Peavey PVM T9000 tube mic: could use a bit of insight into a noise issue

[Braindancer]

I recently acquired a one-owner PVM T9000 mic, and I'm having difficulty with it. This is my first tube mic so I'm wondering if this might be a FAQ of sorts.

This was a one-owner unit, bought from the original owner's estate, and the mic was in regular use until about a year ago when the owner fell too ill to use it. I test-ran it today through my Tascam DP-24 and while the mic itself seems to be functioning properly, I've noticed two disturbing things.

Firstly, there's a fair bit of audible hum coming from the power supply...literally transformer hum like you might hear from an old refrigerator. It's not getting into the mic signal, but it's irritating.

Secondly, there is a LOT of background noise, and I mean A LOT, coming from the mic's output...it gates at about -28dB.

My first thought: dry cap(s) in the power supply? I honestly don't know much at all about tube circuits so I'd like a bit of expert input on this before I go under the hood.

My main weapon is a Studio Projects CS5, but if I can get this noise issue sorted, even if the transformer hum is a fact of life, this sounds like it could really be a jewel.

FWIW once I have this troubleshot, I'll have to sell the mic...I bought it to help bail out the previous owner's family and at the time I promised to try to get more for it than I paid. There was also an AMR VCL-2 compressor and a VMP-2 preamp unit in this package...just putting that out there since there seems to be some interest in these particular units.

 

[witzendoz]

The noise could be condensation on the diaphragm due to lack of use and bad storage, leave the mic in a warm environment for a day or so and see if it improves.

The transformer hum could be a loose transformer mount or loose laminations within the transformer, I have a power amp that does this but it's not loud enough to be a problem. Sometimes if the power supply is on a hard floor, sitting the power supply on a piece of foam will help.

Alan.

 

[Braindancer]

Thanks, Witz. I'll give that a try. It was also suggested to me that the tube itself might be worn out. It was a bit disconcerting to open the mic and discover that the supplied tube has no lettering on it! I downloaded the Peavey manual (thanks Peavey for posting scans of so many of your old manuals...saved my bacon more than once) and would you believe it...complete instructions for swapping out the tube, but no mention in the manual of which tube it used! It took a few keyword combination attempts to learn that SoS reviewed this mic some years back and was kind enough to mention that it's just yer basic ECC83/12AX7A. I guess Peavey assumed that anyone paying a grand for a mic wouldn't need to be told??