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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tubeswell
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Opinions/knowledge of Russian 6P3S

Postby tubeswell » Mon 09/13/10 11:34 pm

These look like an interesting and cheap alternative to 6L6s

Anyone tried them? What do you think? (NB: I cast my vote in the "don't knows" FWIW)

http://scottbecker.net/tube/sheets/084/6/6P3S.pdf
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Postby zaphod_phil » Tue 09/14/10 7:40 am

I've used them, with good results. But I generally prefer EL34s to 6L6s or their Russian equivalents.

FYI from one of my previous posts:
...the original 6L6 and 6L6G's dissipation limit was 19W. The 5881 (mil-spec 6L6GB) was 23W, and the 6L6GC 30W. The 6550 has a max dissipation rating of 40W, while it's near equivalent the KT88 is rated at 42W.

The 6pi3c is also commonly marketed as the "Sovtek 5881", which with a safe dissipation above 30W, isn't a true 5881. Here is some information I've gleaned in the past about this valve.
A friend of mine near NYC has tested these with a high-voltage supply and found that they will dissipate almost 42W before the plates start to glow. I've tested them as high as 40W (approx. 500V @ 80mA) for red plate conditions in a darkened room (when you can see even the smallest trace of red glow.....). Definately not a regular 6L6GC. It can handle rather high voltages (I've heard rumors of 600VDC not being a problem as long as idle current keeps disspation below specs...). The 5881 nomenclature for this tube is really misleading, as they perform like a slightly-higher-transconductance version of a 7581A or 7027A.... Very hard to kill. I've been using a quartet at 500VDC (with a healthy 45mA of idle current) in a musical instrument amp for at least a year with no signs of weakening. No emmision burn on the glass (even when viewed in front of a clean, white sheet of paper), no rattles, no bad sounds. They've been pumping out 35W/channel all this time...They seem to require a few volts less bias than a 6L6/7027--typically needing -44V to -48V where Fender amps state -48V to -52V on their schemo--and so, sound cold/overbiased and kinda nasty when you don't adjust them for a specific quiescent current.

Dutch
So they appear to be safe for operation at around 30W to 35W, which puts them somewhere between 6L6GCs and 6550s. I've never heard of anyone using these in an 18W style amp, although a few people have been known to use 6L6s.
And here's a post from the tube guru "dotfret":
There are two basic Russian designs of 6p3s, one of which is like a 6L6 internally, and the other is an original Russian design.

It is possible to use a 6p3s of either design in any place that was designed for a 6L6, and they will usually work in place of a 5881.

Some of the Russian designed 6p3s will work in place of 6L6GC, but not all of them - you have to check them out, if they don't redplate they're fine - but when they do work they often give a cleaner sound, and less hum.

Here's a pic of a 6p3s-e that is OK in place of a 6L6GC - made by Reflector, Saratov, Oct 76 with the OTK diamond mark which designates it good for military use. The "e" suffix should mean "ruggedised envelope construction" and nothing else, but sometimes it might mean more (they could not change the specs once they were written down).

Image


I'm using these with no problems, replacing 6L6GC.
That 6pi3s-e looks identical to the Sovtek 5881, with it's oval slots in the anode and thin wafer base.
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Postby tubeswell » Sun 09/19/10 9:52 pm

Well a couple of these arrived in the post this morning, so if I get a chance I'll step them up in one of my amps this coming w/e and give it a blast. Turns out that the chap I bought them off has both types, so I'll get the other type next week.
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Postby tubeswell » Mon 09/20/10 9:52 pm

I found some time to set them up today. The datasheet that arrived with each of the tubes were all in Russian, and I could only guess at what some of the words and numbers related to, but I am assuming that they are a 6L6G equivalent, (i.e.: assuming they are a 19W tube) and have biased them to 13.6W. So far they sound okay.

If I could work out how to post attachments, I could upload the datasheet (sides 1 and 2) that arrived with each tube, which I scanned.

Edit: one of the guys at ampage pointed me to this handy eng translation

http://www.rutubes.com/index.php?productID=176
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Postby zaphod_phil » Tue 09/21/10 9:08 am

That's way cold. 6L6GCs are 30W tubes. The Russian ones of the kind in the picture (6pi3s-e aka Sovtek 5881) are good for more than that, probably around 35W, since they only start to red-plate at around 42W. Also if this is a cathode-biased amp of the Marshall 18W topology (remember we only deal with those on this site), then you might bias anywhere between 80% and 100% of max dissipation, depending on the size of cathode cap you're using. Smaller cap sizes are used with hotter bias.

That data sheet is also total baloney in terms of maximum voltages, as well as dissipation ratings. These tubes will happily take 500V, possibly more. They're tough as nails. I recommend re-reading the quotes I previously posted.
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Postby tubeswell » Tue 09/21/10 11:25 am

Yep read the quotes again thanks Phil. The ones I've got are just the 6P3S, and they sound fine. This particular amp is fixed bias with bias wiggle trem, so I don't want them idling too hot. I've also ordered some 6P3Se, so I will get to try those soon.
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Postby zaphod_phil » Tue 09/21/10 3:58 pm

This particular amp is fixed bias with bias wiggle trem, so I don't want them idling too hot.
Just please keep in mind that if the amp isn't a Marshall 18W style design then our companion site PPwatt.com would be where it should be discussed.
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Postby rmoody » Wed 09/29/10 2:00 am

Haven't posted here much.

I know from experience that the standard 6P3S (not -e) will not stand up to higher voltages that a 5881 or 6L6GC will stand up to - fireworks very quick. Have tested them in a few of the bigger fender amps like twins and super twins.
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Postby StarGeezers » Wed 09/29/10 7:26 am

Got some of these 6P3S on the way to try out ... will report back asap.... I do however Love the 6P1P ev s... a quad of those gives a nice Marshally' 18 watt sound ... brighter British sounding ... 8) ... and LOUD!!! :o :thumbsup:
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Postby zaphod_phil » Wed 09/29/10 8:18 am

I know from experience that the standard 6P3S (not -e) will not stand up to higher voltages that a 5881 or 6L6GC will stand up to - fireworks very quick.
In that case they're not good 6L6 substitutes, and IMO should be avoided.
Last edited by zaphod_phil on Wed 09/29/10 9:40 am, edited 1 time in total.
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Postby StarGeezers » Wed 09/29/10 8:53 am

Oh Great !!! Now he tells us .... :o 8O I'm screwed... :(
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Postby zaphod_phil » Wed 09/29/10 9:42 am

Swap them for 63PS-e if you can!
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Postby tubeswell » Wed 09/29/10 11:01 am

FWIW I found another claim that says they are a 20W tube.

http://timelesson.blogspot.com/2010/02/ ... trode.html

(There is a link to a Russian site on that page which is out of my league, Anyone fluent in Russian Cyrillic?).

Those (6P3S) ones I've got are idling at 445V biased to 13.6W and they seem to be holding up, although they do creak and groan a bit on power down (but I read some other reports of that being normal). I suspect that if you treat them like a 19W 6L6 and not a 6L6GC, they may be alright. I had them going for about 1/2 hour the day before yesterday. I going to run them for a while this weekend and see how they hold out. They do sound good.
Last edited by tubeswell on Wed 09/29/10 5:45 pm, edited 1 time in total.
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Postby StarGeezers » Wed 09/29/10 3:41 pm

ZP, too late now , they're in the mail ... :oops:
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Postby tubeswell » Wed 09/29/10 5:52 pm

FWIW some more info on actual experiences with the 'e' types here (especially Steve Connor's observations)

http://music-electronics-forum.com/t2925/

and here

http://music-electronics-forum.com/t12151/
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