flipper wrote:
On Wed, 28 May 2008 17:34:05 +0100, Ian Thompson-Bell
wrote:
wrote:
"In a word: YES...
"The answer is rooted in the harmonic content that the device can pass
or generate..."
Continued: http://easyurl.net/TubesTubes
There is a lot missing from this article.
Yes, as well as full of 'opinion'. There's not a single measurement in
it.
First, it is triodes alone
that generate pleasing 2nd harmonic distortion.
No, you're confusing SE with PP.
No, I was being inaccurate! I should have said triodes generate a larger
proportion of second harmonic compared to higher ones than either
pentodes of BJTs.
Pentodes generate odd
harmonics just as much as transistors do.
No and it's misleading to speak of simply 'odd' harmonics. It's the
higher order harmonics that are harsh and then there's the issue of
the harmonic mix.
Hmm, the ratio of 3rd (and higher odd harmonics) to 2nd harmonic
distortion in pentodes is greater than in triodes because of the
different transfer function.
All of which smacks a bit of voo-doo because, according to
measurements, they're all below 'audible' and so, in theory, should be
of no consequence. But then, and again according to measurements, THD
that's 'inaudible' (or at least unoffensive) in a tube amp offends
like nails on a blackboard in SS amps so an SS amp *must* have lower
THD figures to be tolerable.
The danger here of course is that measuring THD alone is not sufficient.
Second the amount of distortion is level dependent. The output stages of
an amp create by far the most distortion. Any push pull amp output stage
will, by definition cancel most of the even order harmonics
Which includes triodes.
Indeed.
and leave
many nasty odd harmonics in the output - no better in that respect than
a transistor amp.
No.
Which bit is not correct the whole or just the latter part?
So, the ONLY power amp with mainly odd harmonics in its output will be a
triode SET.
Judging from the rest you apparently mean "even harmonics" but what
does "mainly" mean?
Yes, mixing my odds and evens again.
Cheers
Ian