Sunday, February 11, 2007

Conrad Johnson Preamp Upgrades

Conrad Johnson has the unique distinction in my mind of making not just some of the best sounding preamplifiers ever, but also the most successful lines of preamps ever. In terms of sheer volume, the Conrad Johnson line is as ubiquitous Toyota Corolla or Honda Accord.

Let me explain. We can argue about the sound quality of the Conrad Johnson Premier line, and as to whether or not brand X is better than them or not. Some detractors make good points about them being overly euphonic at times, others feel the Audio Research line sounds best for their tastes. However, when you combine the history of Conrad Johnson Premier preamps being consistently rated in the top echelons of preamps, as well as the tremendous success the PV series has had, I don't think there's another company who can claim better success. There are so many past generations of Premier and PV preamps out there that CJ could stop making new products, and still continue to pay the bills for the next 20 years with the service department alone.

So, based on this, and my own personal experience doing extensive power supply mods for my preamp, I plan to offer these mods for most of the PV line. This includes at least the PV5, PV6, PV7, PV8, PV9 and PV10 and PV11. The upgrades will involve a custom designed power supply board based on the PV12's design with upgraded, high output, high reliability regulator stage, as well as the use of modern low noise, low impedance resistors and capacitors on the board.

In the same way that Conrad Johnson designed their gain stages to be modular, the circuit board I will be installing are also modular and can be used in different ways, depending on the customer's needs and tastes. For instance, with a single board you can upgrade a PV-10 to have dual mono power supplies. With two boards, I can offer dual mono as well as double regulation. The end result is an ultra quiet power supply, and an amazingly silent performance. Another way to use them is to add a separate regulator for the phono section alone. Owners of older PV series preamps would benefit by just substituting the new module for the original altogether.

This in combination with parts upgrades on the main board can lift the performance of most PV preamps to be giant killers for a small outlay in cash. Another benefit is that because you leave the audio circuit in tact, you keep the quality of sound that you fell in love with to begin with.

More on this later, as I have to dig out the board design I used originally, and have to figure out how to charge for it. Also, I need to figure out how to get reviews. I talked to Steve at Enjoy the Music, and he pointed out that reviewers don't like to do reviews for mods, because then they would get requests from every weekend modder in the planet, so before I get a review I'll have to get famous, and I can't get famous until I get a review.... :)

Fortunately while I don't have reviews I do have a PV-10 ready for audition which has 95% of the upgrades in place already. Missing are a few resistor upgrades and replacements of the heater caps. However, you would not believe this is a PV-10 if it were not for the sweet midrange and treble. The deep natural bass and precise sound stage will knock your socks off.

But alas, the trouble at the end of the day is really who will pay for the upgrades? Is it worth it for some one to take a PV-5 and put $400 into it, when they could buy a used PV-12 for $600 on Audiogon, or a used Premier class preamp for around $1500? I don't know. It was worth it for me because I could do the labor myself.

Perhaps I will be better off selling the populated, tested power supply modules for around $75 each. Comments? Suggestions?

6 comments:

  1. Hi

    Why not sell your kits via Ebay for DIYers to upgrade themself their CJ ?

    So you will get famous and then reviewed...

    ReplyDelete
  2. I actually did try selling these, it all got too complicated to explain to DIY'ers I'm afraid.

    Basically these are just CJ style voltage regulator boards. You can do all sorts of crazy things with them, like dual-mono power for the phono stages, or quad-mono power for a PV-10 or 12, etc. Just have to populate the boards with the right diodes, and then wire them into place, but most people got too confused, and I think probably want to play with the audio sections isntead.

    Nigel

    ReplyDelete
  3. I'd buy one.

    What a really need is a phono module for a PV12 line stage I just bought.

    ReplyDelete
  4. I'd buy one.

    What a really need is a phono module for a PV12 line stage I just bought.

    ReplyDelete
  5. Nigel,

    Would you still have some upgrade information on the CJ PV7? I bought one years back as a fixer and some of the "repairs" made to it by prior techs are a bit fugly.

    If you don't mind, could you contact me at liquid_audio@hotmail.com?

    Thanks!

    Erik

    ReplyDelete
  6. Let me see if I can find the original design files. I may post this as a kick-starter project. :)

    ReplyDelete