CAT Preamps vs Amps

I'm a proud owner of a CAT JL2 amplifier. Most of the threads on Audigon say great things about CAT's amps JL 1-3. People laud over the musicality, transparency and dynamics of these amps. However, when it comes to the preamps (Signature and Ultimate versions), it seems like the reviews are a mixed bag. In many cases, some CAT amp owners use other preamps.

Therefore, are the current CAT preamps (Ultimate) as good as their amps in terms of musicality, transparency and
dynamics? Are they on par? If not where do they fall short compared to the amps? What are better matches?
CAT preamps are at least as great as the amps. I own both and i would never use another preamp with my JL2. people who say that the Ultimate is lean should look for the problems elsewhere in their systems. Indeed,it does not mask anything like some other colored tubed preamps do. I think with CAT gear, it is not about synergy and matches. If CAT preamp does not work in the system, something must be wrong.

It would work fantastic with your JL2, and not because of synergy. It's because it is utterly neutral and transparent. That's why it works with all good amps on the planet, tube or solid state.

I can reassure you that you have not heard how transparent your JL2 is until you hear it with SL1 Ultimate. You have not heard the low end of it either.

The only close competition to CAT was Jadis JP80 which is much more expensive. It will loose in the bass dapertment to CAT. Midrange would be a close call. I think the latest Ultimate is the best all around preamp reasonable amount of money can buy.
I take it back; unreasonable amount of money too.

Get the latest CAT and you will never look back.
Before I own my CAT SL1 ultimate mk2, I was using a ensemble DAC with built in pre amplifier.
Before i never could imagine what a change it would make to insert the CAT. The combination is wonderfull.
I agree with Gvatchna If CAT preamp does not work in the system, something must be wrong.
I own a pair of CAT jl3 sigs and have tried the conrad johnson art2,asthetix,nagra,pass and levinson and the CAT is the best match by far for these amps.the speakers I am using are the eidolon Diamonds.It just sounds more lifelike and natural.Hope this helps.
Gvatchna, Robertje and Strapper211,

Thanks for your responses. Since I am a very new owner of their Ultimate preamp, it is good to hear that based on your long-term experiences the CAT preamp is on par with their amps and that they are the best match. It seems that those who would disagree maybe having a mismatch elsewhere in their systems. Strapper's opinion is very informative since it is based on the evaluation of some very high-end brands/models and felt the CAT pre was still the best.

Thanks again. Let's see if we get some opposing views :)
no opposing view from my side. I've got an earlier version of the CAT SL1 - the Signature Mk3. This is also a simply excellent preamp, if I may say so.

if you look @ the development @ CAT, you'll notice that the preamp came 1st way back in 1986. There was no power amp @ that time. So, the SL1 has been refined over nearly 20 years to this day! I'm inclined to believe that the CAT preamp is just as musical, transparent, dynamic, etc, etc as their power amps. the CAT gear serves up music without any sugar coating & is one of the few pieces of gear that tries very hard to be true to the recorded playback medium. often I've read people chosing to stick w/ the CAT power amp & give up the preamp, if they have both, on the notion or observation or both that a CAT pre & power might be too much of a good thing in that both pieces are exacting in their sound hence together they would render the music in a too dry manner. Well, it's a personal choice - one man's 'too dry' music might be another's 'just right' music. Admittedly some/many people like their music coloured. So be it! So, it doesn't matter what these other people think of CAT preamps & what they chose to use in lieu. However, it's important to exactly note (when such info is offered/posted) why they opted to use another preamp & see if those criteria exist in your system as well &/or you have a very similar music-delivery taste. If so, you might be better off talking one-one w/ that member &/or trying that other preamp in your system. In the end, of course, select what's right for your system & your ear. It's a system built to suit your needs & not the critics'. FWIW. IMHO. YMMV.
I am both a CAT SL-1 Ultimate Mk I owner and a First Sound Presence Deluxe Mk II 4.0 owner. I love my CAT, which I have had about 4 years, but I also love my First Sound. The CAT has unbelievably great bass, both deep and powerful, a smooth, sweet, lush midrange and detailed, extended highs. To those who think it is lean or bright, and I have heard some claim this on Audiogon, I just cannot figure it out. I would think it is a job to make the CAT sound bright. That is just not one of its problems, particularly with the right tubes. Although the F.S. sounds different, a little quieter and is a little more transparent, if you are a new CAT owner you can be assured that you are hearing the top echelon of preamps made. You can find different and maybe as good, depending on your taste and what matches your equipment best, but without taking into consideration your taste and the other equipment you have, you have one of the best preamps made without a doubt.
Ok ok, I’ll chime in. Aoliviero’s last statement was just too tempting to resist. There’s been so much written in this thread that I want to address. So I’ll stir up the pot here a bit which I do regularly anyway. 8-)

I have owned the JL-3 Signatures for 8 months now. The first few months I was still using the BAT 31SE line stage. But the last 4+ months I have been using the Aesthetix Callisto Signature. The phono stage for 2+ years has been the Aesthetix Io.

For many months I have wanted to try the CAT preamp in my home system. A couple of times almost panned out but the units were sold before I had a chance. I will still continue to try and find a way to hear either the Ultimate or the upcoming Legend, as either a line stage or preferably a full function preamp.

If there is indeed a “house” sound with CAT products, adding a CAT preamp with the JL-3’s would most likely be too much in one direction for me. It’s not a matter of too much of a “good” thing but perhaps rather too much emphasis by a designer to achieve a set of goals and other areas not getting as much attention. Assembling a system is all about achieving a balance of extension and control at the frequency extremes, low noise floor and low-level resolution, tonal coherency and dynamic contrasts to portrayal of space, decays, harmonic overtones, etc. Has anyone out there heard one product which redefines the state of the art in every one of these categories?

I have no doubt that Strapper211’s system sounds phenomenal. But I have no idea what is meant by the CAT preamp being the “best match” vs. the other preamps he auditioned or owned. A little more detail as to exactly the benefits, or simply tonally or dimensional differences, would be of great value to the reader.

On the issue of lean, this is ultimately defined a bit differently by each of us. When I heard the CAT JL-2 amp vs. the Atmasphere MA1’s, I felt the JL-2 was indeed lean! The MA1’s were more full and rich in the lower mids. And this I loved. Were they more accurate or less so? Who cares! And yet, the CAT had an awesome dynamic contrast, see through quality and initial attack that impressed me so greatly. But again, was this a more accurate rendition of the real thing? With all the processing of our LPs and CDs through the recording and manufacturing process, how will we ever know what is accurate or neutral to know how the sound was at the day of the recording? We get so wrapped up on the silly terminology when the focus really is whether or not that each component and ultimately the assembled system gets us one step closer to the real event in our own mind.

