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(Bruce J. Richman) said:

BTW, there still are several tube kits around, I've seen some
mentioned in RATubes.
I could find references if you're interested.

Sure. Thank you.

I'll "fire up ole' Google" and see what I can come up with.
This may take a while though, and I fear the topic was flea power.

Unfortunately, my current speakers demand quite a bit of power and current to
sound their best, and as you know, large tubed amplifiers are pretty expensive.
I'd be interested in hearing more about hybrid amplifiers, especially if they
compare favorably with tubed equipment, subjectively speaking.

Well, there's an area where I have some experience in.
I've built several hybrids, mostly consisting of an E88CC/E288CC SRPP
stage, followed by a single pair or multiple array of complementary
Hitachi MOSFETs.
Those MOSFETs are different from the various V-FET or HEXFET types one
can buy plenty today.
The 2SK135/2SJ50 combo which I use, are out of production, sadly.
There are alternatives, which I tried as well, but since they are
housed in a plastic case, the heat transfer to the heatsink is
somewhat more problematic.
My designs are largely class A (at least in impedances of 8 ohms and
higher), so the heat transfer of the metal-case TO-3 Hitachis is an
advantage.
The option is to put more of the plastic ones in parallel, but this
causes problems with the high gate-source capacity.
A single E88CC or even E288CC can't handle the charge currents
anymore, so this means a more complex driver consisting of several
triode sections in parallel.
Apart from the need of matching tubes, their characteristics differ
with age, so that's still a problem to work out.
I've been there, and I don't have a handy solution for that (yet).
More pragmatic souls probably would use a solid state driving stage
:-)

Because of my use of the MOSFETs as a source follower, the tube
character is largely maintained, and the speaker properties don't work
back to the input stage as well (no global NFB either).

I could send you a schem of one of the amps, in your case it's
probably best to have the simple version with 1 x E88CC and 2 x
2SJ50/2 x 2SK135.
Providing you can find the MOSFETs (they can be found on Ebay
sometimes at too high prices), this could well be a good solution for
you.

Then there's the problem of a good manual and PCB........
I build my stuff on experimenter's boards, wiring it up the old way.
This is not for every one I'm afraid.

Oh well, you just as well might look out for a Moscode (NYAL) 300 or
600, or Acoustat Twin Nova.
They use the same MOSFETs, be it that the Moscodes have a ^CG7 double
triode as a driver, the Acoustats are entirely solid state.

If ever I visit the States again, and get near you, I'll smuggle in
some components for you :-)

My only experience with hybird gear, however, has been quite positive. I have
a DAC made by California Audio Labs, which has 2 12AX7's in its output stage,
while the rest is SS, of course. I use a couple of NOS Mullards, and hooked up
to rugged transport, also made by California Audio Labs, fed by a balanced
digital interconnect, it sounds excellent IMHO. In fact, when I first
auditioned the combo, CAL Delta/Alpha, it reminded me more of decent analogue
sound than digital sound, which is my preference.

Have you ever tried a Wadia combo?
I once had the possibility to listen to a X-64 and associated
transport for a longer period of time.
The closest to analog I've ever heard out of a CD player!

--
Sander deWaal
"SOA of a KT88? Sufficient."

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