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Old 7th April 2014, 07:16 PM   #1
polop1 is offline polop1  United Kingdom
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Default Extreme near field Sub woofer.

Hello there,

If a subwoofer driver is run open baffle, or even no baffle, the room will be completely bass-less. Though in some vicinity of the cone the back radiation should not cancel out the front radiation. Making the baffle bigger and bigger will extend this critical distance until it is comparable to the wavelength of the bass, then it is a normal open-baffle speaker.

Would it work to take advantage of this? say you had a chair that had the sub driver mounted near the head of the listener. They should get clear sub-bass, though the room and the neighbors should be oblivious to it. Would be good for those of us that live in inner cities.

Am I missing something? Does this technique have a name already? any examples of this being done?
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Old 7th April 2014, 11:45 PM   #2
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Read this thread:

Nearfield sub response
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Old 8th April 2014, 12:42 AM   #3
polop1 is offline polop1  United Kingdom
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Thanks, I had read that, though I took the time to read it again and it is quite appropriate. Though these guys are using 'normal' subs, with boxes and the like. So this does decrease the amount of neighbor annoyance by letting you reduce the power in accordance with the inverse square law, though the discussion did not really include the use of a deliberately small baffled OB subwoofer, which should produce attenuation in a much sharper way than the inverse square law due to cancellation.

The question is would this arrangement have some other problem? perhaps the attenuation is so extreme that one would have to have your ear inside the concave of the speaker driver to hear the low notes. Maybe there is an issue with the fact that few drivers capable of decent excursion are suitable for open baffle usage, especially in the 20 - 60 Hz range.
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Old 8th April 2014, 01:18 AM   #4
tb46 is offline tb46  United States
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Hi polop1,

Your's may be a perfect application for the "Ripole", e.g.:

Ripole sub design?

How do you model a Ripole sub?

Drivers / parameters for ripole subs

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Old 15th April 2014, 05:44 AM   #5
badman is offline badman  United States
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No issue with output, really, since extreme nearfield lowers displacement requirements dramatically. What IS an issue is if you move your head. I had a sub about 8-10" behind my head and moving my head even slightly changed it because the distance can easily double if you lean forward, sit another seat over, or halve, if you lean back. I went back to 2 locations (more would be better) since I can't accept "head in a vice" speakers.
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Old 18th April 2014, 02:51 PM   #6
polop1 is offline polop1  United Kingdom
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Yes I am coming to the conclusion that this was not a good idea myself. Lots of expense for 1 cubic foot of bass. Though I am still curious. What about a more traditional subwoofer, built into the bass of the listeners chair. Perhaps in a bandpass alignment so that the output is only out of a port. This port can then be made quite close to the listener, up the back of the seat.

This arrangement should be able to give strong bass to the listener without annoying others. Also it would double as a normal sub if placed off to the side and turned up. Any thoughts?
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Old 18th April 2014, 04:08 PM   #7
DUG is offline DUG  Canada
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Since bass is (relatively) non directional why not mount it above your head.

Leaning forward will not be as much of an issue but just don't stand up.

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Old 18th April 2014, 05:02 PM   #8
polop1 is offline polop1  United Kingdom
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I think mounting a 10 inch+ driver above ones head is a sure fire way to get a ticket to an asylum. :P. Upward firing ports around ones waist would mean that the distance to ears should be pretty constant with minor fidgeting. Since this would be for one seat moderate listening, extreme EQ making the extension very deep could make for a very fullrange one seat system in my opinion.
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Old 19th April 2014, 08:27 AM   #9
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Bass horns and seating...
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