2. amps-preamps
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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
kevziek
323 posts
 
There are just as many people who feel chip or digital amps don't sound natural, and neither does their clarity. Many, including myself, would take issue with your statement that SS amps are dinosaurs on their way out. This haze thing is getting blown way out or proportion in this thread. Every tube amp I've owned had glaze and haze. The only ones I've heard that have the least of this are the VTL Wotans at $40K.
muralman1
1,527 posts
 
Kevziek, there is a heirarchy that exists in chip amps just as there is in tube and solid state. There are chip amps I would not own, nor care to listen to for very long. The best have a clarity that cannot be matched by Mosfet amps, due to the science that governs the switching technology.

My chip amps, connected to my system, are more real than any tube, or solid state amp in any system I have heard. I am a fan of live music, mostly classical. I have a musician daughter who has kept me going to the auditoriums regardless of the venue.

I think Mosfets do have a place in the future powering preamps, and low wattage amps, like Nelson Pass's, "First Watt," amp. My own preamp is solid state. Give a Mosfet and a chip amp a big load to push, and the chip amp will come out on top.
nonoise's avatar
nonoise
10,590 posts
 
Sutts:

I might be totally wet on this but check out Nelson Pass' First Watt series of amps-especially the new J-FET one. It has about 1/5 the distortion of MOSFETS and even though it is of low wattage, your speakers should present a decent pairing. He only makes a hundred or so and then its DIY time. He does it all himself so there is a waiting period.
jtgofish
490 posts
 
Muralman,
I am interested to hear about the way chip amps switch compared to transistors and why this could be a clue as to their sound.
Are there any web articles about this?
cdc
1,685 posts
 
Agree about chip amps being great but don't think they have the drive of bi-polar solid state. They just can't pass that much current.
Digital and chip amps are not the same thing. Look at measurements and digital switching amps (Class T or whatever) and you will invariably see a lot of HF hash or filtering to try to get rid of it. A well designed chip amps has neither.
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