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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
jtgofish's avatar
jtgofish
515 posts
 
The chip amps I am refering to are the Gainclone type.They use Panasonic chips.I have two of these-a paralelled 4780 which is 100watts RMS and will drive difficult loads and a 3876T Sonic Art which is 56 watts RMS.They both sound very similar to me but the 3876T is probably a bit warmer and open in the midrange.

JT
kalan
185 posts
 
I actually used the 47 Labs Gaincard S (higher output version with double power supplies) for about two weeks with the original Coincident Super Eclipses a few years ago. The 47 Labs US rep (can't remember his name) said that even though he believed the Supers were not as benign of a load as advertised that they Gaincard would still be appropriate for those speakers.

I tried the Gaincard S with a pre-amp (Cary SLP-98P at the time) and direct. It sounded much better without a pre', but my normal SLP-98/SLAM-100 combo sounded better in every conceivable way. No aspect of the Gaincard's performance was remotely competitive with the Cary separates. Now, my system was configured for the tubed separates, and I did not have 47 Labs cabling on hand; so the synergy could have been all off.

The minimalist chip amp thing may have come a long way since the Gaincard and with the right speakers it may be the bee’s knees, but I would have to revisit the whole thing with easy-drive speakers, flexible and light cabling, etc. to find out.
jtgofish's avatar
jtgofish
515 posts
 
Kalan,
Yes my chip amps do sound best with efficient speakers but are also very good on hybrid stas that are quite a difficult load.
On balance I still prefer a good valve amp but these things ,to my ears, still leave the vast majority of transistor and digital types for dead.The fact that you can put a kit one together for around $300 makes them really special.If nothing else they are excellent back up amps to SETS or big PP valve amps and great for using when the temperature is just too hot to put up with hot running valves.
cdc
1,839 posts
 
Thanks Sutts, interesting comparison to the First Watt as that also looks like a good design concept.

Muralman1, from what I understand the definition of "chip amp" they are NOT digital as in switching power supply. They are analog amps where virtually the whole amp is on a single chip. Big difference in measured performance as chip amps don't have the HF hash of Bel-Cantos, Charlize, T-amps, etc.
muralman1
1,527 posts
 
Cdc, people are reading, "Chip," as the tiny plate on a circuit board, where actually in the case of the class D modules I have seen, there is a circuit board loaded with minute circuits, and equally miniature resistors and caps, thus they are a module, not a chip.

The modules are analog. What's digital is their power supply. ICE provides a module sans power supply. It is this module, the 500A, that enables a brilliant amp builder, like Henry Ho of H2O, to expand the performance beyond what the digital power supply modules can attain.

I was very pleased with B&O when they spent countless hours improving their 500A. This is a low sell module, as few builders want to trouble themselves perfecting their own power supply. B&O doesn't need to do that. They just want a feather in their felt hat.
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