6R3S SE amp maybe

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6R3S SE amp maybe

Postby soundbrigade » Thu Dec 15, 2011 12:47 pm

I have a spare set of transformers (see below). There was an idea of making a second Clementine using 807, though the transformer may be a little on the small side. I have a ECL82-STC that I can recirculate.
I also have some Russian 6R3S (6P3C in Russian) a dual beam tetrode rated 20W Pa/half. This would give me a two tube 4-5W amplifier.
The problem is that the cathodes are connected to each other internally so I just have to use fixed bias.

I just wonder if there could be any problems using this twin tube with fixbias as a stereo amp.


Tube data:
http://www.tubes.ru/techinfo/HiFiAudio/6r3s-1.html
http://www.russiantubes.com/prop.php?t=12&p=278

OP transformers:
5K 5W OP

Data power transformer
Alt #1:
Secondaries: 2*270 V 0,12 A
2* 50 V 0,12 A
6,3 V 2 A
6,3 V 5 A

Alt #2:
2*270 V 0,2 A
2* 50 V 0,2 A
6,3 V 2 A
5 V 3,5 A
6,3 V 7 A
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Postby EWBrown » Thu Dec 15, 2011 3:57 pm

You could still use the 6R3S / 6P3C with cathode bias, just use half the cathode resistance value for a single section. Bypass, with a capacitor having twice the value for a single section, that should work, as long as the two sections operating chatracteristics are reasonably close to each other. The screen grids are also shared, Ultralinear cannot be used, nor triode strapped operation. Standard "pentode mode only.

Fixed bias would be good, perhaps better., that would give you more output power.

It appears to me that the 6P3С / 6R3S uses the same weird external-keyed "octal" socket type as the GU-50 (???) Much like if one crossed an 829B or 5894 with a GU-50 ;) (lol)

Image

Image

Image


/ed B
Last edited by EWBrown on Fri Dec 16, 2011 4:05 pm, edited 5 times in total.
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Postby kheper » Thu Dec 15, 2011 4:30 pm

807s sound really sweet in triode mode, and your power transformer is perfect at ~382Vdc as a FW. Should get about 4W audio output.
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Postby Wiesiek Lipowski » Thu Dec 15, 2011 4:47 pm

>>I also have some Russian 6R3S (6P3C in Russian)<<

These tubes are called 6П3С in Russian, that's why in the West they are known as 6P3S. There is no letter R in the Russian alphabet. The letter p is spoken r over there, and the letter П is spoken p.

BTW - a 6П3С-e sort of tube is considered a lot better than a plain 6П3С.

Just my two cents.

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Postby azazello » Fri Dec 16, 2011 2:40 am

6P3S-E needs no more 250v for plate.
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Postby soundbrigade » Fri Dec 16, 2011 5:48 am

Mr Brown: "You could still use the 6П3С / 6R3S / 6P3C with cathode bias, just use half the cathode resistance value for a single section. Bypass, with a capacitor having twice the value for a single section, that should work, as long as the two sections operating chatracteristics are reasonably close to each other. "
There are darlings that are constructed this way. Never thought about that. :$

Wiesiek Lipowski: I do hate when Western people read the letters right off Russian tubes. I am so confused when people are talking about 6P3C when they mean a Russian style 6L6, etc.
However the 6R3S is an odd looking tube and the bonus of having TWO elements in one tube is fascinating, saves sockets! ;)

azazello: But the Priboi uses some 420V?? Or that makes less than 250V on the plate?? (???)
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Postby Wiesiek Lipowski » Fri Dec 16, 2011 10:51 am

Oops, I did not realize such a tube exists. Greetings
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Postby azazello » Fri Dec 16, 2011 11:18 am

azazello wrote:6P3S-E needs no more 250v for plate.

Магнус, I mean 6P3S - Е /6П3С-Е/.
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Postby soundbrigade » Sat Dec 17, 2011 11:51 am

I still haven't found the guy(s) who asked about the 4P1L tubes. Maybe I should have a look at those?!
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Postby azazello » Sat Dec 17, 2011 1:47 pm

soundbrigade wrote:I still haven't found the guy(s) who asked about the 4P1L tubes. Maybe I should have a look at those?!

Magnus, Your speakers Sonido are very suitable for amazing 1.5 w SE 4P1L!! (y)
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Postby soundbrigade » Sat Dec 17, 2011 2:05 pm

Oui, je sais.

have to check your diagram and see what can be done.
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Postby azazello » Sat Dec 17, 2011 2:15 pm

soundbrigade wrote:Oui, je sais.

have to check your diagram and see what can be done.

Manus, the diagram of SE 4P1L is in Your Swedish forum.....Always I put
4P1L together with 2A3, 300B.....Maybe it is "the same" 45 tube.
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Postby soundbrigade » Wed Dec 21, 2011 4:04 pm

I haven't run into problems really but I am running out of square inches., so I have an idea of reusing my old STC-amp - ECL82 in STC-mode:
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Postby soundbrigade » Fri Dec 23, 2011 11:48 am

Slightly off-topic. Got my tranfsormers for the pensize tube amp today. Got trannies but my use a 5-10W tranny for a 0,75W amp. Besides I have a VERY small box.

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Re: 6R3S SE amp maybe

Postby soundbrigade » Fri Apr 20, 2018 9:03 am

Was< looking for additional info on 6R3S and found my old thread.
The thing is that I have ended up with a pair of SE-trannies and a suitable mains tranny for something like 6L6-SE, but as I already have something similar going on I decided to go for 829. Now I have no 829 (where did it go?? *) , but a 6R3S. Maybe use that one instead.

Well my first go will be 6SL7-SRPP driver and 6R3S wired as an 829.
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