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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
unsound
7,333 posts
 
"...another nebulous term, accuracy...". Hmmm, interesting choice of words.
davide256's avatar
davide256
400 posts
 
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.
steelhead
318 posts
 
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!
orpheus10 OP
8,668 posts
 

The PV-10 has received more accolades than any single pre-amp that I can think of. Of course as you go up in number, they cost more and sound better; but the PV-10 is the one more people have bought and heard, round the globe. We love our CJ's with the old school Golden Glow.

Enjoy the music
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