2. amps-preamps
  3. 1092643684

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

Showing 13 responses by muralman1

muralman1
1,527 posts
 
Reb, did you read my post? Are the Hexfets Pass Labs currently putting into their amps antiquated?
muralman1
1,527 posts
 
I have a speaker that is as revealing as the Wilson Benesch, the Apogee Scintilla. With this speaker all upstream component gliches are easily discernable.

I have previously employed the well respected Pass Labs X600 mosfet (Hexfet) amp to run the power hungry Scintillas. The X600 is reported to have a signal/noise level of 151 db. That figure is astounding!

An aquaintance of mine talked me into trying a diminutive ICE powered analog amp, rated at 117 db S/N, on my speakers. I was understandably derisive of it's potential, until I tried it.

The new sound was like a thick quilt had been lifted from my Scintillas. The bass gained in authority and control. The mids are absolutely transparent, and there are highs suddenly audible. It is obvious to me, the haze report around Mosfets is true. The Pass Labs X surely is an advanced ss amp.
muralman1
1,527 posts
 
That is what I thought. There are hidden gremlins. I thought the Pass amp was the last word in fidelity. People use my older posts against my evangelizing over the H2O. My defense is, you are only aware of what you know.
muralman1
1,527 posts
 
I did listen to the Pass X series amps, for a period of years. They were my mainstay in powering my system. My last was the X600. I needed the power to drive my difficult speakers. I was fairly happy with the sound. "What could be better," I asked myself.

Well, there is better, a lot better. Mosfets do draw a haze over the signal. It is a thick fog. That is in comparison with my present monos. They are leagues clearer. My X amps bested the solid states, and tube amps that I owned. There was nothing better to be expected. After all, it' s Pass, isn't it? I knew there were deficiencies, like thick midrange, and soft bass, but hey, They are beautiful amps, aren't they?

The future is here. Not everyone knows it.
muralman1
1,527 posts
 
I don't want an amp that colors the signal. I color it to my choosing with a tubed DAC. My amp, and preamp's job is to magnify that DAC's sound, and nothing more.

The question was, do we hear Mosfet haze? My answer is a question, relative to what?

On Bipolar amps. I have preamps that are bipolar, and damn they would make a great amp.
muralman1
1,527 posts
 
Yeah, but I get to choose the color of the day. You know that about tubes....
muralman1
1,527 posts
 
The question still is, "Has anyone else experienced this 'haze' with a mosfet-based design?"

The answer is.......... drum roll........... Yes!
muralman1
1,527 posts
 
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. There was no turning back. My "chip" system has evolved greatly beyond that first baptism.
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.
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.
muralman1
1,527 posts
 
Kalan, Chip amps is just another misnomer, like digital amp. The proper nomenclature is Class D, another analog type. There are chips on the circuit boards. The circuitry board with all it's resistors, capacitors, and chips is called a module.

I don't mind the nick-name, "Chip amp."
muralman1
1,527 posts
 
I use the H2O Signature monos loaded with B&O's newly improved 500A modules. These modules require an add on power supply. There use to be an argument about which class D module sounded the truest. I believe B&O has put that argument to bed.
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.
More to discover