CAT Ultimate

replace the 12AX7's with Amperex 12ax7 for the late 50's or early 60's. Also replace the (6) stock russian 6922 tubes with NOS, again I like Amperex US or Dutch made with white printing and the shield logo 6922 or 7308's. A huge improvement over the stock tubes. John

You cannot replace the stock 6922's with E188CC's in a CAT Ultimate. ECC88's (6DJ8's), E88CC's (6922's), or CCA's are OK. Do not use US 6DJ8's (like Sylvania or RCA, but not limited to these brands) or E188CC's or E288CC's. The manual clearly states which tubes can and cannot be used in the Ultimate. You will risk an expensive repair of your unit if you don't heed the warnings.

As far as which tubes I like in the CAT Ultimate, I like my 1960's Telefunkens, both for the positions that take 6DJ8/6922 and 12AX7. I have tried Amperex, Siemens, Mullard, Mazda, Tungsram and of course the stock Sovtek 6922's and the EI Yugo 12AX7's. Nothing for my money competes with the Telefunkens. I do agree with 42659 that the stock Sovtek tubes do not compete with any of the NOS brands mentioned above. However, the EI Yugo's are not bad even though the Telefunken's are better.

My experience agrees all the way with Rayhall, also Tele or Siemens for the phono section (if you have one).

Thanks guys, I really appreciate the helps, however my Mullard E188CC,shows 6922 as well, but not on the tubes, can it still be used? N also, wht power cords r u guys using, I ve heard the ESP Essence is a great match wiht Ultimate, ve u guys try before.Pls adv. thansk'

If the E188CC was OK to use in the CAT, it would be listed in the manual. It is definitely NOT the same as a 6922, even though it can be substituted for one in some circuits. If you use it, you take the risk of damaging the CAT. If you want to be sure, email Ken Stevens of CAT. His email address is in the Manufacturers Directory.

As far as the ESP Essence with the CAT, I have tried it. In my opinion, it made absolutely no difference as compared to using the stock power cord! I am not biased against aftermarket power cords and use one on my Pass amplifier, so I am doing my best to be objective here. In my opinion, you would be wasting time and money trying this power cord. Perhaps there are others which sound better and do offer sonic improvement but IMO, all the talk about synergy of the CAT with the ESP Essence is all hype.

If I had a CAT Ultimate I'd built two ladder stepped attenuators on Elma switches and put them in where the Volume and Balance controls are now, dual mono, and thus get rid of a mediocre series stepped attenuator that limits the performance of a lot of excellent circuitry. From simple comparisons in passive preamps, it's very clear to me that series stepped attenuators sound a lot worse than ladders. Why CAT uses them is a mystery to me. This upgrade would yield a more transparent, better-sounding preamp, IMHO.