The strengths described of the CAT amp above are what drew me to purchasing CAT amps. But in the back of my mind, I wanted that fullness and presence in the vocals that was so impressively portrayed by the Atmasphere amps. For me, the Aesthetix products were a perfect match at the system level. As two local (Minneapolis) audiophiles (Jadem6 and Artg) can attest, the combination of the Aesthetix Jupiter models with the JL-3s driving Sound Lab A1’s with the Clearaudio Ref TT as source is nothing short of phenomenal.

The Aesthetix products are incredible in the areas of 3-dimensionality. They piano notes and decays beautifully. It only takes one trip upstairs to hit a piano note and take notice that the Aesthetix get it right. So very few line stages or preamps, solid state or tube, do this accurately. And I have no wanting of bass as JD and I have both been overwhelmed with the Callisto handling the low end like no tube preamp either of us has auditioned in our systems. And there is a wonderful openness and extension in the trebles as well that my previous BAT 31SE and ARC LS5 II/III did not even come close to approaching.

I will go out on a limb and predict that the CAT preamps may indeed have a lower noise floor and possibly a greater degree of low-level resolution than the Aesthetix. But I highly doubt the CAT will portray the volume of space and decays anything close to the Aesthetix. And this to me alone is worth the price of admission. Once you hear the piano or a guitarist occupying space on the stage with the Aesthetix, you know something is right. Is having this quality a coloration? If it is, sign me up.

Each of us is chasing a system sound that fits our own set of priorities. The two local audiophiles I mentioned above have very different systems than mine and yet when I have gone to their home, the sound has been so incredible. I hear things there that I do not hear at my home and vice versa. To gain in one area often results in a loss in another. But I would never characterize their systems as being “mismatched” or too lean or fat, or colored, or whatever. There is no absolute here contrary to the claims by many magazine reviewers.

When I do finally get a chance to try out a CAT preamp here, and if I prefer the Aesthetix models or the upcoming full function Aria preamp, it will not be because my system has a problem elsewhere! For someone to say this is due to a system mismatch or problem is ridiculous. And because I preferred another preamp over the CAT here, and thus disagreed with other posts here, for this to imply my system was mismatched again would be ridiculous.

It’s not a matter of one product working in a system or not, or my system having a problem elsewhere but rather how closely the end system result matches what I want from a system. And for those who are convinced that one product is more “neutral” or “transparent”, yada yada yada, over another, well that’s fine. But there’s a lot more going on in the music that many such people never experience until they hear the likes of the Aesthetix Jupiter products. And again, with the CAT amps, this is awesome.

I think anyone who buys one product simply because they already have products by that same company, and they dismiss other competing products is only cheating themselves. There are simply far too many impressive products out there that deserve our time rather than to dismiss solely on the basis of who’s the manufacturer.

And if you have not already realized it, I think Ken Stevens has the most impressive amps by quite a stretch. Only time will tell if his preamp captures my attention the same way. But for now, the sound I have is mighty fine.

Yes, it's a very good pre, esp on line. In particular, it manages to convey dynamic contrast and an impression of "speed" (low frequency energy is good).

As to system "synergy", the CAT drives difficult loads easily and well -- so I wouldn't worry about electrical mismatches.

This said, I preferred the (older model) big Lamm -- except for the dynamics.

Unlike most respondents, I don't own one.
Hi,let me clarify myself a bit.I thought the conrad Johnson,pass and levinson were terrible with the CAT amps,If I were forced to buy a pre with phono because Cat went out of buisness it would be the asthetix.It soundstaged better but missed on the dynamic slam and body of the music like the Cat captures,very easy to listen to.My second choice would be the Nagra,that has wild dynamics but a little thin and to much in your face,great for rock music but overall a bit tiring after a short time.
All my opinions are with vinyl,I do listen to cds.My front end is Basis debut MKv/graham phatom/koetsu diamond platinum.
I read John's (Jafox) long post. (poor John he was "compelled to post!! LOL!)
I think that John underscores my point - know why people are using other preamps, evaluate whether similar or exact need exists in your particular system & audition/purchase preamp accordingly.

To that effect, I think some of the AN-Kondo & AN-UK preamps like the M6 might go well w/ a CAT power amp. AN components are mostly about music & PRaT rather than being exacting & they *could* provide a suitable balance to the overall sound. The M6 is e-x-p-e-n-s-i-v-e but then it seems that you are swimming w/ the real big boys so it should be in your budget. FWIW. IMHO.
Strapper: Thanks for the details.

Bombay: Yes, I like to whine a lot.
I ran the CAT SL-1 Mk. 3 preamp with built-in phono stage in my system for several years and eventually replaced it with the Lamm L2 (line stage) and LP2 (phono stage). The Lamm phono stage came first, and it handily outperformed the phono stage built into the CAT. While the phono stage in the CAT is phenomenal for the money, IMO it is really not competitive with the very best stand-alone phono stages. About six months later, I replaced the CAT line stage with the Lamm L2. To my ears and in my system, the Lamm L2 was clearly superior to the line stage in the CAT.

Just my $.02.
I heard Jafox's Aethetix AND a CAT SL-1 Sig III in my system, and I MUCH preferred the Aesthetix. It was in nearly every way (except maybe bass) better to my ears than the CAT. I found the cat sterile and slightly artificial (but not bright) by comparison.

That's not to say the CAT preamps arent great, they are, but just not for me. At the time, I had Berning amp with Verity Parsifal Encores, and an AA Capitole II feeding the mix. Now, to be fair, i did not have the very best tubes i nthe CAT, and that may have had something to do with it as well...
One thing I forgot to mention in my novel above was that I first heard the JL-2 with the Blowtorch line stage. This pairing had far far more resolution and dynamic contrasts than I will ever have with the Aesthetix. I suspect for you ultra transparency diehards, you better hurry up and order one of these before it's too late. We had the CAT preamp on for a brief moment but immediately we went back to the Blowtorch as something was so very "right". When I go back there in Dec with the JL-3s, I hope to report on the CAT preamp with this as well.

Art, I wanted you to get that Ultimate more than you did as I was dieing to hear it over here. Now I must wait! You should see the floor in here with tubes all over the place. I got a ton of 12AX7, EL34, 6922 and 6SN7 and am swapping all sorts of combinations in the Callisto and Io trying to squeeze out a wee bit more headroom and little less noise.
The Cat SL1 Ultimate Mk II preamp is a interesting piece of equipment. Some folks prefer it and some do not. I put myself in in later category. I recently just sold my Cat Ultimate but I know there are others which really like it. I have owned several SL1 Cat ultimates over the years starting in 1999 with the original Ultimate Mk I and more recently earlier this year I repurchased the Mk II to evaluate. My opinion of this preamp has changed with the passage of time.

