JoshT Posted May 6, 2002 Share Posted May 6, 2002 On Saturday I borrowed a Conrad Johnson PV14L from my local dealer for a home audition with the following HT system: Rega Planar 3 with Grado Silver Creek mm phono stage Sherwood Newcastle Processor Sony S7700 DVD player (using as CD Player as well as DVD player) Rotel five channel 100 wpc power amp Klipsch KLF20 front main speakers (with C-7 and S-6s for surround sound). My goal in auditioning the CJ preamp was to remove the Shewood Newcastle from the circuit for stereo playback with the turntable and CD player, in order to (A) get a pure analog signal from the turntable and CD Player to the power amp and ( to smooth out the highs and mids a bit for the Klipsch KLF20s. Mission accomplished, plus a whole lot more, but with a HUGE caveat: On the one hand, the sound quality of the system improved by leaps and bounds!! Without losing any detail, and in fact by increasing the detail, the system became wonderfully smooth, just as dynamic, and, for the first time, imaged really, really well. Even the bass sounded stronger and tighter at the same time. Not subtle changes. The Sherwood Newcastle clearly does not do justice to these speakers for music. But on the other hand, OH MY GOD, that CL PV14L was LOUD on the KLF20s. There was an audible hiss, from the tweeter and midrange horns, and you could even hear some crackling (like cooking bacon) if you listened closly. The hiss and crackle were not affected by volume, and the right channel was worse than the left. When I described this to the folks at the dealer, they said it was the unfortunate combination of high compression horns (which they HATE) and tubes (which frankly they don't like very much). I suggested that maybe it was a defect in this particular unit, and they said "no way." I find this very, very, very discouraging, because I really loved everything about that preamp except the hiss and crackle. It has the theater loop and a full function remote which is perfect for me. Am I doomed with these speakers not to be able to use tubes? Is the CJ a loud unit? Quote Link to comment Share on other sites More sharing options...
ShapeShifter Posted May 6, 2002 Share Posted May 6, 2002 JoshT, I'm using a Conrad-Johnson PV-14L Preamp with my speakers and have not experienced the conditions you described. There are several possibilities for this; could be tube microphonics. The original tubes in some units were reported as having ringing problems. Could be components prior to the preamp and the additional gain of the pre has intensified them. Could also be the actual amp. Removing all components and adding them one by one will aid in troubling shooting where the noise is being added. But I strongly suspect microphonic tubes? I have the components below connected to my CJ and the Cornwalls are very quiet. However, I replaced the stock 6C4's in my PV14L right after buying the unit. I installed Corvair NOS Black Plates by Westinghouse, which I like much better than the stock tubes. My original 6C4 tubes were also fitted with tube dampners, CJ added these to help with the tube ringing issue. Hope you can resolve the issue easily, it really is a very nice unit! Wes Laurel IIX Mono Blocks Conrad-Johnson PV-14L Preamp Conrad-Johnson EV-1 Phono Stage (Intransit) 71 ALK Cornwall II's (w/Laurels) Ah! Tjoeb 99 CD (Direct to Preamp) Music Hall MMF-7 (Intransit) Fisher 800B Tube Receiver (Outs to CJ Preamp) 84 Heresy's (w/Fisher 800B) Sony CDP-CA80ES Sony Cassette TC-K444esII Akiai GX-280D 4 Track Reel DAK Stereo Power Controller ------------------ "KLIPSCH IS MUSIC"f> This message has been edited by ShapeShifter on 05-06-2002 at 02:59 PM Quote Link to comment Share on other sites More sharing options...
JoshT Posted May 6, 2002 Author Share Posted May 6, 2002 Thanks Wes. I remember now that you own the PV14L. I really loved the sound other than the hiss/crackle. I suspect that something must be wrong with the unit. I did a little bit of unplugging and plugging with different components, and I'm pretty sure the problem was with the CJ, since the sound persisted. I suspect, regardless of what the dealer says, that the problem is in this particular unit, not inherent in the design. But here is my problem -- I feel like I'm gambling a bit if I get a PV14L from this dealer, because if the hiss persists with a different unit, then they will kill me if I return it. In fact, I could almost see them refusing to sell me one, fearing I'll just return it. I am hesitant to replace stock tubes, as I'm not a DIY-er. How complicated was the process? Quote Link to comment Share on other sites More sharing options...
