A Stupid Idea
On Apr 18, 5:59*pm, Bret L wrote:
*The latest AudioXPress has on its cover a stereo amplifier using one
4D32 tetrode in Class AB2 per channel as an output device.
*Why do people persist in acts that aren't just stupid but willfully
destructive?
*The 4D32 was neither designed for nor is it really any good as an
audio amplifier. Its only use today is as an RF output tube for the
beautifully built Collins V-line transmitters and a few military field
transmitters. The supply of these tubes is limited and it is doubtful
any more will ever be made. No really good substitute exists, although
the set can be kluged to operate at reduced power and efficiency with
the VHF twin triodes paralleled together.
*Yet we have self centered and ****ish audiophools who persist.
*Can you see why I get mad? If the 4D32 were a fantastic audio tube,
I'd say go ahead and use them up. Make them make more. But it is in
fact terrible. It sucks as an audio tube.
*Even an 811 is far better. Rein Narma made them work just fine.
Calm down me boy or you'll explode.
One could say an 807 was only meant for RF because there is a top cap
connection for the anode which reduces stray C and makes an amp less
likely to arc from anode to something nearby at lower potential.
Ditto a 6CM5/EL36. Except that the 6CM5 can give SE triode performance
better than a 2A3.
In PP, the ""queer"" 6CM5 line output beam tetrode can make 44W in AB,
and have low Ea, and only 4ka-a.
But 20W in PP near class A is possible. The hi-fi cognescenti and
audio magazines have always hated such tubes like they hate the
6L6.
As time marches along, fewer and fewer DIYer ppl are building anything
with vacuum tubes.
The old wannabes are decaying into decrepitude and or dreamers who
build nothing and can learn nothing, and who can't hear anything
properly.
Given the number of declining ppl making anything with vacuum tubes
and considering the number of tubes being sent to landfill, maybe tube
stocks or rare tubes are actually increasing if you say stocks =
number of tubes divided by users.
The last 20 years has seen a dramatic decline in people wanting to
take up amateur HF radio.
When one does venture out onto a ham band one finds oneself listening
for hours to yet another ancient old giza telling his story about his
bowel cancer operation or prostate troubles, and frankly, after the
first hour you become monumentally bored stiff. So there are these
mountains of suplus amateur radio gear out there lurking in sheds/
barns and gathering dust, fabulous antennas that cost a bomb 20 years
ago but now oxidizing to bits. And to resurrect an antena and its nice
mast on a suburban plot is so difficult because ot neighbours abd
concil regs etc, that only a masochist would bother to make his own
ham radio outfit.
At my wesbite I have around 100 odd different types of OPTs for sale
at prices similar to the lowest common denominator prices charged by
Hammond Engineering. The OPT mainly have C-cores and plenty of
interleaving but the interest from DIYer is almost ZERO.
In fact the total weight of all the transformers I have for sale is
over 1 tonne, and after 18 months I have sold two pairs and used
another two pairs in amps I have made for customers. At this rate when
I die in 10 months or 10 years there will still be a huge pile of
unsold trannys here and they will all go to the re-cyclers for the
cppper and iron if nobody buys them, and I strongly doubt anyone ever
will, even if I reduced the price by -12dB.
So it is with many old vacuum tubes. I know a guy who must be about 82
and last time I spoke to him he had 25,000 tubes AFTER having sold off
all the audio tubes in his collection. He's Morris Obrien at SanRemo
Vic, Aust. When he dies, the tubes in his estate might be auctioned
for $100 and the next die hard will have to find a barn and get
transport for them and then sort them out and that can take weeks of
work. But perhaps they end up all being crushed and secretly dumped to
avoid the problems with expenses of toxic material disposal.
There are some idiots who are trying to make tiny tube amps putting
out huge power for their size and the only way is to go class AB2 plus
a shirt&trouser load of negative feedback. There is a good market for
the 25yo dudes who can think of nothing cooler than having a tube amp
beside their PC for the headphones or small speakers.
So don't worry, be happy,
We all end up expiring.
Patrick Turner.
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