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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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In Reply to: 5751or ECC803S OK to replace 12AX7 as driver for 2A3? posted by Rick R on March 17, 2007 at 17:52:14:
Rick R,This appears to be a quite simple design: GZ34 rectifier, 12AX7 driver, and 2A3 output- interesting.
As for 12AX7 replacements, the ECC803S is an exact 12AX7 substitute- only really expensive. A NOS Telefunken can be $400-600. The Tesla copy- made in the same way with the frame grid construction is very good and those are getting in the $40-50 range. I bought several to use when it was time to replace the various original Telefunkens I have in vintage gear. But the ECC803S sound (at least the Tesla xcopy which is the only kind I'll ever own) is quite different from the 12AX7 and has a super dynamic, but almost delicate approach.
The 5751 is electrically identical to a 12AX7, but the gain is specififed at 70%. I love the sound of the 5751- actually akin to the frame grid ECC803S- a more refined sound with a wonderful transparent bass. The 5751 has caught on- the guitar amp crowd- and the good ones such as the 50's Sylvania triple mica are becoming expensive now- up to $60-120. You might like to read "Joes' Tube Lore" on the FAQ section of this site to read about the different 5751s.
I don't know if the lower gain would affect your amplifier's performance or not. I use 6- 5751's (Sylvania triple mica, black plate, square getter) in my microphone preamp and I've actually never had a problem with gain- the gain knobs are just rotated just a few degrees to compensate. I hope others will comment on this aspect specially for your amplifier.
You might post also on the SET forum of this site and the single ended triode denizens there might have more informed, specific comments.
Fortunately with only one tube of each kind, I suppose it's simpler to experiment and since you don't need several of anything, you may as well have each be a super-duper premium tube- find a nice NOS Mullard for the GZ34 for example.
Cheers,
Bambi B
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Follow Ups
- 5751 or ECC803S in 2A3 amplifier - Bambi B 19:50:38 03/17/07 (3)
- Re: 5751 or ECC803S in 2A3 amplifier - Mechans 21:57:33 03/17/07 (2)
- Thanks! - Rick R 16:23:55 03/18/07 (1)
- My favourite is the RCA tripple mica black plate - Frihed89 14:05:31 03/19/07 (0)
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