Replacement tube suggestions for Premier 12 monoblocks

jimbones

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Sep 1, 2018
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I just purchased preowned CJ Premier 12 monoblocks. They are nice and quiet however sound a bit rolled off and flat. The tubes are supposed to be very good (SED Winged C, GE JAN 5751 and RCA Clear Tops 6FQ7. Not sure of the age but previous owner appears very trustworthy and said he tested the tubes and they test good. Suggestions? Thanks in advance for your assistance.
 

Big Dog RJ

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Feb 2, 2012
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G'day Jim B,
Not sure why no one has bothered to reply... anyway, apologies for the lateness. Here goes;
Been using CJ gear since I was about 15, ran my own dealership network through Spore and Sth East Asian region since 98 to 2004, and CJ was our top marquee brand in tube gear, apart from the few others we also represented, VTL, ARC and Manley Labs.

The Premier 12's are outstanding amplifiers. They are quite old though and may require recapping, along with those nice upgraded metal foil resistors from Vishay. Teflon caps are the way to go, and with these two upgrades done withTeflons and Vishays, the Premier series gear operates at a higher level of refinement.

With small signal tubes (input and driver/phase inverter tubes), we just stuck with the original type required. However, with the output tubes, we changed over to KT120's from Tungsol. To me, they are the most accurate, well balanced and natural sounding, compared to the KT150 or KT170's, which not designed optimally for that power amp circuit, can sound over-blown and way off in terns of musicality. In terns of power, dynamics and so on, yes they do have a blast but nothing compared to a well designed KT120 push-pull based linear pentode design. Of course CJ's newest offerings, the ART150 and ART300's both use the KT150 Tungsols and they're well designed circuits utilising the KT150 output tube topology. CJ hasn't yet decided on the KT170, perhaps more testing is required... I don't know.

However, they've put out a brand new monoblock version called the ART108A's, which are 160w Class A, now that's what I call finesse! However, in this case they're not using either of the KT120, 150 or 170, rather they've gone old school, back to the popular KT88. Genalex Gold Lions reissue I think, and they should perform mighty fine. Need to get to an audition asap!

So, if you're considering output tubes once again for your Prem 12's, it would be either the original 6550C type or the new KT120's from Tungsol will work fine. Either tube will bring those Premier monoblocks to life, it's just a matter of personal preference when it comes to output tubes.

Hopefully you find something excellent. Cheers, and enjoy those fine tunes !
RJ
 

jimbones

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Thanks @Big Dog RJ. I will take my time before I make my purchase. Im leaning towards a 6550.
 

microstrip

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I just purchased preowned CJ Premier 12 monoblocks. They are nice and quiet however sound a bit rolled off and flat. The tubes are supposed to be very good (SED Winged C, GE JAN 5751 and RCA Clear Tops 6FQ7. Not sure of the age but previous owner appears very trustworthy and said he tested the tubes and they test good. Suggestions? Thanks in advance for your assistance.
Can I ask what is the preamplifier you are using with the cj premier 12? I have found that cj tube power amplifiers ask loudly for a cj preamplifier.
 

jimbones

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Sep 1, 2018
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@microstrip I use a Rogue RP7. I have NOS Philips Miniwatt in it. I have lots of other nos varieties to roll.
 

jimbones

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Just In. Jim McShane says Sovtek 6550WE would be a really good choice. I never even considered them so I will look them up.
 

tima

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I owned Premier 12s for several years. I like the JAN-6550A GE with which the amps were originally voiced.

The Sovtek 6550WE is okay. That is the tube Audio Research adopted once the SED 6550C went out of production. Fwiw, the JAN-6550A GE are available, though a tad pricey. The 6550WE will be the cheapest. My preference order would be GE, SED, WE. (I might include the Tungsol 6550 if they were not super expensive.)
 

Big Dog RJ

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Yes, agreed on that Tima. In fact, within that order: GE, SED (winged C) but here I would place the TungSol reissue 6550 and then perhaps the WE. However, as I mentioned before, this is a highly personal preference.

I very clearly remember just a few years back, whiles using the newer Classic 120se, fitted with KT120's, a tube change was required. Someone at CJ HQ highly recommended that I try out the Genalex GL KT88's, and so I ordered eight of these. Although they did sound pretty good, they didn't have that solid thump in the bass and that sense of overall balance in full freq spec, along with the virtual limitless dynamics and transient control of the KT120's. So, I managed to hand over the GGL's KT88's to a chap who adored these tubes, and now he's using them in his Classic 120se and is happy as!

