Altec Small Format Diaphragms With Copper Voice Coils?

[Old Guy]

I'm not an expert on Altec voice coils.

But be aware that copper coated aluminum wire is often used in HF coils. Easily mistaken for copper.

CCA10%

Also that lit only says some coils are copper and some are aluminum. Not that some HF coils are copper. My experience is generally woofers are copper and HF drivers are aluminum. There is a very substantial mass difference. Aluminum wire is one third the mass of copper wire. A copper coil would seriously degrade the HF response.

[bowtie427ss]

Agree with Old Guy on all points.

I don't think the 20275 aluminum ribbon was coated. It's the only one i've ever had to dig out of an Altec gap so i've seen it up close.

Here is the attraction to the 20275, it's visually obvious:



Later HF small format coils look like they're coated although there's no mention of it in any of the slick sheets, they simply say edge wound aluminum ribbon. They sure look copper colored. But, that could be the adhesive or insulating coating i suppose.

A couple interesting notes from browsing the A&E specs on a couple sales slicks,

416-8B edge wound copper ribbon

416-8C edge wound copper ribbon

515G edge wound aluminum ribbon

421-8LF edge wound copper ribbon

515B edge wound copper ribbon

421A edge wound aluminum ribbon

[GM]

The only coating I know of is the tinted shellac used to seal such electrical coil windings whether a driver VC or inductor, etc., with the really thick, nasty yellow/brown tinted being for [sub] tropical, shipboard or similar environments.

GM