John Byrns wrote:
In article ,
Eeyore wrote:
Andre Jute wrote:
flipper wrote:
Andre Jute wrote:
You do know that DC filaments on DHT sound like ****, don't you
I, too, would like to hear that explained.
You build tube amps to have the tone quality under your own control.
Most audiophiles arrived there by observing that silicon amps do not
faithfully reproduce the experience of the concert hall.
Absence of any answer noted.
It sounded like an answer to me, essentially what he suggested was that
you try it both with DC, and then with AC and choose the one that sounds
best to you. A lot of people seem to prefer the sonics of AC heating,
and I will give it my vote too, the only major downside of AC heating
being a greater difficulty in banishing the last vestiges of hum. I
suspect you are actually looking for an explanation of the physics that
make AC heating sound better than DC heating, but the important thing is
the sound.
I can't see why Poopie should need the physics explained to him. He
claims to be an engineering graduate of the University of London.
Surely, he should be explaining the physics to us, rather than the
other way round.
And Poopie should be explaining to us those entirely unconspiratorial
grounding schemes which he smugly bragged of to Chris.
It is past high time Poopie started pulling his weight and contributing
something beyond snide soundbites if he wants to be accepted here.
I'm working, you're working, Chris is working, Nick is working, so why
isn't Poopie working?
Regards,
John Byrns
--
Surf my web pages at, http://fmamradios.com/
And one has to wonder if Poopie is blind to have missed the following
extended explanation of the points on which I make my decision between
AC and DC filaments, or if Poopie's soundbite mode of speech extends
also to his comprehension of plain English.
flipper wrote:
Andre Jute wrote:
You do know that DC filaments on DHT sound like ****, don't you
I, too, would like to hear that explained.
You build tube amps to have the tone quality under your own control.
Most audiophiles arrived there by observing that silicon amps do not
faithfully reproduce the experience of the concert hall.
Then why build tube amps (expensive, inefficient, expensive, hot,
expensive, dangerous, expensive) to sound just like silicon amps? What
you do with the filaments has much to do with the sound you get.
The big modern innovation in silicon amps is actually the constant
current source, not the silicon itself, which is fundamentally
inferior, requiring very much NFB to linearize it. The effect of all
those CCS is to nail down every voltage and every current that in tube
amps in classical times were much freer (they weren't totally free and
the constant current source was not unknown in tube amps either, for
instance in certain WE topologies).
The key thing about the sort of big American tube amp that sounds to me
and many others just like silicon and therefore a big waste of money is
that it ties down all the voltages with regulation: plate, bias,
filaments, everything is very well regulated.
Now return this whole thing from the region of argument to the region
of taste. Audio is not a technical argument but an exercise in
psychoacoustics; that's why the speakers are so much more important
than the amp. Take a banksa6550 amp and first of all change the
invariably series regulation for shunt regulation, everywhere. This
will cost much more (it drops as much current in regulation as the
tubes consume, usually more than that). Already the amp sounds better.
Now remove the regulation in any order you please. Step by step the amp
sounds more natural. Now, DC is a form of regulating the current; all
rectification is. If the other forms of regulation decreased the
ambience of the amp, its closeness to a window on the concert hall,
then so will the removal of the crudest form of regulation, DC. I
haven't touched yet on another form of regulation, which is
overcapping. You might get none of the aural benefits of removing
series regulation, etc, until you remove capacitance to leave only the
correct amount for the operatng points of your tubes.
This sort of engineering development to find the place where some
obsessed meterhead went too far never fails to stun me with the fine
amps that hide inside the most unpromising examples. (Okay, this
assumes that you start with the most expensive and reputable, the only
people with the money for over-engineering, but we are far, far beyond
rational considerations of cost in this thread.)
By the way, the scale of the amp might have something to do with
whether and which currents you want to tie down to an anvil. We shall
see examples in my next project, which is a tube amp for electrostatic
headspeakers.
As I say, Flipper, prove it for yourself by going too far and
discovering that your sound has dried out like an old maid. I'm not
trying to persuade you of anything, just telling you what I did and how
I arrived at the decision.
Andre Jute
Visit Jute on Amps at
http://members.lycos.co.uk/fiultra/
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