Conrad Johnson PV10L Phono stage DIY

[ronenash]

Hi all,

I have a Conrad Johnson PV10L line level preamp which I enjoy. I am in the process of upgrading the capacitors to ClarityCap. When openning the chasis I noticed that the phono stage section of the preamp exists on the PCB and for the line level version of the amp they just did not put in the phono section part.

I am thinking of building the phono section myself and was wondering if anyone has done this before.

Also, can anyone comment on the quality of the phono stage in the PV10? Is it worth rebuilding it DIY? I am using MM cartridges only.

thanks
Ronen

[SY]

The topology is a sound one- when I was a starving student, I made a small living converting early C-Js to something almost exactly like that. I think that, within that topology, there are better ways of doing things, but if you start with their circuit, you'll have a good, solid base for further experimentation and upgrades.

A side note: don't fall in love with capacitor brand-name hype.

[ronenash]

I finally got to doing this project. Fortunately the PV10 PBC already has the wiring for the phono section. I purchased the parts and assembled the parts.
I took this opportunity to upgrade the signal path caps to clarity caps and Hoveland.

After 50 hours of break-in the preamp sounds amazing. Much more detailed than before and extremely quite. the phono section is dead quite which is a real ahievement for a tube amp.

I am using Ei tubes throughout.

Anyone owning the line level version of the PV10 and needing a phono stage should try this. email me if you need assistance.

Ronen

[rd_bumagat]

Hello Ronen/Guys,

What other things that needs to be upgraded since I own a PV10AL? My coupling caps consist of 3.9uF Mundorf Supreme in parallel with 0.1 Mundorf silver gold oil cap. I still need better high somewhat roll off on top? Appreciate your response.

Rey

[ronenash]

Hi Rey,

I am not sure what you mean by " somewhat roll off on top" but a few things to consider are:
1. Bypass capacitors for all capacitors in the power supply.
2. Better tubes
3. Change the resistors in the signal pass to Vishay high precision.

Also, you can replace the volume control to a stepped attenuator.

I no longer own the PV10 so I don't remember the details.

Ronen

[rd_bumagat]

Hello Ronen,

Thanks for the reply. How about using riken resisto rin the signal path? Can I use 0.1uf/600V as bypass? Thanks for the advise.

Regards,
Rey