Rebuilding Graebener's Auricle Ribbons

[gavinson]

A Quick Background: In 1990 I bought a set of David Graebener's Auricle Ribbons just before he left Speakerlab (eventually to begin Bohlender-Graebener with Tom Bohlender). The Auricles were 54'' full-range ribbons in a 57" chassis, with three rows of push-pull magnets and a 5 mil Mylar/Kapton ribbon and two double rows of foil. The soundfield was literally stunning.

After nine months of use, I had to put them into storage for a year. After setting them back up, niether speaker functioned. Apparently the result of humidity and the mechanical connection of the leads to the ribbon element. Hence, they have set in their original boxes for years on end.

I have now opened them up to rebuild them. The ribbons will have to be replaced, which leads me to the need of help.

1. Does anyone know of a source for Kapton that doesn't have to be purchased in industrial quantities?

2. What is the latest DIY thinking on aquiring and adhering the foil strips to the Kapton?

3. I am confident of being able to build a jig to tension the ribbon prior to gluing it to the chassis, but what amount of tension should be placed on the ribbon?

Any help on these questions would be greatly appreciated. Thanks!

[Audiophilenoob]

laminated kapton will be extremely hard to find if not impossible

hell I think dupont stopped making kapton anyway

try a laminated mylar...

[SY]

Kapton is still very much alive. Sourcing it in small quantities is a separate question, but I'd start at McMaster-Carr, then call some DuPont distributors. The heat-sealable grades (FN, FCR, FWR) look particularly interesting for this application.

[Audiophilenoob]

Originally posted by SY
Kapton is still very much alive. Sourcing it in small quantities is a separate question, but I'd start at McMaster-Carr, then call some DuPont distributors. The heat-sealable grades (FN, FCR, FWR) look particularly interesting for this application.

I called Dupont directly and it was MIA

in fact they said they stopped making it.... maybe the guy was just crazy though

[SY]

It's still up on their website and my rep still supplies it to me... It may have been one particular grade that was discontinued, who knows?

[gavinson]

Thanks for the replies.

Kapton...I can get. The more problematic supply seams to be getting .5 mil aluminum strip.

Any ideas on that? I've opened up a few capacitors, but have not found anything thin enough, and certainly not long enough (54"). Household foil is way too thick. Aluminum leaf is available (as is gold and pure silver) but it is actually a bit too thin. I even considered running the conductors down both sides of the diaphram to compensate for the thinner material...but no....I'd like to just get my hands on what has been proven to be effective.

And finally, how much tension should I place on the diaphram prior to glueing it down?

Again, thanks for any and all info.

[SY]

McMaster-Carr has half mil aluminum in sheets. That should be pretty easy to convert into strips.

[Audiophilenoob]

are you trying to laminate this kapton yourself ?

[Marik]

Originally posted by gavinson
[B]Thanks for the replies.

Any ideas on that? I've opened up a few capacitors, but have not found anything thin enough, and certainly not long enough (54").

Try old paper-in-oils. Usually, they are 6um, sometimes down to 3.5um. In one of my computers I have a bookmark for a supplier for 6um-up foil in rolls. I can check it if you are interested.

[gavinson]

I was (wow) able to find a supply of the original Kapton/Aluminum foil ribbons that were used in the manufacturer of these drivers.

I have replaced one of the ribbons, and after a lengthy and frustrating process of discovering the tension needed, I now have the driver working again.

After an initial listening test I am dumbfounded once again at the sweetness and spacial characteristics of these drivers.

When I get a little further down the road on the new baffles I'll post an update with pics.

Thanks to the forum on all your input.