Conrad Johnson PV10AL Tube & Polarity Questions?


I don't have the owners manual for mine but I thought I read somewhere that the CJ's invert polarity? Is this true because it sure sounds that way in my system. I also would like to experiment with changing some tubes around. I listen to Rock & Roll. I have a pair of Tylo Monitors, Mc Cormack DNA-1, Philips 963SA with DH labs cable. I have never swapped tubes & have no idea what should be in there or is what in there at the moment. Where do I begin?
fishwater
You can contact CJ for a copy of the manual, they will be more than happy to answer any questions. But if I remember correctly the PV-10A does invert polarity which means if you have an odd number of invertions you must reverse your speaker leads. If the unit is line stage only which is designated by the (L) it has no phono stage then there are only two tubes inside. You can acquire access to the tubes by removing the top cover. If you go to the CJ web site there should be information there as to what type of tube is in the unit. Hope this helps

Chuck
It has a pair of 12AU7 tubes and does invert polarity.

Begin by taking out the screws that hold down the top plate. Be sure the unit is unplugged before you do this. To remove a tube, gently rock it a few degrees back and forth while pulling up. Some will tell you to wear gloves to keep oils off the tube but I don't think it makes any difference. The pins are not symmetrical so the tube can go back in only one way. Line up the pins in the holes and gently rock back and forth a few degrees while pushing down.
Hi Fishwater,
I have a pv10al that I bought new I do not recall seeing in the manual that it inverts polarity. I also own a premier 11a and it had a seperate paper the size of the manual warning of polarity inversion as well as a note in the manual. I will check to see again, but I'm sure it does not invert. I listen to a lot of types of music but I do prefer music that drives and has punch lower down. A friend lent me a pair of Mullard 12au7 tubes and that started my quest to purchase a pair. They sound a lot warmer than the standard philips tubes and seem to push the lower mids up a bit. I think this helps rock for two reasons one being that most rock tends to be poorly recorded and over prossesed and can sound harsh at best. Theese tubes are killer. Pay the extra bucks and you will I'm sure never regret the $$. Let me know what you think if you do it.

ps I have my pv10al for sale and I have a pair of tubes that are not even broken in yet as well as 3 other pairs. I have listed them all together as one pakage so if you are interested I will sell them.

Tthat is a great little pre amp and I'm not sure replacing mine is the best idea but when I get my new one (premier 14) I guess I'll know.
My pv10al owner's manual did come with the seperate sheet of paper (red, I believe) warning of phase inversion. Your dna does not invert phase, so swap the neg. and pos. leads on your speakers. As always, let your ears be the final judge. As for tubes, I've tried Phillips, Mullard, Amperex, and GE. Even within a brand name, there are variations (military spec, etc.) Even in my modest system, I can hear tube-related differences much more clearly than, for example, swapping different cables. Right now I'm running Mullards, but we probably like different things. My advice would be to buy a bunch of cheapo, used tubes from ebay until you find a set you like--then buy the same tubes from a reputable NOS tube dealer. And do unplug your pre before messing around with tubes.
I did look in my pv10al box and low and behold there was the polarity warning, and shersta you are right it is red!
"ALL cj pre amps invert polarity. It's a given."

Wow--THAT's such a misstatement I'd considered it a lie.

Not all c-j preamps invert signal polarity. Those that have an odd number of gain stages do indeed invert polarity, as do all preamps (or poweramps, for that matter) of any brand that have an odd number of gain stages*.

John, generally, the easiest way to invert the signal polarity of your system is to reverse the speaker positive and negative leads at EITHER the amp(s) or the speakers but not at both locations.

*--a cathode follower is not a gain stage and does NOT invert signal polarity.
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While I am impressed with your knowledge, I insist ALL (atleast the dozen or so models I've USED) cj pre amps invert polarity. I HAVE OWNED THE PV-10 and assure / confirm / can bet it inverts!!
I agree the best way is to swap speaker cables. However, in a digital-only system, you can simply invert polarity at the CD player / DAC stage - if so equipped.
Enjoy !
M, during the last decade or so, c-j has simplified its preamp designs and now uses only one gain stage in the line stages of its preamps. Of course, with an odd number of gain stages, namely one, these do indeed invert signal polarity. I've owned 3 c-j preamps, 2 somewhat old (a PV5 and a Premier 3) and one newer one, a PV10AL without balance control. The first 2 have 4 gain stages (including the fono section), the latter just 1.

My strong language was due to your use of 100%-universal, all-encompassing language when it's simply not correct. For instance, your initial statement AND restatement are as incorrect as saying that all woman drivers are poor drivers. It simply isn't so.

This hobby is difficult enough for some of us without incorrect statements such as yours. Pls understand--I'm not trying to start an arguement here, I'm merely trying to assist in communicating clearly. Perhaps in the future you might say something like virtually all modern c-j preamps invert polarity.

But of course you may write anything you like, just as I can.
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:-)
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I am about to receive a CJ Premier 2 that is coming without a manual. Does it invert polarity?
I would email CJ and ask them and see if they can send you a manual. They have always been extremely helpful when I had dealings with them. A first class outfit when it comes to customer support.
Scott, I believe the Premier 2 has the same basic structure as the Premier 3, that being 2 gain stages each in the fono and line sections. That means that neither section inverts signal polarity.

But do follow Herman's advice and request a manual.
Well, I just checked the tech info at CJ's site and it explains that the early models did not invert phase. The Premier 7 was the first model to invert. Anything before this was phase correct.
Thanks for the support. Scott
Jeffery, I regret the "universal" statement. Perhaps it was somewhat overstated in excitment... You do however confirm that the PV10 inverts polarity - yes ? Good. (For sake of clear communication!)

For the future, I take note of your suggestion with my thanks.

By the way, my best friend's wife is an excellent driver !
M, absolutely the PV10 inverts signal polarity, since it has only 1 stage of gain in its line section.

Thx for the positive response.
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