Tube amp to drive MBL 101's

Yes I agree, I have met Ken and while he is a very nice guy and we did get along, he is, how should I put it, eccentric. He may also have a some what bias-no pun intendid :o) opinion

The development of the CAT JL1s was mainly done using the older MBL101B, which at 78db, is even lower efficiency than the current model. Not only is the 101 very inefficient, it also has an impedance curve which can only be described as highly unusual -- actually bizarre would be a better description. It is EXTREMELY difficult to drive.

One man in NYC had 500 watt tube amps on his MBL101Bs. The MBL designer, Jurgen, visited and told him that those amps did not have enough power. The next time they visited the man had switched to the CAT JL1s. Jurgen was adamant that the man had gotten the 100 watt power rating wrong. He thought that they must have a 1000 watt rating. So they called me to confirm the rating.

This same man wrote the first US review for the JL1 for FI magazine, based upon his evaluation on the MBL101B - and he bought the amps.

The JL3s are even more linear than the JL1. They have much more energy storage and twice as many tubes driving, basically, the same output transformer. Although I haven't heard the combination I have at least two customers who own it and swear by it. I will see if the US owner is interested in posting his reaction.

Playing brute force games with "more powerful" amplifiers will not work. Not only will these amplifiers not sound as powerful and strain free as the JL3 - they will not have the level of transparency and refinement that the MBL needs. This is, after all, the most transparent speaker in the world. Many times it gets blamed for a harsh grainy sound because it is revealing the grain in the preceding system. Recently I had a conversation with an audiophile who described it as "soft, polite and fudgy." Clearly his 750 watt tube amp was not up to driving the speaker.

Ken Stevens
President
Convergent Audio Technology, Inc.

I own a pair of 101E's and use the CAT JL-3s with them. The combination is very good and the JL-3's drive the speaker to reasonable volume in my 14x20 room with authority and finesse. The 101's still have some discontinuity between the MR and lower drivers however.
Its important to understand that I listen at average volume levels of about 85-90 db with peaks in the upper 90's. That is all my room can handle before the room itself becomes a major factor(yes I have treated the room acoustically, but remember the sepaker radiates 360 degrees).
the sound of the CAT amps is not typically tube; it has the subtle finess of SET's but is clear and fast with a very good low end (better than most solid states in having both bass defintion and nuance)It is an amp that blends the best attributes of both tube anbd solid state with out the drawbacks. Having had a pair of Wavac 833 monos as well as Atmas-phere mA-2's i can say that the JL-3's betters both of those amps by significant margins
If you are not trying to go over 95 db average SPL I can whole heartedly recommend the JL-3's (they may play louder but i can't vouch for their efficacy)on the 101 e's

... One more thing, which was not fully clear from my post.

It is only the truly great tube amps like the CAT's that have output transformers of such quality that they can really nail the conversion of tube voltage into current. I cannot speak for Mr. Stevens or Speakerdude, but I believe that this is what they are saying.

My salesman at a well-known NYC store was adament that the VTL 750's, which he sells, could not drive the big PipeDreams, and even more adament that the VAC 70/70 (65 watts/channel) could drive the big Pipes with ease.

If a tube amp doesn't have first-class power supplies and first-class output transformers, it won't drive current-hungry speakers, regardless of ostensible watts. I have VAC 140 monos on my Revel Salons in my main system, not an easy speaker to drive, and have powerful, clean, highly refined sound.

And I have heard the CAT JL1 limited editions on my best hi-fi friend's Salons. Extraordinary.

Hope this helps.