The SL1 Ultimate does have some strengths. It is very clear and clean sounding. It has good detail and imaging and excellent bottom end extension on the bass region, perhaps the best extension at the bottom of any tube preamp I have heard and it is very quite especially with the MK II version. It also has a certain "see through" quality that can be very appealing at first. These traits of the preamp are what first attracted me with the first Cat Ultimate I owned for several years in the beginning. Now for the bad news. I was using my SL1 Ultimate as a line stage connected to the JL2 Mk II amp using the Manley steelhead phono stage. The Cat preamp lacks the substance, size, body and especially tone I have experienced with other preamps. The dynamics are mediocre and it lacks slam impact even thought it is very clear. When I was listening to this setup and closed my eyes listening to familiar source material I was doing less toe tapping. I was not as emotionally involved with the music as I was before. I was thinking to my self "where is the beef", or another way of putting it is "where is the flesh on the bones". The lack of body, flesh and tonal balance left me feeling this preamp was "soulless". There is a certain "sameness" from record to record with the Cat Ultimate. The texture and great tone I previously was hearing on my modified MFA Luminescence preamp were missing with the Cat. While no preamp is perfect and they all have certain shortcomings it was the lack of emotion involvement and tone I noticed the most with the Ultimate Mk II. I guess some people will like the Cat preamp for its strengths but for me to many things were missing.

I do believe Ken Stevens has hit a home run with the JL2 amp. I have owned one now for 3 1/2 years and I love it. I have no desire to change or sell my JL2 amp as the flaws I listed above are not apparent with his outstanding amplifier. The sense of authority, power and "see through" like clarity of the amp have me hooked on this product. A true reference piece and his Statement product. Hopefully Ken's new 15k statement preamp will resolve some of the issues I listed above.
Jafox. Lets get together soon, i want to hear the system with the power conditioning, and you should check out my new toys!
Art, I have been waiting to hear back from you and JD as I thought you were going to bring over a bundle of power cords. Fortunately I got my system up and running again last night after tracking down a bad tube in the Io. Still I have a noise issue here I'd like to get way down. I then had to re-bias the A1s that for whatever reason were causing severe distortion at only medium levels. Must have been the crazy fluctuations in the room's humidity lately to cause this. So hurry up and come on over before something else goes out of alignment!

Good answer. I agree that by experimenting with different brands of preamps you can attain an overall balance preferable to your tastes. In terms of a "better-match", I think Strapper211 means that their preamp is probably designed with the same technical objectives and results of their amplifiers in mind and ultimately voiced together. I think this creates a singularity in that the preamp becomes transparent to the amp and thereby requiring careful selection of the source's musical characteristics to create the preferrential match. However, the choice of a preamp would add another degree of control. But at that point, it will be a compromise of strengths and weaknesses.

At the core of this comparison is the incredibly neutral and musical ability of the CAT Amps to characterize the preamps vs. source components matches. I'm extremely happy with my JL2-II. I think the ratio of resolution/transparency to musical experience is close to 1.


Hi,the legend will be out in a few months so hold tight.Ken says it is a real killer and will complement his amps,and the combination should be Nirvana.
I had an update re. CAT preamps & I thought that I'd post it here FWIW. There are other threads that also talk 'bout this subject here on Audiogon but they might be far back in the archives.

I took member "rayhall"(A'gon) & "TubeNewbie"(AA) advice & got a pair of Telefunken 6922 tubes. I also bought a pair of Amperex 7308 USN-CEP, white label tubes. Both these tubes were bought for the V6-V7 only position. They 12AX7 tubes I use are Electro-Harmonix. All other 6922 are Sovtek provided by the factory.
By merely tube rolling the V6-V7 tubes w/ the above 2 mentioned brands has made the sound my CAT SL1 Sig Mk3 even better! I love it more!
The Telefunken tubes impart more of what the Sovtek 6922 gave - better & fuller bass & a touch sweeter highs are the 2 items I note the most.
The Amperex tubes give a touch of warmth to the midrange. it's more seductive now but not so much that it's syrupy. Bass remains full & robust. The highs remain extended & retain their sparkle.
Both these tubes allow me to seemingly have my cake & eat it too in that I don't seem to compromise the CAT intended sound while I can fine tune it depending on my mood/preferred music delivery.
I believe that 'rayhall' uses Tele 12AX7 in V8, V9 & a Tele 6DJ8 in V10. Wish I could too but my pockets aren't that deep! :-)
Bombaywalla: I recently got a batch of Tele 12AX7's and with the help of a tube tester, I was able to match (by output signal strength) several pairs for my Aesthetix gear. I still have several of these left. If your short on a budget but would like to give them a try, I can ship a pair to you. I also have found the EI tubes to be quite impressive as well and they tend to be dead quiet vs. the majority of Tele's...but they don't have quite the Tele midrange magic. I think I also have one remaining pair of Mullard 12AX7 that you could try; I like these a lot due to their dynamics and very good tonal coherency So I could send you 3 pairs for you to try in the CAT. Should not be more than a few $ shipping costs. This way you can try these out before you spend a lot for something that might make a big difference....and then ship them back to me at a later date. Let me know if you're interested.
Jafox, I dont need any tubes, I want to tell you that you are what we all should be like, helping people, that is what it is all about, I get a warm fuzzy feeling when I see people help each other,you are one of the best, I wish you well in all you do, If you ever need help, you can count on me!!!! Really. Marc
You are most kind to offer me a chance to listen to these prized tubes!
Yes, I would love to have a chance to hear them in my system. Ever since I got the Tele 6922, I've been conjecturing just how the sound would be if I could swap in a pair of Tele 12AX7s.
Yes, Ken Stevens uses the Ei 12AX7 for a good reason, I suppose!
I'll send you an email off-line re. your generous offer. Thanks much!
John, we love you dearly. We should all get together, sit in a circle, hold hands, turn out the lights and sing "Kumbaya"
I do not know how the current units are set up but the earlier preamps (Reference) had their capacitor quite solidly glued to the board with some glue that only CAT can dissolve for service of the caps.

I intended to go through my new (used) CAT Reference phono preamp and upgrade the caps, wiring, and tubes. When we spoke to the owner, Ken Stevens, he made it quite clear he want ONLY CAT to work on his products. I posted it for sale the same day and it is long gone. Too many other options to put up with that proprietary nonsense.
I am one of those CAT amp owners (JL-1s) that tried using a CAT preamp, but went in a different direction. In my experience, I found that the CAT preamps prior to the Ultimate (which I have not heard in my system), were not the equal of the amps. This is not intended to knock the CAT pre's, just a reflection of my belief that the CAT amps are, if not the finest, among the very finest amps made, whereas I found the preamps to be only "very good". Specifically, the CAT preamps lack the dynamics - micro, and especially, macro - the neutrality, or the authority (from the midbass down), of the amps. I found the preamps to be more colored - they err a bit on the lighter shade of pale. The amps and preamps are relatively equal when it comes to resolution - both excel at resolving low level detail. The preamps have a bit of grain in the upper midrange, that is not present in the amps. In the end, I found the amps to be more musically involving than the preamps.

