Have anyone tested Russian 6N2P?

for Dynaco Mark II/III/IV and DIY PP monoblocks

Have anyone tested Russian 6N2P?

Postby spiderman62 » Tue Mar 31, 2015 6:32 am

Hi All!

I am a newbie in the tube sounding world and I am going to modify a pair of Dynaco MK3 with the well known Poseidon PCB ordered from Shannon Parks.
By the way thank you for a fast shipment in case you are reading this Shannon.

Well, here in Europe is easy to find NOS from Russia and now I have ordered 2 pcs. of NOS 6N2P to be used/tested instead of 12AX7.

Have anyone tried these tubes with the Poseidon?
Can anyone tell me if any modifications are necessary to make it work properly?

Thank you for a nice source of knowledge.

Regards from Sweden!
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Re: Have anyone tested Russian 6N2P?

Postby Geek » Tue Mar 31, 2015 11:37 am

Hiya!

6N2P != 12AX7 and I'd love to slap all those ebayers that say it is ;) :P

It gobbles more heater current and the filament pinout is different. You could inavertently run 12V into a 6V heater.

Other than that, sometimes they work without mods, sometimes not.

Cheers!
-= Gregg =-
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Re: Have anyone tested Russian 6N2P?

Postby EWBrown » Tue Mar 31, 2015 8:29 pm

First of all, the 12AX7 filament pins' wiring would have to be reconfigured, as described below. If you just pop one into a regular 12AX7 socket, one of two things will happen:

Best case, nothing happens, as pins 4 and 5 are connected together for 6.3 V filament operation. Filament stays room temperature cold. Just plays "possum".
Worst case, if the 12AX7 has 12V filament power, the 6N2P will light up very brightly, for a very brief period of time, until the filament burns out.

The 6N2P has the same base pinout as 6DJ8, or 6N1P, filament is pins 4 and 5, and pin 9 is an internal shield , so it would not be a "drop-in" replacement for 12AX7.

It is roughly similar to 12AX7 in its basic operating characteristics, mu (gain) is roughly 100, transconductance and plate resistance are somewhat different than the 12AX7, but not so different, that the basic circuit topology and resistance values don't need to be changed. It comes closer to the op chars of the 2C52, which is a mil-spec 12SL7 variant, but with higher gain than 12SL7..

There IS a such a tube as a 6AX7, but these are not very common, they have the same pins 4 and 5 filament, 6.3V requirement.

I once bought a "flat" of 100 6N2Ps, about a decade ago, and ran them through my Hickok 539C (transconductace) tube tester, they varied over a range of approx. +/- 20% worst case. Still very usable, but not entirely suitable in cases where reasonably accurate tube matching would be required. These would be suitable for guitar amp usage, not so much for "audiophile" purposes. 6N2P, some folks swear by them, and some folks swear AT them >:o :'( YMMV, etc...

HTH

/ed B in NC
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Re: Have anyone tested Russian 6N2P?

Postby spiderman62 » Tue Mar 31, 2015 11:45 pm

Thank you very much for your answers.

I know better now and I will go for the real deal. [:)

Cheers!
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Re: Have anyone tested Russian 6N2P?

Postby EWBrown » Thu Apr 02, 2015 6:48 am

A 6N2P and a couple of 6P1Ps would be good for a small 4WPC SEP amplifier, just use any of the common 6V6 circuits.

Or one 6N2P and one 6P1P would work for a "Fender Champ" type of small guitar amp.

/ed B
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