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Conrad Johnson PV 12 Preamp
This little gem was released in the 90's and I still use it in my system. It comes in two versions, with and without the phone stage. The two versions are identical from the outside other than the back nameplate having PV-12 designation with an additional "L". Mine actually reads "PV12AL". In '97 they released an upgraded version where they changed the volume circuit as well as incorporating a new biasing circuit for the input amplifier of the line stage.
The unit itself has the classic simple and elegant design of CJ. Standard faceplate that comes in both the classic bright brushed metal as well as black (I have the black unit). There are four nobs in the front, no remote. Once again, simple but elegant. The inside of the unit as you can see below in the pictures is also very elegantly designed with a large open area for the phono stage version components. There are two tubes in the line stage version and an additional 4 in the phono stage version. Removal of the cover is rather easy with multiple top securing screws and I found tube replacement to be very easy.
I am not going to discuss the phono stage as my unit does not have this, but maybe some other readers could comment on it.... As for the unit in general it's a phase inverting no frills item. But then again, CJ is not about "bells and whistles", it's about sound quality. The PV12 gives a warm neutral sound. It doesn't "flavor" the sound in any exaggerated way that I can tell. It does offer excellent dynamics and clarity. What can I say? "It just sounds right." If you find that this is not the case, check your tubes. I had one of the tubes go out and noticed it with a background noise. However, after replacing the tube, not only did the background noise go away, but the clarity and dynamics went through the roof! I have another posting about my interaction with CJ for diagnosing the problem and replacing the tube here. Oh, and you don't have to replace both tubes if one goes bad!
This is a great unit and you can pick one up used on audiogon or ebay for less than $1000. Highly recommended.
Cool! Heard good things about this...and with the latest Teflon capacitors, etc...i am told it gets even better!
It is interesting to trace the evolution of the PV series preamps.
The PV 5 had one regulator a series pass unit using an MJE 340 to feed the entire B+ chain. Later PV series preamps add additional stages of regulators again feeding the entire B+ chain. The PV 8 had one main regulator and two supplementary regulators , one for phono and one for the line stage. I believe with the PV-11, CJ attempted to make everything star grounded. The PCB was complex and very extensive, but curiously the 11 had more issues with noise in the phono section than others in the series (5,8, 11, 12). The the 12 returned to the grounding scheme whereby the phono section was grounded to the regulator that fed the phono B+. That cured any noise issues.
Of course the 8 had a line stage with a large gain, making that preamp capable of running low output moving coils, although for a CD player you rarely had to crack the volume past 8 o'clock.The later iterations used only a single 12AU7 in each output stage and lowered the gain significantly, although you couldn't run a low output MC anymore. Curiously the PV-10/10A could easily take medium-low output cartridge as long as the sensitivity of your amp was fairly high (.5mV output).
As a technical note the PV-11, IIRC, used the Holco resistors: little black buggers. They have a tendency to failure and their failure mode is that they start sizzling. Apparently although revered by many audiophiles the welding of the wire leads to the resistor body would often crack. They were used in the cathode circuit and the B+ circuit: typically the B+resisters are the ones which fail. It is difficult to predict which one and when they will fail, with some lasting many years with no trouble at all. If you do get a noisy 11, though and once you rule out the tubes, it will most likely be the Holcos. CJ later switches to the large Vishays, and use the little naked ones for their remote volume control (they look like like little piezo capacitors).
thank you for your technical input, I am not a strong specialist in electronic (having a little experience)but In reading the scheme of the CJ Pv series available I understand that the power supply change are the main issue...
For now, I am wondering what would be the sound improvement (or lost) in using teflon caps in the PV series...
thanks again for your topic
Ok, so this is beyond my knowledge base! I tried copying and pasting this into "google translate" but all I got back was "it just sounds right".
