Opinions/knowledge of Russian 6P3S

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How do you rate Russian 6P3S?

don't know
11
52%
wouldn't touch them
1
5%
solid-reliable but nuthin' fancy
1
5%
great value for $$
6
29%
sonic heaven
2
10%
 
Total votes: 21

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zaphod_phil
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Postby zaphod_phil » Thu 09/30/10 9:07 am

I looked at those posts, and here are some further comments:

The 6pi3-e aka Sovtek 5881/6L6GCWX was used in servo systems of Soviet aircraft as a series regulator. So it was basically being used to pass fairly high currents at low voltage. The 250V max voltage rating simply reflects that no one tested it at higher voltages.

The Sovtek 5881/6L6WGC name is misleading and self-contradictory, since 5881s are rated for 23W max dissipation and 6L6GCs are rated for 30W. The "W" in 6L6WGC also denotes a special or extra-rugged version. So it appears that Sovtek decided to use the "5881" in the West for their marketing name, to highlight the fact that these are military/aerospace tubes, like the original 5881. Unfortunately, that name doesn't reflect the tube's true capabilities.

I'm pretty sure that one of the 6pi3s-e tubes that Steve Conner tested was faulty, since it red-plated quite quickly. The vast majority of these tubes that have been put to use by many builders and manufacturers, as well as myself, run happily to 30W and above. A few years back Marshall was shipping these stock in their JTM45 and Bluesbreaker RI amps. However, I wouldn't generally run them at 40W, just to leave some safety margin and preserve tube lifetime. IMO 30W to 35W should be enough.
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dotfret
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Postby dotfret » Thu 09/30/10 7:33 pm

Phil is probably right, and I'm thumping them to bits. The peculiar output transformer design of the Bulk Poppy I use them in is probably the saving grace - but they stand it ... they go a long way past "the paper spec" ...
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Postby bigbeck » Thu 09/30/10 7:56 pm

StarGeezers wrote:ZP, too late now , they're in the mail ... :oops:
They may still work ok for you as you'll only be running around 380V on the plates. If not, AES has Sovtek 5881's for only 28.00 per pair. They also have the coke bottle China tubes for 17.00 a pair.

I looked on ebay for the 6P3S-E and they're 38.00 per pair plus 14.00 shipping.

I've used both the Sovtek 6L6 WXT+ and the China coke bottle with good results
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Postby gwtekman » Thu 09/30/10 8:16 pm

I used Sovtek 5881WXT's in the Ampeg VT-60 I used to own. They do great.
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Postby dotfret » Thu 09/30/10 10:22 pm

If you want to test the limits of CCCP engineering push the Russki g807 to their limits. Because the OP transformers available and the sockets are uncommon, and they need anode caps, people avoid them. They are real KT family, there are some nice circuits to work from, they make a better fit with the 18W than a lot of other valves. WTH they are cheap ...
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Postby StarGeezers » Fri 10/01/10 7:34 am

Big , planning on using the An-1T300 PT which should come pretty close to that .. 420v , less the 10% (previously mentioned losses ) = in the neighborhood of 380V ... So we're good now ??? .... Not looking for the MAX Volume , just Good Tone from cheap tubes, that's the challenge ... ( I'm asking for a lot eh ? :roll: ) But those Russian tubes worked Super in the Dog Sled ... which sounds just like a Marshall 18watt .... should... :roll: :lol:


Dot , I must confess myself confused... please elaborate ... :? Sorry, I'm just a "builder"... :oops:
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Postby dotfret » Sun 10/03/10 11:22 am

6p3s-e are a Russian design, and they are clean sounding compared to original Kinkless Tetrode designs.

Of those old designs, the GE 6L6 was first on the market, followed by the KT66. The EL34 was Mullard's answer, the 807 was (I think) RCA's answer.

The Russians learned how to make both the 6L6 and the 807 (designated g807 in Russia, the cyrillic g looks like r). You can get NOS 807 and Russian 807 very cheap, and they don't sound country ...

