Mosfet amps A true compromise betw. tubes and SS?

I will totaly agree with Bob Bundus. Bipolar amps sound dull in comparison to Mosfet amps .Mosfets characteristics give high thermal stability and very high output current and voltage with reliable operation. Power Mosfets are sonically superior to the Bipolar transister, but have the sweeter qualities found in tube equipment.

I agree with Bob bundus, as well. Good mosfet amplifiers do NOT sound like tube amps. I use mosfet amps in both my HT system and my 2-channel system and would not find them satisfactory if they sounded like tubes. I've tried a number of tube amps from the cheep to the way expensive and none of them gave me the clarity, precision, speed, dynamics, and detail that I get from good SS gear.

That being said, I'm first and foremost a musician and only secondarily an audiophile. My objective is to hear the music with as little sonic degradation as I can manage. The warm, euphonious distortion introduced by tubes is seductive but ultimately--for me--it gets in the way of the music.

Different strokes and all that.

will

will

Hi Will

I would be interested in your list of good tube amps that fall short of ss in the areas of clarity, speed and dynamics and even detail, my you have me curious. You might want to hear a good OTL design with a proper load to put that assumption to further test. This aside from your preference of ss over the warm, even ordered distortion characteristics of tube circuits. btw, the Atmas-pheres have among the fastest slew rates of any amp, period.

I am a big fan of the Counterpoint hybrids amps from the 80's. Mike Elliott truly got the best out of those designs other than their tendency towards premature failure (mosfets). The SA-100 was the best 1K amp that I can recall in its day.

Yes Tubegroover, I too was a big fan of the old Counterpoint sound, with their tube/mosfet hybrid amp design. Tried some other mosfet-output SS amps in recent years like Gamut, Belles, Pass. I think the mosfet amps really do give a certain "dimensionality" to the music, and a palpable midrange. Most recently I discovered the Llano Design Trinity amps (small-signal tubes for voltage gain stage, mosfets for output current stage). To me this is the best-sounding design so far. They are fast, clean, and reliable amps (and no mosfet mist!). Plus, not nearly as expensive as Lamm!

Mosfets & Hybrid amps = not equal. On one hand Mosfets are actually "pentodes" when it comes to the transfer curve. So, to that extent they are "tubish." They also tend to have a soft saturation, meaning that they tend to clip gracefully, not as soft as tubes, but not hard and sudden like BJTs.

No amp is any "faster" than the source that it has to reproduce - which in our case is fairly pathetic these days, being bandwidth limited like a brick wall at 20kHz. Having said that, there is some benefit to a bandwidth on the order of 250-500kHz. and the resulting slew rate that comes along with that.

The sound of "fast" amps, IMHO, has little to do with the nominal specs - it has more to do with the distortion products and how it handles things like leading edge damping in the realm of real world loads. The power supply design and size plays a great role in the way a given amp will sound - all other things being about equal and the circuit being well executed and reasonably designed (not always the case...)

Hybrid amps, perhaps the original being the Moscode, usually have a tube in the front end. The *only* purpose for this is to provide some degree of euphonic coloration. Which, it can. So, if you *want* that slightly "tubey" coloration (not a bad thing in many cases) for your system, one way to get that PLUS a reasonable DF, and power is to use a Mosfet output stage. The only caveat is that the Mosfets want a fair amount of drive power, so there should be something between the tube and the mosfet to drive the output stage. Usually there is...

Personally, I'd get a rock stable, solid, low distortion, high current, high bias class AB FET input Mosfet output amp and "adjust" any desired coloration in a line stage, if that is what I wanted to acheive. My Symphony No.1 amplifier is an example of such a design... you can hear the effect of whatever you put in front of it, very nicely. Makes it easy to set up a system, not having to worry about the "color" of an amplifier in the equation. (IMHO)

As far as OTLs, nice, if you get them to be stable, if you can control the leading edge, and IF you have *enough* output tubes to provide a sufficiently low output Z and high enough current *for the load you have to drive.* But they have nothing to do with Mosfets...