Microphone Diaphragm sources???

Hi,
where do you recomend to obtain mylar/polyetylene/polyester films for microphone diaphragms? Or even better, already coated with gold or nickel?
I need to repair my capsule for this microphone, but just cant find the right thickness material. The ripped pieces of diaphragm from that microphone measured 0,015 mm.
http://www.elektroakustika.cz/tesla_amc420.html

What do you recomend?

I take it you're well versed in capsule reskining then ?!

Well if you have some advice, I would be more than happy to hear them. Anyway I guess I can do the job with these capsules.
What I am not sure is how much tension do they need, and I think we can only guess.
Please let me know where to get the materials for a reasonable price...

You probably shouldn't guess at diaphragm tensioning. Much like a drum head the capsule has a resonance. The tension determines the resonance. If you don't get this aspect correct, your mic will not sound the way it was intended to sound.
If a replacement isn't available through the manufacturer, you may find a capsule repair person to be a better alternative.

-James-

15um sounds far too thick.  For something like that, it should be about 5 - 10 um.

Gold or Nickel sputtering is a very specialist process.  If you use these, you have to deposit on an already tensioned film.  If you deposit Gold or Nickel on untensioned film, it will crack when you tension it.

Aluminium is much easier to use and you can buy Polyester (Mylar) already Aluminized.  I used Aluminized film on the Calrec mikes.

Most sources require you to buy a zillion sq. m.

However  http://freeflightsupplies.co.uk/ will sell you a sq m or so.  Look under LW Covering  for their '5 micron aluminised' and '10 micron aluminised'

In most Cardioid condensors, the correct tension is when the diaphragm is just clear of collapsing at the correct polarizing voltage.

Omnis will be stretched as tight as the Mylar allows.

Double diaphragm mikes are tensioned like cardioids.

..and as a last resort, you could unroll an alumininized polyester capacitor. Higher rated voltage=thicker base material.

Jakob E.

ps: very good link, ricardo!!! Never seen this sort of material for sale anywhere else - and I looked a lot...

Also try the word "Bespannfolie" on german ebay.

-max

In US you can get Al Mylar in different thicknesses here:

http://www.homefly.com/products.asp?id=31

Best, M

Thank you all so much for the links and suggestions!!!

Love!

I looked for the foils just as "gyraf" did and I couldnt find anything.

I am from Slovakia->Europe.
So I have to try to find something over here!
I did not know about the tensioning rules for omni a cardoid microhpones!
Mine is an omni-so I will stretch as much as it takes...
Well, damn it, I should have made some photos when I had the capsule apart... Now I am away from home, and god knows when I will have opportunity to tangle with it again. DAMN you school!!!

here I made a quick sketch of the microphone body.
http://www.scribd.com/doc/124972338/TESLA-AMC-CAPSULE-CONDENSER

Note the rings at the bottom of the "HOT" electrode, I guess they are raising rings to get the electrode to correct heigh. In my capsule there where three rings. Two aluminium and one obviously dielectric. Measured around the same as the diaphragm 0,015 mm.
I GUESS!!! They are for rising the capacity as well, though I dont see the point, since there is a plexi glass isolator...

here's a german ebay link: http://www.ebay.at/itm/Bespannfolie-6-7-g-Quadratmeter-Alu-bedampft-5-m-/350124610538?pt=RC_Modellbau&hash=item51850d93ea

somorastik said:

http://www.scribd.com/doc/124972338/TESLA-AMC-CAPSULE-CONDENSER

Note the rings at the bottom of the "HOT" electrode, I guess they are raising rings to get the electrode to correct heigh. In my capsule there where three rings. Two aluminium and one obviously dielectric. Measured around the same as the diaphragm 0,015 mm.
I GUESS!!! They are for rising the capacity as well, though I dont see the point, since there is a plexi glass isolator...

Click to expand...

Thanks for this.

The rings are to adjust the diaphragm spacing and this is usually measured by the capacitance of the capsule.

The construction is sorta like the B&K omni capsules.  What is the diameter of the capsule?

If it is an omni of this sort, the film might be 15um after all.  (B&K & DPA omni capsules use solid Nickel)  Thicker film allows more tension but in most cases, the resonance of a small omni is set by the air cavity.