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Yes ! - I was also thinking about the Boffle the other day, I like the idea a lot and have been collecting information (including from your website). Yesterday I came across somebody who actually knows a man who heard from a friend that his pal's neighbour met this chap down the pub who actually built one and he said "I can tell you that it worked brilliantly" (it was posted on a hi-fi vision forum Aug 2010 but I can't get the link to work from here)
I ran some box simulations a couple of weeks ago and found that a good number was around 250 litres but I figure my box will give me a bit more than this which can only be better.
Since the CSA plans were mentioned, I was largely just dreading they were going to be run as a BR (since their record isn't great when it comes to box alignments).
Absolutely - I wouldn't really see a BR as an option here, although there have been boxes that look like a BR but were in fact MLTLs. Anyhow, seems we're both on the same page !
In terms of experiments - my plan is to build a box with removable back. This gives me a well-braced solid platform to try a) open backed box (a.k.a. Yamamoto YS-500), b) a boffle, c) closed box with aperiodic vent, d) sealed.
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I mean most of CSA's cabinets are at best IMO of questionable merit and you'd get better results by using them in a properly designed enclosure.
What's a boffle?
I bet they would sound in these:
http://www.passdiy.com/pdf/KleinHorn.pdf
Also, to get any sort of bass from them, you'd need a BR. Think high-eff, big magnet, heavily overdamped. Eminence Deltalite 2515 II. It's really a midbass.
It doesn't want any more air in the back damping its cone motion at resonance, it's huge magnet is doing that already.
I bet they would sound in these:
http://www.passdiy.com/pdf/KleinHorn.pdf
Also, to get any sort of bass from them, you'd need a BR. Think high-eff, big magnet, heavily overdamped. Eminence Deltalite 2515 II. It's really a midbass.
It doesn't want any more air in the back damping its cone motion at resonance, it's huge magnet is doing that already.
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I have built and measured this for the AN 15, and yes it does work quite well.
Sometimes I think you are my twin brother. Hahaha
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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.
Norman
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.
Norman
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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 !
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.
Yup, that would be interesting!
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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.
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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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
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
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.The boffle i was thinking of could also be described as a damped U-Frame
dave
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