Super narrow sub to take everything below midrange - AVS Forum
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post #1 of 9 Old 06-07-2014, 04:01 PM - Thread Starter
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I have an installation in my cabin that just has to be done by the end of next week. I was planning to use a stock subwoofer, but because of a few changes by the architect (my wife, of course...) I suddenly had a lot less room for the thing. it's going to be rather tricky to get this to sound good (not talking about hifi good, more like "rock'n'roll cool and fun" good) because:

I have to use ceiling mounted speakers for midrange and treble. I have some I want to use, and they work nicely. But the room is only one narrow hallway away from where my daughter sleep, and I really don't want to wake her up when she's sleeping or have to play very low volume to avoid waking her up (what's the fun in low volume?). So I have spent a week insulating the room where the installation is going to be, with double fiber gypsum towards the hall, 70 mm of Rockwool in the wall and a 40 dB door. The result is nothing but stunning. If I could have used regular speakers I'd have no problems. But there is no place to put them that will even be close to usable. The only, and I mean only, solution is to have the directonal part of the sound (from the treble and as far down as I can) in the ceiling. Why not bass? Because that will be transfered by the ceiling beams straight to my daughter's room! And in addition to that there is only regular, 150 mm mineral wool insulation in the ceiling. But I figure that when the sound that is directed downwards has to go up through 150 mm mineral wool up to the attic and then having to go through another 150 mm and the ceiling boards on the other room to get down again that should stop more than enough of any sound that isn't a vibration in the materials. I have tested with regular speakers and like I said the results of the sound proofing is impressive. So I will use a AODA SC-202 active crossover to tune the ceiling speakers until they don't transfer vibrations.

And this lengthy explanation brings me to the actual question: I need a sub in one corner to do everything below what I can send to the ceiling speakers. My guess is that it will be anything below 400 Hz, or 250 if I'm very lucky. I have 25 centimeters max width, and I can probably go to around 50 cm height and 40 cm depth. I have looked at the tapped horn system, and if that can do full bass frequencies that will probably be nice. But I have read up on them and it seems like I can't really count on them above 150 Hz or so. So my question is this: Would it work to build a narrow and tall (25x50x40) subwoofer box with two drivers mounted in the side? I'm talking about a 10" woofer at the bottom and an 8" above this, with a partition wall between the two parts of the box. I would use MDF for the actual box, but then use the same type of wall plating that the room has on the outside of that for looks (wife/architect again...). So what would look like one box (probably with a flower pot or something on top, insulated with sorbothane) would actually be two separate subwoofer cabinets. I built something similar a few years back for a Chevy Suburban I had then, only with two 12" JL Audio subs in one very broad, wide and thin box that was parted inside.It was so thin that the drivers had maybe 10-15 mm from the bottom of the magnet to the bottom of the box, but it still sounded incredible, much better than the ported box that the previous owner had used. Only this time it will be two different sizes of subs and different frequencies. I have an Alpine SWS-1043D laying around, and I could use that for the 10". It's a very low profile, but extremely good and powerful driver. I can probably get a 8" Alpine or similar quality sub in the area.

So please tell me if I'm barking up a totally wrong tree here, or if I'm actually on to something!

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post #2 of 9 Old 06-07-2014, 04:36 PM
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You'll have a problem running any higher than 100Hz, if that, as the subs will be directionally locatable, and integrating them with mids will be very difficult, if not impossible. Remote placement of subs and mains relies on the subs not being directionally locatable.

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post #3 of 9 Old 06-07-2014, 04:40 PM
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You didn't mention a budget. One full range speaker might do it. This one is expensive but can do the job

http://jtrspeakers.com/home-audio/noesis-215rt/

Edit. Sorry just noticed you spec'd cm not inches. The jtr is too big.
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post #4 of 9 Old 06-08-2014, 01:26 AM - Thread Starter
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Thanks, Bill. I thought the limit for the directional part of the sound was higher than that. Just goes to show how much I know... Maybe I will have to resort to my very labour intensive plan B, which is to isolate the ceiling speakers completely from the rest of the cabin, by building a sound dead box with two or even three layers of fibre gypsym over the ceiling of the room, hung up in and at the same time insulated from the beams with elastic glue. But since you know about this stuff, would splitting at 100 Hz and firing the sub either towards the wall or towards the cabinet (it has to be put between an outer wall and a cabinet) help on directionality? Also is there a point in making the sub with two different drivers, or is that just a waste of time?

Samps, yeah, if I had that many inches it wouldn't have been that difficult.

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post #5 of 9 Old 06-08-2014, 02:24 AM - Thread Starter
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Maybe firing the 8" woofer down towards the floor could help on this? Wouldn't that make it a bit less directional? Or am I trying to sway the laws of physics with a suggestion here? wink.gif

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post #6 of 9 Old 06-08-2014, 04:13 AM
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if using a bandpass box, you might be able to stretch it to around 150-200hz or so.

the acoustic low pass will attenuate much of the harmonic distortions that may give rise to localization.

bose did this with their "bass module". iirc, those little cubes covered down to around 200hz or so. probably not very well, but it did kind of work.

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post #7 of 9 Old 06-08-2014, 05:12 AM - Thread Starter
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Really? So that will be less directional than a sealed box? I've always prefered the sealed boxes because I like my bass dry and quick, not boomy. But if a bandpass can work, it's worth a shot, thanks! I should have the correct figures for the Alpine sub.

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post #8 of 9 Old 06-09-2014, 01:45 AM
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one of these for >100hz
https://www.parts-express.com/dayton-audio-pa200-8-8-pro-woofer-speaker--295-025

and one of these for <100hz
https://www.parts-express.com/dayton-audio-rss265ho-44-10-reference-ho-dvc-subwoofer--295-463

In a partition sealed box like you speak of would be pretty good.

and one of these to power it:
https://www.parts-express.com/behringer-nu1000dsp-inuke-1000-watt-power-amplifier-with-dsp--248-6702


It would be even better if you could build two of them, one for each front corner or each side of the TV.

Or you could just buy a buttkicker and call it a day. Or maybe do both?
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post #9 of 9 Old 06-09-2014, 06:59 AM - Thread Starter
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Interesting. But I live in Norway, so I can't get anything from the US soon enough. And Dayton Audio subs aren't sold here, I'm afraid. As fot the buttkicker it really isn't going to work, this is not a HT installation, it's a small common room without a TV and a couch. But that Behringer was pretty nice. I can get that for around $500 here, so I will consider that, thanks!

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