Skorpio I like your box design. For some reason I would have never thought of that with the volume on the sides. If you go for it maybe try to keep at least the diameter of the pole vents between the magnets, a little more would be better, unless you wanna hear them. Run a hard mechanical link between inner magnet assemblies one way or another for increased rigidity, and definitely one from side to manifold. I'd look for aluminum cone drivers and PRs (preferrably black) to help keep the heat down in the sealed boxes at high power.
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These don't appear to suck. Unfortunately their smaller ones are a little goofy, particularly the 12.
TC Sounds VMP 18" Passive Radiator | Parts-Express.com
TC Sounds VMP 18" Passive Radiator | Parts-Express.com
I'd be tempted to try both sides of the manifold open, top and bottom. I'm not really sure how the wavefronts would combine. If you were not on a concrete floor it would result in less floor drive. That part's easy to see. Ruins the end table option for sure. I just wonder if it would essentially be a pair of drive modes that could end up less particular about placement or whether it'd be a total loser. I don't bet on the latter, since both ends would have very different coupling characteristic but should be close in phase at very low frequencies. If one started hooking up too well because of resonance the energy would take the easier route, the unloaded side. It would essentially be a differntial load.
What's your planned upper cutoff? How high off the floor are you planning?
Anyone have any ideas about this?
What's your planned upper cutoff? How high off the floor are you planning?
Anyone have any ideas about this?
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Skorpio was quoting one of my posts with my conceptual sketch.
The drivers i was thinking of with this are 12" fosters with no pole vents (i have 20+ i need to use up or sell). 4 arranged this way would require ~50 litres net volume. Feet and spaced table top are assummed. One of my buddies is into granite, so likely an inch think chunk in my case.
If it suited the driver, enclosure can be vented (with a port or a PR).
If one is to build this, careful thot has to be given on how to make it so that it is possible to assemble. Top (or bottom) & 1 of the inner baffles will likely need to be removable.
The biggest issue is getting wires (power & signal) or speaker wire if it is out in the open.
dave
>Feet and spaced table top are assummed.
Ah, so the manifold is to be vented on both sides anyway?
Having 20 of these drivers is a Great reason to use or sell four at a time. I guess I got carried away by some of the posts about beat-you-in-the-chest designs. Of course you can butt the magnets if no pole vent. I suppose I'd try making the manifold panel assembly and then put the rest of the box on that with the two "end" panels removable.
For any applicable driver the single open volume design allows long port tube along the longest dimension if necessary. Cool feature.
Ah, so the manifold is to be vented on both sides anyway?
Having 20 of these drivers is a Great reason to use or sell four at a time. I guess I got carried away by some of the posts about beat-you-in-the-chest designs. Of course you can butt the magnets if no pole vent. I suppose I'd try making the manifold panel assembly and then put the rest of the box on that with the two "end" panels removable.
For any applicable driver the single open volume design allows long port tube along the longest dimension if necessary. Cool feature.
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As he said, Planet10 did the drawing not me, I ran across his drawing trying to find a picture of what I was thinking. My drawing has passive radiators in it and is substantially more crude:
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I described in a lot more detail what I was thinking for my project in my post "donut sub". For me I was trying to come up with a workable design for a very low volume enclosure, like 9.5" high x 14" deep x 32" wide that would fit on a lattice work shelf under a wood entertainment cabinet I have with a center channel mounted in front of it.
My mains and rears are Ohm Acoustics Ls and already go down to about 50hz but probably really start losing their legs around 70hz or so. I was planning on constucting a center channel with 2 6.5" drivers and in the WinISD model have a pretty close curve to the model I did of the "L"s. Plan is to get a solit mid 30s out of a sub and do an active cut at around 80Hz on the high end as well as the low on the Ls. Makes the Ls work less and moves the cut to under typical human voice range. With a boost at 37.5 of around 5-6db parametric the design models out a good flat 35-85hz using 8" drivers and 8" high (10mm) xmax passives.
In my application there is an oak floor below and basically a boom chamber above, so I'd probably try and direct everything down with a stone slab on top. Shelf is about 8" off the floor.
Should work, it's basically an EV MTL2/MTL4ish design with a common enclosed airspace (I think the MTL had a seperate chamber for each driver) and I'm replacing ports with passives and drivers for Isobaric pairs, the EVs already used inverted drivers, so kinda look iso-y. In my sound production days we built scaled down versions of MTL2s that were basically 80% of fullsize in every dimention including the drivers, and they were strong fast tight base bins that could do Top Fueler level SPLs. Pink noise was like an earth quake through those. Actually our scaled down version was probably tighter (15s) than the real EVs (18s) just because 15s have less slop.
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