Tube Preamps under $10k with deep bass extension

Rayhall, What is the input sensitivity of your Pass amps?

The CAT has low output impedance: 100 Ohms (and high gain). The Lamm LL2 also has a low OP imp: 250 Ohms (and medium gain).

Both of these pre-amps are know for their smooth, detailed, liquid, natural sonics. Agreed. But in some match-ups--in which plenty of other pre-amps do just fine, there appears to be too much output to mate properly with the power-amps. It's a matter of balancing the right levels of signal strength among the components.

I have come to the conclusion that the Cary SLAM-100 power amps don't do well with pre-amps whose OP impedance is lower than about 400 Ohms. Such pre-amps seem to "over drive" their .75 V inputs. I know that engineers will dismiss me as ignorant and scream at me that it does not make any difference. The lower the impedance, the better. I know, I know.

At least one other user (Musicluvr) reported a similarly aggressive sound from the CAT when mated to his Plinius amps. Another A-gon poster (different thread) surmised that the CAT would sound "in your face" solely based on the SLAM-100's input rating. He was right. I have never said that CAT pre-amps categorically sound bright and aggressive. I have always qualified my comment with the mis-match issue. Also, the CAT I heard in my system may not have been broken in all the way (dealer demo).

The Lamm LL2, too, is known for its organic, life-like sound. I hear only some of this when paired with the SLAM-100s. I also hear an electronic glare that is reminiscent of the CAT's sound. Another LL2 user said that it sounded aggressive when paired up with the Joule Electra VZN-80 amp. Interesting to note that the Lamm ML 1.1 pwr amps have an input sensitivity of 1.3.

Both the First Sound and Audible Illusions pre's have an OP impedance of 1300 Ohms. The Cary SLAM-100's love to work with these pre's. Does this mean that the CAT and the Lamm are aggressive across the board? No. I hope no one assumes that I assert that. A friend of mine who has heard the CAT in a couple of installations was instrumental in me auditioning one. He swore up and down that it was smooth, musical, warm, etc. I am sure the CAT and LL2 sound that way in those systems; they just don't sound that way in mine.

I can't fault the Cary pwr amps out of hand either because they sound truly glorious with other pre-amps--better than a stock, unbroken-in pair of ASL Hurricanes (HP's five-star amps) that I tried for a week with two different pre-amps! A pattern has emerged: The Carys can only mate with certain pre's. It's a quirk I have to put up with, or I will have to sell them off. Likewise, the LL2 is probably wonderful with the right amps--probably Lamm's own.

Kalan,

Your post is interesting since I was a Plinius SA-100 owner prior to owning the Pass. I had both amps (Pass and Plinius) for about 3-4 months. I LOVED the CAT/Plinius combo and it was a tough decision to sell the Plinius. In my opinion, those two had a terrific synergy. The only reason that I decided to keep the Pass rather than the Plinius even though the synergy wasn't as great was that I felt that the Pass was a better amp overall: greater bass extension and high frequency extension, better detail, more neutral. Plinius had a lot more slam in the bass and was a little brighter with the CAT than the Pass, but I wouldn't call it an "in your face" combo. At that time, I was using 90 db sensitivity Snell C/V loudspeakers as opposed to the 86 db sensitivity Vandersteen 3A Signatures which I use now. With the Snell's and the Plinius, use of the volume control on the CAT was frustrating due to the CAT's gain and, I guess, the Plinius high sensitivity, but when you set the volume correctly, you got a quite reasonably balanced system frequency-wise. In my opinion, the system wasn't forward or "in your face". It was more forward, however, than my current system, just not overly so.

Here are the vital stats on the Pass:
Pass Aleph 4

Gain: 26 db
(unbalanced)

Sensitivity: no rating

Input impedance: 10,000 ohms
(unbalanced)

I don't doubt what you hear, Kalan. It is surprising that such a sensitivity mismatch would affect one set of frequencies as opposed to others, since I interpret "in your face" to mean an overemphasized midrange.

Rayhall, Thanks for your info about the CAT/Plinius combo. Perhaps other factors are coming into play that I have no way of accounting for. For all I know, I have drawn an incorrect conclusion in my little theory. It would not be the first time that I labored under false assumptions.

As for "in your face" sound, I mean mainly an upper mid and higher frequency exaggeration, a forced presentation that gives me the impression that the signal is being slammed into the amps instead of just flowing. (I know that sounds really stupid and "new age.") The leading edges are fast and the effect is initially exciting, but the trailing elements of the first notes are clobbered by the attack of the subsequent notes. The natural arc of attack, further harmonic (and hall sound) propagation, decay, and trailing effects simply got lost in a hyper, super-charged onslaught of everything kind of stumbling over everything else.

The CAT I auditioned may not have broken in (advertised as "dealer demo") enough. How many hours would you estimate it takes for a CAT Ultimate to break in?

It is too bad the input sensitivity of the Pass amp was not given in its specs'. My pet theory hinges on this. You supply information that does not support my ideas because you say the CAT/Plinius combo worked (works) just fine. I am at a loss then....