Conrad Johnson PV-10A mod experiences?

Have continued to work on this as the board layout is easy to work with. Since last post I have taken out the 2uf Solens SE capacitors in the phono and pre sections because of "edginess" and replaced them with REL Theta's. In the phono section I have substituted Rel RT 0.1uf values (the original 0.15's have few quality manufacturer options). In the pre section I have swappped out a 13.5 Solens to 2x6.8uf Mundorf supremes, a 4.0uf Solens for a 3.9uf Mundorf Supreme, the power supply pair 20uf Solens for 20 uf Clarity TC series and replaced a 4700uf Electolytic
with a Mundorf MLGO.

Overall very pleased, none of the CJ character has been lost, just rejuvenated with greater transparency and extension in the highs. I plan over the next 90 days to take two additional steps before calling this done (1) the power supply diodes are original (slow), will replace with HiperFRED's (2) the phono section was remarked as not the quietest in the original product review, age hasn't changed this. There are a number of bare wire runs in the phono section and I'm suspicious of how close some of the cap terminal wires are to the tube socket contacts, will report if I find any steps that reduce the phono section noise.

since last post I have actually made 3 changes. (1) in general I prefer to stay within manufacturer specs and I was curious about the Obbligatos so I've swapped in a 0.15uf Obbligatto to replace the Rel RT 0.1uf. So far its nice, sweet sounding, no negative consequences. More to come after I get some burn in time on it. (2) replaced the slow GI 854 8818 diodes (ttr =200) with Hexfred TXYS 15A 1200V soft recovery diodes (ttr=40). A very pleasant change eliminating what before I thought was "digital hardness" in recordings. However all is not completely well in Mudville as the hard percussive sounds (block bell) have lost some authority and I'm suspicous that other transient areas are damped. So will be swapping these out for "BY228TR, Vishay 3.0A 1500V" sinter glass diodes next when they arrive... these have an even lower Time To Recover (ttr)than the other 2 and no soft recovery characteristics. Mean time I can enjoy listening at an extreme end of tube sweetness.

Now for change 3 which was an unexpected positive surprise. After much fussing with various 12ax7's and replacing the bare wire board jumpers I was still no farther ahead with eliminating the phono section rushing noise that occured at about an 11 oclock position (my normal playing level). I decided to swap in 12AU7 instead. Big smile on my face as I turn the volume knob all the way up and not a rushing sound to be heard. Granted, my normal playing position has now changed to 1 oclock but sound is gloriously quiet, musical and all 12AU7's tried are quiet.

So more to post later once the new diodes arrive.

sorry, busy with other things. So since last time
1) in the phono bypass caps the 0.15uf obbligatos were nice, open sounding... however the cap casing is a hum magnet and microphonic. So yanked them out and threw in some Mundorf Supremes temporarily
2) the Vishay sinter glass diodes are great, fast. Believe I'm there for power supply clean up
3) seems the rushing noise finally cleared up completely in the phono section after I rechecked lead proximity and cleaned up solder joints.

I plan 1 last step, to add VCap teflons as the phono bypass caps at end of month. These do take about 60-90 to break in which would be about May to report back.

You might wish to try a JJ E83CC or better yet an E803s I think it is. Very low noise tube. Did you not change the gain by changing to a 12AU7? You may just need some good low noise resistors around that set of tubes rather than change to a 12AU7. Just a thought.

I actually talked to a very helpful gentlemen at a shop in Springfield that does repairs on audiophile gear. He advised strongly against replacing any resistors in the phono section as they were all there for precisely calibrated RIAA equalization. And since the noise went away after I did some circuit cleanup, all is well