Mullard 12AX7 re-issue Cryo vs Non Cryo

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...

Thorman:

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?

Markd:

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

Anacrusis
I only tried the Ei Cryo version from Tubeman.com 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.