I have found that, as far as line stages go, a top quality transformer passive (e.g., Silver Rock) is substantially better than the CAT SL-1 Signature Mk III (the most recent version with which I have had any experience). I tried a C-J Art (older version) in my system, and found that to be a better match with the CAT amps (the C-J amps, by contrast, are nowhere near the quality of the CAT amps). I also preferred the diminutive Audio Synthesis Passion (not as exceptional bass, but lower noise floor and more transparent through the midrange) to the CAT SL-1. I did prefer the CAT to the BAT VK-5i and the Thor TA-2000. For whatever reason, the CAT also worked better in my system than the Placette passive (which surprised me).

The phono stage used in the CAT preamps is very, very good, and definitely better than the line stage - in fact, if one were building a phono only system, it would be a top choice. However, I do not believe it to be the equal of the Manley Steelhead or the Counterpoint SA-9. Based on limited hearing, I would say the Aesthetix Io Signtature and Lamm phono stages are possibly better as well, but wouldn't bet the house on it.
I listen through my ediolon speakers, it is by far the best and most life like and natural. Easy to go along with different external phono stages.
Hi All,
I posted my findings plugging in the 12AX7 tubes that Jafox kindly sent me. I posted this in a more relevant forum. Here's the link
if anyone is interested.
The SL1 Sig MK3 has been the centerpiece of my system for several years, with consistent, solid performance that never dissapoints. Musical yet detailed and it does all the audiophile things with apparent ease. I have worried about what I would do if something ever happened to it since I know it would be extreamly difficult to replace with something sounding as good, let alone better. BTW, the phono section is excellent IMO and I use it for 90%+ of my listening.

I haven't tried a large variety of tubes but I feel it hates the sovetek stuff but sounds great with EI 12AX7 elite golds, and in the 6922 position either the 6h23, JJ E88cc, or EI 6922. I've found it to be easy on tubes and easy to feed when it does need a pick me up.

I guess my comments will be somewhat redundant. I have owned the CAT Ultimate MK2 (linestage only) for about a year. I found the CAT with stock sovtek tubes to be awful.
Agressive, edgy and downright uncomfortable to listen to.
Replacing them with Amperex PQ 6922's and 12AX7's was transformational. The PQ's made in Holland are a little more forward than the USA made PQ's but both are MUSICAL.
I read this post for no other reason than I was "passing through." I have to admit, I was -- and am -- agog at reading that the CAT preamps lack micro- and macro- dynamics. Of course, I owned mine back from 1995-1993, and perhaps they have changed since then, but my system(s) were composed of Versa Dynamics 2.0 and 2.3 turntables , Goldmund Mimesis 9 and Jadis Defy 7 MIT, XLO and Transparent Reference interconnect and speaker cables, and Avalons/Watt/Puppies/Goldmund Super Dialogues and I cannot fathom that the CAT did not have micro-dynamics. Macro, perhaps, and only JUST perhaps. In fact, if you read issue 38 of TAS, you will see that that trait was mentioned as one of its strenghts. Ditto TAS #60, Sounds Like..#3 and a couple of other mags. I could never say that the older CATs lacked micro-dynamics, particulary with the Jadis Defy 7, which was inarguably exquisite in micro-level inflections (macro was very different on that amp, no matter WHAT I used). What I can say is that everything since, including my VAC 70/70s, sound slightly slow by comparison. Are you using vinyl or cds? I have trouble getting my cds to "inflect" anywhere near as good as my Versa did (but then, it cost $15,000, so it had darn well better sound better than most CD players of that time), but I'm genuinely interested to know what the front ends being used are.
I own a First Sound now, but unless the CAT has lost its touch completely, I can't fathom problems with its dynamic abilities. Only my First Sound preamp (my current preamp) has made me wonder if the woofers on my speakers were going to blow out in the way the CAT used to. And that's macro. For micro, the CAT is an exquisite preamp, and having been an edtior for Fi, I heard a heck of a lot of preamps and amps and speakers in my time there. And frankly, I miss the sweetness of the CAT, and I hear orchestral music at least once a month, and live music, depending on the composer, does sound sweet. The CAT, with its inflections, was dazzling. Has it changed that much since the late 80s??????
I spoke with Ken Stevens for about an hour and a half today.
We spoke about many amps and preamps but mostly his in relation to others. He told me that his preamp is amoung the best and the best at it's price point but there were preamps that were as good or better that cost more. He threw out a few familiar names, Aesthetix, Acoustic Research REF3, and a few others that elude me at the moment. He said that without reservation his amps JL2 and JL3 were head and shoulders above anything else. He said that he is marketing his Legend preamp to reclaim the best preamp cost no object product.
I, like Gbmcleod, am agog by what people have written about CAT preamps. I find them to be certainly among the best in dynamics, smoothness, liquidity and high frequency detail. They have stunning bass, in both depth and power. In my opinion, the bass is like nothing that I have heard from other preamps and once you have heard it, it is hard to give up.

Where I think that they fall down is in the area of low level noise, which obscures transparency and imaging to a slight degree.

This is why I spend more time listening to my First Sound Mk II 4.0 rather than my CAT Ultimate Mk I, but both are very fine products which, in my opinion, exceed the efforts of the other top brands which I have heard. Admittedly, my evaluations are prejudiced in that many of the brands which I have heard were not tube-rolled and, in my opinion, this can make all the difference between a presentation that is just so-so and one that is outstanding, but only if the preamp "has the goods".

What I have found is that it is difficult, if not impossible, to compare preamps with stock tubes. Despite what the manufacturers say, stock units do not come close to revealing what these units can do when tube-rolled.

If you are evaluating a CAT Mk III or later with stock Sovtek 6922's in V6 and V7 on line, or in phono add V1 and V2 to V6 and V7, you are really doing yourself a disservice. These MUST be replaced. I have tried a number of NOS tubes, but obviously not all, and I do prefer the Telefunken 6922 in the CAT Ultimate Mk I, like Bombaywalla said above. The EI 12AX7's are surprisingly decent sounding tubes in the CAT, but if replaced at V8 and V9 on line and if you use phono, replace the ones at V3 and V4 also, you can eliminate some muddiness in the bass that you didn't know was there until it is gone. Telefunken 12AX7's work well for this purpose.

Nothing that I have heard goes down deeper, giving both bass depth and power, a better lower midrange transition, with smoothness, solidity, liquidity and with dynamics to spare. Highs are sweet and detailed and extended. High frequency decay on the CAT when a cymbal is struck hard is exceptional and with these tubes, there is no brightness or forwardness anywhere.

