CAT Ultimate/Tube rolling

Telefunken (matched) -- IMO they enhance the CAT's characteristics: clarity / resolution, effortless dynamics, and tube beauty. However, take more than usual care when changing... Beautiful machine, IMHO the best tube pre. Enjoy!

I have tried Telefunken 6DJ8, Telefunken 6922, Telefunken cca, Telefunken 7308, Sovtek 6922, Amperex 6922, Siemens 6922, Telefunken 12AX7, EI 12AX7 and Tungsram 12AX7. I would rate the Telefunken cca's highest of all the 6DJ8 tubes, but for those for whom that is too bright, I would use the Telefunken 6922's. I did not like the Telefunken 7308's at all (too bassy, rough and unrefined). The Siemens and Amperex were somewhere in between. IMO, the stock Sovtek's were clearly inferior. I liked the Telefunken 12AX7's the best, although the EI's were very good and I could easily live with them. I felt the Tungsrams were rolled off in the bass. Generally, I feel that Telefunken's in the CAT Ultimate give great bass extension, great dynamics and a smooth, neutral, liquid midrange.

I use the SIEMENS goldpins at this moment, very very good performance. and they keep up doing their job.
I have a good stock of EDISWAN 6922 on hand, very musical easy sounding, but exemplary failure when used in the CAT.
The Siemens goldpins ARE not much around anymore...
my CAT is an mk 3.
i must confess i think about moving to Atma-Sphere MP-1.

This is a real old thread but I thought that I'd revive it 'cuz I've been tube rolling some in my CAT SL1 Sig Mk3.
Audiogon member Jafox was mighty generous & sent me 3 pairs of 12AX7 tubes - Telefunken, Ei & Mullard.
Additionally, I bought a pair of Telefunken 6922 off Ebay recently.
I also bought a pair of Amperex 7308 USN-CEP, white label, Made in USA. These have 1964 production codes on them.
The Tele 6922 are in the line-stage in position V6 & V7 (in lieu of the factory supplied Sovtek 6922).
In my case, I have 12AX7EH in the phono & line-stages from the get-go of owning this preamp. I.E. I never had the factory supplied Ei 12AX7. So, I've never heard them before until Jafox sent me a pair.

I have listened to the Tele 12AX7 & the Ei 12AX7 (yet to plug in the Mullards) & here's what I found:-

My reference is the Sovtek 6922 with 12AX7EH (original combination) – accuracy, a little lean, 12 o’clock sound without a shadow. With my power amps that are on the tubey side & warm, this combination suits me quite a bit.

The Tele 6922 with 12AX7EH took off the edge in the hi freq extremes, made the mids less gainy, mid-bass in fuller now. The CAT pre sounds really very, very nice now!

The Amperex 7308 USN-CEP with 12AX7EH added some warmth & gave up some details. A little more musical than the immediately prev combination & a little less analytical. A fantastic break from the "usual" CAT sound. I like it!

The Tele 6922 with Tele 12AX7 added more sweetness to the mids & made the CAT more “wet” sounding. Is this overkill/too much of a good thing? I can’t say for now. It was very intoxicating & I had a hard time switching the system off. It was past midnight & I simply had to!

The Tele 6922 with Ei12AX7 was modestly less noisy (lower amplitude ‘shhhhhh’ from the tweeter) but these tubes have no more than 20 hours on them. They certainly sounded very dry. It made me prefer the Tele 6922 with 12AX7EH combination. I probably need to run in the Ei12AX7 a bit more to see what it might really sound.

So far, the Tele 6922 - Tele 12AX7 is my favourite combination. 2nd favourite is the Tele 6922 - 12AX7EH combination.
The Amperex 7308 - 12AX7EH is for days that my mood is seeking bloom from the CAT.
Like I said, I've yet to plug in the Mullard 12AX7. From what Jafox tells me, it might entirely change my conclusions!!

To all,

In your experience, is the CAT pre rough on tubes. One of the apparent virtues of the Sovtek is that it is a long-lasting, reliable tube.

How do NOS tubes do with this preamp in terms of longevity?