Repair or mod CJ PV-12?



The transformer on my Conrad Johnson PV-12 bit the dust. I'm debating whether or not to send it to CJ for repair, or off to get mods and a new transformer. If the mods included a transformer upgrade, that would be a fantastic choice.

Some people here have had good luck with mods, could they provide who did them; from what I've heard they got fantastic results.

Any help you can provide will be greatly appreciated.
orpheus10
Ahhhh, neutral, whatever it means as if to say that it is somehow right. The best audio is not "neutral" it is what serves the music in a manner that engages the listener in the performance. If that doesn't happen then neutrality or, another nebulous term, accuracy may appeal to the brain of some that somehow think it "right" but not necessarily to the purpose of music and the end goal. I've given up on trying to reconcile the two, there is none. The only thing that matters is engagement which is less a function of brain but of emotional involvement. While the vintage CJ sound always had an innate "musicality" that is to say engagement factor, improved passive parts can exponentially improve performance and attain greater enjoyment without paying a premium to realize it. The same could be said of many "classic" designs.

I picked up this unit for a really good price and thought it had enough potential to improve on the things I REALLY liked without having to spend a premium for something new. It was a no brainer gamble that worked out quite nicely for me, especially when you are communicating with someone that understands the goals and brings them to your realization. Enjoy the music!


Tubegroover, I know exactly what you're talking about. I bought the original PV-10 that had apparent noise and distortion, but still sounded good. I sent it back to CJ where they made extensive changes to reduce both. I changed the electrolytic in the power supply to "Black Gate" to make it quiet as little mouse; so although it's changed, it's still the same.

Enjoy the music.
"...another nebulous term, accuracy...". Hmmm, interesting choice of words.
I modded my PV10A, would suggest the following based on evolution of my own changes

1) get the CJ replacement transformer, not a substitute
2) replace the big solens caps with Clarity MR caps where space allows these are nicely detailed for sound... Solens wont die with age but are dry/acerbic sounding. if you check your cap voltages, you will likely find that 300v dC rating is adequate in a replacement
3) if the unit has the small white CJ design bypass caps these are likely toast/dulling the highs because of age. replace with VCap like value
4) the stock power supply diode bridge has slow diodes, dulls transients. Replace with avalanche diodes for better transient response
5) add an IEC socket as your existing power cord is probably toast with corrosion inside its wrapper.

If you have the same blue corning resistors as the PV-10A, they are excellent, no reason to replace.
Ok, I have had some brew so have to chime in.

I owned the HK Citation 16 and bought it brand new. A CJ tube amp will destroy it any day of the week with any album, sacd, cassette, cd, or mp3 you want to compare it with.

Bill Thalman is the man and a very easy recommendation. How do I know? He modded a PV11 for me decades ago and did great work at a very fair price.

Expense, Yes, that hurts. How do I know? I sent a pair of CJ 12's from Alaska to the Backert Boys in PA for repair and mods. The shipping was very expensive both ways but the 12's have never sounded better. I just deal with it. Best on Earth, No, I have heard some SET's that just floor me, but the combo of power with the golden glow of old school CJ has me more than satisfied.

Go with Bill or Backert Boys and you will be well taken care of.

Conrad Johnson Rocks!