Mullard 12AX7 re-issue Cryo vs Non Cryo

Has anyone compared the Mullard 12AX7 Cryo to the non Cryo. While the Cryo exhibits a startlingly clear upper midrange and treble, it does seem somewhat tipped up and a little cold compared to my control tube. Probably perfect for someone but not for, what I consider, the neutral balance of my system. Has anyone else had this experience? I foolishly bought the Cyro version without ever having listened to the non Cryo. Is it worth my while to try the non cryo or perhaps the Groove Tube version?

I appreciate and respect conjecture but would really like some actual accounts if possible.


I have the Mullard Non cryo and found that the Ei cryo ( )is a much better tube..Nothing wrong with the Mullard repro but the Ei cryo is much more refined and more transparent... ( Thor T1000 mk2 linestage )
Well, I'm not sure if this helps you, these were my findings using them in my CAL Alpha DAC. YMMV.

I bought a 1/2 dozen New Sensor 12AX7 for the Tube Store, as I wanted to try them. The price was reasonable enough.

Was previously running a pair of GT 12AX7M Platinum Graded from Upscale Audio. Neither I believe were cyro'd.

While I thought the New Sensor was OK, and ran it for about 20-30 hours, it seemed like something just wasn't cutting it, and wasn't sounding as good as the GT Mullard. The GT Mullard sounded a bit richer, seemed better detailed, and slightly more real to me. I won't say the NS Mullard Re-issue was a bad tube, I heard lots worse in the Alpha, and some better as well. The GT Mullard I felt in my application, came the closest to a NOS pair of '50's RCA 5751 TM Blackplates that I also got from Upscale Audio. Hope this helps.
Very interesting...


My control tube is the Ei and I really like it quite a lot. Have you heard this tube cryoed and non cryoed and what was the difference? I have both the grey plate and silver plate but really have not compared the two at length. If I were going to go with a cryo version, which would you suggest it be?


Oh I might just bite the bullet and try the GT Mullard.. or should I read between the lines and try the NOS 5751 RCAs???
Most will probably agree, that you'll get the best performance from vintage tubes, and you'll no doubt pay the price for them as well.

I don't believe Kevin at Upscale carries the NOS RCA 5751 Triple Mica Blackplates anymore, but an email to him won't cost anything, and he may have some good suggestions for you for your particular application.
He's helped me in the past.

I cannot comment on the Ei, having never used it, and I as well don't consider myself any type of Tube Guru.

But, the GT Mullards, provided you get some good ones (I hear there has been some variability), are a good tube, and the price of admission is certainly reasonable enough. Kevin weeds through, tests-grades all Tubes he sells, and I believe he even backs them with a warrantee.

I understand Aspen Pittman has liquidated Groove Tubes, so these GT Mullards might start getting hard to acquire as well? Mark
I only tried the Ei Cryo version from and very satisfied with it ( $50 ish pair ) ..The 5751 Rca black plates ( which I have ) sound totally different..Warmer and more lush ( but a great tub )..I have tried a ton of 12ax7 new production and NOS and found for my likeing the Ei cryo ( as mentioned to be the best ( keeping the sound neutral )the best....
You might want to add NOS 50's GE triple mica black plates to your list. I tried the RCA and liked them but overall I thought the GE's were a tad smoother or lush and not quite as dry sounding. Don't get me wrong the RCA's were good but I just preferred the GE's. I compared both of these in a Jolida CD player.

Blindjim here has a Thor preamp. You might want to give him a shout.
I do think that all tubes mentioned are all good tubes..You really have to keep in mind that most will agree thats its all about System Synegry...I have been using Thor T1000mk2 for many years and have talked with many Thor Users and many of them have there tube set up a little different..Knowone can guarentee a perfect tube in a given situation..All that you can do is offer advise on what "might" work...or what works for them...
I can't talk about cryo differences, but if you are comparing non-cryo EI's with non-cyro New Sensor reissue Mullards the sound should be poles apart. Whether you would like one or the other is another issue. The Mullard is about as warm a new production 12AX7 as I have heard, where as the EI (either grey or silver plate) is more neutral, with the grey plate being a tad warmer than the silver plate and the silver plate being a bit cleaner. If cyro processing is making the Mullard cold, I'd hate to hear a cryo'd EI. :-) FWIW, in equipment that needs a bit of added warmth over the entire FR I've used the Mullard successfully, when I only wanted warmth in the upper bass/lower mid range I liked the New Sensor reissue Tung-sols, but when you don't need it the EI's will do quite nicely, and I have preferred them. OT, the NOS (pre-war) EI's with grey short plates are an interesting alternative - they seem to have a bit more 'body' without taking on the nature of a 'warmer' tube like the reissue Mullard, or Tung-Sol.

Very Interesting... Thank you all.

It seems that with the benefit of a few hours of burn the Cryo Mullard has settled in and portrays a more linear, more cohesive presentation. While it has lost a bit of it's mid treble presence, it is still detailed and transparent in this area.

It's a really nice counterpoint to the Ei, which I like enough to not even bother cryoing. It's the first and only time I would characterize "midrange warmth" as a positive attribute, having been put to sleep by Telefunkens in the past. The, Tele in my experience, is the one manufacturer of nos whose sonic signature is really quite all over the place, <> or not, depending on the vintage and specific model. Amperex, Siemens of this type you can set your clock by, but the the Tele takes an expert to really know what they are getting. I guess the fact that the Ei, ostensibly, is a Telefunken attests to not only the potential of this brand but the good taste and depth of knowledge the guys at Ei had.

I would like very much to hear the early Ei Grey Short Plate, especially if there was a EG version. Can anyone point me in the right direction?

I'm not familiar with the different types of Ei 12AX7's, but Thorman was kind enough to send me a couple of the cryo'd tubes to try.

They definitely have a bit of that "mid-treble presence" that Anacrusis alluded to when used in either my phono stage or the input of my amps. Whether or not you are seeking that characteristic - as was stated before - is ear/system dependant.