CAT Preamps vs Amps

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?"

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/phonostage.Result...in 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!!-:)

Best!

Jafox,

I started rummaging through my tube drawer, because I know that I have a pair of Brimar's, but I think that they might 6922's rather than 12AX7's. Nevertheless, if I have them, I have tried them in the CAT before and am still stuck on the current Telefunken combination. When I find them, whether they are 12AX7 or 6922, I will evaluate them and report back on this thread.

I have noted that some Audiogoners tend to compare tubes across various tube equipment and I think this is a mistake. I find that while one might be able to make certain generalizations about a certain brand of tube, no matter in what piece of equipment it is used, generalizations that any tube is perfect, great or even good in nearly all equipment are a grave mistake. Characteristics which make a particular tube sound so right in one application are often completely absent when that tube is placed in another product. An example of this would be the Telefunken 6922: Rich, dynamic, with a very ripe midrange, great extension at both extremes in a CAT Ultimate, but undynamic, slightly bright and boring in the First Sound. The same could be said of a Siemens 7308: in the CAT, too forward in the midrange, a little thin-sounding and undynamic; in the F.S., exceptional dynamics, great imaging and midrange smoothes out. You really do have to compare tubes in the particular circuit in which they will be used. If you get too hung-up that a particular tube is great or terrible based on some previous experience in another piece of equipment, you may never hear your tube equipment to its best advantage. I have been surprised by this phenomenon several times.