Mullard CV4004

I'm thinking upgrade de stock 12AX7 of my Primaluna Two for two Mullards CV4004. I would like to know opinions about these tubes.

I have tried a matched pair in my DAC and found that they made the system sound indistinct. For example, Miles Davis' trumpet on Miles and the Jazz Giants sounded tubby and a wall of hiss arose around the music. Gillian Welch's opening notes on her most recent CD sounded grainy. Christa Ludwig singing Mahler sounded hoarse. And so on. I gave them a week, then they went into a drawer where they've stayed ever since. Sylvania, GE and Raytheon 5750s have worked much better for me -- more clarity, no tubbiness, and more quiet. Maybe I latched onto a bad pair because there are people who like these tubes--who knows? But at their price, I'm not eager to experiment with a new set.
I purchased some CV4004s and found the same results as Zinfan2. However, just recently purchased a matched quad of Mullard ECC83 tubes from 1959 and these sound fantastic. Sometimes it all depends on who you buy them from. The vendor in CA I bought mine from and the most likely vendor you purchased your Prima Luna from sold me the set of Mullards I did not like (very microphonic and he wouldn't take them back). The Mullards are hard tubes to come by in excellent matched condition. More reasonable are the RCA 12AX7s from the '50s. Andy at VTS carries a good stock of them and can match them nicely to your amp.

If interested email me as I have some '62 Telefunkens that could be available.
Hi Masimong,

As a former owner of the PL2, may I suggest a few tubes options that made this amp sing. I did try the Mullard CV-4004 Ca. 1980's and found them rather boring so to speak. No real advantage over the stock 12AX7.

After speaking with a fellow Agon member who's opinion I trusted on the best tube for this particular amp..I found that the old 1950's RCA/Tung Sol Black plate's used in combination with a pair of Sylvania Labeled CONN 12AU7's also ca. 1950's was by far the most pleasing and life like sound I obtained from the PL2. These tubes gave the music weighty presence in the lower mids and a textural midrange with clean highs. If your interested in looking for them..Give Andy at a try.
If you really want the best 12AX7,
try the Amperex 12AX7, 7025 and the old Tesla ECC803S ( Telefunken copycat ) would be better choice.
...and don't forget the NP GrooveTube 12AX7M, an intended duplicate of a Mullard ECC83. They sure sound good in the frontend of my poweramps. Probably they'll be less expensive than the old ones recommended above.
I'l be the only one to argue that it was an improvement over the stock 12AX7s I got with my Jolida CD100. I have several variants of these tubes in NOS Mullard which do in fact sound better to my ears (I have used them in other applications,) but for the price they made a tremendous improvement in the sound of my Jolida Tube output CD. I put them in and my wife won't let me roll them. She is a violinist who finds the tone and timbre excellent. I haven't been able due to anti-WAF to try them elsewhere they have been in place for over 2 years. Maybe they are just an excellent pair, bought them from a friend who got them from the Prologue dealer- I think about 4 years ago. So in sum, I think they are an improvement. How much I can't be sure because I secretly rolled all the other tubes in (her) my system so she wouldn't interfere, now its sound quicker and more transparent overall. At the same time I switched the ICs to Silver without her knowing etc. So take that for what its worth, they may not be the ultimate best choice, but if the price is right, I would give them a try. They do take some time to break in.
I found the 4004 to have a big and warm sound
Pure garbage! These are modern [mid-1980's] tubes, not NOS tubes. White boxes and no Mullard name on the tube. Stay away!
I use Mullard CV4004s in the phono section of my VTL tl5.5 and like them just fine. They are a big improvement from the Sovtek 12ax7s that were in there when I got it. The Mullards are quiet and have a nice full mid range and a smooth top end. I used to use them in the line stage but I found I like early '60s Tung Sol (American) grey plates 12ax7s better. My preference in general as been for early 60s American tubes to the "CV" Mullards and 60s Telefunkens I have tried.
Thanks Kehut

Please.. which are the that you comment "old 1950's RCA/Tung Sol Black plate's" in this page ?

And.. Where can I get Sylvania Labeled CONN 12AU7 ?