To Teflon or not to teflon
 

thinking of t boning my new pr 12s with the teflon caps and go thru the expense and miserable break in period. Has anyone does this to an older cj amp. am worried it will bve richer/slower or ruin the magic. thanks to all ray

None of the above but you need a minimum of 300 hrs on the amps to make a judgement.

thank you

Teflon caps are generally the opposite.

Check out Vcap CuTF caps.

It will definitely improve the amps considerably. More detail, more transparency, larger stage and better focus. It will not bring the Pr12 to the level of current cj offerings. In their current amps they use better resistors and better power supply design as well.
With that said a Pr12 with Teflon caps and KT120 output tubes will sound exquisite.

I might be wrong (sure Lew will correct me otherwise) but I think that VCap makes cj's Teflon caps. Not a cheap date.

what is the sonic difference between 6550's and kt 120s??

I'm real glad I did the teflon upgrade on my Pr11a. Whether its a good deal for you or not depends on your goal. If you like the sound of your amp and plan on keeping it for a while, then the upgrade is well worth it. It manages to maintain the basic sound signature of the Premier line while increasing the speed, transparency and clarity by a noticeable margin. I think it will bring your Pr12 pretty close to the newer LP models.

Naturally, that’s going to some degree depend on the amplifier you’re using and the associated system. Your unmodified Premier 12s, I’m guessing, fall somewhere between bi-amped 11As and the Premier 140, maybe.

There are two main schools of thought here in this forum. And please guys, if I’m misstating anyone’s feelings, please jump in because I don’t want to put words in anyone’s mouth.

The majority view is that the KT120s combine the best characteristics of the 6550 with the KT88. They may not be more powerful when used in a circuit not designed for them, but they seem to be a little more dynamic and have better headroom. They present a strong bass line without bloat and are articulate in that presentation. Mids and treble are smooth without being rich or warm.

The minority view (caveat: I’m one of this group’s members) is that the KT120 is an excellent sounding output tube. However, when compared to a good 6550 (e.g., SED =C= 6550C or a Tung-Sol reissue 6550), the KT120s lack a little top-to-bottom coherence, may be a little bit on the rich side of neutral and don’t have the same degree of clarity in the upper midrange and lower treble.

I’ve listened to the KT120 in both an unmodified 11A and a 140. I’ve yet to listen to them in the 140 now that it’s had the Teflon caps put in.

That's not what I find with the ART; perhaps the tubes are revealing issues elsewhere in the system? (One thing is that you don't realize the ultimate in transparency with the cj gear unless everything in the chain uses teflon caps.) These tubes, when you really get your AC power line issues together, are stunningly transparent and neutral. The SEDs are way more colored and muddy.