RE: The most expensive 12AX7s - TFK, Mullard, GEC.....

Posted by ivan_terrible (P) on July 2, 2024 at 01:10:03

In Reply to: The most expensive 12AX7s - TFK, Mullard, GEC..... posted by andy evans on July 1, 2024 at 08:57:53:

Nothing special.
Yet another scam.*

Another is trying to palm them off for 500 quid a pair with this speel.
this is a valve to die for!
xxx is proud to have some of these rare gems

GEC didn't make many 12AX7, preferring to use their own numbers like Brimar. eg. B339

ie.
Why compete with Mullard who made bazillions of the darn things?

There are also the 7025 and the multi .ax7s in the 12 pin TV valves like the Compactrons used in Ampex etc or in the 7247?
They cost peanuts & are excellent quality.
Bet not many people have tried to use them.

Other things were made also.
eg.
The Mullard ECL83, or UCL83 which is not a well known pentode - considered to be for cheap old record players/TVs etc, was actually made with Brimar-called the HN3x9, with a 12V heater for car radios. (I have a few NOS).

The pentode section has a gain somewhere close to the old 6V6, but with much lower Pa than the (noval) xBW6 and half the height.
It's the half height bit is the attraction.

They always ran HOT, but the pentode can be wired as a power triode, which of course is undocumented like most interesting stuff.

As a power triode, the UCL83 thing will drive a 600 ohm type line no worries,-great for headphones!

The actual triode section is similar to the 12AX7 or more like the 5751, but with Ra of 34K ohm. That's high gain low impedance -

The 12AX7 is double that at 62k ohm, while the 5751 is lower at 58K ohm.
All will sound quite different if wired into a similar circuit.

Probably the most interesting .ax7 oides are found in the 6EU7, which is a much better quality valve - but requires rewiring the socket.

FYI, some nut tried to sell me some diode/rectifiers claiming the sound was astonishing with them.....
Here is the claim:-
"22DE4 Raytheon NOS Vacuum Tube - Proven working - Beyond rare."
yea right!

*Beware!
The scammers are out there, claiming everything is rare and exciting!
There is no scammer worse than an EBAY scammer!

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Follow Ups Full Thread

Topic - The most expensive 12AX7s - TFK, Mullard, GEC..... - andy evans 08:57:53 07/01/24 (13)

RE: The most expensive 12AX7s - TFK, Mullard, GEC..... - ivan_terrible 22:30:22 07/02/24 (2)

RE: The most expensive 12AX7s - TFK, Mullard, GEC..... - Triode_Kingdom 00:17:40 07/03/24 (1)

RE: The most expensive 12AX7s - TFK, Mullard, GEC..... - ivan_terrible 00:45:54 07/03/24 (0)

RE: The most expensive 12AX7s - TFK, Mullard, GEC..... - Jim McShane 14:08:31 07/02/24 (5)

Scarcity = High Pricing... Swedish Standard 33S29B - opalize 13:30:55 07/03/24 (0)

Ah....GECs are scarce..... - andy evans 02:43:36 07/03/24 (0)

RE: The most expensive 12AX7s - TFK, Mullard, GEC..... - ivan_terrible 00:54:16 07/03/24 (2)

Bangy-Bang - Byrd69 15:44:05 07/03/24 (1)

RE: Bangy-Bang - Triode_Kingdom 19:07:32 07/03/24 (0)

RE: The most expensive 12AX7s - TFK, Mullard, GEC..... - ivan_terrible 01:10:03 07/02/24 (3)

Where's My Thumbs-Up Button? (nt) - Triode_Kingdom 02:14:15 07/02/24 (2)

RE: Where's My Thumbs-Up Button? (nt) - ivan_terrible 08:52:07 07/02/24 (1)

Yep, Been There - Triode_Kingdom 14:56:00 07/02/24 (0)

Follow Ups

RE: The most expensive 12AX7s - TFK, Mullard, GEC..... - ivan_terrible 01:10:03 07/02/24 (3)

Where's My Thumbs-Up Button? (nt) - Triode_Kingdom 02:14:15 07/02/24 (2)

RE: Where's My Thumbs-Up Button? (nt) - ivan_terrible 08:52:07 07/02/24 (1)

Yep, Been There - Triode_Kingdom 14:56:00 07/02/24 (0)

RE: The most expensive 12AX7s - TFK, Mullard, GEC.....

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