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

5.66.112.120
Posted on July 1, 2024 at 08:57:53
andy evans
Audiophile

Posts: 4401
Joined: October 20, 2000
 I can understand the high prices of Telefunken and Mullard 12AX7s. We're used to that.

But GEC ones are completely silly prices. Why? What do they have that's special?

https://www.ebay.co.uk/itm/226199263737?

 

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RE: The most expensive 12AX7s - TFK, Mullard, GEC....., posted on July 2, 2024 at 01:10:03
ivan_terrible
Industry Professional

Posts: 220
Location: Ivangorod
Joined: April 26, 2015
 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!

 

Where's My Thumbs-Up Button? (nt), posted on July 2, 2024 at 02:14:15
Triode_Kingdom
Audiophile

Posts: 10181
Location: Central Texas
Joined: September 24, 2006
 nada aqui

 

RE: Where's My Thumbs-Up Button? (nt), posted on July 2, 2024 at 08:52:07
ivan_terrible
Industry Professional

Posts: 220
Location: Ivangorod
Joined: April 26, 2015
 Thumbs up/down....
ha, you wanna see the stuff I found on the DB110 thread and more!

It's the case, that under test, very few amplifiers actually deliver the claimed performance - these being from so called "golden era".

I rest my case against all the scamming going on for both the amps and the valves.
The amps typically always deliver about HALF the claimed output with double the claimed distortion - particularly IMD.

I wouldn't like to imagine anything from PRC or modern RU production....

When I buy brand new NOS stock supposedly "pure gold"(made in England).
The production spread was enormous.

eg.Out of 250 NOS pentodes, I get static idle currents varying from 50-150% and these were GEC best ever.
Making matched pairs is real mess.




Same from STC MIL SPEC beam tetrodes. 2 of them arced over at startup.
Out of 15 NOS I could just about make a matched quad, with 2 rejects.
oh well!

here's a good NOS one that worked sitting next to it's perfect 70yr old JAN friend from the 40s.
The 254m has a smaller top cap so alu foil has to make up the size diff.






Here of course was another (EBAY) numpty who sold me this DOA KT8.




When I ran the other 4, (supposedly new but not) the ceramic had expanded and torn the wires out of the base pins, requiring total dismantlement, resoldering etc to stop the constant intermittent contacts taking place.
(drove me crazy for my 250 quid spent!)

'nuff said eh?

 

RE: The most expensive 12AX7s - TFK, Mullard, GEC....., posted on July 2, 2024 at 14:08:31
Jim McShane
Dealer

Posts: 5919
Location: Chicago
Joined: January 13, 2003
 They are scarce! Hard to find tubes routinely cost significantly more than tubes that are more easily obtained - regardless of their "quality".

The law of supply and demand applies here. And if the supply is VERY small it takes just a tiny demand to push the price up.

 

Yep, Been There, posted on July 2, 2024 at 14:56:00
Triode_Kingdom
Audiophile

Posts: 10181
Location: Central Texas
Joined: September 24, 2006
 I lost a good deal of money on defective NOS 211 tubes about 20 years ago. I've been a lot more careful since then, and in conjunction with eBay's revised return policies, haven't experienced anything like that again. About the older gear, you are correct of course that much of it didn't meet the output power claims. The situation worsened when all the major manufacturers moved to solid state, which is why the FTC eventually got involved here in the U.S. Personally, I don't care much whether a 60-year-old tube amplifier makes 20 watts instead of 25 watts. It's the sound I want. :)

 

RE: The most expensive 12AX7s - TFK, Mullard, GEC....., posted on July 2, 2024 at 22:30:22
ivan_terrible
Industry Professional

Posts: 220
Location: Ivangorod
Joined: April 26, 2015
 "Personally, I don't care much whether a 60-year-old tube amplifier makes 20 watts instead of 25 watts."

well actually I do.
It has to deliver, which means it measures well, and then ultimately it sounds much better.
I am no fan of that 50s and 60s distortion.
There are reasons why the reluctance or magnetic flux density/behaviour of the old transformers sounds different.

Usually an amp I have reworked produces more power than the original with a giant size drop in distortion.

I have some of the studies on this collected over some time.
Dave Gillespie has also gone into this in some detail.
He also is well known for improving the old amps well beyond recognition.

"It's the sound I want. :)"
Whatever that means!

I don't want the dirty old sound of the badly working old designs.
It's exactly what the Chinese are copying in their ignorance with the materials of today.
It has very little to do with this hyping of old valves and jacking up prices, which is exactly what people on the ASR forum are often moaning about.
ie. ASR consider and have measured many valve amp products and rightly consider them as horrible distortion pumps with bloated prices, - but because they never measured a good one trash the whole lot.

In the end your get an anti-valve lobby and the "audiophile" lobby fighting, both of which are basically wrong.

Btw.
out of the 5 KT8C I got there was only THAT dead one.
The others I revived by removing the bases and resoldering everything -using modern car exhaust paste to seal it up and stop the bases moving again.

