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Old 4th February 2012, 03:18 PM   #1
M Gregg is offline M Gregg  United Kingdom
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Default Unusual amps..

Just an interesting link..

I find the tube art and paint jobs interesting..Not sure on the newspaper clip but their you go..

Just to point out I have no link to this..I just found it interesting!

Vacuum Tube Amplifiers by Steve White

Does anyone have links or schematics of unusual topologies/circuits?

Small to medium size amps..

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M. Gregg
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Last edited by M Gregg; 4th February 2012 at 03:24 PM.
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Old 5th February 2012, 02:20 AM   #2
Cassiel is offline Cassiel  Libya
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Erm....

Click the image to open in full size.

Not into American artists () I prefer Japanese's.


Well Come My WebSite Audio Collections
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Old 5th February 2012, 02:57 AM   #3
GloBug is offline GloBug  Canada
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Take a peek at the old Magnavox schematics.
He was a student Lance Cochran, who primarily sold rehashed Magnavox on eBay.

Maybe try contacting him at his Website. Hard to say if he is interested in sharing details or not. EMPIRE ELECTRON AMPLIFIERS Vacuum Tube Amplifiers by Steve White
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Old 5th February 2012, 08:40 AM   #4
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Quote:
Originally Posted by M Gregg View Post
Does anyone have links or schematics of unusual topologies/circuits
Don't know; don't care. When I see nonsense like this, I get mighty suspicious.
Quote:
Iíd 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, itís a very robust and powerful tube capable of 750 vdc on itís 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 ĎSparkyí 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, ďIíll meet you for an 807 later on.Ē 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 Iíve 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 ĎHamí 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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Old 5th February 2012, 09:09 AM   #5
chrish is offline chrish  Australia
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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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Old 5th February 2012, 09:59 AM   #6
M Gregg is offline M Gregg  United Kingdom
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Originally Posted by Miles Prower View Post
Don't know; don't care. When I see nonsense like this, I get mighty suspicious.
That was my thought when I read the newspaper clips...I found it interesting what some people do..

It was just for interest...

The point was did anyone have links to unusual amps or topologies..

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Old 5th February 2012, 10:07 AM   #7
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by Cassiel View Post
Erm....

Click the image to open in full size.

Not into American artists () I prefer Japanese's.


Well Come My WebSite Audio Collections
Yes I much prefer the site you have linked to..LOL
Whats with the photo? Is that what it looks like or a copy?

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M. Gregg
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Old 5th February 2012, 10:48 AM   #8
FLT is offline FLT
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Quote:
Used as the final output tube in field radio transmitters, itís a very robust and powerful tube capable of 750 vdc on itís 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.
EL34 has the same socket and was used at plate voltages up to 800V...
(The old stock, not the new stuff)

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Old 5th February 2012, 11:17 AM   #9
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Originally Posted by chrish View Post
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
Full ack.
I like those shiny neon colors, but not as if the amp was dunked in bucket of paint.

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Originally Posted by FLT View Post
EL34 has the same socket and was used at plate voltages up to 800V...
(The old stock, not the new stuff)

regards
But also had problems with arcing due to the clode-by heater pin.
Don't diss the new production EL34
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.

Quote:
Originally Posted by M Gregg View Post
The point was did anyone have links to unusual amps or topologies..
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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Old 5th February 2012, 12:01 PM   #10
FLT is offline FLT
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Quote:
Originally Posted by the_manta View Post

But also had problems with arcing due to the clode-by heater pin.
Don't diss the new production EL34
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.
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...

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