Home » Audio » Thermionic Emissions » 6eu7 vs 12ax7
6eu7 vs 12ax7 [message #8592] Fri, 03 December 2004 12:49 Go to next message
jim denton is currently offline  jim denton
Messages: 162
Registered: May 2009
Master
My question here is to provide the best range of sound and the best bass responds I can get to my FRD speaker--so---I am reading a auction on E-bay to the effect that the tube 6eu7 has a deeper or wider bass behavior in the tube amp when used as the pre-amp tube and that the 12ax7 is just more popular and cheaper --then I find an old Wollensak amp using 2 of the 6eu7's in the preamp function---yet some of the finest vintage amps are 12ax7's and EL84's---your thoughts gentlemen-----Jim

Re: 6eu7 vs 12ax7 [message #8593 is a reply to message #8592] Fri, 03 December 2004 22:43 Go to previous messageGo to next message
Thermionic is currently offline  Thermionic
Messages: 208
Registered: May 2009
Master
Hmmm. I don't know about that one. Maybe Eric will chime in.

I have owned amps using both tubes, and even have some Mullard 6EU7s and all flavors of European made ECC83s stashed back. As far as a noticeable difference, I think the circuits made the difference.

For what it's worth, the two are electrically pretty similar. The gain is identical, and the plate resistance is very close. The 6EU7 has pretty low transconductance, lower than the 12AX7.

Thermionic

Maybe not. [message #8599 is a reply to message #8592] Sat, 04 December 2004 20:27 Go to previous messageGo to next message
Poindexter is currently offline  Poindexter
Messages: 108
Registered: May 2009
Viscount
Technically, the 6EU7 is a 6V heater 12AX7. You may get a little different bass response, treble response, midrange response than a 12AX7, depending on brand, series, et equivocating cetera; same as the 12AX.

Get some. Listen. Post back. Then you gonna be the eggspert, not us guys.

Peace,

Poinz

Re: Maybe not. [message #8601 is a reply to message #8599] Sat, 04 December 2004 22:31 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18676
Registered: January 2001
Illuminati (33rd Degree)
Good sage advice!

Re: 6eu7 vs 12ax7 [message #8607 is a reply to message #8593] Thu, 09 December 2004 00:09 Go to previous message
metasonix is currently offline  metasonix
Messages: 103
Registered: May 2009
Viscount
>Maybe Eric will chime in.

okay, if you insist.

No difference. The 6EU7 was a 12AX7 in a noncompatible pinout. NOS 6EU7s were like comparable 12AX7s of the period, they had better cathodes and closer quality control than the stuff currently being manufactured.

Any major sound differences are due to circuit design variations.

Don't believe anything you read on an eBay listing. It's like Audio Asylum---incoherent ravings and outright lies are commonplace, nobody tells nutcases they can't say whatever they want to sell the item.



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