Convergent Audio JL2 Triod Amp MK II Upgrade

I agree the original (6) resistors on the JL2 have been a problem with some amps as I recently found out. The resistors fail rather than damage the very expensive input power transformer in the rear. Ken recently altered the design of the CAT JL2 to include (10) resistors which he believes will very greatly reduce the occurance of failure. Other than this one problem the amp the JL2 has preformed flawless for over 2 years.

JM

I also have same problem with my JL2, and am not very happy with the customer service at CAT. Returning phone calls or respond to email is not their forte.
Nkta

A issue at Convergent Audio is that Ken Stevens is the go to man for everything and he does not delegate so all authorization and communications must go thru him and as you mentioned he can be difficult to get a hold of. Sometimes I call back 3-4 times during the day to catch him at the workplace but when I do finally get him on the phone he will talk your head off for at least one hour. The conversations I have had over the years with him have been quite informative and interesting even if I only understood 1/3 of the technical information he was telling me. If your JL2 goes out for any reason Expect to be down at least 30 days, it takes several weeks to transport your amp back and fourth to the factory plus several weeks in the shop. Yes I wish there was better customer service with Convergent Audio regarding repair of there products but it is what it is and I don't expect that to change anytime soon.

The resistor problem with earlier JL2 amps will probably force most owners to ship the heavy beast back to the factory sometime in the first 3 years of the life of the amp for the repair and summer time is probably the best time to get the work done. The JL2 amp gets hot, is heavy, has allot of tubes (22) and hard to move so why do we go thru all of this? Because it sounds so good and at its price point or even much higher has no completion in my biased opinion. The taunt bottom end and beautiful clarity is something to behold on the Convergent JL2. Late at night after several hours of warm-up with all tubes glowing and the music flowing I ask myself is it worth all the extra work and the answer to me is Yes, Yes, Yes.

"Because it sounds so good and... has no completion in my biased opinion."

Are you saying it's not a complete amp? Did you buy it as a kit? To the best of my knowledge, CAT equipment is only available in complete form.

"The taunt bottom end..."

How did the bottom end taunt you? I've heard the JL2 and I think it's got about the best bass response of any amplifier I've ever heard, tube or solid state.

Sincerely,

Holton Corsey

Most manufacturers make no effort to protect their output transformers, but our transformers are considerable more expensive due to both size and exotic low loss core material and so we REALLY don't want to have to replace one. As a former equipment modifier, in my tweak years, I can attest that most old amplifiers have compromised output transformers due to sudden tube death. (A Dynaco ST70 with two good transformers is a very rare thing!)

But, that being said, I must admit that our six pack of metal film resistors have been overly protective (we could use one wirewound or power film instead but this hurts the sound and a fuse is even worse). We have upgraded this now to a ten pack of resistors and hopefully this solves the problem. If not we may consider just eliminating the protection altogether.

Ken Stevens
Convergent Audio Technology, Inc.