Conrad Johnson PV11 tube noise

Mr C- Chances are good, that he has solved the problem by now(check the date previous to your post).

Sorry, previous link didn't seem to work. Search for "Conrad Johnson PV11 tube noise" in the forum search.

Thanks!! Keep it coming you guys.

It can be frustrating. Even with the best testing NOS tubes can go zingo. But I have about 1 in 10 Mullard CV4003 that we select that seem to be hanging together. Just for clarity....we have stock now and a process that works. While we have about every 12AU7 under the sun, and have always had them, there were two problems with that preamp. As I recall it has no feedback, which is why they do sound quite good. They also have a bit of gain. So when a tube starts to "burp" you will know it. Also some preamps that suffer from the tubes starting to ring need the tube sockets OR the transformer rubber mounted. I have suggested this to some folks that have doine it with good results. Transformers ring and over a period of hundreds or thousands of hours the micro-vibrations are picked up through the tube pins and the elements loosen up. It seems to be more evident in a few products using 12AU7's. As to eagerness...it depends on what I hear from a customer. Sometimes I will get a call like "I can't get tubes to last and they go goofy every couple months. I've gone through six pair this year...what's your warranty?" You can see how that may not be an attractive sale. The PV-10, 11, and 12 are fine preamps.

Gthirteen. I suggest you call Antique electronics or whoever your favorite supplier is, and order Amperex 7316 tubes to try in place of the 12AU7. The Amperex is lively, quiet and has excellent tonal balance. If you find it is not warm enough, then try the Telefunken 12AU7. Neither of these will do any harm to your CJ.

Thanks guys.

I have PV10al that I have had a proble with over the years and have sent it back to Conrad Johnson but it comes and goes and I have tried about 5 sets of tubes including theirs. Good luck!

Its not a tube thing.Some C-J can be picky.Try Tubeworld or vintage tube services if Upscale cant help.all 3 are pretty good sources.The Parts Connection are very good also.

I find the tubes conrad-johnson sells to be thin and wiry sounding. These are the east german rft types. Dick Olsher says these are head and shoulders above the rest. I disagree. I own a pv11 and have mullards that sound great. Also have had good results with the yugos but they are a little on the tuby side. Whenever I experience a high pitched microphonic tube I turn the preamp off and on and this usually takes care of the problem. I have a friend with a pv11 that really likes the telefunkens and they were sold to him by upscale audio so I dont know why they werent in a hurry to sell you anything perhaps get a more knowledgable person on the phone next time you call.

Sounds like you have a microphonic 12au7 linestage tube. I had the same problem in my pv11 a couple of years ago. I tried nos 12au7 tubes (tele,mullard,amperex) and found them pleasant sounding but lacking in "liveness" and a bit opaque when compared with the tubes supplied by c-j. I recommend sticking with them. They test and burn in their tubes, and, IMO, are quite reasonable in their pricing.