Yes, the First Sound will stun you with its much lower noise floor. Yes, it will stun you with its "you are there" transparency. The small and well-defined images in the soundstage cannot be achieved on the CAT and the female vocals on the First Sound are truly exceptional in their up-front intimate presentation, but all this again, is only achievable after tube rolling.

Nothing is better than hearing the CAT properly fed go full out on music written for pipe organ. If the rest of your system is full-range, or nearly so, you will rattle the windows like few other preamps are able to do and yet you will hear all the subtlety and delicacy of the small trupets and whistles that pipe organs can also play, presented without any non-musical artifact When all the pipes get going in unison, you might feel that you are in church or that you are taking a tour of the great churches of Europe.

So my answer is an unequivocal no as to whether the CAT is just "very good" or lacks dynamics -micro or macro. Yes, it has been surpassed in some respects, but in overall presentation, it is worthy of very high praise indeed.
It's interesting to see this thread have activity again. As reported elsewhere here on A'gon, earlier this year I had a CAT UII on loan for a couple months to compare to the Io/Callisto.

The consensus here is that the Sovteks in the CAT must go and my experience indicated the same. There is too much fatigue and sharp edges with these tubes. And as others have reported, the Tele 12ax7 did not work at all in the CAT line stage nor phono stage. It does not work well in the Callisto either but it is magic in the Io.

For the CAT vs. Aesthetix comparisons, the two line stages use the exact same tube compliment. I had enough of the Mullard 6922/12ax7 sets to keep both line stages warmed up for hours. No doubt about it, the CAT line stage has greater dynamics, more clarity and openness in the very top and indeed has a greater presence and weight in the bottom. All of these were instant and quite impressive. But it only takes one return back to the Callisto to hear the multitude of underlying subleties to know something is very right here. There is structure, body, dimensionality with the Callisto that is lacking with the CAT. And this for me was all it took to hold onto the Aesthetix.

There is that instant boogie factor with the CAT. The dynamic contrasts and frequency extreme coverage just gets your blood flowing. And it is never excessive. This with the JL-3 amps is exciting. But once the piano starts or vocals begin, the CAT UII line stage falls short.

The difference with the phono stages was much more dramatic. There has been so much praise about the CAT phono stage. With the Io (non signature here at the time, but getting completely overhauled now at GNSC to far beyond an Io Sig), the CAT phono stage had no chance. The CAT phono had one-note bass vs. far greater tonal coherency with the Io. It was as if the second octave in the CAT phono had a dip; the Io was portraying string bass notes with phenomenol clarity that were lacking with the CAT phono. This was more evident with the full CAT vs. the Io/Callisto compared to the CAT phono into the Callisto vs. Io/Callisto. I think the CAT line stage's deeper coverage into the bottom octave more clearly shows the lack of coherency in the CAT phono's bass coverage.

Whereas there were clearly some pros/cons of the CAT line stage vs. Callisto, the Io tore up the CAT phono stage in every way. This was the opposite that I would have expected. I can only imagine how the GNSC rebuilt Io will perform.

I have since gotten some Tele 6DJ8 tubes and these in the Io and Callisto are phenomenol. The Mullard 6922 were my ref tube here, but the Tele has now taken this spot. But I find a mix of these two types is the way to go with the Callisto. I would like to hear how they perform in the CAT. I suspect it would be a similar step up. But still, not at all enough to bring on the magic of the Aesthetix. As much as we like to refine the sound with tube rolling, it all starts with a specific design and the CAT as well as the Aesthetix have their fundamental sonic character no matter what tubes we use in them.

For a system that needs some help in the dynamics or resolution departments, the CAT preamp has no peers. But if you are looking for a more spatial presentation, great decays, textures through the vital mid 4-5 octaves, the CAT will most likely not work for you. Perhaps the Legend will address these areas and conquer the opponent. But for now, for me at least, the Io/Callisto reigns above the feline preamp in pure musical enjoyment. And this is with the JL-3s.

Too bad you live in Minneapolis, Jafox, because I would like to get together with you for a preamp shootout. I have noted your posts in this thread and elsewhere and they does not correspond to my experience. I auditioned the Callisto, probably almost 5 years ago, in a store alongside the Hovland HP-100. I thought my CAT clearly bested the Hovland and the Aesthetix competed with neither. Of course, it is difficult to make these comparisons as tubes, associated equipment, cables and room/setup all play a part and as we have belabored here, tubes can play a huge part. There is no doubt that I missed smoething in that audition for some reason, as too many people speak of the dimensionality of the Aesthetix, even though there was nothing special going on in that audition with regard to dimensionality and the Aesthetix.

On the other hand, I would agree with you from my experience that day with the Aesthetix that the CAT clearly had better dynamics, bass depth and weight, better clarity and openness in the high frequencies than the Callisto, at least at that time.

I've never heard the CAT Ultimate Mk II and that may account for some of the difference that we hear, but I doubt that it is the full reason. I have heard many CAT's all the way back to the original ca. 1985, and while some sound a little different, they do maintain a similarity that I don't think that Ken Stevens created an entirely diifferent product in transitioning from Ultimate MK I to MK II.

As far as tubes in the CAT are concerned, I did follow Bombaywalla's link to his other thread where he discussed results of his tube rolling in the CAT. It seems that he
did not confirm your position that the Telefunken 12AX7's do not work in the CAT. It seemed to me that he rated the "Tele/Tele" combination second best to the "Amperex 7308/EI 12AX7" combo and he rated the Tele 6922/Mullard 12AX7" combo third. It seemed that the Tele/Tele combo was a little too "sweet" for Bombaywalla, although he found it very seductive and had a hard time turning off the pre in order to go to bed. He also described the Tele/Mullard combo as very sweet and seductive, but a little brighter, with the bass on the weak side. I can confirm this that the Mullard is both a brighter tube and is not as extended or powerful in the bass with the CAT.

In looking through all the responses with regard to the CAT, the main thing that we all agree upon is that the Sovteks are God-awful. To hear a properly set up Aesthetix
would be a treat and I would take on the challenge of trying to demonstrate what the CAT is capable of. When I participated in these sessions before, it is often much more difficult to achieve consensus than I thought it should be, but if I thought, after such an in-home audition, the Aesthetix was either better than the CAT or had qualities that I valued highly, I would admit it in a minute.

Too bad New York City to Minnesota is too far to carry my system on my back.

Hello Rayhall - I too wish we were closer. It is very exciting and educational to visit other audiophiles' home and try our gear in these other systems. I learned much from two local guys on the issues of PLCs and PCs specifically. The things that seem to be passed around over and over are the preamp and cabling.

I had the CAT UII for 3 months and played with it off and on, before and after the multiple day/night comparative process ... and reported what I heard/learned back to the CAT dealer. And he in turn made further suggestions on things for me to try. I went far beyond simply trying one piece in the system, then switching to another, maybe back again and then coming to a conclusion. The one thing I regret not doing then was to go back to all Sovteks in the Callisto, including those dreadful EL34's in the PS. This would have given me a more accurate comparison test that everyone else out there has most likely heard the Callisto when comparing to its peers.

