Noisy, low output U87

[flaheu]

Hi,

I just got that U87 (P48-early 80's) which was very low output with a lot of noise, when you talk close to it it also cut off and come back a few seconds later. I have read all posts about it here, and after having tested the electronic which seems to work fine I came to the conclusion that the capsule should be cleaned. Apparently, that mic wasn't stored properly for years without any kind of protection.
The capsule looks fine, but I tried to clean the clear edge of both side of the capsule with a very fine soft brush.
To me it's not enough to bring it back to life. I'm reluctant to clean it with demineralized water, I have never done that before.

Looking for somebody to clean it for me, Possibly in EU ?

Any help appreciated.

Thanks in advance.

Regards

 

[sliebers]

You are smart to not attempt a cleaning with water.  Neumann capsules like the K-87 have a small pinhole in the diaphragm that equalize the inside air chamber to the outside atmospheric pressure.  Water can get inside the capsule and ruin it.

I don't have any contacts for cleaning a capsule in Europe.  Perhaps Thiersch, or Neumann themselves?

Good luck, I hope it's just a dirty capsule.

Scott

 

[flaheu]

Thanks Scott,

Ok, when I said in EU I meant possibly....
Do you provide such a service ?

Neumann is f....... expensive, maybe Tiersch, but if one guy from this group can do it for a reasonable fee, I prefer.

Thanks.

 

[Matador]

Send a PM to tskguy:  I bet he can re-skin it for you.

 

[anjing]

keep us informed i have a k-87 to reskin as well...

Regards,

Pierre

 

[RuudNL]

If you are in the Dutch speaking part of Belgium, this might be interesting for you.

 

[sliebers]

Thanks Scott,

Ok, when I said in EU I meant possibly....
Do you provide such a service ?

Neumann is f....... expensive, maybe Tiersch, but if one guy from this group can do it for a reasonable fee, I prefer.

Thanks.

I don't do anything with mic capsules other than send them off to guys who know how to fix them.  I'm sure tskguy can clean, or re-skin.  I've used Doug Walker, (Walker Microphones) in Canada for re-skins of 2 original CK-12's and 2 original K-87 capsules and they turned out great.  Doug is quite reasonable for prices as well.  I'm not sure if he cleans capsules?  It wouldn't hurt to ask him.
PM me if you want his e-mail.

Scott

 

[flaheu]

Thanks guys,

I have contacted Tiersch, and his price is reasonable.
I think I'm going to send him the capsule.

Regards

 

[tskguy]

Hey guys,

Yes I can re skin as well, I recently also had some Mylar coated 100% so I can do edge terminated capsules as well. Pm me and I can give you a price.

Eric

 

[Gus]

Are you sure it is the capsule?

Have you tried a cap sub for the capsule

 

[flaheu]

Hi Gus,

I'm pretty sure it's the capsule (but i'm not an expert), I have changed the "obvious" electrolitycs and I have injected signal to the Fet (without the capsule) and the preamp showed a healthy output. I have also looked for shorted/open Tantalum capacitor but they look ok.
What do you mean by a cap sub ? Like putting 2 +/- 50pF ceramic instead of the capsule ? ANd from there what to check ?

Thanks

 

[HellfireStudios]

Hi Gus,

I'm pretty sure it's the capsule (but i'm not an expert), I have changed the "obvious" electrolitycs and I have injected signal to the Fet (without the capsule) and the preamp showed a healthy output. I have also looked for shorted/open Tantalum capacitor but they look ok.
What do you mean by a cap sub ? Like putting 2 +/- 50pF ceramic instead of the capsule ? ANd from there what to check ?

Thanks

That is exactly right. I would look at the Neumann schematic, check the test points on the sheet, and compare them to your mic. You could also substitute a cheap chinese U-87 stule capsule and confirm the problem is/isn't the capsule.

-James-