Altec 12/15 'alternative'...

gable

Senior Member
Where-ish do you live?
A long-term loan of something EV-ish could, perhaps, be arranged :)

Oh, you know what could (?!?) be interesting?
These. 😏

A pair of EV "Wolverine" LS-15 OEM, branded RCA, and - at some point (not by me!) - de-whizzered.

For comparison, here're a pair of normal LS-15s avec their whizzers.


info on the LS8, LS12(A), and LS15 from EV at https://www.electrovoice.com/binary/LS8, LS12A and LS15 EDS.pdf
Note that the sensitivities are given relative to the EIA specification (1 mW at 30 feet, or something like that); add ca. 50 dB for 1watt @ 1 meter. This guy sez 49 dB :) EIA sensitivity?
I live in Texas, South of Austin, in the HOT AS <expletive> BELT.

The LS15's look interesting, I'm not familiar with them. Have you tried them in your system?
 

je2a3

Junior Member
I experimented with Beymas when I was in Manila because I knew the dealer and Altecs are much harder to come by there.

Since my return, I've been tempted to try modern drivers like Eminence, Faital Pro, etc., but these modern drivers aren't really cheap. As evidenced by the pictures posted, there are still unexplored classic alnico/paper cone drivers from EV, Jensen, etc. I've also seen vintage Pioneer 12" woofers on eBay that may have potential.

Happy hunting!
 

gable

Senior Member
So I got a pair of SP12B's from @rusomon. They were delivered last week, and the pictures don't do them justice. They are in fantastic shape, dcr is good.

IMG_1335.jpgIMG_1337.jpgIMG_1338.jpg

Now, with those acquired I started looking for information for what size box to build. I found an EV bulletin, #10a iirc and read through it. I'll attach it here as well.

So based on the doc I'm building a ~4cu/ft box, the port is causing me some headache. Maybe I'm reading that section incorrectly. I came up with a 2" tall, 4.25" wide, 7.5" deep port. Don't ask me how, but that's what the piece of paper on my desk says after I read through it and 'mathed' it out like a champ.

Any insights would be awesome...fairly certain I did something wrong.
 

Attachments

Hmm.... I am no expert, but the depth of 7.5" seems odd to me. In my experience, the cabinet designs of the period made do with a suitable hole in the baffle, and no 'depth' beyond the thickness of the wood itself. The deeper port designs came when the monkey coffins got too small to just cut a hole into.

Taking the advertised "40 to 50 cycles" resonance of the SP12B, and a 4 cu. ft. box, the 60's Altec Enclosure Plans indicate a port of up to 20 sq. inches, which I would cut as 2 by 10 inches. Admittedly, Altec and EV may have had differing ideas about box tuning, but the underlying physics hold... and I find the Altec chart a bit easier to read.

Have you looked at the EV Marquis? And with respect to mathing it out - I recommend Wolfram Alpha as a useful calculator with on-the-fly unit conversions, as in this example where I gave it inches and asked for cubic feet in return.
 

gable

Senior Member
Thank you Andy, I thought the depth sounded odd as well. I'll checkout the links and see if I can get it figured out.
 
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