CAT JL-3 mono amplifier

Category: Preamps

CAT JL-3 mono amplifiers

Context: amp were purchased to evaluate against my resident amps: Wavac 833 SET monos. The balance of the system is as follows: Digital – CEC TL-0 mkII, modified Meitner Bidat Dac. Analog – Vyger Indian Signature tt with Dynavector Karat 17D2 and Ikeda EMPL cartridges. Micro Seiki SX 8000 tt, Schroeder Refernce arm with ZYX 1000 Airy 2 cartridge, ELP laser tt.. Cables – Silversmith Palladium ic and speaker cables. Amps – Wavac 833A mono’s. Speakers – stacked Quad 57’s rebuilt by Wayne Piquet. Primary music preferences are singer/song writer, symphony and vintage rock.

Like the CAT SL-1 preamp the JL-3’s are built with a high level of attention paid to sonics. Various dampening materials are employed internally to keep internal resonance’s to a minimum. The chassis is quite sturdy and weighs in at a hefty 170 lbs each (!). One clue that CAT designer Ken Stevens takes performance seriously is the built in bias and PP balance meter with attendant adjustment knobs. The user is instructed on how to maintain ideal PP balance and overall all bias of the twelve (per chassis) 6550 tubes. I have found this to be a minor headache to keep the bias set at the desired reading of 37 but the sonic rewards are worth it. If bias drifts too low (which it will do if not periodically inspected) the sound will take on more of a grainy texture and sound strained. If the bias drifts too high you risk buring up the tubes at an accelerated rate.
When properly biased the sound is extraordinary, as will be described shortly. The amps are a little unusual in that they have RCA inputs on the sides instead of back (mirror imaged on each chassis, thus Ken S is sympathetic to the logistics of having such large amps and how to route cabling). They also have dual speaker cable posts on both lateral sides of the amps (as opposed to the rear of the chassis). This helps in the case where one is bi-wiring. Make no mistake: these are big, heavy amps. You do not want to move them any more than is necessary. You either need to be a serious body builder or have two people to move them around! They seem extraordinarly hefty for an amp that is only rated at about 150 wpc.

For over two years my reference amps have been the Wavac HE-833 monos, replacing my previous reference Atmasphere MA2 (mk II). These are unique 100 wpc SET amps which have never failed to please when driving a variety of ESL speakers. They beat the MA2s in every area, except for the low bass, bringing greater transparency, dynamics and musicality into my system. But most importantly they bring the prized ‘SET sound’to the real world of less efficient speakers. I was honestly pretty skeptical that any amp was going to displace the 833’s in my system. I was completely hooked on the “magic” of SET sound and assumed that no non-SET amp could ever diplace my beloved Wavacs no matter what other virtues it may have. Upon swapping in the JL-3’s and listening to them I was somewhat stunned. My two overwhelming impressions were: the JL-3s had significantly lower distortion while increasing transparency and that the JL-3’s were in another (higher)category for bass reproduction. Yet, and heres the clincher the JL-3’s retain all of the virtues of the classic SET sound.
It only took two songs to realize that the 833’s, as good as they are (and they are good), were about to go up for sale.

