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Solid-State and High Voltage

This
Issue

There is a bumper sticker that reads:

Audio Rule
#1:

Use a Transistor

Go To Jail

It's The
Law*

I own this bumper sticker, but not necessarily the viewpoint.
An apostate to most one-and-only true paths, my viewpoint is closer
to "whatever works, works." Yes, transistors and tubes can go
together, if care is taken in the design. Thus, this month issue
covers hybrid designs. Usually, the word "hybrid" evokes memories of
tube front ends driving MOSFET output stages. But those designs past
observed a sharp dividing point where the tubes left off and the
solid-state began. In this issue we will erase that dividing line,
mixing the two technologies in the same stage.
Remember,
if you have a request or suggestion of your own for either an
article topic or circuit, please e-mail:

Editor

*
Copyright: Vacuum Tube
Valley

In general, like oil and water, transistors and high voltage
do not go together well. High voltage is were tubes shine, as a tube
will easily absorb an ultra high voltage pulse and keep on working,
whereas in the presence of high voltage, solid-state devices seem
delicate and fragile in comparison. Although recent advances in
applying safety circuitry internal to  solid-state devices have
made them more robust, as little as a shuffle of leather shoes on a
nylon carpet is enough to blow out many ICs and MOSFETs. So maybe
the better cliché is, like a fool and his money, transistors and
high voltages will be parted. Unless, that is, we take many
precautions.
I have built many solid-state high
voltage regulators, current sources, and DC servos that have worked
perfectly up to the very minute one of the devices blew and took
most of the circuit with it. (DC coupling has its advantages and its
disadvantages and cascading catastrophes is one of them.) One result
that was borne out of the electrical autopsy was that generic, low
performance circuits were much more robust than the more expensive,
tweaky, high performance versions. Do not fool yourself into
thinking that this is somehow analogous to a race car versus a
family station wagon, wherein the race car is actually much more
reliable than the family car, but as it is required to work at the
increased limit of reliability, it breaks down more often. The tweak
circuit is not asked to do any more work (energy over time) than the
stodgy circuit, both only needed to power a preamp or power
amplifier, yet the tweaky, high performance version fails more
readily.

In This
Issue

1
7
14

Solid-State and High Voltage
Solid-State
as AC Circuit Support
E-mail
Publishing
Information
Glossary
of Audio Terms
Glass-Ware.com
Articles
Classic
Magazine articles

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