Conrad Johnson Owners.com

Hello,

I'm new here.. I thought you fellow CJ lovers might shed some light on this for me..

I currently run a CJ PV10A and have been thinking about sending it in to Bill Thalmann to have it upgraded. I have an opportunity to purchase a PV5 for a cheap price... and was wondering what would be a better preamp to send in to get fixed up? I am also confused by the PV10's line stage reversing phase.. any insight on what the reason for that is? I noticed the PV5 has both Phono and line stage that are phase correct... is this better? It also has more tubes in the signal path.. Anyone out there have experience with both of these pre's?

Thanks in advance!!

'Modern'* c-j preamps have only one triode section in a line stage. Each triode gain stage reverses signal polarity*. I don't know with what piece c-j started using only a single triode in line stages, but I know that the PV5 uses 2 triode gain sections in each of its fono and line stages. Hence neither stage inverts signal polarity.

If I didn't need a fono stage, I'd have the '10 upgraded as it's a more-modern design, a newer unit more likely NOT to have its circuitboard 'baked', and it's MUCH-less complex and will be less expensive to upgrade.

Polarity inversion is easily offset, unless you have a complex system, by reversing both channels' speakercable leads at EITHER the poweramp or the speakers.


*...unless it's a grounded-grid type, which does not reverse signal polarity. AFAIK, c-j has never used grounded-grid topology.

Thanks! For the info! I think I'm going to send in the PV10 as I already own that so it will be the most cost effective!

Hi Joethekid72,
Welcome to the site, it's nice to have you. As for your questions:

Don't worry about phase inverting, just flip the positive/negative speaker cable on your speakers (or AMP side) and you just reversed phase. This does not have any positive or detrimental effects on the sound.

I would probably stick with the PV10 and get the upgrade vs getting a PV5. That's just my opinion however. If you need the phono stage on the PV10, then that complicates matters as you have to weight the costs of adding a phono preamp or getting the phono stage to the PV10.

Thanks Admin!
Mine is actually a PV10A with the phono.. i primarily use it for vinyl so.. I think I'm going to stick with it and get it upgraded! I love it but I think it could be freshened up! So glad this site exists!

Thanks!!

You'll have to be careful with the choice of phono cartridge if you went to the PV5. Early cj preamps didn't have a huge amount of noise free gain. You'll really need around 1 mV with those older units.

Thanks for all your responses!

I thought that maybe because the PV5 is non phase inverting that it might be more desirable? I switch from phono to line stage and don't bother switching the leads on my speaker cables and listen like that all the time... I honestly don't find the sound that off putting..

Responding to Myles Astor's comment:

Lower output pickups - usually moving coil types - will benefit from a well-designed transformer. Two effects here: noise free gain and closer-to-optimal impedance matching (which will affect frequency response somewhat).