On Tue, 19 Apr 2005 18:58:04 +0200, Sander deWaal
wrote:
Stewart Pinkerton said:
How about it Stewart?
What properties do you think a good tube (valve) amplifier should
have?
At least 100 watts output, with 20-20kHz THD and HF IMD of less than
0.1% at 80% of full output, and a *power* bandwidth of 15Hz to 50kHz.
OK, I think that could be done.
Yup, there are several on the market.
And do you think you could design an amp according to those lines?
Anyone can. The trick is finding a really good output tranny. The
basics of paralleled KT66s in an ultra-linear configuration remain at
the heart of all truly top-class valved amps. This basic design has
been around for at least fifty years.
Ah, but there's more than just the power stage to worry about.
How about the choice of a phasesplitter, input circuit, choice of NFB
path, choice of components, the power supply..........
Sure, and the best methods are all well established, and have been for
many decades. It is indeed not rocket science!
I think there's a lot more to be said about a tube amp than just "6
paralleled KT66s in push-pull" ;-)
However, it's all *been* said over the past sixty years........
There really is no excuse for not producing an optimised design in the
21st century - even if you do insist on using 19-th century
technology..............
Finally, are you willing to take up on this challenge?
It's not much of a 'challenge', the design work was all done many
decades ago. Besides, why would anyone go to such trouble and expense
to make something which can only ever be a pale imitation of a decent
SS amp costing a quarter as much?
I'm trying to get you to think about designing a tube amp.
It's a start if you just described what circuitry you would use.
I wouldn't *use* tubes if I was designing a *good* amplifier, don't
you get that yet? KISASS was simply an amusing diversion to prove a
point. As with KISS and any other basically single-ended design, it
will never be a *good* amplifier.
After all, dissing tube amps should be based on actual knowledge of
the subject, shouldn't it? ;-)
Actually no, it should be based on experience of what the end products
*sound* like. As I have already noted, I have nothing (except the
unnecessary expense) against tubes per se, and there are several
excellent tube amps on the market. My 'dissing' is primarily directed
at the lunatic fringe SET gang.
He may not have time.
By this time next week he might be Pope Angus the First.
You aren't confusing me with Angus Pope, by any chance? :-)
Just heard they have chosen Ratzinger.
Another dark middle ages ahead.................
Indeed, but great news for Protestant evangelists, as the converts
should start rolling in! :-)
OTOH, I could think of a few excellent candidates for the gentle
inquiries of the Inquisition, when Roland Rat brings them back. Oh,
you weren't expecting that? Remember, *no one* expects the Spanish
Inquisition! :-)
--
Stewart Pinkerton | Music is Art - Audio is Engineering
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