Sealed, Ported, Bandpass, ABC, Dual-reflex? - Home Theater Forum and Systems - HomeTheaterShack.com

 
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post #1 of 4 Old 12-17-09, 07:54 PM Thread Starter
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Paul
 
Join Date: Dec 2009
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Sealed, Ported, Bandpass, ABC, Dual-reflex?

Hello...I'm just looking for some input on a subwoofer box I am about to build. It IS for the car (a van, actually) but my questions concern box types and response in general, so I thought I would get more feedback here.

I have a TC-9 motor and 15" 12 spoke frame that I plan on building with soft parts from David Moore at fixmyspeaker.com (PSI), so at the moment I don't have specs on the sub.

I have 16" x 18" x 50" to work with so room is not really a problem. I plan to power it with a class D amp in the 500 to 1000 watt range.

My questions concern the response of two types of boxes, ported and aperiodic bi-chamber (or a dual-chamber reflex enclosure) an example of which can be found here:
http://www.diysubwoofers.org/prt/dual_chamber.htm

The reason that I'm even considering the dual chamber box is a box I built for another vehicle a few years ago for two 12" subs. The face was angled and I cut the port on the inside straight, resulting in a lower tuning than planned. The lows were great, but the trade off was reduced output in the 50-60hz range. Because of this, it never sounded as loud to the ears as it was capable of.

For my new box, I still want the <30hz performance and the upper bass that sounds louder to the ear. So I'm thinking the dual tuning points of the dual chamber box might make this possible. My listening tastes range from classic rock to classical, and rap to jazz...a mix of everything. A middle ground between SQ and SPL is fine with me.

Any suggestions are welcome and feel free to ask questions about details I have left out.

Thanks,
Paul

Last edited by The Natural; 12-18-09 at 12:41 PM.
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post #2 of 4 Old 12-18-09, 12:39 PM Thread Starter
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Paul
 
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Re: Sealed, Ported, Bandpass, ABC, Dual-reflex?

Here's a pic of the design I am thinking of building...



Here's a link to it if it shows any more detail:

http://photos-d.ak.fbcdn.net/hphotos..._6271228_n.jpg
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post #3 of 4 Old 12-18-09, 01:32 PM
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Re: Sealed, Ported, Bandpass, ABC, Dual-reflex?

If that's what you want to try, go for it. I've never been overly impressed with the performance from that sort of alignment and it ends up working exactly like a 6th order bandpass, which makes the dimensioning super critical if you really want to "get it right" ... as is taking proper RTA readings in the vehicle to discover the "correct" tuning frequencies if you really want optimal results. Me, I am always happier with a simple vented enclosure. But like I said, go for it and let us know how it turns out!
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post #4 of 4 Old 12-18-09, 07:19 PM Thread Starter
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Paul
 
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Re: Sealed, Ported, Bandpass, ABC, Dual-reflex?

Thanks for the reply David. That super critical dimensioning is one of the things I am concerned about. I have been happy with simple vented boxes before, maybe I'll just stick to that.


I am considering rebuilding an Atomic APX 18 that I have laying around...I wish I could make up my mind.

If I go with a straightforward vented enclosure, are there any drawbacks or benefits of using a single 6" port as opposed to two 4" ports, since there is only a few square inches of difference in area?
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