Skin for mic capsule

Andriejus · Sep 29, 2014

Good evening all,

Maybe some of you has experience in buying gold plated replacement skin for capsule? If it is available somewhere for purchase, maybe someone could share the link? Thanks a lot!

Respectfully,
Andrew

Pip · Sep 29, 2014

Thats a vast question. What thickness and what material. Gold Sputtered Mylar or PVC. This is the kind of thing that unless you are getting into doing this regularly in my opinion is best left to those who do it all the time. But do a search for gold sputtered mylar film. or

http://www.lgafilms.com/

http://www.thiersch-mic.de/en/estm_geschichte.html

Andriejus · Sep 30, 2014

Thank you for the links.

gyraf · Sep 30, 2014

I did early experiments with unrolled film from capacitors. Higher voltage rating = heavier film

Jakob E.

Andriejus · Sep 30, 2014

Thanks Jacob.

Andrew

ricardo · Sep 30, 2014

There are many problems with DIY using Gold flashed Mylar. Les Watts enumerates them at http://tech.groups.yahoo.com/group/micbuilders/message/15817

This is a very long thread covering many useful topics so have patience and go through it all.

For DIY, probably the simplest is Aluminium Flashed Mylar. You can get this as

LW Covering at http://freeflightsupplies.com/

I cover some of this in Fig-8capsule in MicBuilders Files. You have to join.

shaggy · Oct 1, 2014

Thanks Ricardo. Do you know of a US supplier of that 5 micron aluminised Mylar? I only see two places online, including the one you list, and they're both in the UK.

thanks!
Dave

ricardo · Oct 1, 2014

shaggy said:
Do you know of a US supplier of that 5 micron aluminised Mylar? I only see two places online, including the one you list, and they're both in the UK.

A sq. m. will see you for several dozen capsules and Free Flight Supplies ship to any part of the world at very reasonable cost.

But why not go to your local Model Shop with an ohmeter and check out their Aluminised Mylar? They can tell you the thickness and you just have to make sure, the Aluminium layer is exposed and the stuff isn't pre-glued.

shaggy · Oct 1, 2014

Hi Ricardo, thanks for the suggestion. I'll check my model shop out. But yes, shipping from the UK should be no problem.

Is this stuff be the same as used making in film capacitors? What prevents the 'bare' aluminum layer from oxidising? I wonder is there a gold ('space blanket') version with the same range of thicknesses. So many questions(!)

It occurred to me you could probably remove the aluminium layer around a 1" spot to make a center-terminated skin. I'm sure it's been tried.

cheers
Dave (shaggy)

ricardo · Oct 1, 2014

shaggy said:
Is this stuff be the same as used making in film capacitors? What prevents the 'bare' aluminum layer from oxidising? I wonder is there a gold ('space blanket') version with the same range of thicknesses. So many questions(!)

It occurred to me you could probably remove the aluminium layer around a 1" spot to make a center-terminated skin. I'm sure it's been tried.

Bare Aluminium always oxidises. The Oxide layer protects the rest unless the layer is too thin. The layer in film capacitors is so thin it will oxidise perceptibly before your eyes and bits will fall off a little later.

Read Les Watts (ex Shure) on Gold sputtered film in the MicBuilders thread. You have to sputter while the film is TENSIONED correctly else the layer will crack when you tension it. That's why space blanket Gold film isn't much good.

If you are making EVIL Neumann style centre terminated capsules, you have a problem

Calrec's heritage is from AKG via Clem's (my mike mentor) friendship with Bernhard Weingartner who did C12 for AKG. Hence we sneer at the Neumann centre terminated rubbish ;D

shaggy · Oct 1, 2014

ricardo said:
shaggy said:

Is this stuff be the same as used making in film capacitors? What prevents the 'bare' aluminum layer from oxidising? I wonder is there a gold ('space blanket') version with the same range of thicknesses. So many questions(!)

It occurred to me you could probably remove the aluminium layer around a 1" spot to make a center-terminated skin. I'm sure it's been tried.

Click to expand...

Bare Aluminium always oxidises. The Oxide layer protects the rest unless the layer is too thin. The layer in film capacitors is so thin it will oxidise perceptibly before your eyes and bits will fall off a little later.

Read Les Watts (ex Shure) on Gold sputtered film in the MicBuilders thread. You have to sputter while the film is TENSIONED correctly else the layer will crack when you tension it. That's why space blanket Gold film isn't much good.

If you are making EVIL Neumann style centre terminated capsules, you have a problem

Calrec's heritage is from AKG via Clem's (my mike mentor) friendship with Bernhard Weingartner who did C12 for AKG. Hence we sneer at the Neumann centre terminated rubbish ;D

Thanks Ricardo. Very valuable and interesting info .
BTW, I know aluminium oxidises. Was just curious why, on Mylar, it doesn't seem to lose it's shine - thought there must be a protective coating applied (other than the natural oxide).

Re your mention of Neumann/center-terminated... I always wondered why anyone would want to poke a hole in a perfectly good diaphragm 8>]

cheers
Dave (shaggy)

poctop · Oct 7, 2014

Re your mention of Neumann/center-terminated... I always wondered why anyone would want to poke a hole in a perfectly good diaphragm 8>

¸

Actually it is accomplished on Neumann Vintage K87 capsule in original fabrication and also in reskinning technique where the backplate are isolated with a piece of mylar of higher density , hence the hole on the back diaphragme permit the chamber to equilibrate with the atmosphere preventing it from becoming a barometer.

Best,
DAn,

shaggy · Oct 7, 2014

"... preventing it from becoming a barometer"

Or make a hole in a capacitive barometer, and turn it into into a microphone(?) 8>]

...of course, without a major redesign, it wouldn't have the necessary transient response...!

Dave (shaggy)

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