Suggestions for aluminium ribbon damping?

[audioquestM-40]

The fine pitch was a success.

That corrugation looks almost identical in pleat size to my Apogee Scintilla ribbons. Nice work!

 

[dacen]

@ hanski. Thank you for sharing info and pictures. 3D printing? That is new to me. Any more info to the forum about that. Fantastic work! Impressive.

 

[RogerGustavsson]

However even 0.6um thick foil has resonances and needs damping.

0.6 µm sounds unrealistic to me. Maybe you meant 6 µm?

 

[hanski]

0.6um alu foil can be bought as "Imitation silver leaf foil".
At first it felt really thin, but when I started experimenting with leaf gold (0.2um)... oh man that's thin.

I used Sketchup for modelling the corrugator. A gear drawing plugin is available on the web.
Trimble SketchUp

Shapeways material called "Frosted ultra detail" is good for fine detail printing.
3D Printing in Frosted Detail Plastic on Shapeways

 

[hanski]

Hi all,
I haven't had any luck in finding thinner than 6.5um foil.
so I started thinning down my foil with simple etching process (I used a strong alkali solution). See pic..

The results are as expected. Thinner foil has less resonances in 2 - 8kHz range.

Regardless of foil thickness, embossing seems to be more effective way of killing 2 - 8kHz resonances in pure alu tweeter ribbon than corrugation.

I wouldn't like to repeat the etching, and I woudn't recommend anyone to try it.
So a hint or a tip of thinner foil source would be very welcome, thanks.