CAT JL-2 amp upgrade

I just purchased the CAT JL2 and am also trying to determine from people who have had the upgrade to Sig to describe the improvements and quantify the improvements (obvious improvement, subtle improvement, etc.). The person I purchased the amp from (a dealer) said that he has the new Sig but doesn't hear much improvement so far.
The Sig isn't really broken in yet but he will let me know when it is. My thoughts on the JL2 versus the Manley 350 monos I was using are as follows. The Manleys have a much fuller (sweeter, richer) sound across the spectrum (I prefer this), the JL2 sounds lean in comparison. Where the JL2 betters the Manley is in detail, transparency and coherence at high SPL's especially with large ensemble bands. I think where the JL2 gets this tendency toward detail and accuracy is from the output tubes (6550's). VTL used to use these in their old 300 monos and when they switched to KT90's the sound became decidedly more musical.
I did almost immediately get rid of the sovtek 6922 input tubes in favor of Amperex SQ 6922 made in Holland (nice improvement). I also replaced the stock EI 12ax7's with Amperex 12ax7 D getter long plates also a nice improvement.
I have some Amperex 12au7's d getter long plates in transit. For my taste the Manley was a better match in terms of musicality but the CAT does everything else better. So I guess I will start down the path you have travelled John. Finding a preamp (to replace the CAT Ult MK2) with full textural qualities to mate with the CAT's somewhat analytical presentation. Johnny, if you got the MK2 upgrade for 1000,
you did well. Ken told me he is charging 3000 for that upgrade and is urging people to do the Sig upgrade for another 2000 which is much more comprehensive

I know what you mean regarding the Manley vs. CAT products. Both operate from totally different design philosophies. For the past year and a half I have owned the Manley steelhead phono stage and it is rich, full bodied, has nice tone and is very enjoyable to listen to. The cat Ultimate preamp is faster and more detailed than my manley but lacks size, substance and body which is my I sold my cat preamp and bought a Jadis JPS 2 (the linstage version of the Jadis JP80). Ken Stevens will insist when you talk to him his design is superior to others but this is true with most manufactures and the reality is all designs are imperfect. When I go to live concerts I hear the excellent detail and great bottom end extension of the Cat. When listening to live music I also hear the rich full body sound of the Manley and Jadis products which add size, substance and rich tonality to the music, something sorely lacking the Cat preamp.

The Cat JL2 amp has the common Ken Stevens design signature that the preamp has and yes it is not as rich or full bodied as other amps but I will accept this one weakness for the many strengths this amplifier has. I prefer the Jadis line stage and Cat JL2 combo where Ken prefers the JL2 and Ultimate mix. Going from the JL2 Mk I to the JL2 MK II was a nice upgrade Ken did for me while my amp was in the shop for some repairs and for 1k the price was well worth it because of the reduction in noise and greater transparency. The Jl2 went from a numeric rating of 9.1 to 9.4, very noticeable and positive but not huge as the basic character is the same. When talking to Ken Stevens about the JL2 Signature $5,000 upgrade he said the improvement would be about the same as going from Mk I to Mk II, what I did in late 2004 with my JL2. The biggest improvement in the JL2 Signature over the standard JL 2 is the addition of black gate caps in the power supply. He told me the other circuit board design changes were very minor sonically and was done mainly to improve reliability. If I had to guess based my past experience the signature upgrade would take this already excellent amplifier to a 9.7 but at 5k the improvement becomes quite costly and there are a lot of other ways to spend 5k including buying more records, upgrading your preamp or upgrading a turntable all of which I suspect will provide more of bang for the buck improvement for the money. Yes black gate caps nice to have if you have the money to spend but not a necessity, the JL2 is already so good in many ways.

There are three things you can do yourself to really improve the performance of the Cat JL2 for very little money, about $200.

1) Remove and replace the cheap tin male IEC connector in the JL2 with a pure copper or bronze furutech IEC. This made a bigger improvement than I expected giving cleaner power to the power supply resulting in greater energy and more drive.

2) Remove and replace the two poor quality Cardas brass female rca’s on the side of the amp with Vampire pure copper rca’s. You will notice cleaner and clearer sound and improved bass that is fuller without the bloatness of brass.

3) Remove and replace the two brass cardas speaker binding posts with copper. Eichman cable pods or a good pure copper posting will yield positive results similar to the rca’s mentioned above.

If you want even more performance from your JL2 bypass the internal 20 amp fuse and fuse holder located next to the IEC and expect another 3-5% improvement in sound. All these just take a little time, very little money and a good soldering iron.

Johnny

Thanks Johnny for the report here. Your evaluations of the CAT preamps and amps to the competition very much mirrors my reports elsewhere on A'gon. These amps are very special indeed.

Your suggested DIY updates sound interesting but I would be weary of bypassing the fuse. These amps pull a lot of current from the wall and any little problem I would prefer to have protected by a fuse. Perhaps a "safe and sane" compromise would be to replace the fuse with one of the "audiophile grade" fuses? If it fails, it ends up costing you $20 or $30 vs. a major amp disaster .... or your house burning down.

John

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I talked to Ken Stevens before bypassing my fuse and fuse holder and since I already have a 20 amp circuit breaker at my main fuse box we both agreed it should be fine. The 20 amp fuse was designed in for warranty reasons but in the 8+ production years for the cat amps he is aware of no problems with any potential power surges or damage that resulted. Ken indicated in a previous conversation that the JL2 is "self contained" meaning all major parts and assemblies are enclosed in a seperate retangualr steel case. The input transformer, output transformer and all wiring is enclosed with thick gauge steel greatly reducing any risk. In the rare event a fire does occur in one of these steel enclosures, none has occured yet, the damage would be limited to that specific area.

Johnny

Enjoy

Johnny

Johnny, thanks for the info. Has anyone experimented with tube rolling the output tubes in their CAT amps? Ken told me I was asking for trouble and I would end up blowing up the amp. I ordered the SED Svetlana 6550C tubes today from Upscale Audio. Kevin from Upsacle gave me a similar warning as Ken's about fooling with 6550 variants (KT90's, KT88's etc.)in CAT amps. I have got to say as I am listening to the CAT JL2 right now that the improvement from changing the 12AX7's and 6922's has made the amp much more musical and when my Amperex 12AU7's arrrive it should add more musicality to the presentation. I am very happy with the sound right now. My JL2 sounds very quiet, I don't feel the need to do the upgrade to improve performance in that area. My previous plan was to find a preamp to replace the CAT Ultimate MK2 to increase the musicality of the presentation but I am rethinking that option now. I may turn my attention to the digital front end instead.

Bart