2. amps-preamps
  3. 1297052009

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
usblues
1,216 posts
 
Hi Davide256,breakin time perhaps?Cheers,B
orpheus10
5,988 posts
 
I used Black Gate caps when they were available to replace the lytics. Someone told me Jentsen work well. The tubes you're using are good. I'm sure the sound will tighten up if you replace the electrolytics. I use RCA NOS 12 au7 cleartop, mullards are probably better.
jeffreybehr's avatar
jeffreybehr
805 posts
 
WHICH MultiCaps???????????????????????? There are several versions.

The RTXs, 'styrenes, are VERY-good-sounding caps and do indeed require a hundred or 2 hours to break-in and sound their best. The metalized PPMFXs are entry-level-hi-end caps, ones I'd never use unless low cost were the primary goal, and then I still wouldn't use them, I'd use SoniCap gen.1s. I think the PPMFXs, if that's what you used, will sound a bit edgy forever.
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davide256's avatar
davide256 OP
362 posts
 
looks like its the usual with audio, fix 1 problem only to reveal another. I've known for a while that I need to send my Sota back for a new bearing but with the old caps the problem hadn't been "glaring". I've swapped in my backup AR ES turntable and the problem is gone albeit nowhere near as silky in sound as the Sota. As to caps used they are the RTX Multicaps. so will let this ride for 100 hrs or so of play and see what happens. I do have to admit the VCAPs (teflon/w tin foil)have my curiosity piqued, but that would run about $330 for the 4 required bypass caps vs the $50 for the Multicaps I paid.
orpheus10
5,988 posts
 
Those white capacitors you are referring to are teflon capacitors, they last indefinitely; it's the two electrolytic capacitors that need changing. Find the best capacitors of the same value and replace them
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