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Unusual amps..

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#4
M Gregg said:
Does anyone have links or schematics of unusual topologies/circuits
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Don't know; don't care. When I see nonsense like this, I get mighty suspicious.
I’d like to talk a bit about the 807 radio transmission tube for a minute. The 807 was originally intended and designed for the military during World War II.

No it was't. The 807 is the same asthe 6L6, that was released in 1936. Different packaging for higher voltage operation, but otherwise no different. The 1625 and 6BG6 are also 6L6-oids.

Used as the final output tube in field radio transmitters, it’s a very robust and powerful tube capable of 750 vdc on it’s plates or anode.

The only thing that prevents you from running a 6L6 at 750V is that the plate pin is right next to a heater pin.

The operator of the field radio was called a ‘Sparky’ due to the fact that he was often jolted with the high voltages used in the radio as he operated and maintained the unit.

Not true. The moniker "Sparky" goes back to the days of spark gap "wireless". It was old by the 1940s.

All 807 tubes are military tubes and therefore are superbly built able to withstand just about any environment.

More nonsense. After the war, just ESSSSS-loads of horrid 807s flooded the market, giving the type a bad reputation that lasted well into the 1950s

These operators were highly skilled and a tight bunch that used to hang out together and share thoughts and ideas. When they would say, “I’ll meet you for an 807 later on.” they meant a cold beer. The 807 tube having that Coke bottle shape to it was the reason for the reference.

The 807 was therefore never intended to be used as an amplifier tube in audio Hi-Fi, but since I liked the shape and the grid wire on the top, I made adjustments and designed my circuit around the 807 to accept the unique voltage and operating parameters of the tube.

Grid wire on the top!!! 😱 WTF is he talking about here? More BS: the 807 (in its 6L6 incarnation) was designed expressly as an audio final.

Success meant that I would have an amplifier available to my clients that no one else could offer. So beautiful and unique, the 807 amplifier sounds as good or better than any other amplifier I’ve ever heard.

Let's compare it to the Vixen, shall we? At least I know where 807s came from, who designed them (O. Schade) and why (audio final with some of the lowest THD figures of any audio power pent).

It has a lot to do with the large glass envelope and very high voltage capabilities. As far as I know, the 807 amplifier is an exclusive offering that only I manufacture as a regular offering. All of my 807 amps run at voltages far below the maximum allowable so expect the tubes to last many many years, and since the 807 is so plentiful at very reasonable prices,mainly because the only ones using the 807 are ‘Ham’ radio operators that have tubes based equipment making the 807 amplifier a bargain to re-tube.

So do mine. Run them at 6L6 voltages and currents and you automatically don't abuse them the way hams did/still do.
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#8
Used as the final output tube in field radio transmitters, it’s a very robust and powerful tube capable of 750 vdc on it’s plates or anode.

The only thing that prevents you from running a 6L6 at 750V is that the plate pin is right next to a heater pin.
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EL34 has the same socket and was used at plate voltages up to 800V...
(The old stock, not the new stuff)

regards
 
#9
chrish said:
That 'now its finished, darn forgot to paint it - better just spray the whole darn thing with rustoleum' look does not do it for me 🙁
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Full ack.
I like those shiny neon colors, but not as if the amp was dunked in bucket of paint.

FLT said:
EL34 has the same socket and was used at plate voltages up to 800V...
(The old stock, not the new stuff)

regards
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But also had problems with arcing due to the clode-by heater pin.
Don't diss the new production EL34 :grumpy:
Svetlana Winged-C will work well with 800V. Shuguang, too. I don't know about EHs. JJ's will have problems with that. A friend of mine and myself(in an ALtec 1568A) have had problems with their EL34. Since then I didn't buy any JJ power tubes anymore.

M Gregg said:
The point was did anyone have links to unusual amps or topologies..😀
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Questions is how unusual or high-end it has to be. I once built a nice SRPP/SEPP Power amp based on a Philips TV Set with 800Ohms speaker. I used a good quality mains transformer to achieve 8Ohms output. This thing only needs 2 cheap tubes, produces 6W and needs no expensive OPT. Due to positive current feedback and negative voltage feedback the output impedance is low. You can leave the Zobel out or adjust it. I needed it for some cheap speakers here.
 

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#10
the_manta said:
But also had problems with arcing due to the clode-by heater pin.
Don't diss the new production EL34 :grumpy:
Svetlana Winged-C will work well with 800V. Shuguang, too. I don't know about EHs. JJ's will have problems with that. A friend of mine and myself(in an ALtec 1568A) have had problems with their EL34. Since then I didn't buy any JJ power tubes anymore.
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I dont diss anything.
But i remember those old PA-Amps having massive problems with arcing in the
OPT windings, not so much at the sockets.

I would not use EL-34 at 800V - but friends do so...

regards
 
#15
Cassiel said:
His amps remind me of Pimp my Ride. Yes, they don't look Chinese nor Japanese, they look American. Anyway, Miles was talking about his technical descriptions not being.....very accurate.
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I hear ya.

Although his beefs were not very technical from my point of view, just semantics and typos.

The kid is an EE of sorts after all, so I doubt you really want to go down the technical road with him.

I once coined the "Pardon my french"
 
#17
The kid is an EE of sorts after all, so I doubt you really want to go down the technical road with him.
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Well I did second at the literary fair in high school and that doesn't make me a writer. Frankly, I couldn't care less about the guy but you obviously like him so I took the trouble to read his self- made bio and found this:

Everything about vacuum tubes and vacuum tube amplifiers fits. For instance; I am a huge fan of the Art Deco movement, and everything about the look of vacuum tubes is Art Deco.
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The guy doesn't know what he's talking about but that's normal for many...he shows enthusiasm....that's good....I guess.
 
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