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Old 23rd August 2011, 06:23 AM   #1
dgta is offline dgta  United States
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Default 6L6 guidance needed

I need a fresh set of tubes for an amp and I'm not that well versed in what's available out there and what's good.

Amp is a dual mono Williamson homebrew, PP 6L6GC ultralinear, one pair per channel, running about 470V B+ with fixed bias, individual bias pots for each tube. Currently delivering about 30-32W before clipping with some pretty well worn Sylvanias. The ones with top halo getter, yellow print on the base. They sound really good to me, but looks like they are getting scarce and expensive.

Looking for preferably some NOS decent sounding and not very expensive tubes, might consider new. Suggestions?
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Old 23rd August 2011, 07:28 AM   #2
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From modern production stuff:
"Winged C" Svetlana - more expensive than JJ and similar but worth the extra cash in terms of sound quality and reliability.
My Opinion ONLY - see waht others have to say.
Cheers,
Ian
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Old 23rd August 2011, 07:33 AM   #3
ryuji is offline ryuji  United States
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There are many variations of 6l6 type tubes. There are also similar tubes you can substitute with. You already seem to know about 6l6 and 6l6gc. but there are also 7027, the 5881, the KT66, and the 807. all but 807's should work with only minor changes to the circuit. 807's will require new sockets or adapters. Your fixed bias will assist you in using different tubes, as your operating points and bias points will be different with different types of tubes


forgot to add: keep heater current specs in mind, it sometimes varies with different types of otherwise equivalent tubes. Dont want to overload your transformer windings

Last edited by ryuji; 23rd August 2011 at 07:37 AM.
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Old 23rd August 2011, 11:21 AM   #4
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After building few amplifiers with these, I am very satisfied :

6P3S-E 6P3S MILITARY NOS 4 TUBES 6L6GT 5881 | eBay

And not so expensive.
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Old 23rd August 2011, 01:08 PM   #5
dgta is offline dgta  United States
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Artosalo, as far as I can tell those 6P3S and 6P3S-E are nowhere near equivalent to a 6L6GC. They only dissipate 20W (not 30) and probably can't take 500V either. See this thread:
Datasheet for Russian 6p3s-e
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Old 23rd August 2011, 01:37 PM   #6
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Quote:
Originally Posted by dgta View Post
Artosalo, as far as I can tell those 6P3S and 6P3S-E are nowhere near equivalent to a 6L6GC. They only dissipate 20W (not 30) and probably can't take 500V either. See this thread:
Datasheet for Russian 6p3s-e
I've sold thousands of the 6P3S-E tubes, they work just fine as a replacement for a 6L6GC. I actually run them in at 465 volts on the plate and screen, -50 on the grid. They come through with no misbehavior. At those specs typical cathode currents run from about 25 ma to about 50 ma., with most in the 25 ma to 35 ma range.

Out of the box some are gassy - don't judge their performance until they've been run in and then see what you think. These tubes are by and large NOT ready to run out of the box.

On the data sheet - the 250 volt spec does not appear to be a limit/maximum - it seems to be part of a "typical operation" spec set.

I also must tell you I have not dealt with the 6P3S (without the "E" suffix). I hear it isn't in the same league sonically. Also, reports are the old stock 6P3S-E is far superior sonically to the later production branded "Sovtek". The tubes I've sold have been predominantly mid- 1980s vintage.

I hope this information is helpful.
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Old 23rd August 2011, 02:12 PM   #7
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Quote:
Artosalo, as far as I can tell those 6P3S and 6P3S-E are nowhere near equivalent to a 6L6GC. They only dissipate 20W (not 30) and probably can't take 500V either. See this thread:
My knowledge is not based on any threads anywhere. I have practical experience about these tubes. For example with Ub= 450 V, I(a+g2) = 50 mA and Rl = 6,6 k the output power is some 32...35 W (UL) and distortion very low. What else should this tube do ?
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Old 23rd August 2011, 04:49 PM   #8
rongon is offline rongon  United States
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Location: Across the river from Rip's big old tree...
Is the "Sovtek 5881" a 6P3S or a 6P3S-E? Anyone know?
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Old 23rd August 2011, 05:26 PM   #9
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Possibly it is. The base is different but otherwise it looks very similar.
I just compared my 6p3s-e tubes with this: Sovtek 5881WXT

Edit: This looks exactly same as 6p3s-e: Sovtek 5881 / 6L6WGC

Last edited by artosalo; 23rd August 2011 at 05:30 PM.
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Old 25th August 2011, 01:17 PM   #10
dgta is offline dgta  United States
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Thanks guys. Good info.

Any opinions on what's a good NOS American tube that's not overpriced?
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