Neumann U67 capsule - needs cleaning?
« on: October 01, 2008, 05:00:14 AM »
A friend of mine has an old Neumann U67 capsule. I hope someone here can tell if it needs cleaning or not. Both sides are little dusty but not much. One of the sides is bright and the other more matte. What does it mean? See the pictures below.

http://audioxxx.googlepages.com/U67_capsule_side_1.jpg

http://audioxxx.googlepages.com/U67_capsule_side_2.jpg


Neumann U67 capsule - needs cleaning?
« Reply #1 on: October 01, 2008, 06:04:34 AM »
No, don't clean these, that's very little dust and some spit and not a problem. I would go as far as saying don't clean unless you hear a real problem.

Martin

Gus

Neumann U67 capsule - needs cleaning?
« Reply #2 on: October 01, 2008, 10:17:27 AM »
Like Martin posted I would not clean then unless you have a problem.  They do not look that bad.   Cleaning old capsules can be problematic.  The gold often lifts very easily.

Neumann U67 capsule - needs cleaning?
« Reply #3 on: October 01, 2008, 11:18:50 AM »
Before you take any advice from anyone , make sure you get advise from someone who:

1. owns a U67
2. has experience cleaning it

Did you tell us what caused you to reveal the capsule in the first place ?

was it :
1. just dirty looking
2. does it make stange noises when powered while giving it a listening test

Does it have any discolored residue on it, caused by saliva, dust, cigarette smoke, especially on the dull matt side you described ?

In many cases if the capsule is cleaned properly but does'nt survive the process, the capsule was probably on the way out anyway.

Check the condition of the capsule membrane with a hand held maginfying glass to see if you can spot any surface defects in the caspule membrane, like pitting or gold flaking, lifting or any surface that is not smooth. Often , it takes a handheld maginfing glass to see the beginings
of capsule membrane deterioration. If all looks good then the capsule will
survive a cleaning assuming you have the experience to perform it. Its not terrribly hard, but you have to be extremely gentle. During the cleaning process, the water has to glide off the caspule membrane with absolute featherlike presence on the surface.

If you decide to clean it yourself, I have had good luck with a small lab style squirt bottle and distilled water. Very very gently allow the water to run off the capsule while it washes the small particles off. Afterwards, let it dry completely, and take note that if there is any pitting in the capsule membrane the distilled water may find its way into the capsule body. If there is any pitting you will be able to see it with a handheld maginfying glass. In fact the pitting, may be more visible after the distilled water wash. The best scenario is that your capsule membrane surface is smooth, with no surface defects. A dirty capsule when cleaned does sound better because the moving physics of the membrane material is effected by surface matter. Just depends how much surface matter is clinging to the membrane.

lastly , always store the mic with the head grille/basket covered with a clean plastic bag and rubberband to hold it on. This keeps the membrane from attracting dust particles when not in use.
curiousaudioparts at  gmail  dot  com
https://sites.google.com/site/diypartsstore/

Marik

Neumann U67 capsule - needs cleaning?
« Reply #4 on: October 01, 2008, 01:11:37 PM »
Quote from: "Gus"
Like Martin posted I would not clean then unless you have a problem.  They do not look that bad.   Cleaning old capsules can be problematic.  The gold often lifts very easily.


+ another one.

One should attempt to clean capsule ONLY if you can actually hear there is a problem.
Samar Audio & Microphone Design

www.samaraudiodesign.com

The Art of Ribbon Microphones

amorris

Neumann U67 capsule - needs cleaning?
« Reply #5 on: October 01, 2008, 01:17:59 PM »
Quote
get advise from someone who:

1. owns a U67
2. has experience cleaning it


+10!

a 67? get an mxl and practice. if you can clean the mxl (even though it is brand new) and you dont mess it up at all, then still talk to someone who has done a 67 first!

my favourite mic, dont mess one up!

I dont think the pics look bad at all. I wouldnt touch if for 10 or so years...

Neumann U67 capsule - needs cleaning?
« Reply #6 on: October 01, 2008, 01:50:01 PM »
Quote from: "maxwall"
Before you take any advice from anyone , make sure you get advise from someone who:

1. owns a U67
2. has experience cleaning it


I have two U67s and have cleaned them both, which fixed the problems they had. Do I pass as qualified to give advice?

:-)

Martin

Neumann U67 capsule - needs cleaning?
« Reply #7 on: October 01, 2008, 04:34:27 PM »
Martin ,
somehow , I sensed your authenticity already, but to keep this real it had to be said eventhough it was implied. :cool:

Although the pictures supplied don't really give the super detailed picture of the membrane surface and any particles clinging to it. I agree that the general surface condition in the photograph and the particles we can see do not seem to pose a threat , but this may be speculatory since its difficult to evaluate through a forum. A listening test is really the answer and even then the surface tension and movement of the membrane are sensitive to any particles or residues electrostatic or not. Just slicing hairs I guess but the discussion is no doubt interesting from the aspect of experience.

These are no doubt great mics which call for careful attention.
curiousaudioparts at  gmail  dot  com
https://sites.google.com/site/diypartsstore/

Neumann U67 capsule - needs cleaning?
« Reply #8 on: October 02, 2008, 09:43:35 AM »
Thanks for the information. My friend has only the capsule not the rest of the mic. So listening tests are not possible at the moment. But our plan is to DIY the electronics...

I am still wondering why one side is bright and other side matte. The matte side is not dirtier than the bright side, it is just matte. Anyone?

Neumann U67 capsule - needs cleaning?
« Reply #9 on: October 02, 2008, 01:42:46 PM »
Audiox,

Don't really have an answer for the matt finish, but speculating maybe that side was re-skinned at some point in its life. There is a picture below that might explain why. Its not a U67 capsule but one side is kaput due to the membrane being sucked into the backplate. Don't know if there's a easy fix for this problem since the membrane itself is still in good shape. Seems it lost its tension and the electrostatic charge pulled it in. Notice the surface is not smooth like it should be.

http://img.photobucket.com/albums/v611/maxwall/U87SuckedInMembrane.jpg

As far as the U67 pics go, here are some examples you can compare to. These U67 shots are from a perfectly working example. Thought this might be helpful.

Frontside
http://img.photobucket.com/albums/v611/maxwall/U67frontside.jpg

Backside
http://img.photobucket.com/albums/v611/maxwall/U67backside.jpg

As you can see the membrane is a little matt as well. Not a shining example like on other capsule membranes.
curiousaudioparts at  gmail  dot  com
https://sites.google.com/site/diypartsstore/


dale116dot7

Neumann U67 capsule - needs cleaning?
« Reply #10 on: October 02, 2008, 07:47:58 PM »
No, once the diaphragm lets go like that, you can't really retension it. The diaphragm is tensioned with the extra material, then the ring is tightened, the diaphragm is optionally glued to the ring, then the excess mylar is trimmed off. Once the excess is gone, there is no way to grab the diaphragm and tension it evenly. Any of the K67-style capsules require even and precise tensioning. Normally, the diaphragms are tensioned either with a tensioning jig or with a weighted ring. The weighted ring has a diameter of about 60mm which gives enough mylar to stretch a bit - that helps get the tension even.

Neumann U67 capsule - needs cleaning?
« Reply #11 on: October 04, 2008, 02:18:15 PM »
Dale,

thanks for your posting

What is then done with the old diaphram, I cant see throwing it in the trash it has a small recycle-able amount of gold on it , yes ?
curiousaudioparts at  gmail  dot  com
https://sites.google.com/site/diypartsstore/


 

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