Ribbons and Corrugator

[Marik]

Hey guys,

My first message here.
I shifted from building ESLs and ribbons to making ribbon microphones.
Just wanted to share a few tips.

One of the biggest problems is to make a good corrugator. I machined mine on a mill with indexing rotary table.

On my artist friend's bench I found this device:

http://www.dickblick.com/zz049/07/

I had problems with ribbon corrugation for microphones, using this one, but I am working with 0.6-1.5um thickinesses. With something like 4um up it should work fine.
Make sure to get a metal one. The plastic is uneven in the middle.

If you want to try thinner than 11um household aluminum foil look in older paper-in-oil capacitors. The thinnest I was able to find was 3.5um Illinois. The lower the voltage rating, the thinner material. Usually, it is about 6um. Just unroll the thing, place on a clean glass, and clean with isopropyle alcohol.
Do it outside. I heard it is not a good idea to breath odor from these babies.

Hopefully, it helps.

Cheers, Mark

[SY]

Great find!!!

[Audiophilenoob]

Originally posted by Marik
Hey guys,

My first message here.
I shifted from building ESLs and ribbons to making ribbon microphones.
Just wanted to share a few tips.

One of the biggest problems is to make a good corrugator. I machined mine on a mill with indexing rotary table.

On my artist friend's bench I found this device:

http://www.dickblick.com/zz049/07/

I had problems with ribbon corrugation for microphones, using this one, but I am working with 0.6-1.5um thickinesses. With something like 4um up it should work fine.
Make sure to get a metal one. The plastic is uneven in the middle.

If you want to try thinner than 11um household aluminum foil look in older paper-in-oil capacitors. The thinnest I was able to find was 3.5um Illinois. The lower the voltage rating, the thinner material. Usually, it is about 6um. Just unroll the thing, place on a clean glass, and clean with isopropyle alcohol.
Do it outside. I heard it is not a good idea to breath odor from these babies.

Hopefully, it helps.

Cheers, Mark

very good find indeed... the metal one works for 4um material GASP!

I got to buy me one of these

[mwmkravchenko]

Excellent

MArk

[Marik]

Glad it was of help.

Some more:

You can increase ribbon compliance by beating it, prior to corrugation. That is, place the ribbon in between household soft paper towels, and beat this sandwich with a spoon. After that place the foil on a clear piece of glass and roll it with wide enough ball bearing, untill it is smooth. Use thin machine oil, and then clean with alcohol.

This kind of technique was used for ribbon preparation in Coles 4038 microphones. Mind you, they used 0.6um foil. I worked with that--crazy stuff. You need to wear mask, or don't breathe.
Sometimes it takes up to 2 hours just to install the ribbon.

Take a Royer tour to see another corrugator. I have something similar:

http://www.royerlabs.com/Royertour/Tour_SFp4.html

Anyway, try to use at very least 6um ribbon foils.
If you can handle it, for small ribbons try 2.5um foil. It should work very well, as the ribbon mass will be around the same with that of loading air. Along with very good damping, compliance would be excellent, so it will be pretty much free of resonances and you can tune it even down to 20Hz (not that you need it ).

[Paul W]

WOW! I thought 5 micron foil was tricky to work with...guess I should recalibrate my thoughts!

[moray james]

I don't know about the oil found in oil/film caps but just in case there are any PCB's in there (as in old transformers) use latex gloves and good ventilation. Regards Moray James.