As a huge fan of the JL-3s, and feeling that the multitude of chassis with the Aesthetix pieces is a major pain in the neck, if there was ever someone who wanted the CAT UII to perform like a GREAT preamp, I was/am that person. And the synergy preachers out there would tell me this would be THE BEST match with the JL-3s. And yes, the CAT's dynamic contrasts, absolutely incredibly resolving top end and bass performance won me over. But when I heard the Callisto do the decays and the leading edge of instrument and human-voice tones to bring on the body of such tones, the CAT lags far behind. The initial great impressions of the UII become a moot issue as the Callisto brings on enjoyment to the listening like no other.

To get another viewpoint on this, I had one of the local guys, Jadem6, come over. If there was ever a super critical listener and system tweaker perfectionist out there, this guy earns the blue ribbon. He too was very impressed with the CAT's strengths. But he dismissed the CAT immediately because it was not even close to the Callisto's spatial abilities. The UII ends up sounding hi-fi-ish compared to the Callisto.

I agree that the CAT preamp differences over the years can not be all that significant. But I can not imagine how you did not hear the Callisto's strengths over the CAT U1. When I first heard the Callisto with the Sovteks, the capability of this product was still clearly evident. The other tubes do take it to a new level as they do with the CAT.

Unlike Bombaywalla, I had no access to Tele 6922/6DJ8 at the time. I only had Amperex 6922 and Mullard 6922. And for both line stages, the Mullard was far more to my liking. Now that I have tried the Tele 6DJ8 as reported, this is my new reference. But contrary to Bombaywalla's report on the Tele 12ax7, I stand by my statement that it did not work well in the CAT nor in the Callisto. In both units the top-end openness was greatly reduced and thus the harmonics and ambience of the mid-range frequencies. And this is an area that I am hyper-critical. I would have loved for the Tele 12ax7 to work here as I have many of these for the Io and a pair for the Callisto or CAT would have been very convenient to use here as well. Here again, a scenario where I would have benefited from the result, the desired outcome did not occur.

It was the UII's weakness in the decays and dimensionality that I was trying to get one way or the other. The Purist Dominus PC helped, like it does with anything else, but it did not rescue the UII here. And the Dominus IC between the DAC and line stage as well as between the tonearm and phono stage, again did not do it. Believe me, I tried! And perhaps the Mullard took away some of the tonal coherency vs. the other tubes in the UII. But it helped this unit significantly in the areas of its weakness ..... but again, not even close to the Callisto.

I can tolerate a reduction in performance at the frequency extremes or in dynamic contrasts and not having the ultimate in low-level resolution. But I need instruments and musicians to convey real space with the tones going on forever and ever. It started for me 23 years ago with the ARC SP-8 and later the SP-10, and I have wanted it ever since. And today, the Aesthetix models do this like no others and they do a very good performance in every other sonic character. The areas which they do not reach the top of their class are easily made up for by the JL-3s and SoundLab A1s.

An interesting comment by another local audiophile who visited me a few months ago - he said he had never heard decays in any system like this before. I never did hear back from him on what line stage he ended up with.

When the Legend is available for me to try, you can be certain that I will be in line to hear this. I have not given up on the CAT preamp yet.

If you ever have a reason to be in Mpls, throw me a note and stop by for a listen.

Hi Rayhall & Jafox,

Jafox: good to read your review of the CAT UII after having played w/ it for 3 months. I guessed, when I spoke to you earlier this year, from your choice of words, that your review was not going to be favourable towards the CAT UII.

Rayhall cites my experiences w/ the tube rolling correctly from the other thread.
The Tele 12AX7 definitely is a winner in the CAT. It should come as no surprise - the Ei12AX7 is supposed to be a copy of the Tele smooth-plate 12AX7. I believe that the Ei factory even has some original Tele tube making equipment. Of course, it does not mean that it has to work. However, it comes to me as a major surprise that the Tele 12AX7 does not work in the CAT UII.
I'm using this combination at present - Tele 6922 & Tele 12AX7 & am enjoying it immensely.
It looks like we are hearing things/music in totally different ways!
Also, Mullard tubes are wrong, wrong, wrong, wrong, wrong, wrong tubes for the CAT!
Of course, one is allowed to tube roll any & every tube that one has on hand - nobody is there to stop the user from doing this. However, I've found it worthwhile to solicit an opinion from the designer/manuf before doing so. If nothing, I take his words under advisement. More often than not I follow his guidance 'cuz I feel he knows more about his design that I do.
One minor communication w/ Ken Stevens will tell you how wrong Mullard is for any CAT!
It is indeed unfortunate that you had Mullards for the 3 month audition period! I feel that you severely hobbled the CAT UII by using those tubes. The CAT *should* have performed terribly w/ Mullard tubes & it did, as you stated!
2ndly, talk to the designer/manuf of the CAT before you try the Tele 6DJ8. From my conversations w/ Ken Stevens, DO NOT use 6DJ8 in the CAT. They'll work but the bias is not set correctly for that tube. If memory serves me correctly, the 6DJ8 tube takes more bias current than a 6922. The bias in the CAT is set for a 6922 & it'll not let the 6DJ8 perform to its max/best. It'll hobble the CAT UII (once again).
I think that the correct tube complement(s) need to be used in the CAT UII before a conclusion can be made vs. the Aesthetix.
I cannot believe that Ken Stevens, who is absolutely behind the 8-ball on dynamics, timbral accuracy of instruments & voices, attack of instruments, soundstage width & depth, would make a preamp that lacked these qualities.
If he did (consider this for grins), then, how did the CAT power amps, all of a sudden, get these qualities???
A man/designer who has no knowledge of dynamics, timbral accuracy of instruments & voices, attack of instruments, soundstage width & depth for his preamp can, suddenly, discover these qualities for his power amp??
You do not see the inconsistency of this??
Thank you Bombaywalla for your response. Let me addres your issues one by one. And yes, I knew my comments would get people's blood boiling.

First of all, as stated before, I have not heard the Tele 6922/6DJ8 tube in the CAT. I have no doubt it would work very well here; every place I have tried the Tele 6DJ8, including the Counterpoint NPS400 amp, there was a marked improvement in tonal coherency. I am 110% sure of one thing: Tele 6922 tubes in the CAT UII are NOT going to rescue this line stage from its weakness in portraying space and decays. This tube was a very nice refinement in the Callisto and Io, but it did not take either of these units to a new level in this sonic area. So if anyone thinks they are going to get the Aesthetix strengths by putting Tele 6922 tubes in the CAT, they are in for quite a disappointment. No tube change is going to do this. The differences here are inherent in the respective designs here.

