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Old 14th August 2012, 11:14 PM   #31
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it is sort of like tweaking out am powerless radio. Getting the most out of it with tweaks. You are right, that's a big box for 1mm xmax, but if we are going for that driver by itself, you do what you do to get the most out of it, rather than 1.5 way, or 2 way with 6db, or worse (a 12db or more, yuck).

I think of the fridge sized boxes used for the urei coax time aligned monitor from jbl with its weird ladder delay circuit.

Didn't most of the old 15" with whizzers have huge boxes back 50's and 60's ?

Once you add xmax, the inductance goes up, and there goes your mids and highs. Then again, adding a copper cap or shorting ring, you may be able to offset the longer xmax. That would be a bunch of trial and error. I remember Paul at Wild Burro commenting that he tried either copper cap or shorting ring but the highs were way too strong.


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Old 15th August 2012, 12:50 AM   #32
doggy is offline doggy  Canada
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The "boffle" looks intriguing, baffles provide resistance to air flow, like the ports on the onken design?
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Old 15th August 2012, 01:05 AM   #33
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Sorry. I don't know why this beast interests me but I'm guessing that with a helper bass driver on the back you'd need zero bsc and party down in front. Big is Badass.
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Old 15th August 2012, 01:31 AM   #34
Bigun is offline Bigun  Canada
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Originally Posted by Melon Head View Post
keep going bigun


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Originally Posted by Cal Weldon View Post
You know I love big speakers but I must say I am having trouble wrapping my head around a refrigerator sized box and a 1mm Xmax.
this is the price to pay for using a single driver I fear. On the other hand, 1mm with 15" is a lot better than 0.5mm with 4" Fostex !

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The "boffle" looks intriguing, baffles provide resistance to air flow, like the ports on the onken design?
I think more like an OB but with the back wave absorbed so that there's much less dipole dip-and-bump to worry about. Or perhaps more like IB. Either way it does look worth trying so the bracing has to designed to allow for it. Of course, there won't be any bass reinforcement from the box with this setup.

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Sorry. I don't know why this beast interests me but I'm guessing that with a helper bass driver on the back you'd need zero bsc and party down in front. Big is Badass.
Yup, that would be interesting!
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Last edited by Bigun; 15th August 2012 at 01:35 AM.
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Old 15th August 2012, 01:41 AM   #35
Bigun is offline Bigun  Canada
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What thickness of plywood to use for the box? I can buy 11.5mm and 17mm thick panels. I can glue panels face-to-face. But I'd rather brace the hell out of it than have panels that are so thick and heavy that I can no longer move it without help from a neighbour.

what if the box was made using only 11.5mm panels and then lattice braced ?

the floors in my house use wooden i-beams, very stiff (much better than my last house that used regular joists) and lightweight (photo) and much more practical than using thicker and thicker floor boards.
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Last edited by Bigun; 15th August 2012 at 01:45 AM.
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Old 15th August 2012, 02:26 AM   #36
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The "boffle" looks intriguing, baffles provide resistance to air flow, like the ports on the onken design?
The boffle i was thinking of could also be described as a damped U-Frame

Click the image to open in full size.

dave
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Old 15th August 2012, 05:20 AM   #37
GM is offline GM  United States
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Didn't most of the old 15" with whizzers have huge boxes back 50's and 60's ?
Yeah, 8 ft^3 was about the smallest I remember with 12-15 ft^3 being the most common. As late as the mid '70s I was putting cheap 8"ers in up to 7 ft^3 MLTLs to get enough bass out of them to do DSOTM and the few other LPs that got down into the low 30s.

GM
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Old 15th August 2012, 05:31 AM   #38
GM is offline GM  United States
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What thickness of plywood to use for the box?
Braced with I-beams, you can use 1/4" [6-7 mm], but that would be a lot of work, so the 11.5 mm is doable.

Frankly, minimally braced 1/2" ply was typical for this type of driver in a big cab as any 'breathing' the cab did helped to damp its high Q. You can always go back and add bracing if you don't like how it performs.

GM
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Old 15th August 2012, 05:53 AM   #39
freddi is offline freddi  United States
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although its motor is small/weak, you could put it into a Karlson enclosure from K15 to K18 size. Coat the front chamber well with varnish, etc. and enjoy.
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Old 15th August 2012, 08:01 AM   #40
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The boffle i was thinking of could also be described as a damped U-Frame

Click the image to open in full size.

dave
that just looks like a labyrinth to me dave, albeit one with a vent area equal to baffle area. Ignoring semantics tho, it would be worth a try.
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