edster00 Posted May 6, 2002 Share Posted May 6, 2002 JoshT, While I don't have the CJ-PV14L I do have a tube preamp and have auditioned several. I agree with Wes, that the "audible hiss, from the tweeter and midrange horns, and you could even hear some crackling (like cooking bacon)" that you heard is definately not normal. I'd bet there is something wrong with the tubes in the unit you listened to...may be as easy as re-seating them. As for "tube rolling" it is quite easy. You may have to remove the cover of the CJ (if the tubes are not exposed) and simply gently pull the old ones out and gently plug the new ones in. If you are buying from a dealer they will certainly show you how to do it. ------------------ 2 Channel System: '78 Khorns w/ALK networks Welborne Labs Moondog 2A3 amps AES AE-3 Superpreamp DJH mods McIntosh MCD 7007 CD McIntosh MR-78 Tuner DIYCable Twisted Cross Connect Speaker Cable DIYCable Superlatives (preamp/amp) DH Labs Silver Pulse interconnects (sources/preamp) f> s> Quote Link to comment Share on other sites More sharing options...
ShapeShifter Posted May 6, 2002 Share Posted May 6, 2002 Josh, Very easy to replace. Only two of them and they're the only tubes in the unit. I'm at work know, but I as best I can remember, their were 2-3 small screws on each side & 3-4 small screws on top of the cover. Lift the cover off and the tubes were visible, removed them with a gentle rocking motion. I removed the "O" ring like dampners and put them on the replacement tubes. Cover back on with screws and fired her up. Bulk of the time involved removing and replacing those small screws. Take care to not loose those little screws and you'll be OK. I'm confident that you could easily change them! Wes ------------------ "KLIPSCH IS MUSIC"f> Quote Link to comment Share on other sites More sharing options...
j-malotky Posted May 6, 2002 Share Posted May 6, 2002 Hi Years back when I lived in an apartment, I had a tube amp that had excess hum. Found out the apartment was wired wrong and my polarity was out of phase. It did not sound that way when I had a transistior amp plugged into the same outlet. JM Quote Link to comment Share on other sites More sharing options...
ShapeShifter Posted May 6, 2002 Share Posted May 6, 2002 Josh, Here's a pic of the EV-1 Phono Stage. It and the turntable were left by UPS this afternoon. Got home after 5PM and I've replaced the stock 12AX7's & 12AU7 with NOS Mullards, replaced the stock 5751 with an NOS RCA Command 5751 tube. Not much time required. Opening the Phono Stage and removing the tubes is the same procedure as the Line Stage. The Preamp has two less tubes. Both units have 3 screws front and back of of top covers, has 2 screws on each lower side of covers. Note those tiny screws I mentioned. Hope this helps. Wes ------------------ "KLIPSCH IS MUSIC"f> This message has been edited by ShapeShifter on 05-06-2002 at 05:08 PM Quote Link to comment Share on other sites More sharing options...
Jobman Posted May 6, 2002 Share Posted May 6, 2002 Josh: Last month, when I got my AMC tube preamp, I had the same problem. Lucky for me, Jazman helped me out and let me borrow 2 12AX7's and 2 12AU7's to see it that was the problem. Turns out that both of my 12Ax7's were causing the noise - crackling and popping. Changing those 2 eliminated the problem, and I have since replaced them with a pair of 1963 GE Longplates. (I changed the 12AU7's as well, just to be safe. Now, it is very quiet and a much richer, fuller sound, with a wider soundstage. (using my K-horns and Wright 2A3 monos) It just sounds like this dealer would not support you much if you do buy it and run into problems. Better to find a more sympathetic and realistic dealer, even if it is long distance. Mike Quote Link to comment Share on other sites More sharing options...
ShapeShifter Posted May 6, 2002 Share Posted May 6, 2002 Unfortunately, there are a lot of dealers who's sales personnel aren't very familiar with the products they sale. Others don't know or are unwilling to acknowledge that there are issues with noisy or ringing tubes in some units. None I visited stocked replacement tubes anyway. Most just stressed CJ's quality, reputation and excellent warranty record. I bought fully aware that there were potential problems with the stock tubes. But I knew Brendan at Tube World had NOS Corvair 's for $35 a pair. For me the cost was well worth it, because the replacements definitely offer better dynamics than those stock tubes. I'm very pleased with my PV-14L. Wes ------------------ "KLIPSCH IS MUSIC"f> Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.