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[John Halliburton]

Nice thing about coax's is eliminating the time alignment needs. This also makes passive crossover an option. The asymmetry in the crossover is also do-able passively. Many amps w/dsp don't allow it. Where are you headed with this?

Agreed, the alignment is better from the start.  I've used my BMS loaded 12" coaxials for ten years now, and I've lost track of how many musicians compliment their sound.  Curtis List, RIP, designed a great passive crossover for them for my cabinet design. Here is a shot of an empty, Line-X finished cabinet. Very compact, all 18mm Baltic Birch plywood, dual Speakons, handle on one end, pole cup. All of 42lbs. when loaded with the 12N680 driver.  Mark Seaton was working on a B&C loaded version of the cabinet as well, although it's been in the background what with his regular business demands.

Best regards,

John

[Jim McKeveny]

Curtis List, RIP,

I did not know...RIP indeed, Too Tall.

[Tim McCulloch]

I did not know...RIP indeed, Too Tall.

Indeed.  I hadn't heard of Brother List passing.  RIP, Too Tall.

[Chris Hindle]

Curtis List, RIP, designed a great passive crossover for them for my cabinet design.

Holy crap. When did that happen?
RIP Too Tall.
Chris.

[John Halliburton]

Holy crap. When did that happen?
RIP Too Tall.
Chris.

July 6th last year.  As many here knew, he had some very serious health issues that put him in a wheelchair for the last years of his life.  I drove up to see him a few years ago with a pair of Magnaplanar speakers he'd found for sale by me here in Chicago.  Afraid that was the last time we saw each other in person.

A talented engineer and friend.

John

[Scott Holtzman]

Yup, I'm exploring the mysteries of turning out documentation for a modified version to send to a local CNC shop to make flat pack parts for the two B&Cs I bought before the world changed.  I'm not sure their choice of 1800 hz for a crossover point isn't based more on reducing warranty clams than on the best performance at least based on my testing of the drivers. 1100 Hz low pass and 1250 high pass 4th order was the sweet spot for me.

14" is a very interesting sweet spot size wise.  Do you intend to sell these flat packs?  If not would extending the run for another dozen help you bring the cost down?

[John Halliburton]

14" is a very interesting sweet spot size wise.  Do you intend to sell these flat packs?  If not would extending the run for another dozen help you bring the cost down?

Scott,

I suspect I can have the CAD files for my 12" version expanded a bit until the baffle cutout fits the 14".

Best regards,

John

[Jim McKeveny]

14" is a very interesting sweet spot size wise.

Interesting enough that JBL had some 14 inchers over the years.

[Mal Brown]

Old thread alert!

B&C has a design for this driver.
https://www.bcspeakers.com/media/W1siZiIsIjIwMjEvMDIvMDIvMTVfNDdfMTFfNjMyX0NYMTQucGRmIl1d

How might one go about modifying that design to make it a 40 degree horizontal box.  Array 2 for 80 with minimal boundary interference...  I have 6 old Renkus trap boxes that array really well but are too large and heavy these days...

[Art Welter]

How might one go about modifying that design to make it a 40 degree horizontal box.

Mal,

The HF/woofer determine it's basic 80 degree conical pattern, the HF driver uses the cone as the mouth of the horn. You could extend the pattern to a lower frequency by making a cone extension "waveguide" of about 90 degrees, like the DSL SM-80. Mark Wilkinson did that with a pair of his co-ax, made the waveguides from foam core- lightweight.
Attempting  to reduce the pattern to 40 degrees would cause nasty internal reflections that would screw up the polar response more than simply stacking them. Put a pole cup both top and bottom, with a short pipe between them.
Stacking won't mess much with the horizontal pattern, but will cause some vertical lobing.
That said, you could put an  L-pad on the lower cabinet's HF, as it won't need to be as loud as the upper cabinet, which would make the vertical lobe fairly benign, especially if the lower cabinets are pointed in a bit as center fill.   

Art

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