CAT Preamps vs Amps

I have been following this thread since its start along with two others: Cat Ultimate/Tube Rolling and Cat vs. Aesthetix vs. Supratek. My experience compared to others is limited to a novice level and recently in the past 4 years resumed my interest again after 12 years of absence from the hobby. During this time I have upgraded my system which is currently B&W Nautilus 801's, Bryston 7BSST Monoblocks and the Cat Ultimate MKII pre line stage only. My digital source is extremely old and is the weakest link being a Nakamichi OMS7aII CD player (at some point this will be my next upgrade). Speaker cables are AQ Volcano biwired and AQ King Cobra Interconnects.

I would like to first say that I fully appreciate all of your passion that you have imparted. I previously have owned a modded Counterpoint SA-3 pre, Audio Research LS25 MKII and now the Cat Ultimate MKII. This has the stock tubes, which are the Sovtek 6922 in the V6, V7 and V10 position and 12AX7Ei in the V8 and V9 position. The A.R. LS25 MKII without a doubt (for me at least) was more detailed and refined. I have not heard the Aesthetix, but can only imagine the detail that Jafox is talking about. With the A.R. there was more sense of a separation in soundstage. Background vocals were very distinguishable almost to the point of "seeing where they stood." Even with this musical detail that the A.R. gave, it lacked body & soul, as if a veil were over the music, sterile-like. Don't know how else to describe it. Maybe due to the Sovtek tubes. My desire was to combine the Counterpoint and AR into one unit which I believe to some degree the Cat has achieved. The opportunity came to purchase the Cat and upon direct A/B comparison in my system I was sold on the Cat. I will fully admit that some of the detail has not been duplicated to the same degree which the A.R. gave, but ever so minutely. The Cat over all gave body and soul back to the music. Hopefully soon I will be looking into tube rolling the Cat (but for now my hectic schedule doesn't permit it). There is an ever so slight slant towards the top end of being overbearing or grainy, maybe again this is due to the Sovteks, or possibly the B&W 801's, don't know until I try different tubes (any precautions with changing tubes in the Ultimate MKII?)

The ultimate in music reproduction (no pun intended) will always be continullay strived for and I don't believe ever fully achieved, but the input of other Audiogon members such as Rayhall, Bombaywalla and Jafox is extremely valuable and appreciated. Especially to those as myself who do not have the resources at hand to compare, nor the bigger obstacle of a budget. I know that we can get passionate about our gear and its performance because I do! Throw into the mix the tonal differences of each ones ear and most important of all our own preference which is unique to each one of us, that's what makes us individuals.

Thanks for the great effort which will cut out alot of trial and error and for the most part narrow things down for us. Hats off to you all!

Reading Bart's (POSBWP555) first post of 6/20, wow ... CAT is sweet and musical, almost with any tube that you use. Even with Sovtek 6922, it is not awful. CAT circuit masks how bad that tube sounds, however. With other tubes, CAT will always remain more than listenable. In my opinion, the CAT is particularly excellent with the Tele/Tele combo, giving you sweet musicality AND excellent dynamics, but not dynamic slam like a solid-state powerhouse amp. Deepest bass, sweet, musical midrange, excellent, wide and deep soundstage, excellent dynamics, no upper midrange glare, almost no matter how hard you try to find recordings which are "hot" and it has very detailed highs. It shades a little to smoothness, richness, and musicality, as it is ever so slightly on the warmer side of neutral, possessing both the magic midrange AND the thunderous low end. It is definitely a tubed-based product with extension AND dynamics. Is it perfect? No. Is there anything better? Yes or probably, depending on your particular viewpoint. Are there any tube combo's which would work better? Yes or probably, depending on your tastes and associated equipment and room, etc.

At this point, I like the First Sound probably a little more than the CAT. Neither is perfect and, on a scale where 100 is perfection, neither comes close to my ears.

CAT is not as transparent, nor does it image as well, not having the equivalent resolution or separation of instruments, nor is it as quiet as the F.S., nor is it as dynamic when each is optimized tube-wise, but it does have a sweetness and smoothness, particularly in the mids and upper mids, that the F.S. will never have. The F.S. can be a little too much in the upper mids with the wrong recording. This is very difficult to do on the CAT.