I'm going to be an OAP myself one day, Glen ...
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Postby StarGeezers » Sun 10/03/10 1:00 pm

Dot , those G807s look pretty strange with the cap and all ... 8O Never seen any used around here... :?
Now by sounding "country" , might that be country and western , or just rural (plebeian) ???
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Postby zaphod_phil » Sun 10/03/10 1:04 pm

Of those old designs, the GE 6L6 was first on the market, followed by the KT66. The EL34 was Mullard's answer, the 807 was (I think) RCA's answer.
Actually, they came in a somewhat different order. The KT66 came out fractionally after RCA's 6L6, following joint development work between RCA and Marconi-Osram Valve (M-OV). The 807 is simply a 6L6 with a top-cap anode connection. GE would have had to license the 6L6 design from RCA, although RCA was originally formed by GE after buying out Marconi's US arm.

Here are couple of excerpts from "The Saga of Marconi-Osram Valve" by Barry Vyse & George Jessop (RIP). I have a copy given to me by Barry Vyse, who was originally a valve design engineer and eventually became the General Manager over M-OV's plant in Hammersmith,

Manufacture of the pentode, a Philips invention was fraught with serious patent issues for companies such as M-OV. Out of adversity, however, came triumph, because the work devoted to ways of avoiding the Philips pentode patent led directly to the invention of the beam tetrode by CS Bull, who was working for M-OV's parent EMI, see British Patent 432932. Valves made to this design were marketed under the type 'N40'. George recalls how difficult the assembly of these valves was to handle. This basic design was worked on by the engineers at RCA and M-OV and from the development emerged the classic output beam tetrodes, RCA 6L6 and the M-OV KT66 (1936)... The Americans described this new class of tubes as beam tetrodes, but M-OV, uniquely hung on to their own graphic terminology, Kinkless Tetrodes'.

This class of valve developed and perfected in cooperation with RCA in the period up to 1936, proved to have the ideal characteristics for the audio output role. In particular the KT66 (M-OV development of the RCA 6L6) and its later higher-powered offspring, the KT88...."
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Postby dotfret » Sun 10/03/10 5:44 pm

Yes, SG, "country" in terms of "country and western". If y never did see such a thing - that is the point ... anode cap scares half the world for no sensible reason. I had to find them in a Bell and Howell cine projector at an early age before I got rational about them - not elegant but they work.

Other question -

Hmmmm ... this is confusing me, but nothing Phil has said actually contradicts what I understand to be the case.

What I believe to be knowledge:

Preliminary Background:

Marconi sold off his Marconiphone subsidiary to the Gramophone company, which eventually set up Electrical and Musical Industries Ltd as a holding company for their divers interests around 1931.

Marconi Osram Valves was set up as a joint venture between Marconiphone and GE to produce valves; GE had rights to the Osram name in English speaking countries. The name was abbreviated to MO Valve soon after it was founded.

RCA was formed with GE involvement (and Westinghouse involvement, and Rockefeller money) - but they were not making valves, they were building radio equipment. Soon after RCA took over Victor to become RCA Victor, they went into a three way partnership with GE and Westinghouse to form RCA Radiotron, also around 1931, which was to market and manufacture valves, initially supplied by Westinghouse from Indianapolis. The US government didn't like the structure of The RCA Radiotron Company, forcing GE and Westinghouse to largely pull out - which was why it became a distinct and separate force in the valve market.

Argument -

The way I heard it, Bull invented the beam tetrode, and engineers at MOV improved the design to minimise the kink in the gain curve, but the management didn't have the nerve to put the radical new valve on the market. They passed the details of their research over to GE in the US, and the 6L6 was in production and on sale in less than 6 months - very little work was needed to get a working design, and I understand most of that work was to put it in a metal envelope. MOV was encouraged by the success of the 6L6 to start producing the KT66.

