Mosfet amps A true compromise betw. tubes and SS?

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...

Very intersting points of view here. I predict, however, that you will like the Wolcott/Prodigy combination. I borrowed a friend's Wolcotts and they were superb running the CLS's in my Mini-Statement system. I understand that the Atmasphere's are even more sympatico with big esl's.

If MOS FETs are so superior, why would AYRE, who used them in their earlier amps, now prefer bipolars for their latest design? Which sound pretty good, at least in a store audition.

MOS-FETS, bipolars -- listen to each amp and judge it on its own merits. The circuit design and parts make the biggest difference. I certainly wouldn't buy a MOS FET amp based on how much the designer brags about his own creation.

For my taste, tubes are where it's at.......As far as being colored and slow -- NO WAY, JOSE. I hear more detail and realness from my tubes than I hear from any solid state amp.

Nelson Pass Amps .Try this link you can get answers directly from Nelson Pass himself and even build your own Pass designed amp .http://www.passdiy.com/amps.htm