Is this M7 capsule broken?

[Kingston]

I have here a Thiersch STW 7 PVC film (blue line) capsule. It seems the back side of the capsule has a scratch or something. I don't know what happened to it. I must have been careless installing it. It certainly didn't come like this from mr. Thiersch.

It sounds fine, or if it doesn't I haven't got the tools or ears to tell the difference. It doesn't seem like the film is skewed or bent either.

Please have a look at the image. I didn't clean the ordinary dust to show some reference with the scratch. (The smaller bright line next to the scratch was hair, by the way.)

Is it time for a re-skin?

 

[shabtek]

if it sounds good...
is it just the skin?
if there is a hole in the membrane I imagine damping will be changed
compare capacitance of the sides.

over the years pictures have been posted here of capsules that looked bad (filthy or flaking gold) but sounded good enough for regular use.

 

[RuudNL]

As long as it sounds good, I wouldn't change it!

 

[Kingston]

I suppose this falls roughly under the category "flaking gold". No hole or bending of the membrane.

Comparing capacitance of the sides.. measured how exactly?

 

[shabtek]

capacitance meter across a membrane lead to backplane lead--I think it should be 50-100nF each side---matching side to side will be less important in cardioid-- use the better sounding side as front. 

 

[Pip]

If it sounds good it is good. You will know when a capsule has been conpromised it will start to drop out.

 

[RuudNL]

I think it should be 50-100nF each side

Isn't that a bit too much? I think 50-100 pF would be more realistic! 

 

[granger.frederic]

Thiersch blue line has a PVC diaphragm which crack with time ...
Neumann M7 has the same issue
IMHO, it's time for a reskin ...

How old is the capsule ?

regards
Fred

 

[zephyrmic]

From the look of the photos, the membrane doesn't seem to have been perforated, so it should not affect the performance of the capsule. How easy it is to slip in assembling mics! Been there, done that, but not with a capsule! Not too much damage done, from what I can see. IMHO leave it alone, relax, reassemble the mic, and enjoy using it.

Kindest regards,

zephyrmic

 

[Kingston]

Thiersch blue line has a PVC diaphragm which crack with time ...
Neumann M7 has the same issue
IMHO, it's time for a reskin ...

How old is the capsule ?

regards
Fred

This capsule is only 5 years old. I'm almost certain this scratch has to do with the fact the original center wire of this side was too short for the application and I had to replace it. I was probably being clumsy and I only noticed this now.

 

[zamproject]

use the better sounding side as front.

According to Thiersch, the side where "back" are hand labelled on the tape have a hole in the diaphragm.
Recommendation is to use this side as rear diaphragm.

 

[Kingston]

use the better sounding side as front.

According to Thiersch, the side where "back" are hand labelled on the tape have a hole in the diaphragm.
Recommendation is to use this side as rear diaphragm.

What can this even mean? There's a hole on both sides. Both sides have a screw in the middle. Perhaps you're thinking of some capsule other than M7?

 

[zamproject]

use the better sounding side as front.

According to Thiersch, the side where "back" are hand labelled on the tape have a hole in the diaphragm.
Recommendation is to use this side as rear diaphragm.

What can this even mean? There's a hole on both sides. Both sides have a screw in the middle. Perhaps you're thinking of some capsule other than M7?

I talk about my M7 red line. It's not the hole in the middle to connect the diaphragm!. They call this "capillary hole", i think it's for atmospheric pressure matching in and out, maybe for humidity too.
I have to admit I was surprise when they told me that, and i'm not able to see the hole (maybe with a microscope?)
My previous dale M7 have this hole on the side of the backplate

 

[dmp]

How much is a reskin by Thiersch?
The economics seems like the key question, since the capsule as is sounds fine (and has value as-is).

 

[Kingston]

I talk about my M7 red line. It's not the hole in the middle to connect the diaphragm!. They call this "capillary hole", i think it's for atmospheric pressure matching in and out, maybe for humidity too.
I have to admit I was surprise when they told me that, and i'm not able to see the hole (maybe with a microscope?)
My previous dale M7 have this hole on the side of the backplate

Interesting. Didn't know this and I must have missed the note if there was one when I got the capsule. I wonder if I have them installed backwards.

What color were your M7 red line wires, front and back?

 

[zamproject]

Interesting. Didn't know this and I must have missed the note if there was one when I got the capsule. I wonder if I have them installed backwards.

What color were your M7 red line wires, front and back?

No note about this, i got this info in email exchange. It's a recommendation. I can just imagine some difference with intensive voice micing producing humidity. But as I say, the hole are so thin i was not able to see him.

By memories i have yellow wires in both side

On the tape (blue for you) around back plate shoulder you should read "STW7" and serial n° in both tape, and in one side only "back"

 

[Kingston]

On the tape (blue for you) around back plate shoulder you should read "STW7" and serial n° in both tape, and in one side only "back"

I had to verify this and you are right. Luckily I had them installed correctly. I must have seen the text and simply forgot about this detail.

I did some figure of 8 testing with this capsule once again and can't detect any difference in sound on either side. I decided not to pursue this issue further. Certainly no point reskinning.

 

[Kingston]

On the tape (blue for you) around back plate shoulder you should read "STW7" and serial n° in both tape, and in one side only "back"

It turns one other mic I have with Thiersch capsule was installed with the "back" text on the front. I turned it around just in case. I couldn't hear a difference, but I prefer technical correctness.

Thank you for your help.

I should device some kind of a mic measurement test rig for these kinds of things. Just don't quite know how to create one to provide repeatable/consistent data.

 

[tskguy]

Do not Ruskin that capsule! Like others have said if it sounds good....then leave it. Not only that 99 percent of visual imperfections on the surface of Mylar or only cosmetic and will not affect the sound. I actually keep all of the Mylar targets that look bad for my own capsules simply because most folks would look at it and think that it would sound band but in fact the ugly Mylar always sounds great.
And front to back is really no difference in fact if there is a difference it would be bad for fig 8 and omni..

 

[o3misha]

Carefully examine your cap on the magnifying glass . The main thing that PVC film itself was not torn through. Scrapes and scratches on the gold coating does not affect the sound completely . The most critical place for sound - edge membrane. As far as I can see , scratch is closer to the center. We can say that nothing threatens the M7 . The central region of the gold layer does not affect the sound. I pretty much had to deal with old M7 from Hefell . M7 capsule has a unique vitality. Even with huge cracks in the surface of the gold they continue to work and sound great . My friend works old microphone capsule which on the face of missing half gold plating ! And cap sounds great nonetheless . 8)