Mic Problem - U87

[Jonny Quest]

I picked up this old U87 circa 1970's and it sounds great but there is a problem:

After initial, fully functional use, the mic signal will intermittently fade off, then a period of no signal from the mic, then the mic will signal will fade back on. As one can imagine, this poses a problem for using the mic.

Is this a problem with the phantom power perhaps? I know there is some sort of battery inside the mic, but don't know what purpose that serves when phantom power is going to the mic. Any help or advice much appreciated.

Thanks,

Jonny

[C00kie]

Sounds like flakey wiring...

[living sounds]

Dirty capsule, after some use it gets moist and conductive where it shouldn't.

Ask the good (and very knowledgable) people at groupdiy.com for more information.

The safe way would be to have it cleaned professionally, those capsules are expensive and doing it yourself might destroy it (although they are not as frail as rumored).

[living sounds]

BTW - to my knowledge - there is no battery in a U87. There are caps and a transformer though, you might have mistaken them for a battery.

[freddemillio]

I agree with living sounds. The fact that it fades out and fades back in makes it seem like it is an issue with condensation on the capsule (rather than flakey wiring). It could be that it needs a cleaning, in which case this is best left to experts, but maybe just spending some time in a dessicator will do the trick. Another thought, and please excuse me if this is too obvious: if you are using it for vocals, make sure that the vocalist is not too close to the capsule or else spit or humidity from their breath will collect on the capsule. If this is the case then a pop-filter is a cheap solution.

[Danno]

Agreed. I've had mic's repaired for this problem. (and this symptom)