So what do they sound like? Nothing for the most part. They seem to just pass through what ever is being fed them in a highly amplified state So what does that sound like? Relative to the standards set by the Wavac’s there are three characteristics that stand out on the JL-3’s:
1.) The most surprising thing is that they have the same texture and subtlety of the SET designs. This is the first non-SET amp in my experience to do this. Vocals have all the soft and subtle detail that clue the listener in to idea that this is actually the way the music was recorded and not a facsimile thereof. They also have that SET ‘focus’ where instruments sound like they are hanging in a three dimensional space as opposed to a flat two dimensional presentation. Thius is not to say that other , non-SET amps lack depth, only that the individual instruments sound less like they exist on various twp dimensional flat planes and more like real 3-D instruments hangin in space. One comparative surprise was that the Wavacs sound distinctly ‘fuzzy’ in comparison to the JL-3. This was especially surprising considering how mush LESS fuzzy the Wavac sounds compared to the well respected Atmashere! Yes the Wavac is ‘warm’ and fuzzy, but still fuzzy all the same with a mild amount of distortion which is never noticeable unitl listening to the CAT’s. The Wavac’s sound like really good tubes amps while the JL-3’s sound more like real music.
2.) In my experience the JL-3’s set a new standard for transparency. The JL-3’s let you see right through to the back of the sound stage while preserving the integrity of all that’s going on up front and in between. Yet harmonic integrity and tonal balance is not ‘bleached’ out like it is on some solid state amps, or even most other tube amps. The ‘window’ into the music is crystal clear relative to all other amps I know of. The purity of the high frequincys and the resulting soundstage is almost like surround sound on some music; you feel as if the sound stage is starting to draw you in and try to wrap itself around you. You feel much more a part of an actual event rather than watching a recreation It is most involving.
3.) The bass of the JL-3 next most surprising feature of all: it is as solid and powerful as any solid state amp you would care to consider but with the nuance, intelligibility and texture that comes from a good tube amp. It is amazing. You really have to hear it. Bass is no longer just lurking under the main body of the music but now comes to life and provides a much cleaner and intelligible foundation to the music. The JL-3’s seem to take the best characteristics of solid state design and marry them with the best of tube design. Yet it is an all tube layout.
Ken Stevens is neither a tube nor solid state aficionado. He instead seeks to recreate the real musical experience. He finds that tubes do a better job at this than s state devices. There is a great deal of sonic similarity between his preamp and his amps. I would have to say that the amps are more of a revelation when compared to the competition. Indeed, when one considers that these amps combine the best of transistors and SET amps in one package, these amps don’t really have ANY competition. With these amps and appropriate surrounding equipment you can achieve startling life like sound given the proper recording.
I have long sought to obtain life-like sound. Real music is not warm and soft, its is not hard and strident. It is vibrant, resonant and vital. The JL-3’s allow you to hear the initial attack in proper proportion to the subsequent resonant fundamental and the resulting harmonics. Assuming a good front end, the ear instantly recognizes the sound as being more lifelike. There are some who may find the sound to lack warmth but when you sit up close to a symphony, where the microphones are located, you immediately sense the ‘bite’ of bow against cat gut or the vibrating reed amplified through the instrument body. This is what the microphone captures as well, not the euphonic, somewhat reverberant sound of mid-hall (unless it was recorded that way). Because they preserve the integrity of and balance between attack, fundamental and harmonic the JL-3’s will instantly reveal where in the hall the recording took place. They simply pass through more information in its original state than any other audio device I know of. Again I would say that as marvelous as the Wavac’s are that they sound like a good tube amp reproducing live music while the JL-3’s sound more like the mucic itself. They seem to lack any specific ‘sound’ or coloration except for what precedes them in the audio chain
To me, the JL-3’s are landmark piece of equipment. They combine what are commonly thought of as the top virtues of both solid state and tube amplification. An audio Nirvana. Yet the most attractive feature of all is how they enhance the listener’s involvement. By revealing more of the music and its structure they draw the listener in closer to the original performance. You hear deeper into the various cross sections of the recording and the listener is given new a new perspective through the revelation of previously obscured information. Once again you can rediscover all of your favorite music with new insight and pleasure.
Very good Review!....I own the JL-1 Monos and was this impressed when i first brought them home about two years ago....maybe its time for an upgrade?
I have owned a JL2 stereo amp for several years and its interesting that it is one part of my system I have no desire to try to change or upgrade. Convergent Audio's premier products are the amps (Stereo and Mono)and not the preamps although the CAT Ultimate is excellent but there is competion on the preamp level. The Convergent audio JL2 is the most transparent and resolving amp I have ever owned and I have no desire to try and change it.

I agree with the reviewer that the convergent amp produces the most like like sound I have heard. Sure other high dollar high end amps my be different but the strenghts of the JL2 and JL3 are many. It has great mid bass and slam impact on percusion and has a clear see through like mid range that is stunning.

As a side note tube rolling makes a nice and noticeable difference in the postive direction. Using good NOS tubes on both the amp and preamp is both educational and interesting with convergent products, I use Amperex and Raytheon tubes in my amp for best results. In a perfect world I wish that the (6) small input tubes on the JL2 amp were 6SN7's instead of 6922, 12AX7 and 12AU7 as is the case on the current design. Also a good powerchord improves the performance of the amp very noticeably and is worth the extra money with this product. Keep it up Ken Stevens.....
I'm glad to see Roy is enjoying his new amplifiers.
Just a few points to clarify the comments:
1. His WAVAC HE-833 was one of the originals built in 1996 and reflects numerous outdated design concepts that have not been in production for many years.
2. Since then, the "basic" 100w/ch monoblock has evolved technically (and musically, of course) with many significant upgrades.
3. In addition, the three new 150w/ch monoblock models reach an even higher level of circuit design, purity, power and refinement.

I hope this clarifies the comparison.
What power cords did you find worked best. I have a JL2 amp and wish to upgrade the stock cord.
Thanks, Steve