CAT Ultimate/Tube rolling

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?

Andrew,
the CAT Sig Mk1 USED to be hard on tubes. Back then Ken Stevens used 12AU7 instead of the 6922.
Then came along the Sig Mk2 wherein the internal cktry was changed & the 12AU7 was thrown out & replaced with a 6922. Ever since that rev, the CAT uses 6922 tubes.
It NO LONGER is hard on tubes any more than any other tube pre out there.
For example, I've been using the 6922 & 12AX7EH tubes since Nov 2001! These were used tubes. Now I need to send the unit back to CAT for re-tubing.
I have no info on how long NOS tubes will last. However, I suspect that one will be able to get approx 2000 hrs from them IFFFFF the NOS tubes are bought from a reliable source that can guarantee them to some degree.
I think Vintage Tube Services' website says it very well "85%-95% of Life, 100% of performance....". Usually with NOS tubes one is never going to get 100% life (you could but you'd pay thru your nose for NIB NOS tubes!). So expect the number of hrs of usuage to be accordingly less.
FWIW. IMHO. YMMV.

NOS means NEW old stock; ie, NOT used...if they are used then they are not NOS.they are simply used

right?

true, C123666. however, even w/ NOS the skeptic in me does not expect 100% life owing to the fact that these tubes are 30-40 yrs old & the vacuum is probably compromised some. If i get full life from them, i'm very happy & it's like icing on the cake but I go in w/ the mind-set that i'm going to get less life from them.
Anyway, that's what I meant to indicate in my prev post.