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I have a conrad-johnson PV-12 preamp. I love the sound of it, with one exception -- tube whistling, noise, microphonics. I'm currently using relatively new Ei (Yugoslavian) 12au7's. I've tried everything from putting new tubes in (Ei only though) to putting cones under the pre-amp. Pretty quiet for ten or fifteen minutes, then I can hear the whistle from one channel or the other from 12 feet away.I would like to solve this problem, but am not sure what to do. I could try new tubes (suggestions?) or a Variac to reduce the voltage in my home from 121.5 to around 116 (someone mentioned that this might help).
Or, I could sell the PV-12 and buy another, quieter tube pre-amp. Suggestions and opinions on the Audible Illusions 3A, CAT Ultimate, or others are appreciated. Thanks.
John
Have you heard the Lamm LL2? This preamp will easily best anything this side of 10k. Strangely so few people have heard this preamp. Its one of the most musical, neutral and detailed preaplifiers ever made.Lamm's reputation speaks for itself when it comes to quality.
rgds, david k.
I have the CJ PV12, and it was noisy at first too. But I changed the stock tubes with the Radiotechnique 12AU7 (bought them for $40/ea) from Kevin @ audioupscale)and it now sounds awsome and quiet too.
I've had a Modulus 3A, moved to a BAT VK-5i, then to a BAT VK-50, back to a 5i and, finally, I think, back to the Modulus 3A. All were dead quiet, even though 6922s are supposed to be pretty microphonic themselves. The 5i has a very seductive midrange--vocals are very bloomy--and the overall sound is, to paraphrase Debby Harry, "cold as ice cream but still as sweet". The Mod 3A has a slightly richer midrange, with a bit less air and sparkle on top than the 5i, and no remote, but it's got a built-in phono stage. The volume controls can drive you out of your mind--the gradations between settings are huge and it always seems to be a bit softer or louder than you'd really like, but hell, it's half the price of the BAT and uses fewer tubes, so you can play with new old stock like Amperex and Tungsram and try to tailor the sound. It even has internal switches to shut down the capacitors in the signal path for a "purer" sound, and various combinations of inputs and outputs that allow you to shape the sound even more. I've kept both the BATs and the Mod 3A on a rack on the front wall between the speakers, and even in this absolutely horrible, vibration-ridden location I've never heard a peep out of any of those preamps.
...but if they are anything like the Ei 12AX7's they are some of the noisiest most microphonic preamp tubes you can get! ( FWIW I still like the Ei 12AX7's in my Fender guitar amps though ).
My PV12 was also noisy. Tried different tubes but never did resolve the problem. I'm now using a BAT - it's dead quiet and I like the sound a lot better to boot.
The problem's not the preamp; it's those ei's. Try some nos 12au7s/5814s/6189s. There are plenty of inexpensive, decent sounding 12au7's out there. Anything will be better than those ei's.-neil
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