In a vacuum tube, nobody can hear you scream.

[rayheinrich]

Moved from Poetry Forum › Serious Workshopping > "The Prophet" thread.

(in response to Leeanne's poem "The Prophet")
...
in studio six.  Behind my lids, miles of  Beware the man of two books. I could draw
the power output stage, class A, push-pull pentodes, no neg. feedback of the studio
six all-vacuum tube amplifier...too obscure? Too esoteric? Too much jargon? Well,
you started it Smile Still, I am mythtified ( and if that ain't a word it should be).

P.P.S.  
Pentodes are noisy
Triodes are sweet
But power corrupted
Now they're obsolete

Your PPS is far from true,
though pentode's glow is not now blue
and triodes still are best for bass.
Pity they're still made from glass*.

http://tiny.cc/vacuumnouveau

Oh, and they still get as hot as this thread.

Sure, they're not non-existent, but in this day of straight-to-digital
(their inputs, not our brain [though that's coming]) 50mz over-sampled
1-bit a/d parametric amplifiers they're technically obsolete.

*Vacuum tubes (valves to you Brits) don't just come in glass envelopes.
They have metal, metal/ceramic (like the 12K watt one [a triode] that was
used in an FM transmitter I used to repair [it was about 12" high and 6"
in diameter]), and quartz ones as well. I came across the quartz one when
repairing the instrumentation for a scientific furnace at the U.S. National
Bureau of Standards (now called NIST). Its chief claim to fame was its
ability to maintain temperatures in the 800ºC (1500ºF) range to an accuracy
of +/- .05 ºC . It used a vacuum tube (custom-made for this very purpose)
with an envelope of quartz so that it could operate within the furnace.
Its conducting elements were made of invar and it required no filament as
the cathode glowed (as well as everything else in the furnace) quite nicely
on its own.

Obsolete but still running: I use a Dynaco PAS 3 vacuum tube pre-amp I built
from one of their kits a zillion years ago. One of its inputs is connected
to an AR AX turntable (though I am not a vinyl freak; I much prefer the quiet
of the quiet passages on CD's).