On Tue, 14 Aug 2007 04:18:28 GMT, "maxhifi" wrote:
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!)
Could be done, but nobody would buy 'em. Everybody's already
got guitar amps; nobody has a personal MIG fighter plane; like
that. But, Arf!
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!)
Transconductance is the natural enemy of cathode poisoning. These
tend to devolve into issues of material purity - not a good subject
to broach "in these days of modern times". Vacuum valve manufacture
is no less complex now than it was in the Kennedy era; the difference
now is that nobody cares.
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.
That's a Russian type 6336. Get 'em while they're hot. No magic of
design can do more than that within design constraints.
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
Stranger than fiction, something like this might actually happen. Hot
cathode emission has only been used in easily-visible-size valves to
date, but maybe that's just a failure of imagination (and
manufacturing capability, a temporary thing).
There are technical advantages to vacuum valves over roughly similar
silicon wafer valves (parasitic capacitance, for example), so the
future is still undefined.
And, let's all give Thanks for that. I think. No, I hope.
No, I wish. No, I'm really glad.
But anyway, thanks, as always,
Chris Hornbeck
"It's just this little Chromium Switch.
You people are SO superstitious."