Conrad Johnson PV-12A - Remove Phono Board?


I have a CJ PV-12 Preamp that I would like to remove the phono board from and turn it into a completely separate phono-stage. Anyone know what exactly might be involved in performing such a project? I love the CJ's phono section but a friend wishes to purchase my PV-12 but does not need or want the phono section; rather just a linestage version.

I would love some technical knowledge and expertise here as I am fairly able to perform minor audio surgery but would love an instructional from anyone who might know how to do this :)

Well this would take some work. You would need to build another power supply to start. The power supply will have it's own sound so you would need to copy it. It's been years since I looked at a PV12 but if I remember right the transformer is tapped for the B+ and heaters?

So you would need another transformer, case and parts. You could get another power supply "different" but it would change the sound and character of your preamp. But if you have the skills for DIY give it a go.

If you really want to do this there are schematics available for the PV12. You could send me a couple of pictures and I would be happy to guide you a little.
Why are you selling the PV-12A? I love mine and can't wait until I can upgrade my TT to take full advantage of the great phone stage in it. I sold my Marsh hybrid preamp to get the CJ and I'm glad I did.
I would advise against this. You can purchase a better phono unit than the PV-12A's phono section very reasonably. And your PV-12A is worth more with the phono stage than without it.
To answer the specific question, it is very easy to remove the phono board if you choose to do so. The phono board is fully self-contained (with its own power supply regulators) and is held into place with screws fastening it to the main board. The electrical connections are made through a series of jumper wires from the main board to the phono board. It can be installed or removed in about a half an hour.

However, as Detredwings notes, to use the phono board alone, you would need to build a new power supply including a transformer and new chassis. That is a major undertaking and would require some experience with scratch builds.

I think you would be better served by selling your full function preamp and buying a used PV-12 line stage.
C-J does make a nearly identical stand alone phono unit called the EV-1, I believe. However, the coupling caps, at least the final output cap, is not polystyrene, and would have to be replaced to duplicate the performance of the PV-12 phono stage.
Thanks for all the great responses....

Gmuffley, would you happen to to know off hand the specs of what the new power supply to be built would have to be if I decided to undertake this scratch build? I would love to do this for a notch in my belt if you might be able to get a bit more detailed possibly...

By the way, I have a second PV-12A in my main listening room which I believe that you modified for T. Jenkins; who then sold it to me. It's a truly fantastic piece of gear!