Re: A Challenge for Stewart Pinkerton
- From: Stewart Pinkerton <patent3@xxxxxxxxxxxx>
- Date: Mon, 27 Feb 2006 17:49:51 +0000 (UTC)
On Mon, 27 Feb 2006 15:09:30 GMT, "Ian Iveson"
<IanIveson.home@xxxxxxxxxxxxxxxx> wrote:
John Byrns wrote
In response to Andre's KISS amp you gave us your solid state KISASS
amplifier design, although you never built it. Considering this is
actually a tube group, and you are a very clever engineer, I challenge you
to design a tube amp for the group that will meet your exacting standards,
show some originality, and be relatively simple in concept and design. In
this challenge, since you are a solid state guy, negative feedback can be
used freely, and there is no need to actually build the amplifier, as long
as it is a reasonably simple and practical design capable of an output of
a few Watts of high quality audio. The question is do you have the
necessary engineering skills to actually meet the challenge?
Maybe not the best approach if you want a favour.
Valve amps don't need much "engineering skills" so it's not a very good test.
Indeed - that's the beauty of them from a hobbyist point of view -
they use a relatively small number of large and easy to handle parts,
and the optimum operating conditions and circuit topologies were all
done and dusted by 1960. Plus of course they are sufficiently
nonlinear that in many cases you can actually change the sound by
simple substitution of the active devices!
"Show some originality" might be a big ask. What is that a test of? Imagination?
Would a hybrid be allowed?
I've never had a problem with those which have SS output stages, as
valves do make nice linear drivers and voltage amplifiers. Of course,
so do high-voltage FETs... :-)
AFAIK, Stewart's position is that amplifier design is all done and dusted. I'm
inclined to agree.
That would indeed be my position. AFAIK, the only ones which still
need truly optimum care in implementation are phono preamps, where you
really are working on the edges of what is possible with available
devices, if you wish the lowest possible noise figure *and* good
overload capability, especially in the treble for scratch control.
Naturally, I would never recommend anything as noisy as a valve, as
the input stage for such a device, although you could certainly
combine an instrumentation amplifier at the input, with valved
equalisation and output stages, to good effect. Of course, such a unit
would work just as well (and more reliably) if you replaced the valves
by FETs... :-)
What do you think, John? Is an innovative valve amplifier still a possibility?
cheers, Ian
Those were pretty much my thoughts on the matter
1) Why would I have any interest in designing a *valve* power
amplifier, when the essential function can be performed much better by
solid-state technology? To put it another way, my 'exacting standards'
would not be met by valves.
2) How would I 'innovate', using a technology which has been obsolete
for fifty years, and which was fully mature by that time? For the
highest quality at medium powers from a valve amp, you still can't
beat a Williamson, or a Leak 'Point One'. If you want more power, just
use a big modern ARC or C-J.
3) If relatively simple in concept and design, it would be a 3-stage
device with push-pull output, for which literally dozens of pretty
much optimised designs exist, vide the generally excellent WAD kits.
But it wouldn't be a patch on a SS equivalent, so why bother?
--
Stewart Pinkerton | Music is Art - Audio is Engineering
.
- References:
- A Challenge for Stewart Pinkerton
- From: John Byrns
- Re: A Challenge for Stewart Pinkerton
- From: Ian Iveson
- A Challenge for Stewart Pinkerton
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