Conrad Johnson PV11 tube noise

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.

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.

Thanks!! Keep it coming you guys.

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