Altec 413-8A pair woofers speakers granadas mint condition 15" | eBay
my best guess is 421 something. when did they start using ferrite mags?

Altec 413-8A pair woofers speakers granadas mint condition 15" | eBay
my best guess is 421 something. when did they start using ferrite mags?
Sonic Barbarian
It's ~ a weaker motor 3" VC version of the 411 apparently as a cost cutter since in later years it was used in the Santiago even though some catalogs continued to list them with 411-8A.
I first saw ferrite in '70-71 [memory's getting kind of fuzzy] with the 421A, 411-8A, 413-8A.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
It might also be the first version of the 413\411. The first 411's had the same cloth surround before switching to foam. Cant remember if the first 16" frame heavy coned 411's were labeled as 413's , but i think they were.
It preceded the 411/ became the 411. Basically, an attempt to create the equivalent of the 411 from off the shelf parts already in house. If you get to see/handle one in the flesh, check out the dust cap it's aluminum about 1/8 thick apparently for the sole purpose of adding mass to lower fs.
Altec lore tells us the 411 was designed by a microphone engineer, certainly he cleverly installed the spit screen from a mic in the vent. Not sure how much of the rest of that story i buy these days as most of the moving assembly is the same as LE 15, and the 616-8A duplex takes that up a notch and also uses the same alnico slug as LE 15. Eventually, somebody came to their senses and revised the design getting rid of that problematic single roll doped cloth surround. Certainly much of the 411 engineering was born from the mistakes/shortcomings of the 413.
Note that the 413 never appeared in a flagship speaker model or a monitor.
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I don't believe there's any such thing as 16 inch 411's. Altec frames are not made to accept a 4 inch voice coil.Cant remember if the first 16" frame heavy coned 411's
The basket/frame of the 411 is unique to only itself and the 616-8A, the only Altecs with 4 inch VC's, no other Altec drivers use that frame.
Study some photos carefully. With their light gray paint the 616 shows the frame details a little more clearly.
Not all vegetables make good leaders.

it just looked cobbled together. with the stamped frame and the ferrite magnet. so it's really a piece of history then? that's cool.
Sonic Barbarian
It's a cast frame, just the(later) 15 inch version, early 15 inch cast frames use a split rim that sandwiches the outer edge of the surround instead of using adhesive.
The large drivers that used stamped frames were very early, like late 40's field coil drivers and the frames were sourced from Utah. They used the 12 inch stamped utah frame well into the 50's on the 600/600B, and there might have been a handful of 412's and 414's also built on the same frame.
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601 duplex in Utah stamped steel frame(field coil 604) courtesy of Steve Schell:
Stamped 412 bi-flex:
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Not all vegetables make good leaders.
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