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CJ PV-12 mods & upgrades by Bob & Gary Backert

I recently shipped my 15 year old CJ PV-12 preamp to Bob & Gary Backert of RHB Sound Design to have a few modifications and upgrades installed on the CJ.

My very first conversation I had with Bob was very enlighten to say the least. I informed Bob, I would be using the CJ PV-12 preamp for my phono stage only with the VTL 7.5 preamp. To make a long story short Bob & Gary completed their modifications on the line stage, phono stage, caps, gold/silver wire, power supply & IEC conversion.

Father & son went further to build a custom head amp stage, to increase the gain so I would have the ability to use a Dynavector 0.3mV. The technical construction completed by Gary is flawless and his soldering skills are impeccable. Gary’s workmanship is actually beautiful to look at. This is one heck of a father and son team.

Bob suggested that I listen to the CJ’s line stage before strictly using it as my phone stage only. So agreed to listen and it was magical.

If I could only use one word to describe the performance of my CJ PV-12 with RHB Sound Dezign’s modifications that word would be “Heavenly.”

The bass the highs the lows the midrange the vocals the sound stage the imaging have all vastly improved and it’s so much more transparent, liquid. and dynamic.

For the record I have not listen to the VTL since I setup the CJ, simply because the CJ is blowing it away. I know some of you may find this hard to believe but if I didn’t hear it for myself I would not believe it. The CJ’s dynamic linearity is stellar in all aspects. Well I guess I’ll be boxing up the VTL getting it ready for RHB Sound Dezign modifications and upgrades.

The CJ will be performing constantly for the next week or so to allow the V-Caps, wiring and all modifications to break-in nice & smooth for my musical enjoyment.
Bob & Gary, keep up the great work you are truly the man.
jmo
phaelon
1,049 posts
 
Hi everyone,
I'm currently waiting to take delivery of vintage conrad johnson Premier V mono blocks to replace a cj Premier 11a. While I'm confident the gain in power will out way any deficiencies of an older cj design, I'm very interested in modification options that will improve speed, detail and performance at the frequency extremes without interfering with conrad johnsons house sound or unique virtues. In other words, I guess I'm looking for the Premier V that conrad johnson might make today. I'm particularly interested in an upgraded power supply and V-Caps, but I've been informed that V-Caps are hideously expensive. Any comments will be appreciated, except the most obvious one: At least wait until you hear the amps before you start talking about modifications idiot.
phaelon
1,049 posts
 
Good gravy! I really am an idiot - Of course I meant to write "outweigh" instead of "out way". Let this be a lesson to all you kids out there: Stay in school!
mrjstark
1,112 posts
 
My best advise would be to wait .......then listen....and listen some more. Roll tubes, play around with cables to tune CJ to your taste. Only then and only if.......there is area that you feel needs attention and no matter what you do - you can not achive that last refindment and magic , give Bob a call. I should also mention that Bob is very, very knowlodgable when it comes to CJ gear and no need to worry about lost of signature house sound characteristics.......just explain what are you looking for with this mod and let Bob do what he does best.......- puts smaile on his costumers face. If you decide to do it be prepare to spend some extra money for wiring upgrade with his silver/gold plated wire, I did not opt. for that upgrade but I keep hearing from others that it is a worthy move.

Enjoy your amps .......and call Bob for advise and recommendations.

Cheers

Mariusz
jmo OP
115 posts
 
Mrjstark,

The silver/gold wiring modification/upgrade is well worth it, that was one of the many upgrades I had Bob complete on the CJ PV-12. Phaelon, the V-Caps were another dollar well spent. I'll be sending Bob & Gary my amp for the following modifications..

1. IEC Upgrade
2. Power Supply
3. Gold/Silver Wire
4. (1) Internal 1/2 amp FB HiFi turning fuse I have already replaced the other (5) HiFi tuning fuse.
jmo OP
115 posts
 
Father & son have done it again, modifying a very good amp and transforming it into a totally awesome killer amp that will rival the so called best. I recently had the following modifactions/upgrades completed on my 16 year old CJ Motif MS 2001 amp by Bob & Gary Backert.

IEC with silver wire to PCB
Two new Vampire input jacks
Gold/silver wire from input jacks to PCB w/shielding
Dual power supply mod’s
Gold HiFi tuning fuse

The Motif MS 2001 was CJ’s intro to Solid State. CJ cut no corners with the components they used to build this amp and put together one hell of an amp. The Backert’s have made it better in every way possible. Upon completion of the break-in period I will give you a full report.

I can tell you this I have put my Ayre mono blocks on hold...
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