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!!

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.

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.

Hi John,
no word yet on the Mullard. Listened to the Ei12AX7 last night again - gave it a 2nd chance, so to say. A little better. I think that I haven't heard what this tube is capable of until I think that it reaches 75 hrs. That's too many more hours more to go!
So, I'm going to try the Mullard either tonight or tomorrow night (depending on the domestic situation).

Hi All,
Heard the Mullard 12AX7 tube last night & wanted to share the experience:-
The Mullard was placed in position V8 & V9 (like the other 2 12AX7 tubes provided), which is the line-stage section for those familiar with this preamp.
* high freq extension is very good. Much like the Tele 12AX7. For the 1 1/2 hrs I listened last night with a limited set of CDs, I could not discern any glaring diff between the above 2 cited tubes.
* mid-range - glorious! I think that this is what Jafox had been "warning" me of. Esp. with vocals. The voices soar & there's a certain sweetness to the voice (bloom?). Slightly more than the Tele 12AX7. Listening to trios/bigband with vocals was a pleasure.
* mid-bass - weak in my system.
* bass - weak in my system.
These 2 ranges of the freq spectrum, the Mullard came up short vs. the Tele 12AX7, the 12AX7EH (that I've been using for 3+ years) & even the Ei12AX7. The Ei12AX7 lost big-time to the Mullard in the midrange but it did have very nice bass. I realize that the Ei12AX7 is not broken in.....
Anyway, the Mullard does have mid-bass & bass but it's light-weight in my system & the sound spectrum seemed tipped up. I know & I've heard that my system is capable of more. If I hadn't heard any other tube besides it, I would not have realized this. Unfortunately, I have!!
Since I like a balanced sound nearer to neutral than not, the Mullard would be a 2nd or 3rd choice, I'm afraid.
Anyway, that's the long & short of it. Sorry if I have stepped on your toes. FWIW. IMHO. YMMV.

one more data point, guys & gals, if anyone is reading this out there:
i just tried the combination of an Amperex 7308,white label, USN-CEP, made in USA in position V6, V7 & a pair of Ei12AX7 in position V8, V9. Executive summary: simply excellent! :-)
this combination seemed to gel like a hand in a glove. At no time was I ever made to feel that the Ei12AX7 was not broken in. Somehow the house-sound of the Amperex (which I've noted to be on the slightly warm side) counter-balanced the accurate sounding Ei12AX7 for an overall superbly balanced sound.
I played a number of tracks from a number of CDs & I got it all, I felt: excellent hi freq extension & performance. i did *not* feel that it was rolled of at all *nor* did I feel that it was fatiguing. I got excellent mids - not the sweetness of the Tele 6922-Mullard 12AX7 nor that of the Tele 6922-Tele 12AX7 but pretty darned close to the Tele-Tele combination. I got excellent bass - plenty but *not* boomy. clear bass & several shades of it. Mid-bass made a strong recovery after what I heard in the Tele 6922-Mullard 12AX7 case. Overall, I was a very happy - the sound was just what the doctor ordered & it played to the CAT's strengths.

I never stated the music I've been playing in heavy rotation. So here it is if anyone cares:-
Diana Krall "Live in Paris"
Diana Krall "Steppin' Out"
Dee Dee Bridgewater "Dear Ella"
Bob James & Earl Klugh "Two of a Kind"
Duke Ellington & Ray Brown "This one's for Blanton"
Chet Baker "Chet" - JVC K2 recording
Art Pepper "Winter Moon" - JVC K2 recording
Robben Ford & the Blue Nile - I *think* that this album is self-titled
Albert King "I'll play the blues for you"

IMHO. YMMV.