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Designing around non-traditional driver sizes?
Designing around non-traditional driver sizes?
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Old 20th May 2015, 09:42 PM   #1
wg_ski is offline wg_ski  United States
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Default Designing around non-traditional driver sizes?

I've been thinking about designig a new system for a while, and mostly it's been just Hornresp sims and a little preliminary horn folding. It will soon be time to make some actual hardware - starting with a new horn kick bin for 80-300 Hz. It's going to be a new form factor more suitable for line arraying, and an easier build than the old design. Traditionally I've used 12" drivers. I've got the old Kappa Pro 12's in my old ones, and a stash of OEM Delta Pro 12s, both of which will "work". On a whim, I modeled the B&C 14NDL88 and I like what I see. The 12" version does not do as well, and neither does the 15. Unfortunately, this now leaves me with a dilemma. Should I commit to a design around a 14" - which may or may not disappear without warning, perhaps before the entire project is finished? Or stick with a 12" which I should be able to obtain pretty much indefinitely? Or are those drivers gaining enough ground in the industry where they'll be around in 2-3 years? I had the same misgivings about building those old lab horns - but that "custom" driver did seem to survive the test of time.
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Old 20th May 2015, 11:03 PM   #2
ErnieM is offline ErnieM  United States
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Can always make an adapter ring if it comes down to that. Lots of work though. Kind of curious why they decided to market that driver. Maybe one of the major line array companies use that size.

The B&C's are pretty rugged. Those also have double spiders with silicone damping. They will last many years with stable performance when used with good safety margins.

Edit: http://www.fbt.it/ENG/INSTALLED-/PRO...ow/Shadow-142/

Last edited by ErnieM; 20th May 2015 at 11:07 PM.
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Old 21st May 2015, 09:38 AM   #3
chris661 is offline chris661  United Kingdom
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I'd probably cut a 15" hole and then make up some donuts. Shouldn't take too long with a router, and would give you a lot of flexibility if they do pull the 14" drivers.

Alternatively, what about a pair of 10"s? The Sd should come out similar to a 14" driver.

Chris
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Old 21st May 2015, 10:37 AM   #4
AndrewT is offline AndrewT  Scotland
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If you horn load, then you will find that the horn "shape" determines the flat passband of the speaker.
The driver size is almost irrelevant.
The driver size has a big influence on the max SPL available at the LF end of the passband.
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Old 21st May 2015, 12:07 PM   #5
wg_ski is offline wg_ski  United States
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Adapter plates may not be a bad idea. I was originally just intending to "use what I have", but since the ultimate goal is going to be expensive and time consuming (unity's on top, 1 for 1 with the new bottom, at some point some 21SW152's in labhorn+ size boxes) I figured I'd shop around and see if I can improve on the Kappa's response and/or output. Nothing else seemed to work in a 12. The big boys with the big motors didn't give a nice resposne in that size box, and any thermal advantages got eaten up by lower efficiency. A couple of 4" coil 12's did look nice - but at only 3.75mm x-max, who cares? But I'll be damned if the driver that beats the original - and is a drop-in upgrade with only a rear chamber adjustment - happens to be a new product in an odd size.
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Old 21st May 2015, 08:21 PM   #6
chris661 is offline chris661  United Kingdom
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If you shoehorn the 15" in there, would the response be totally unusable?

Sounds like you're designing a 4-way system here, so I'm expecting a lot of DSP. The extra cone area would give you some headroom to EQ if needed.

Chris
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Old 21st May 2015, 09:49 PM   #7
wg_ski is offline wg_ski  United States
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I'd have to design aound a 15 to make it work with one. The bigger the driver, the more space has to be wasted in the final fold. Regardless of piston diameter, the offset feed point needs to be the same - and for a 12 it works out to be the "right" distance to push the null up high enough to cross over at 300. For larger drivers, the frame goes past the end of the horn - the unused portion needs to be blocked off and is thus wasted. Even with a 14", there would be some wasted length - and if I went ahead with it and later had to go back to 12's I'd be a little miffed. Certainly wouldn't go with a 15 unless it was over-the-top better, and so far all I've found is equivalent low end and a gradual roll off starting around 200 with any I've tried simming.

My existing bins are end fed, and as such changing driver sizes is easier. But the build is complex enough that I don't want to make any *more*, and the flare angle is wrong for doing anything other than the originaly intended 2x2 array with traditional boxes on top.
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