that you can conclusively narrow the cause of the sonic differences between the two amps solely to the presence or absence of MOSFETs, which was my point.

But, perhaps you are an audio savant. If so, I salute you, sir.

:)
muralman1
1,527 posts
 
That did not make a lick of sense, Tvad. I know you are a fan of Pass amps. Are you saying all the bold difference between my present amps and the X600 are those tiny pass component boards? I think not. The huge difference is due to completely different amplifying designs.

I'm a savant if you are a clairvoyant.
tvad
9,467 posts
 
Muralman1, I believe we are perhaps stating the same position, but have passed like ships in the night. No pun intended. If you contend that the sonic differences you heard between your two amplifiers are due to circuit design, and not merely the use of MOSFETs, then I'm in absolute agreement.

Am I mistaken in my impression that you were taking a position of being able to discern so-called "MOSFET haze" as evidenced by the differences you heard between your supersymmetry monos (I have no idea what these are, and I assume they use MOSFETs), and your chip amps? Because, my position is that few audiophiles, if any, can conclude that any difference they hear between the sound of SS amps utilizing MOSFETs or bi-polar output, or between SS amps with MOSFETs and chips amps, can be attributed solely to the MOSFETs as opposed to the entire circuit which utilizes the MOSFETs. We apparently agree on this, do we not?

I have never heard a Pass amp, and therefore I am neither a fan nor a detractor of their amps.

Hope I made myself more clear. Sorry for any confusion.
sutts OP
668 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.
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