CJ's latest and boldest approach to Class A topology in push-pull config, introduced as the ART108A monoblocks ($24grand each) apparently uses these GGL KT88's, also the exact same tubes used in their ART27A. So, as you can tell, output tube selection is definitely a personal signature sound choice.

I think Jim B prefers the 6550C's, although I wouldn't be surprised if he does like the WE version, and ends up with those in the Prem12's. Only he would be able to decide that. Would be interesting though to find out which ones he settles for...
Cheers,
RJ
 

jimbones

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I ended up buying the TS 6550 reissue before prices went bonkers. They sound close to the NOS SED Wing C. However I did not swap back and forth as I want to be kind to the tube sockets. Also they only have about 15-20 hours on them.
 

Big Dog RJ

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Nice one JB! Very smart idea as not to swap around... it definitely messes things up with the sockets. Sounds like you got a great combination there, sit back and enjoy those fine tunes!

Cheers, RJ
 

Marcus

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I just purchased preowned CJ Premier 12 monoblocks. They are nice and quiet however sound a bit rolled off and flat.
If you want more extension and dynamic contrasts, upgrading to CJD teflon caps, Vishay resistors and better diodes is mandatory. Also, no matter how good old tubes measure, replace them with brand new ones and hurry. In Europe prices of all tubes have gone up considerably…
 

Big Dog RJ

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Yes, that's a definite!

The only thing in upgrading to the SE version of CJ's amplifiers is that the parts aren't too cheap. It comes at a cost and these are top notch quality- Teflons, Vishays, plus further metal foil resistors can be done in a full layout. Exactly what I did with my monoblocks over a period of two year, plus a final adjustment / mod on the Class A bias operation, which now delivers 60w Class A and 140w Class AB. So, it can be done, the only question is, is it worthwhile to do such upgrades on vintage gear... only the owner can determine this. In my case it was fully worth it, simply because I'm not selling these amplifiers and looking to upgrade, at this level it's not necessary. Although CJ's newest ART108A's look mighty fine!!!

Woof! RJ
 

COF

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Sep 29, 2017
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If you want more extension and dynamic contrasts, upgrading to CJD teflon caps, Vishay resistors and better diodes is mandatory. Also, no matter how good old tubes measure, replace them with brand new ones and hurry. In Europe prices of all tubes have gone up considerably…

I'd be careful about expectations upgrading the Premier 12s to the Teflon caps. I've done so and while there are some sonic differences, "extension and dynamic contrasts" are not one of them in my experience. (In fact the non-T-Cap version sounds more open and dynamic IMO - the Teflon version sounds more relaxed and laid back).
 

jimbones

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I'd be careful about expectations upgrading the Premier 12s to the Teflon caps. I've done so and while there are some sonic differences, "extension and dynamic contrasts" are not one of them in my experience. (In fact the non-T-Cap version sounds more open and dynamic IMO - the Teflon version sounds more relaxed and laid back).
Thanks. I am not going to touch the caps unless there is a problem with them.
 

Big Dog RJ

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Yes, although this may be the case, what I've experienced is a sort of thin, laid back smooth sound that takes an awful long time to break in...
Most don't have the patience to allow appropriate time for these Teflons to fully break in, and once they do, the results may not be to everyone's liking.

Keeping this in mind, when I was contemplating about the C1 upgrade, I did a lot of auditions as possible, including home trials and derived a certain set of criteria towards an overall upgrade that will provide a custom sound, these points:
1. The set of Teflons for each monoblock (a total of 6 caps per amplifier).
2. The set of Vishays- 3 resisters per amplifier.
3. KT120's, which were already installed but further mods done on the bias.
4. Adding Mundorfs in other critical stages.
5. A redesign on the Class A bias operation to generate upto 60w Class A. Anything further 80w switches into Class AB going into 150w...

This last mod was very important in getting further bass control on the CLX's. I had experienced what SS Class A can do in terms of full grip and super fast tight LF detail they have on the CLX's bass panels. Ordinary tube amplifiers don't quite have this sort of grip & control on LF unless they were designed with the KT150 or KT170 topology. From these extensive auditions and finding the right service techie to do this final mod was a challenging task.

