The Official 909 8As have a 1" throat thread.

[BillWojo]

That suggest that the conical expansion angle is different than the 902/908 drivers if they have the same overall length. It also looks like the conical expansion piece is part of the driver unless the mounting surface was machined after it was pressed in and the parting line is not visible.
I wonder who has all the original manufacturing prints for these?

BillWojo

[Phil-G]

in the drivers I've taken apart the throat is a separate casting like the 902 I have. with the 909 it appears to be machined as part of the faceplate. and visually the conical expansion seems greater.

[mah]

Thanks for posting, Phil.

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Bill, the Altec spec. sheet drgs, show the 909 motor to be 0.2 inch longer than the 902/908s.

[bowtie427ss]

Remember folks, 909 came along nearly a full decade after the 902/908 and while Altec existed under an entirely new and different corporate umbrella.

Things were getting cheap, look at the cheesy push on terminals, little or no protective plating on the steel parts, no more rich looking gold colored foilcal. Looks right on par with 416-8C from the same time period, worst they ever made. EEEEEEEEEEEEEWWWWWWWWWWWWW!!!!!!!

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I wonder who has all the original manufacturing prints for these?

Since they were a product of OKC, there's a chance that those drawings could actually surface someday.

It's my understanding that when the final move from Anaheim to OKC(circa 1983ish) was made, thousands of original documents, drawings, and data were hauled to a local landfill and burned.