Audio Devices, Inc. company history?

[Chuck Guzis]

I've got a few old reels of milk-chocolate brown 7-track tape here and
was wondering if it's possible to date them accurately.   The reels
themselves have the Audio Devices name molded into them; the rear white
flange is quite yellowed with age.  The tapes have been used quite
heavily as they've been shortened to much less than 2400'.

I know that AD and EMI had a merger agreement with Capitol on their
vinyl business around 1967 and that the result was spun off as EMI.
That leaves the tape business.  It seems that CDC acquired some or all
of AD in 1969, but I can find no details.

Does anyone remember these folks?  They used to be *the* major tape
supplier in the USA.

--Chuck