At the end it was fully worth it because now these amplifiers sound truly unique and have an extraordinary performance in dynamics, openness, clarity, definition and most of all the ability to control and drive the CLX's to their full potential. That was my goal and one that I achieved arriving at a special custom sound that I've not heard on any other ML's. If not for the CLX's, I don't think I would have done all these mods. Since I decided to keep these amplifiers and the CLX's as my final speakers, I believe it was worth every penny of hard earned dollars.

At the end if the day, you really have to know what you want, it's a highly personal preference!
Cheers, RJ
Oh! Enjoy those fine tunes!
 

COF

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Sep 29, 2017
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Yes I was commenting on my experience with the usual CJ Teflon Caps upgrade (and in this case also some other caps or resistors I believe).

They were done in 2009 so fully broken in. I think the Teflon CJ sounds gorgeous. But "better?" I'd say there's something to be said for the sound of both the regular version and the Teflon version. "Six of one, half a dozen of the other," as they say.

I'd also say neither of my CJs - original or Teflon version - sound flat. Especially the originals with the Winged C 6550s...very far from rolled off. They are super alive and vivid and punchy as hell!
 

Big Dog RJ

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Nice one Cof, sounds like you know what you're after and the type of sound that you prefer. Like I said it's a personal preference and one area that many really don't know what it is they're looking for... hence they keep going in circles.

I've used the 6550C's before on the Premier 11A and the Premier 8A's. Driving Apogee Diva's partnered with the original ART preamp, it was probably the best system going at the time on our tiny island. People who visited for get togethers and auditions in general wouldn't leave until after midnight! Had a similar visit the other week, one chap arrived at 2pm and didn't leave until 10pm. So, the system must be playing those fine tunes right, aftetall the music better be good!

BTW what speakers are you using now? Are your monoblocks driving them effortlessly as they ought to... CJ are designed on 4 Ohms so they drive with no issues. Connecting them to 8 or 16 Ohms is not required, I'm my opinion.

Cheers, RJ
 

COF

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Sep 29, 2017
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I'm driving Thiel CS2.7s and Joseph Audio Perspective speakers.

The 12s seem to have effortless power and punch with both speakers. They certainly didn't slack at all relative to the Bryston 4B3 solid state amp I had on hand for a month of comparisons.

Especially on the Thiels the sense of palpability, density and dynamics are among the best I've heard (in similar sized speakers).

Before that I had the larger Thiel 3.7s, Audio Physic (Virgo, Libra, Scorpios), Hales Transcendence 5s, Quad ESL 63, various others and even until recently I had the punishing-to-drive MBL 121 Omni Radialstrahlers. The CJs never seemed to break a sweat.

(My room is 13' x 15').
 

Big Dog RJ

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Ah! The Thiel's fantastic match indeed!

I clearly remember setting up CJ's Premier 12's for doctor, who had arrived from the UK on his summer break... had a nice beach house going in the coast, would spend about 6 months in Colombo and head back to the UK after winter. During his last trip, his UK dealer had persuaded him to buy 4 AudioLab monoblocks with the matching AL preamp, and a pair of Paradigm Studio 100's. He never quite got the sound he was after once he heard our own demos with CJ gear... So he finally got rid of all his AL amps and his Paradigm's and purchased the Prem12's from us. Then asked which speakers? After about a week we got back to him based on his room dimensions and listening tastes (mostly classical & Yanni, big orchestra stuff...) we recommended the big Thiels. Still to this day he has the very same system, he never looked back, only upgraded his CJ preamp from a PFR to an ET7S2, absolutely loves it!

Those Thiel's are legendary stuff, one of a kind and sadly no longer in production. I remember listening to some top line Revels driven with CJ's LP275M's, quite similar to the Thiels, very easily addictive. That's a very nice setup there Cof.

Enjoy those fine tunes! That deserves a mighty WOOF!!!
RJ

*forgot to mention which Thiel's we set up for him, they were the 7.2's
 
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justubes

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Aug 10, 2015
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My 12's really woke up with the Ei kt90's III and was the only type of output tube that made mine sound like a V12!

That was so long ago and rolled NOS Tungsol 6550, GECs KT88 which were beautiful in their own way.

With smaller floorstanders, the Kt90's were really spectacular!

Energy and power sounded like x2 the wattage which no other tube type could provide, extended, open and detailed.

The RCA cleartop are about the best 6CG7s.
 

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