| --- | | Le Basseur |
| Mon Nov 8 16:40:11 2004 | |
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Hi Per,
1.The main problem with your amp seems to be the insertion of those two ECC85 tubes.Obviously,in an all-Russian tube amp,the 85's have no place.
I don't know the amp's schematic therefore I can only guess about the configuration,but most probable issue is that in the place of the two 85's originally were 6N1P's (note that I write with Latin letters,not Cyrillic).
The 6N1P,6N2P and ECC85 share the same pinout and al three have a 6,3V heater and pin 9 connected to an internal shield between the two triodes so I assume that for this reason someone replaced the original (Russian) tubes with the 85's,not taking into account the electrical differences.
Partially you're right,the ECC85 is a rather rare tube in guitar amplifiers,but this doesn't mean it cannot be used (of course,after a proper tweaking:))
Try to identify what's the circuit(s) of those two ECC85/? tubes.Are they in the reverb chain,phase splitter,gain stage?After identification it shall be much easier to indicate the right (Russian) tube to use in that place(s).
2.The 6N2P's are indeed the (early) Russian versions of the ECC83/12AX7 tube BUT with a heater voltage of 6,3V between the pins 4 and 5.An average 6N2P (grey anodes) is a little too noisy-hissy for use in early stages and,if you don't know how to modify the heaters on the socket,I advice you to get some 6N2P-E or 6N2P-EV (shiny anodes).These are the military versions and they're much quieter and non-microphonic.
2.The output tubes are 6Pi3S ?(again,note the Latin letters)
If yes,they're a real pain in the butt and yes,they need to be replaced with Russian military 6Pi3S-E (wafer base,somewhat equivalent to 5881's but much more tougher).Or,if you can afford and you care about logo's,get some 6L6's of current production.6L6 made by JJ Tesla is a serious candidate and the prices are friendly enough.
HTH,
Le Basseur
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