 

RE: The most expensive 12AX7s - TFK, Mullard, GEC....., posted on July 3, 2024 at 00:17:40
Triode_Kingdom
Audiophile

Posts: 10181
Location: Central Texas
Joined: September 24, 2006
 "I don't want the dirty old sound of the badly working old designs."

Hey pal, don't use me as a launchpad for your personal pet peeves. 99% of what you wrote here has nothing to do with me or what I said, and certainly not my capabilities as a designer or engineer. I simply don't care about a few watts give or take. If that sort of thing bothers you, you're welcome to deal with it however you want. You know NOTHING about my work in audio, and my previous comment is not an open door for you to imply that my standards are lacking.



 

RE: The most expensive 12AX7s - TFK, Mullard, GEC....., posted on July 3, 2024 at 00:45:54
ivan_terrible
Industry Professional

Posts: 220
Location: Ivangorod
Joined: April 26, 2015
 "don't use me as a launchpad for your personal pet peeves"

eh? you misread!

"I don't want the dirty old sound of the badly working old designs"

I don't think that has any personal ref to you at all, I was referring to the vast majority of PRC made stuff saturating the market now.

As for my experiences
"I simply don't care about a few watts give or take."

I certainly DO are about a few watts give or take.
It's all about the dreaded distortion curve of valve amps, which spirals upwards from anything over about 30% of max.

A few watts give or take is a giant sized problem for an amp of 10W when it it only delivers 5-6 cleanly.
It leaves no margin for peaks.

Drive a bit hard and you get low resolution mud with massive clipping
+
anything over 1-2W and up comes the IMD, but of course people are claiming they can hear the difference of the 12AX7 when the amp is actually incapable of managing 14 bit resolution.

It's clear that magic dust is just bollox, and more and more web sites are using it to jack up prices with more and more hype.

Add to that most of the current transformer winders today (as many have noted) make glorified guitar amp OPT nothing so close to hifi unless you blow those mega bucks.

I had some guy going on about Cayin SET last week driving mega buck headphones....but he wouldn't have it - when I state he clearly LIKES distortion.
ASR when measured both bits found they were just horrible.

Proof in my book was changing a 50W amp from a miserable barely 20W clean to delivering 50W with nice low distortion.
That is a quantum leap in performance which is very very audible esp with 2 in stereo.

To be fair a lot of that hinges around very poor PSU performance especially on those old classics.

I never made a single remark "imply that my standards are lacking".
I dunno where you got that from!

 

RE: The most expensive 12AX7s - TFK, Mullard, GEC....., posted on July 3, 2024 at 00:54:16
ivan_terrible
Industry Professional

Posts: 220
Location: Ivangorod
Joined: April 26, 2015
 ...And the demand is being pushed along by bloat, hype and ignorance.

There are "investors" and speculators in this market now who look for reduced supplies of any product in order to pump and dump.
It's a technique as old as the hills.

They make fantastic and ridiculous claims in order to buy cheap and make a killing out of their crazy claims.

Some of us know the worst - eg. bangy-bang and much worse.
They are rip-off merchants, who often do their stuff thru E-pray.

It's funny to see people banging out stuff thru that site when if you know the proper merchants out there - you can get better over the counter with a guarantee in a proper shop - usually who has been there since the 60s!

 

Ah....GECs are scarce....., posted on July 3, 2024 at 02:43:36
andy evans
Audiophile

Posts: 4401
Joined: October 20, 2000
 I'm curious because I have one or two of them and thought nothing of it.

Obviously some mystique around them. I have no equipment that uses them so can't check sound quality.

Interested in anything else on the GEC ones.

 

Scarcity = High Pricing... Swedish Standard 33S29B, posted on July 3, 2024 at 13:30:55
opalize
Audiophile

Posts: 114
Location: NorCal
Joined: March 18, 2021
 High price for rarity? Witness the very rare Swedish Standard 33S29B, equivalent to 6SL7GT. It has a very similar design to the RCA 5691 which the Tube Depot touts as the "holy grail of 6SL7 tube types" - but the Standard version is much more rare. Sellers offer it for hundreds of dollars up to $1500 per.

The sonic quality of the vaunted 33S29B? Meh! Just as bland as the less expensive RCA 5691. There are much more exciting 6SL7 types, offering rich tonal balance and clarity, to be had for 1/10th the cost.

Anyone want to discuss the rare 7729? 12DT7? Others?

 

Bangy-Bang, posted on July 3, 2024 at 15:44:05
Byrd69
Audiophile

Posts: 2934
Location: East Syracuse, New York
Joined: August 23, 2004
 Can't say it here. It would be deleted, rightfully so.


Your interest may vary but the results will be same. (Byrd 2020)

I can't compete with the dead. (Buck W. 2010)

Cowards can't be heroes. (Byrd 2017)

Why don't catfish have kittens? (Moe Howard 1937)

 

RE: Bangy-Bang, posted on July 3, 2024 at 19:07:32
Triode_Kingdom
Audiophile

Posts: 10181
Location: Central Texas
Joined: September 24, 2006
 Nut-job pricing. There, I said it.

 

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