Conrad Johnson PV-10A mod experiences?


Has anyone had experience performing a mod on the CJ PV-10A? I'm fond of this preamp, it has that wonderful tube openness and sweetness for harmonics. However over the past 6 months as I've delved into PC audio and DAC improvements, I've come to realize two things about it

1) its slow on transients
2) its dynamically compressed.

I'm using Mullard NOS tubes throughout as these seem wonderfully detailed with excellent base.

Since the preamp is built like an engineering prototype (overbuilt)my gut hunch is that some caps have aged (circa 1993)and need replacement, specifically the white CJ caps
and am thinking about replacing them first with Multicaps.

Wondering if anyone has experience trying to revitalize a PV 10A?
128x128davide256
Just getting back to this thread after a while. The small white caps in the PV-10A were
definitely toast. As to being teflon, thats speculative. From the era the PV-10A was made in
they might have been Wonder caps or they could have been rebadged Rel caps
based on materials construction.
After break in the RTX Multicap replacements had solved much of the dynamic range issues but the high frequencies were still soggy (splat, not snap). Both the mains and phono section have a pair of 2uf capacitors in their output stage. I decided on the mains to replace those first with Solens polypropylene and tinfoil caps, 2uf / 400VDC, SE Series. These I installed last night and they immediately made a big difference in high frequency range
and crispness of percussion transients. Still not getting quite the low base response I can
get by going DAC direct to amp but above 40hz all appears right now. Will let this bake
another 30 days and update
David, if you're talking about the low frequencies of music, it's bass, not base.

:-)
.
Very happy so far with the Solen replacements in the pre main section. While the pre is not as fast as going DAC direct for transients, the preamp now comes quite close and cause more smiles :<). Played a few LP's last night, I can definitely hear some of the same blurring on the phono side from the old 2uf caps so will pull the trigger this week on ordering Solen replacements for those. I do notice that the phono section is noisier than one would like, one of the original review critiques of the PV10A, still scratching my head on what can be done to improve that.
Hi there,
You will find the cheapest Multicaps are far quicker and more resolving than the Solens. I would suggest you try these instead. Search on this site for Carey caps for others experiences. Good luck.
Hi Davide,
I would recommend the Bob Backert power supply mod for your PV10A. I have it in my PV12. I am now getting it put into my Art Audio 'Vinyl One' phono preamp. It's like getting a whole new amp. I believe the cost was $900.
I fully agree with your first 2 comments about the PV10A:
1) it's slow on transients
2) it's dynamically compressed.
With the Backert power supply, speed and dynamics will increase very noticeably. The compression will mostly vanish. When I heard my "new" PV12 for the first time, I went nuts. Bass punch was incredible, way better than any preamp I've ever heard, tubed or solid state.

I have no financial interest in Mr. Backert's mods business. I am, however, going to team up with Mr. Backert and try to get audio companies interested in using his power supply. So, even though I won't benefit directly if you get this mod done, if you publicize your opinion of the results, I could benefit *OR* I could suffer, depending on what your publicized opinion is. Everybody I know who has gotten it so far has loved it to death.
Mr. Backert's company, RHB SoundDezign, is at 215-355-0529.
-Hukkfinn