If what I said doesn't hold true for the CAT Ultimate MK II -- remember I have a CAT Ultimate MK I -- then Ken Stevens broke something in doing that upgrade or your associated equipment or cables are the problem. I find it hard to believe that Ken Stevens, in trying to keep his product with the best available, suddenly screwed up to the degree you seem to indicate.

As far as CAT tube rolling is concerned, the CAT SL-1 Signature MK III and above, listen to the stock unit, then chuck the Sovtek 6922's. Replace them with any NOS 6DJ8, 6922 or 7308 that you can find. When you are satisfied, substitute the Telefunken 6922 in V6 and V7. Listen again. Replace the EI 12AX7 with any 12AX7 you would like to try in V8 and V9. Then try the Telefunken 12AX7. Listen again. I think that you will find that the Sovteks a must-replace, despite what Ken Stevens has said. The EI's are decent, but you will be able to find a better tube. After all that testing, if you find a set of tubes which you like better in the CAT than the Tele/Tele combination for what the CAT's strengths are, let me know! Send me an email, but please describe in detail WHY.

Rayhall - Just tonight I finally had a chance to try Brimar 12ax7 vs. Tele and Mullard in the Callisto and 4 different stages of the Io. There was a consistency of the Brimar that I have to believe would be true for the CAT. Wish you could have heard this....it was very impressive. I have 4 pairs of these to play with.

The Brimar has a most incredible bass foundation that the other tubes can not begin to approach. This was true in the Callisto and each of the Io's 4 stages. This might be a perfect fit for the Ultimate II phono stage's upper bass valley. The Brimar also had more energy on the very top. How it portrays the metalic percussion pieces is really beautiful. This is more natural vs. the ringing of the Mullard or lack of fine detail of the Tele.

The Tele indicated more midrange presence and bloom but some of this is due to its lack of bass energy and less resolving top end. This can be addictive but the Brimar is more coherent....whether this is a good or preferred thing or not.

The Brimar's bass and treble detail displaced my long standing Mullard 12ax7 reference in the Callisto. There was no noise issue here. Just enough more bass weight and clarity on the top.

As much as I liked the Brimar it had a little too much tube noise for the Io's first stages. This could be an issue in the CAT phono stage. I then tried the Brimars in what looks like the Io's phase splitter stage, the Tele's midrange bloom was so powerful and addicting over the Brimar; but I loved the Brimar's frequency extreme strengths here. The bass with the Brimar added much of the boogie factor but it also caused the images to be a bit distant in this position. I felt that it was not a good fit in these first stages.

I then tried the Brimar in the next (RIAA stage) and it performed well vs the Tele. It was a tradeoff of the midrange fullness of the Tele vs the Brimar's freq. extremes. The Brimar's higher noise issue was just faintly noticeable over the Tele with the volume high and no music from the speakers. A return to the Tele, and the Tele was beautiful; these tubes are so magical in the Io. How they portray voice and piano is so nice. But I hated to lose the Brimar's strengths in this stage. There was one more stage in the Io and here the Brimar fit perfectly. That last chance to get the Brimar's strengths and here they outweighed the little bit of loss of midrange fullness.

As you can see, I liked the Brimar a lot. The frequency extremes are its strengths. But then again, this is the case for the CAT so it might not be an ideal fit....too much of a good thing. So it might be an easy decision to stay with what you already have. With the Aesthetix, it was really close and only the phenomenol midrange of the Tele with the Io made for the final results in 3 of the 4 stages. But the brimar is a tube to give serious consideration.

John

Sorry if I sound like I'm a defender of a topology,but the Rowland 8t/9t series amps are SUPERB,in every meaningful category,on Avalons.Especially the four chassis 9t's!!I DO LOVE tubes,yet the Avalon vintages of the Ascent/Osiris era do sound wonderful with these amps.Better than the overrated Spectral line(overrated in timbral honesty).Configuration is everything.

BTW--I have NO doubts that the CAT will be fabulous,but will be ergonomically better in the winter months.

Best!

"Hey security, who let this solid state man in here?"