As I have heard the Callisto vs. the Calypso many many times now, they are so very much the same except in one key area - the issue of dimensionality. And the two designs are quite similar except one key factor - the Callisto has a tube PS. Hint, hint. This could very well be the reason why the UII lags behind the Callisto like the Calypso does in this manner.

Obviously, our experiences on how the Tele 12ax7s worked in the CAT are polar opposites. I like this tube very much, but so far only in the Io. What it does in the CAT UII, Callisto and Manley Ref DAC is consistent - the soundtage and dimensionality are greatly diminished in my system. Perhaps there is "synergy" between the Tele 6922 and 12ax7 in the CAT, but this too sounds more like a leap of faith rather than a reality.

I am not going to get into a pissing match over what tubes are right or wrong in any product. To lecture me that Mullard tubes can not work is nonsense. They might not be the ultimate tube here, but for $100, just one pair in the line stage took the UII into far greater sonic performance. This is the tube I had at the time, and with it, I observed a significant improvement over the Sovtek. If nothing else, it is a wonderful starting point if it is the only available tube at the moment.

That Ken Stevens shared with you that the Mullards were not a got tube here is fine - I accept his opinion here. Let me be frank - he does not want any of us to even change the stock Sovteks. And yet it is a consensus here - until we get rid of them, one has not begun to hear the potential of this product.

As for me hobbling the UII experiment with only Mullards indicates to me that you're getting a little ahead of yourself with coming to judgement here.

"I cannot believe that Ken Stevens, who is absolutely behind the 8-ball on dynamics, timbral accuracy of instruments & voices, attack of instruments, soundstage width & depth, would make a preamp that lacked these qualities."

You are not paying attention to what I have written in this thread at all!!!!! In the context of dynamic contrasts and initial attack of notes, I have repeatedly stated the UII line stage outperforms the Callisto by a significant margin. And this is very evident with the JL-3s. From my amp listeneing sessions, no amp can touch the JL-3s in this regard. And we are driving some very resolving speakers here: SoundLab A1s. So nobody needs to lecture me about dynamics or transient speed. It is why I bought the JL-3s and it is what I immediately noticed was the UII strength.

I have been very kind to simply state that the Io was far beyond the UII's phono stage. And this was why I did not put anywhere near the effort between these two as I did with the line stages. As stated before, I threw everything at the UII but Tele 6922s and the kitchen sink to bring on the magic and it just did not happen. I suspect very few people would have done so much with this unit as I did.

"The CAT *should* have performed terribly w/ Mullard tubes & it did, as you stated!"

And again - you were not paying attention. I never said it performed terribly. I stated the UII's strengths over the Aesthetix. And I then followed through where the Aesthetix excels over the CAT, i.e., harmonic textures, layering, decays, ambience, etc., etc. Rather than you scold me for my incompetence and/or lack of responsibility for sharing my experiences here with the Mullard tubes, I suggest you get on down to your Aesthetix Io/Callisto dealer, and take a box of Mullard, Tele and Brimar tubes, and hear for yourself the areas where the UII falls behind. Oh, and so there will be no bias on lack of dynamic contrats from the audition, maybe you can also borrow a pair of JL-3s.

As for the issues of soundstage, decays, body of the instruments, etc., even the CAT amps lose out to some of the competition here.....the Atmasphere amps driving the SoundLabs bring on a most incredible performance in these key areas over the CAT. And this was observed with a direct comparison between the amps. When I heard this at the dealer, I remember telling him I wanted both amps in one. And the same holds true with the UII and Aesthetix. But this is not possible so the best I can do is pick one from each side of the fence. And to me, the Aesthetix/JL-3 pairing is incredible. Everyone who has heard this with the A1s, has said the same.

Perhaps the UII and the Atmasphere amps would be the flip side of this success. But a CAT/CAT setup is just too much into the neutral zone for me. Other people love it and I respect that. I just need a little more direction into the dimensional zone.

"You do not see the inconsistency of this??"
Not at all, and maybe you won't either once you pay more attention to what I have written all along. There is no perfect product in the CAT nor Atmasphere nor Aesthetix nor whatever camp. The key is to assemble a system in such a way that brings on the strengths of certain pieces that stand out and try to improve on that component's weaknesses through other changes in the system. And this is what I have done.

The post by Bart(Poswbp555) where he spoke with Ken Stevens is interesting. This ought to be very exciting when the Legend comes along. But the full function preamp by Michael Elliot is also much on my mind. We all benefit when these very talented engineers continue to improve on their past great achievements.

I think I have shared all that I can here to convey the pros/cons of the products under evaluation. For me to continue here will only result in rehashing the same information through and through. And as exhibited by Bombaywalla, my instincts were correct - people get upset when their reference product is put under a microscope.


Thanks for your update. Appreciate your time to write a detailed rebuttal post.

>> And yes, I knew my comments would get people's blood boiling.
NO! my blood is not boiling. Far from that, let me assure you & double assure you, if I may.
When I wrote my post earlier today, my intention was to invoke a debate & not a screaming match.
At no point did I "lecture" you about Mullard tubes - it was 1-line statement.
At no point did I "scold" you for your "incompetence" or "for your lack of responsibility for sharing my experiences here with the Mullard tubes".
You have become way defensive & aggressive than, I think, my post called for, if I may say so.

>> And as exhibited by Bombaywalla, my instincts were
>> correct - people get upset when their reference product
>> is put under a microscope.
Let me say again, I'm NOT upset that you put the CAT UII under the microscope. On the contrary, thank you for doing so! My ego is not hurt, my sentiments are not hurt. OK?
I'm not here to convert you to a CAT preamp person & my post was not intended to do so either.

I will say this: you & I are hearing music *very* differently. There is a wide gap.
Maybe I'll conclude the same as you when/if I get to hear an Aesthetix product? Who knows.....

I have to agree with John (Jafox) on the sonic qualities of the CAT U2. I am hearing similar strengths and weaknesses to those he describes. I value a liquid, musical, melt in your ear three dimensionality over dynamic slam (it would be nice to have both obviously). I may try the Atmasphere in combo with the CAT U2 in the future to split the difference between their strengths. Bombaywalla,
I haven't read your thread on all the tube rolling combos you have tried in the CAT yet but I'll bet you that the Amperex 12AX7 D getter long plate (circa 1950's at 200 to 300 a pair)will significantly outperform the EI 12ax7. John is also correct about Ken Stevens adamantly rejecting swapping the stock tubes in the CAT U2, so why are you referring to his rejection of the Mullard as a suitable replacement for the stock tubes when we all agree the stock Sovteks are dreadful. Anyway, thanks for doing the tube rolling, these are the kind of experiments that can save us money in a very costly hobby. Bart

>> but I'll bet you that the Amperex 12AX7 D getter long
>> plate (circa 1950's at 200 to 300 a pair)will
>> significantly outperform the EI 12ax7.
maybe so. The $ amount is a bit too extravagant for me - I cannot convince myself to spend this much on NOS tubes!
I also tried the Telefunken 12AX7. I think that I had a smooth plate pair (if memory serves me correctly). Like Rayhall wrote, I found the Tele 6922/Tele 12AX7 combination the best. The Amperex 7308 USN-CEP/Ei12AX7 combination the 2nd best.

