"Chris Hornbeck" wrote in message
...
On Mon, 13 Aug 2007 07:35:40 -0700, Andre Jute
wrote:
If you were promised that your dream tube would be made at a
reasonable price, if only you can describe it adequately, what would
you ask for?
Clearly, whatever you specify must not breach the laws of physics,
such as asking for a tube giving a hundred watts in Class A for a year
on a single AA battery.
A pretty broad, but still very interesting question. Small
signal and medium signal tubes are already pretty great, so
the hunt must go to output tubes.
Linearity and long service life favor a pretty primitive
tube family (1000 volts, thoriated tungsten filaments, the
whole 1930's shtick) but there is one exception. The WE
type 300 managed, by sheer will power, to run linearly and
well at 500 volts on oxide-coated filaments.
So, my fantasy tube would be a type 300, but
WITH A SEPARATE ****ING CATHODE! Is that so ****ing hard to do?
Jeez.
How about a matched pair of 6L6GC's in a compactron envelope, made large to
resemble a 300B... or better yet a matched pair of 6L6's, and a 6SL7 in one
envelope, with a new, 20 pin base. Guitar amps would never be cheaper to
make, and you'd only have one tube to change (ok maybe it would need another
12ax7 or something, but could have a one tube power amp!)
Or technically speaking, if someone could make a very linear beam power
tube, with a 50W anode dissapation limit, which has such a high gain it only
requires 3V of drive to achieve full power, but stable, and not prone to
'meltdown'. Then you could heap on the local NFB and have a nice low output
impedance, without worrying about your driver having to swing a huge
voltage. (8417 was the best in this category, so far as I know!)
Or... a linear triode with a huge flat cathode, large enough to handle
several amps, designed especially for OTL amplifiers. This could be in a new
envelope style, with a specially designed base. No need to make it octal and
glass, or to look anything like the tubes we're used to.
How about a microscopic sized planar tube, made on a nano scale, with some
new method of etching the grids photographically, rather than winding them.
It could be in a little metal case, like a crystal. Maybe even make it
surface mount, and overbuilt and derated so it would never need to be
replaced. It could be attached to a heat sink like a transistor if you
needed more power, and for the really powerful ones, the anode could be the
inside of the case. Then you could buy a cell phone with a tube output stage
