Paul G. Allen wrote:
Now I have to ask (because you guys got me thinking):
How many people on this list, or that folks on this list know of, have
ever designed a circuit using tubes, or know anything about tubes? It
sounds like analog may not be taught much or well these days, let alone
anything about tubes.
I have. I built a two-stage microphone/instrument preamp using 12AX7s
and a 145W two-channel push-pull final drive amplifier using 6L6s. Those
were fun projects. I should never have sold them. Finding transformers
capable of driving tubes nowadays is next to impossible :( it's really sad.
It seems as though tubes aren't really taught at all anymore -- old
technology? What about the subtle nuances that made tubes great? Those
second- and fourth-order harmonics that give the sound beauty and warmth ...
Electron tubes are something I wish would gain in popularity once again.
It's sad that something so revolutionary and so neat gets passed up
because it's too big and too difficult (read: expensive) to manufacture.
Scientists still aren't able to duplicate their effects in silicon (and
you EE people -- don't even get me started on MOSFETs. They don't sound
the same! :D)
Gone are the days of diode, triode, pentode, getters, heaters, plates...
Most of you probably only saw tubes in your grandparents' ancient radios
or (god forbid) their 1950-era black and white televisions (still
working, I might add -- says something about the quality of today's
electronics).
One thing most people probably don't know: tubes are still used in some
places today because they're capable of a lot more power output than
silicon. Almost all commercial radio stations utilize large electron
tubes for the final drive stage in the RF amplifiers. Reason?
Transistors (or arrays thereof) which can handle between 35,000 and
100,000 watts of output just don't exist. It's more cost-effective and
smaller (believe it or not) to manufacture a large tube to do it
instead. These tubes range in size (depending on wattage) from the size
of a pony beer keg (5-10kW), to the size of a large washing machine's
drum (20-60kW), to even the size of a water heater (60kW+). These are
ceramic-jacketed tubes, with huge copper heat sinks on the outside, with
channels running through them for liquid cooling. They're actually
pretty neat. If you ever get the chance to get a techincal tour of a
radio station, do it. :)
Anyhow, I had best get back to work.
-Kelsey
--
[email protected]
http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
