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Old February 6th 08, 08:22 PM posted to rec.audio.opinion,rec.audio.tubes,uk.rec.audio
John Byrns
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Posts: 116
Default Bipolar Transistors for Audio

In article ,
robert casey wrote:

George M. Middius wrote:


Poopie tries the Kroogerian "selective editing" ploy.


Donkey brayed:


Face facts, Witless -- the Krooborg stepped in the doo-doo again, and
now
it's getting its comeuppance.

No, Arny was actually totally correct and John Atkinson has merely
introduced
a red herring.

That's one possibility.

I'm ... entirely brain dead...



That's the first step toward solving your problem, Donkey.


I hate to interrupt this fine flame war :-) But back in the early
70's, table radios made the transision from the "All American 5ive" tube
circuit to a solid state circuit that used a high voltage bipolar
transistor and output transformer for the audio output.


I'm not sure exactly when this transition was made, but I do know that
it occurred sometime well before the "early 70's", I would say that the
transition occurred in the mid 60's, I know from personal experience
that these radios were already in production by late 66, when they first
went into production I don't know.

Looking at the
collector side of things, it behaved like a pentode. Look at the curves
of a vacuum tube pentode, and then a bipolar transistor with respect to
output current. The inputs are different (voltage vs current) but if
you ignore that, they look pretty similar. So it should be possible to
build a SS amp that sounds like a pentode amp. But that's not triode
sound...

But pentode curves are significantly different from triode curves, and
triodes tend to be many tube fans' favorite device. And it's not easy
to get a transistor to act like a triode.


I thought the common bipolar transistor was a "triode".


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/