>> John is also correct about Ken Stevens adamantly
>> rejecting swapping the stock tubes in the CAT U2,
Having spoken to Ken Stevens several times at length, he informs me that he has "optimized" the CAT preamp design for the Sovtek 6922. That's why he's so insistent on retaining those tubes. I didn't ask him specifically what he meant by "optimized" but I surmise that he means creating the bias specifically for that tube to run it in its most linear region + the power supply filtering for its heater supply.

>> so why are you referring to his rejection of the
>> Mullard as a suitable replacement for the stock
>> tubes
Again, speaking at length w/ Ken Stevens informed that the Mullard tube was ill-suited to the design on the CAT. As you know, certain tube types work well with certain tube preamps i.e. if a certain preamp uses a 12AX7 then not all brands of 12AX7 will suit this preamp. The CAT is no different - the Mullard tubes make the CAT perform at its lowest. I found the same when I tried a Mullard pair generously lent to me by Jafox.
However, I did write the following in my original post:-
"Of course, one is allowed to tube roll any & every tube that one has on hand - nobody is there to stop the user from doing this. However, I've found it worthwhile to solicit an opinion from the designer/manuf before doing so. If nothing, I take his words under advisement."

I'll have to listen to an Aesthetix Callisto & determine for myself how its sound compares & contrasts to the CAT preamp. I'm not convinced that the CAT can be faulted for the lack of portraying space, decays & harmonic textures.
Bombay, if you followed Ken Stevens advice you would still be using the stock tubes. Have you considered the cost differential between the stock tubes and Teles or Amperex may be the deciding factor in Ken Stevens tube selection?
The 6922's or 12ax7's have certain output parameters that are the same regardless of the tube manufacturer. That is why they are measured by classification (6922, 12ax7, 12at7, etc.) not by manufacturer. So for you to say that Ken's design was optimized for the Sovtek is absurd. Does it sound optimized to your ears or any other ears on this post with the Sovteks? Bart

>> So for you to say that Ken's design was optimized for
>> the Sovtek is absurd.
I'm merely conveying to you what he told me. For a clarification you should call Ken & ask him yourself what he exactly means.
Bombaywalla - The reason my response came off as defensive was because I made an effort here to convey my observations; these descibed the strengths and weaknesses of the two preamps under test. Never did I refer to either as terrible. That (dis)hono[u]rable title belongs to a few other preamps that I have auditioned over the years and noted here on A'gon.

I do indeed take a manufacturer's or an audiophile's suggestion for a starting point to use a specific cable, tube, matching component, etc. But the road to refinement on a per-system basis is only possible if we experiment with other options, and some of these will likely be contrary to the initial suggestion/advice we got. The Mullard tube is a classic example here. It did not work for you - but it worked for me ... if nothing else, as a significant improvement over the stock tube used to "voice" the product.

Another factor is that my tests were with the UII and yours with a Mk III. Besides our very different systems, could the difference in the CAT preamp models be a factor for our opposing conclusions with the Mullard 6922? .... very possible. And the same for the Tele 12ax7? .... again, very possible. Can you imagine that one brand of 12ax7 might lock in for the CAT line stage and another lock in for the CAT phono stage? ... And swapping these two could be a worse result that what we had with the stock tubes? This is exactly the case between the Io and Callisto for both the 6922 and 12ax7. Afterall, they were designed by the same engineer and also voiced with Sovtek tubes. And yet when other tubes are tried, the two components react very differently to the same 12ax7 or same 6922. Even Mr. Spock would be perplexed by such a outcome.

I think that if we evaluate a tube's performance, or anything else such as a cable, with a specific product, all of our conclusions about that specific tube or cable are relative to the one product under test....and in the context of that system. We can not judge the performance of that tube or cable onto another product until we repeat the test process for the product.

What I was trying to do with the resources available to me, was to max out the CAT UII and max out the Io/Callisto and in the final analysis, the results for each was very impressive. But through so many changes to each, tubes and cabling, a "house" sound for each became very evident...and the design engineers' priority in a resultant sound for each became evident. We can tweak and refine a product to get it to be a little more to our liking, but if we still find something lacking, we must continue our quest to find a more suitable product; expecting a $1200 pair of golden tubes to save the day is not realistic.

Btw, I did a lot of playing of 6922/12ax7/12au7 with the JL-3s. With Mullards and Teles here, the JL-3's performance took quite a step forward - hardly a surprise. And this was long before I ever had the UII here. I have paid a lot more money for a component change and gotten less improvement than I have with some of these $200-300 tube "upgrades".

I don't mean to get so philosophical here, but so many people here, as shown by the multitude of "best of" threads on A'gon, are obsessed with what is best.....and there is no such thing.

Bart - I get the DAC and Io back from GNSC tomorrow. Once I burn these in for a couple weeks, then try out a matched octet of Brimar 12ax7's for the Io's first stage, the pair in the Callisto and pair in the DAC, I will be ready to borrow some Stealth cables. Hopefully the JL-3s will return very soon too. I am very excited to try the Steath products. I will keep you posted on this.

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 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.

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.

"Hey security, who let this solid state man in here?"
No solid state man!My boy!Prefferably tubes in my heart of hearts,yet having had both on my Ascents,the two chassis modified 8t is of the ilk that even my tube "only" crowd is hard pressed to identify a sonic signature!Runs dead cold,too.What's not to like,Sir Fox? -:)BTW--the Spectral
/Avalon marketing began with the campaign to compete with the Wilson designs using the "2c3d"(two channel/three D)moniker.All while driving the later Avalon Radians,which had bass and mid drivers that pushed a good deal more air than the earlier Ascents,but were NOT as detailed here(yet played Watt/Puppy loud with the SPECTRALS).The Ascents were designed with,and voiced for Rowland's amps of the day(8t/9t),which can be updated to the latest power supply technology.I'm having that done now.

BTW--I had Sir Steve Huntly do massive work on my Pre/ a comparison with a friend's CJ Art(orig,and modded)/Premier phonostage,Huntley managed to get me deeper bass with a blacker background.All else very similar.Of course my secret weapon are Siemens CCa's in phonostage.Super quiet/super pricey.Hey we all cannot be perfect.HMM,maybe I am doing a bit of rationalizing.NAH,I'm actually not.

As Ripley would say,of the previous words stated,by little, very old, me....believe it,or not!!-:)