On Mon, 11 Oct 2004 18:50:04 +0100, Chris Morriss
wrote:

In message , Stewart
Pinkerton writes
On Sun, 10 Oct 2004 18:56:20 +0100, Chris Morriss
wrote:

In message , Stewart
Pinkerton writes

what I said was that I was considering
designing and building a triode amp. I most certainly did *not* say a
single-ended amp, since they're fundamentally incompetent, and my
point was that it should be possible to build a *good* amp, even when
technically challenged by using valves........

I was at the National Vintage Communications Fair at the NEC today. One
chap had a pair of 833 triodes for sale at only £10 each. Now if you
were prepared to have the OPTs made (about 12K primary Z at 200mA dc
should do) and you build the 2kV supply then you could have a stereo SE
triode amp to beat the Japanese monsters.

Which part of 'they're fundamentally incompetent' did you fail to
understand?..................

Also, why would one save a few quid by buying those triodes, when a
pair of suitable wideband output trannies would cost the best part of
a grand? That's the *other* reason that SETAs are a bad idea, the
trannies have to be absolutely *huge* because of the high level of DC
current.

I had a look at the anode curves on the Duncanamps site. As far as I
can see, there's no way to get any sort of linearity out of one of them
single ended. A pair in class-B P-P must have made a scary PA amp in
the old days, but certainly not one on its own.

An OPT would cost a fortune, I paid enough to Sowter to have a couple of
SE OPTs custom wound for my DA100 triodes, and they're only 900V at
90mA.

I actually like properly designed SET amps (using proper triodes like
845's or DA100's of course, not weedy little 300Bs), but I would NEVER
claim that they are high fidelity!

Properly designed SET amp = military intelligence.............
--

Stewart Pinkerton | Music is Art - Audio is Engineering