[robinje]

Tonight I swapped in a pair of Sovtek 12AX7 LPS tubes for the stock JJ's in my Ultra SL preamp's phono section.  I did this just for kicks since I had the Sovtek tubes laying around and they are reportedly very low noise and good in phono preamps.  Well, I can't tell much of a difference, personally.  They might be a smidgen quieter than the JJ's, but it's very close.  In terms of sound quality, I think the Sovteks and JJ's are virtually identical based on my limited trial.  Anybody here play around with other 12AX7's in your AVA phono preamps?  I'd like to try some other tubes, but man, those NOS Tele's and Mullards sure are pricey!

[boycephoto]

I have a Super PAS 3 not a Ultra so you may want to take that into consideration.   I have tried several different tubes in my preamp.  Chinese 12ax7's from AVA, JAN Sylvania 12AX7, Sovtek 12AX7LPS, and NOS Telefunken 12ax7's.  The best by far are the Telefunken aa, then the Sovtek, followed by the Chinese and then the JAN Sylvania 12AX7's.  The Telefunkens make it sound like a different preamp, the image blossoms, it is much smoother and the image has more depth and focus. Crisp attack and speed are also notable.  I think you get what you pay for most of the time.  There is a reason those NOS tubes cost so much, it's simple supply and demand.  If they didn't sound good there would not be the demand for them and then the price would be much lower.   Good luck. 

Dave

[Brett Buck]

I have a Super PAS 3 not a Ultra so you may want to take that into consideration.   I have tried several different tubes in my preamp.  Chinese 12ax7's from AVA, JAN Sylvania 12AX7, Sovtek 12AX7LPS, and NOS Telefunken 12ax7's.  The best by far are the Telefunken aa, then the Sovtek, followed by the Chinese and then the JAN Sylvania 12AX7's.  The Telefunkens make it sound like a different preamp, the image blossoms, it is much smoother and the image has more depth and focus. Crisp attack and speed are also notable.  I think you get what you pay for most of the time.  There is a reason those NOS tubes cost so much, it's simple supply and demand.  If they didn't sound good there would not be the demand for them and then the price would be much lower. 

  I did a similar test with a Super PAS, and it was pretty clear right away that most of the current tubes weren't very good. But the JJ ECC83s (the kind with the teeny short plates) was a good match for any of my Telefunkens (various provenance and age) in the phono section.  And in the line section, too, although the tubes that were terrible in the phone were only mediocre in the line section. I no longer lust after Telefunkens.

    The other observation was that no matter what tube I put in it, the Super PAS was not nearly as good as a prosaic Omegastar (not Insight). And that doesn't care what tubes you have.

      Brett

[martyo]

I've never met a current production tube I prefered, in any AVA gear I own or that I'm familiar with, over NOS. In my SuperPas 3i I ran NOS RWN Neuhaus ECC83's.  The TubeMonger has them right now for $40 ea. It's subjective, different ears and sets, there will be different opinions. Careful with the TELE's, in the '70's they started having them made by others and it's evident.

[ricmon]

I'm using NOS Telefunken 12ax7's in my phone section and Telefunkin ecc81's in the line section and yes the JJ's have a similar sound but the NOS Telefunken 12ax7's sound outstanding or more to the point they sound more lush particularly with voices but all my vinyl has a incredible organic texture. The Telefunkens are staying in, no need to tube roll my T7 any more. aa

[rajacat]

Hmmm.... I'll soon have some Telefunkens 12AX7s for my T7 phonostage. Electro -Harmonic are in there now. I hope that the change will be as profound as when I switched the EH 12AT7s in the linestage to Mullard CV4024s.

-Roy

[martyo]

Hmmm.... I'll soon have some Telefunkens 12AX7s for my T7 phonostage. Electro -Harmonic are in there now. I hope that the change will be as profound as when I switched the EH 12AT7s in the linestage to Mullard CV4024s.

-Roy

I'm sure they will, but a very different flavor than the Mullards in my experience.

[rajacat]

The Telefunkens are being pulled from a decrepit Scott LK48 that two different techs couldn't, without using excessive hours of labor, get to operate well. They are old but Telefunkens are supposed to last a very long time. I imagine they will have more emphasis on the highs and lows than Mullards but not be so organic in presentation.

I thought that the Mullards were better, more realistic in almost every way when compared to the EHs.

-Roy

[robinje]

Here's a question for you experienced tube rollers... 

Is it important to have the 12AX7's in the phono section be a "matched" pair? 

[avahifi]

We look at tubes in the phono section with an unequalized 50 Hz square wave and dual trace scope.  This is about the turnover frequency of the RIAA network and will show up a lazy tube like a sore thumb.  The amplitude response will droop, as will the shape of the top and bottom curve.  No need to guess about the gain of the tube, this test shows it in circuit very well.

Regards,

Frank Van Alstine

[mark funk]

Boy I well tell you, I have a lot of old NOS tubes (12AT7-E81CC,ECC81,ECC801s,6201). I wish I would have got those Telefunken's first, would have saved me a lot of money. But after all the fun of rolling all those tubes I like the West German tubes like Telefunken, Siemens, Valvo in that order but if you want that mid range dripping in syrup I have a pair of 54 Mullards made at the Mitcham works, but you give up a lot for that mid range like bass that is mud and no high end. I only know a little about tubes and only in the 12AT7 family. IMO there are no new tubes made today that are close to NOS tubes in any way. Oh ya, about Telefunken after 1970 is right, for a time Siemens made them and RFT and there could be a few others. Old Telefunken's from the 50s and early 60s came in an all white box so any tube in a colored box you must see the bottom of the tube for the <> mark. I run Telefunken in all of Frank's stuff and the days of rolling are over, tubes that is  . So if any one that runs 12AT7s are looking for some NOS tubes I have a few I well part with.  

[avahifi]

Speaking of tubes, the Super Pas Three preamp advertised at our web site, and that will be on display at the AKFest, is equipped with Telefunken 12AX7 tubes I selected myself for high gain and low noise.  These are all "real" Telefunkens with the logo molded into the tube base.

Frank