Now, from what Mr Vyse wrote, I would guess that GE chose to subcontract their side of the work to RCA. My knowledge is vague about US manufacturers, but I don't think GE actually made many valves in US until WWII started (after which they appear to have bought Kentucky for the sole purpose of making valves).

Whatever, GE owned the "O" of MOV, it was their original research that was being used - GE would not give that to RCA and license it back.

I wrote "the GE 6L6 was first on the market, followed by the KT66. The EL34 was Mullard's answer, the 807 was (I think) RCA's answer."

6L6 first, then KT66 is the only statement of order. The Vyse & Jessop book also says it. I didn't impose any order on the "answers", although it is likely that the 807 preceded the EL34 - I don't actually know which came first.

The Vyse & Jessop quote also says CS Bull was working for EMI - this was a "dodge" to give EMI the benefit of owning the patent. In those days, the holding company would have about ten employees, all doing accounts.

If RCA were making the 6L6 things, it was nonetheless a GE design, and given the circumstances it is likely that the RCA 807 was a variant to get around GE restrictions.

And just to clarify another point - the original Marconi company never made valves. The name "Marconi" was used as a marketing style on valves marketed by MOV/GEC-MOV after he died, but Mr Marconi's firm sold equipment and technology. That's why Mr Marconi objected to the name Marconi-Osram in the first place, and why the name was quickly changed to MO Valve.
Last edited by dotfret on Sat 02/26/11 9:37 pm, edited 2 times in total.
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Eric
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Postby Eric » Mon 10/04/10 1:02 am

It sounds like the 6p3s ( the lower rated one) might be a replacement for the 6L6GB, rated for 19 watts and might be a good fit in the early 50's amps that came with the 6L6GB ?
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Postby StarGeezers » Mon 10/04/10 9:42 am

So there is some hope !!! 8)
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Postby tubeswell » Sun 10/24/10 2:40 pm

Well yesterday I was running those 6P3S's (at 442 on the plates) and although they had managed the first few hours biased at 13.6W dissipation, there was some odd distortion noises happening, (fuzzy low ghosting distortion on some notes, which I've had before when power tubes are going south), and then as I added the volume - Pop! no sound. I switched off straight away, checked the fuses everything was okay. Got it on the bench checked everything over and put a new set of power tubes in and fired it up and checked all the voltages and everything was working fine. So I decided to change to the 6P3Se's (which I had a spare set handy) and they took way more current to bias to 13.6W. So I think I'm going to revise my opinion about how much voltage the 6P3s can handle. 2CW lesson from experience for today
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Postby tubeswell » Fri 03/04/11 6:18 pm

More on this from "Stan" FWIW

http://music-electronics-forum.com/t571 ... post202623

Causes me to wonder whether the 6P3S is really more like a JJ6V6S and possibly could be better running at something more like 6V6 voltages (but perhaps with a 4k load?)?
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Postby dotfret » Sat 03/05/11 9:16 pm

tubeswell wrote: Causes me to wonder whether the 6P3S is really more like a JJ6V6S and possibly could be better running at something more like 6V6 voltages (but perhaps with a 4k load?)?
The 6p3s, no suffix, is usually a straight copy of the 6L6G and was supplied into Western markets by Brimar as the 6L6GT (T = straight envelope as opposed to "coke bottle"). Don't try to push them too hard and they work OK. After deep thought, I would say 12W is probably the limit, but I'm pushing my addled brain there. There are ways and methods of "starving" valves so that they will run at higher voltages than intended - a lot of Accoustic designs worked like that - I'm getting too old to think about it.

6p3s-e is usually a Russki design that can handle a lot more power, but also gives a lot cleaner sound.

They are definitely two different animals. The Russki valve classification system was immutably written in stone and kept in a vault in Moskow. Sometimes the engineers had to be creative with their designations to get things done. With some designations, every factory had their own ideas -
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