I have lived with the PV12 for about 10 years and am completely satisfied with the performance. I do find that tube rolling can have significant rewards in this preamp. Currently I am using a nice pair of Late 50's Bugle Boys 12ax7 in the Phono stage, I do also like A pair of Mullards and or Telefunkens there as well, but the BB's seem to have it all. The most critical is the line stage. It seems to be very unforgiving of the 12au7's and I have found the most reliable and overall best performer to be the RCA Cleatop 12au7. The best sounding (depth , tone, fullness, sound stage)has been the Amperex BB late 50's . One of my Amperex 12au7 developed and noise and I do not have any other to sub in at the moment. So I am back to the Cleartops and they are excellent. I tried two different pair of the much hyped Mullard military Box plate CV4003, graded NOS in original packaging and both times they were bloated sounding and microphonic. Actually one of the worst I thought, The original CJ 12au7 were the equal at least.
I understand there are a few different circuits for the PV12 so it may be different in yours. I also understand that the issue could be the grid resistor value used on the 12au7 stage and I may someday try a better value there. But the RCA's work so well I never bother.
I am using a CJ Premier 11a, with RCA 6550a , RCA 5751 and Tungsol 6cg7's. The RCA 6550a are a bit more muscular sounding than the stock Svetlana's . The Tungsols are pure gold though. I primarily listen to a DIY plinth/ Lenco l75/Jelco/lyra Helikon into a Pair of Peerless 4722 Trannys. Speakers are Merlin VSM w/BAM.
Thanks for the input. I am always looking for potential tube switches/upgrades. I have the line stage version of the pv-12 so I'm I will keep an eye out for some of your suggestions for the linestage components. I would really like to experiment with different tubes as one of my favorite things about tube based components vs solid state is that you can make subtle changes to the sound that are impossible with solid state components.
I recently installed a nice NOS pair of French "Radio Technique" 12au7's in the line stage. So far they are holding up well, not microphonic very quiet. I am still with holding judgement about the sonic qualities. I understand they are from the French Philips factory and similar to the Amperex bugle boy. They do appear to have the same construction. I do not think they have the same sound though. Never the less, they are enjoyable and I will leave them in hoping they break in and open up to sound more like the BB.
What's the verdict on the Radio Technique?
Is the balance knob super subtle on the PV-12? Each click of the dial is barely noticeable.
About two years ago I got a PV-12AL and EV-2000 from different sellers, and both units came with terrible tubes. The PV12 seller would later confess that he sold me the preamp with some tubes he found on ebay for a couple of bucks. It wasn't long before the balance knob could no longer swing far enough to correct the gain mismatch. So I made my very first tube purchases...
http://www.tubedepot.com/bsct-12au7-rca-ct.html (one pair for the preamp)
http://www.tubedepot.com/bsct-5751-janphilips.html (two pairs for the amp)
...and now having read billyz's posts I can see how lucky I was with the RCAs. I had no idea how much to attribute to the brand verses the cryo treatment, or simply because the tubes were new. It was instant world class sound.
Twice I tried to upgrade the PV-12 but I'm incapable of letting it go. A Premier 18LS came and went. An ET3 almost did the same but after a DAC upgrade I now feel the ET3 has it's own strengths with very high sample rate recordings. It's been a year and the two preamps are like a couple now so in all likely hood they'll grow old together.
With the PV-12 sounding so good, would I be vain to run it through the teflon/vishay upgrade? It seems as wrong as a beautiful women getting plastic surgery. Is there a chance my PV-12 will turn out like Michael Jackson's face?
To answer some of your questions: The balance knob is very subtle on the PV12 with only a small attenuation with each click and max of 4 db. Another user actually posted this same question which you can read here:
Tubes are super important. I actually had one of my tubes go bad in the PV12 and because it was a slow process took me awhile to figure out. I actually ordered a replacement tube from CJ and the improvement in sound quality was dramatic. I would stay away from cheap tubes, which you found out the hard way!
I don't have any personal experience with upgrading the PV12, if you do decide to do it, let us know how it turns out. I really like the sound of the PV12 but I always wonder what my equipment would sound like with that "next upgrade."
Wynn, the coupling caps that c-j uses in these preamps, including my MET1, large 'propylenes bypassed with small 'styrenes, are very good sounding caps, in that they do little wrong and lots right. But that combination is not as transparent and tonally neutral as only 'styrene caps and absolutely not as transparent and neutral as Teflon-film caps. I replaced the c-j combo-coupling caps in my MET1...
