Which is the ultimate 12AX7 preamp tube for studio/low volume playing?

There is no ultimate. NOS Mullards and Telefunkens command the highest prices, but that's no guarantee that you won't prefer something cheaper. I did some tube rolling in my Heritage SVT and ended up preferring the stock JJ's over some NOS tubes I had laying around. They weren't Mullards or Telefunkens, but a couple were made in Japan by Raytheon on old Mullard equipment

 

In NOS I am going with Mullard military spec CV4004 it has a MU of 80 so slightly less gain than a conventional 12ax7/ECC83 tube.
We use them in the Mesa dual rectifier amps in studio to tame the fizzy nature of the distortion.
The problem is that the HiFi nuts will pay silly money for them as they have also discovered that they improve the headroom of the input stage in many hi fi designs.
Telefunken 12ax7 are great but 100 MU, RCA 12ax7 are also great.
GE, Brimar and Valvo are well worth checking out too.

 

I'll second all of this, especially the mullard comment. I have a few, some old brit stuff, and just got some japanese versions in a traynor amp I bought. Nice tubes and all but not much cup o' in my ampeg bass amps. Really depends on what you want to put the tube into. Some hifi gear? Studio pres? Tube compressor? High gain amp? Buy 'em all and see what works.

 

I've bought nos rca blackplates all around and have bad exp with all that stuff, too muddy/noisy... Dunno I prefer stock now

 

Some consider the "Bugle Boys" the finest ever. You could buy one for about a grand, after it makes $0.01 worth of difference you'll only be out $999.99 for the experience

 

Save your money and try a new production Tung Sol or gold pin JJ.

 

I finally broke down and bought one of those new Tung Sols and put it in V1 of my V4B, HSVT-CL, and SVT 7 Pro. Made the 7 Pro just a shade brighter than the stock regular JJ, but made the V4B and HSVT noticeably brighter than the stock JJ, even brighter than an 80's Japanese Raytheon made on old Mullard equipment. As a matter of fact, with the Tung Sol, my V4B ended up reminding me of the Mesa Buster I tried at GC a month ago, which was extremely bright and tight. Wasn't quite that level, but it definitely made a noticeable difference. Ended up going back to the JJ in all cases, but I think I might really dig it in my 73 Super Reverb.

But since most users of Trace Elliot gear go for the bright and tight sound, the new Tung Sols might work out very well for our OP here.

 

Shuguang!

 

In that case, believe it or not, I might recommend regular JJ's. They tone down the highs but not the tightness.

 

Some amps are more sensitive to tube rolling than others. The Orange TB's is very sensitive, you can easily tell when the stock J&J comes out and another one comes in in the v1 slot.

As mentioned, the Mullard CV4004 is one of the better ones and could cost you $150 or more.
Then there are the 5751 GE and RCA Blackplates, a bit more affordable at $50~60.

But it's the wild west out there as far as buying NOS.
I bought some at Brent Jessee Recording & Supply.
http://www.audiotubes.com/
He tests them, and offers a full refund if not satisfied.

 

I like the regular JJs.
Eurotubes.com

 

One thing a lot of folks don't realize...not all tubes of a certain brand are the same. A 12AX7 tube marked Sylvania might actually be made by GE sometimes, or maybe by Philips sometimes, or maybe even by Sylvania, depends on their factory's orders. And even all Amperex/Philips-made 12AX7's are not the same...there's a dozen or more different versions. So to just say "Amperex 12AX7's are the smoothest sounding" (or whatever description) is ignoring the wide variety of designs they made even within the 12AX7 type. This page touches on some of the many Philips/Amperex/Valvo styles http://www.tube-classics.de/TC/Tubes/Valvo ECC83/ECC83.htm

Furthermore, there were some pretty wide manufacturing tolerances back in the old days--despite all the hype that the NOS tube sellers are spouting. So within a given batch of 12AX7's, some might perform differently than others. To test ONE fifty year old tube and then proclaim "XYZ brand has the smoothest highs!" is completely ignoring statistical variation.

Finally, as has been pointed out, some circuit designs are less tolerant of tube variations than others. (A well-behaved circuit shouldn't sound particular different if you substitute one 12AX7 for another, IMHO.)

So in short, there is no "ultimate" NOS or new production tube. Just a lot of marketing hype and opinions. For not a lot of money, you can buy a few new-production 12AX7's and see which ones you prefer. Your ears, your wallet!

 

I'd skip any one real expensive tube. Take whatever your budget is and buy as many tubes as you can and try them all. I've got the JJ gold pin ECC83S in my SVT and like it the most of any I've had in there.

 

after trying many older and/or NOS vintage tubes ..$$$$$ ... I settled in on the Tesla JJ 803s ... the one with the longer plates ... seemed to be nice for bass/low end .... either gold pins or regular pins , I think they make that in both ..?!? i'll go look for the exact number , then ad it to post .. JJ ECC803s

found some nice tubes at tubedepot.com

and I always liked any JAN or JHS or RAF military spec'd tubes ...!!

 

I recently replaced the Russian and Chinese Mesa tubes in my Walkabout with JJ ECC83s, and they sound great. These are high-gain tubes.
If you are looking for low-gain options, I was advised that 12AU7 preamp tubes are the way to go.

 

If you're looking for lower volume/studio applications, I found using 5751s in place of 12AX7s to be a nice change of pace. With approximately a 30% lower gain rating, they can work well bringing some volume and excessive hair out of loud amps. Or, because they are a little quieter, you can push an amp's master volume farther, and get into power tube saturation, which is where it seems a lot of guys feel that 'tube amp' magic comes from.

 

I have tried a lot of different 12ax7's and really like the Electro Harmonix in my amps.