...with SoniCap Platinum (Teflon-film) caps and 2 pairs of powersupply caps with Platinum and Jupiter combos. Transparency increased so much that even this often-tin-eared audiofool could hear the difference. I replaced no resistors.
I imagine Jeffrey Glowacki's Sonic Craft... http://www.soniccraft.com/ ...could do that kind of work for less money than c-j, but either way, if you love the sounds of your preamp, you'll love it more with Teflon-film coupling and PS-bypass caps installed.
This parts-upgrade process has nothing to do with plastic surgery or Michael Jackson.
Tin-eared audiofool, large-scale-Classical-music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."
Thanks Jeffrey. I sent them a note asking for an estimate. I wonder what uses I could make of the replaced vintage caps. If I had a necklace made I probably could get my GF to wear it to the Chester Group audio show. Keychain. Cork screw handle. Tree ornaments.
It is good one for sure.. Thanks for sharing true review.. I am looking to get the system soon and hope prices have come down.
Last edited by WilsonBall on Sat Dec 28, 2013 1:05 pm, edited 1 time in total.
Wilson - there is a PV12L auction running right now that is ending Sunday @ 1am, and the price is around $300 right now. I can't remember if you need to be an audiogon member to bid on an auction.
http://app.audiogon.com/listings/solid- ... iers-18235
There are scratches on the lid, but you can flip the lid upside down and the opposite side should be spanking new. Keeping the lid's screws off makes tube rolling and messing with tube dampeners easy, but if you must screw the lid on upside down then you'll need to change the screws because the holes are bored out to conceal the tapered screws only on the outside.
Anyway I spent $1000 on my stock PV12L. I would recommend sniping this unit for between 500 and 700. That's about the minimum you'll want to spend on a decent 2ch DAC as well.
Most tubes that I bought online were not suitable for high quality audio circuits, expecially phono stages. I try to only buy tubes from Andy Bowman of Vintage Tube Services who actually has the knowledge, test equipment, and NOS tube supply to put you into some really good tubes. My C-J EV-1 phono stage soon had one of the factory original Yugo Ei 12AX7 tubes go noisy and microphonic. I replaced the entire tube set with VTS supplied tubes. Andy knows more than others which tubes will work best, and he can spot the fakes that are everywhere in the NOS marketplace these days.
Andy knows Conrad-Johnson amps and which tubes will work best in them. If forced to use new production tubes, he knows the few that are closest comparable to the quality that the famous western manufacturers once produced.
If they go bad or I am in the mood to experiment I probably will try Andy as you suggest. I would be interested in hearing what he recommends.
I have a PV-12A. Had it for more than 10 years. I feel, that at least right out of the box, it's one of the very best of PV series C-J preamps. Mine started as a PV-12 and I had it updated to an "A", and it was fitted with the phono stage from new. It's a pretty early one, dating back to '93. It has some interesting differences from the later PV-12s. The phono stage I feel is utterly outstanding. I've rolled just about everything ever made, and every combination of these, in every socket (I hate to admit I have thousands of tubes :/ ). The stock RFTs I feel are excellent, and a good go-to and benchmark. For different systems, rolling can really help get things just right. To help go from good to great. Tube rolling makes a HUGE difference with the PV-12, where it doesn't nearly as much in earlier PV designs. I attribute this the lower level of feedback used in the 12 compared with earlier preamps.
Mine finally failed. One of the voltage regulators feeding the linestage tubes? I tried to save some money and to learn something more about the PV-12 by looking at repairing it myself. I was very fortunate and appreciative to have the gracious and knowledgeable assistance of some folks. Finally, though, I've sent it Bill Thalmann at Music Technology to repair. Couldn't be in better hands than BIll's.
Sadly, I don't have room to set up a proper system so when I comes back I'm going to sell it.
Hello from France,
A great preamp you have and the phono stage is always an add value acknowleged with CJ preamp.
I own a PV8 for years as well and the only repear to be achieved has been a power supply regulator (to be change every 20years as usual
You are Lucky to stay at the US since Bill Thalmann is probably the best specialist of the vintage CJ gear in the world!
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