Subwoofer Firing Direction

Groverkb · 05-30-2009, 09:15 PM

Anyone have any reasoning/theory/calculations on which is the best direction to point a sub in the trunk? I've seen them pointing forward through the ski hole, and pointing rearward towards the trunk and was wondering if anyone has looked at the difference the two methods make. Thanks in advance.

Drakos · 05-30-2009, 11:30 PM

Bass is multidirectional so it doesn't make that much difference. I would recommend that you point them towards the back seat though. If they are powerful subs, it would rattle the trunk and the licence plate.

retrodrive · 05-31-2009, 01:51 PM

The way your box faces makes a huge difference. Just build a box, face it different directions and listen to what sounds best. I havent played with e9x BMW trunk to get the best box position quite yet.

Tegs4tugs · 05-31-2009, 10:52 PM

Quote:

Originally Posted by Drakos

Bass is multidirectional so it doesn't make that much difference. I would recommend that you point them towards the back seat though. If they are powerful subs, it would rattle the trunk and the licence plate.

+1

If you hve powerfull subs point them to the rear seat preferanly through ski hole, its much clearer and less vibrations.

kaigoss69 · 06-01-2009, 09:45 PM

It depends. In a rear-facing set-up much has to do with the wave length of the bass notes in relation to the physical dimensions of your vehicle. The "transfer function" will give you a "boost" in bass response, if you position the box correctly. Slide the box back and forth in the trunk and listen for the best response, in therms of SPL, if that's what you want. Some people have even achieved best results by aiming the box toward the rear corner of the trunk, but it all depends so just experiment with it. generally speaking, you are most likely to get the best result with the box rear-facing, placed as far toward the front of the trunk as possible (against the back of the seats). With a rear-facing set-up you will pick up a lot of rattles, as the sound waves bounce around a lot off the walls inside the trunk.

A forward-facing set-up is generally better in terms of SQ as you will have less reflections and rattles. However, the output will also be less. That is, unless you have a ski hole in which case you can slide the box against the back of the seats and have the subs "firing" through the the ski hole. I have personally tried this but it sounded better facing the subs toward the rear. To take it a step further, you could seal off the sub box against the back of the seats, so that the subs would directly pressurize the cabin. In that case you are virtually eliminating any back waves from bouncing around in the trunk and you can have the front waves going directly into the cabin. While such a set-up will probably sound better in terms of having a cleaner sound with less vibrations, I still think that in most cases a rear-facing set-up will produce more SPL.

05-30-2009, 09:15 PM	#1
Groverkb New Member 3 Rep 6 Posts Drives: 2008 E92 6MT Join Date: May 2009 Location: Peoria, IL iTrader: (0)	Subwoofer Firing Direction Anyone have any reasoning/theory/calculations on which is the best direction to point a sub in the trunk? I've seen them pointing forward through the ski hole, and pointing rearward towards the trunk and was wondering if anyone has looked at the difference the two methods make. Thanks in advance.
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05-30-2009, 11:30 PM	#2
Drakos Lieutenant 70 Rep 534 Posts Drives: 2022 G42 M240i Join Date: May 2009 Location: Canada iTrader: (1)	Bass is multidirectional so it doesn't make that much difference. I would recommend that you point them towards the back seat though. If they are powerful subs, it would rattle the trunk and the licence plate.
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05-31-2009, 01:51 PM	#3
retrodrive Lieutenant Colonel 152 Rep 1,938 Posts Drives: 335i Join Date: Jan 2007 Location: Irvine, CA iTrader: (8)	The way your box faces makes a huge difference. Just build a box, face it different directions and listen to what sounds best. I havent played with e9x BMW trunk to get the best box position quite yet.
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06-01-2009, 09:45 PM	#5
kaigoss69 Brigadier General 301 Rep 3,969 Posts Drives: '08 335i Join Date: Jul 2008 Location: JAX iTrader: (6)	It depends. In a rear-facing set-up much has to do with the wave length of the bass notes in relation to the physical dimensions of your vehicle. The "transfer function" will give you a "boost" in bass response, if you position the box correctly. Slide the box back and forth in the trunk and listen for the best response, in therms of SPL, if that's what you want. Some people have even achieved best results by aiming the box toward the rear corner of the trunk, but it all depends so just experiment with it. generally speaking, you are most likely to get the best result with the box rear-facing, placed as far toward the front of the trunk as possible (against the back of the seats). With a rear-facing set-up you will pick up a lot of rattles, as the sound waves bounce around a lot off the walls inside the trunk. A forward-facing set-up is generally better in terms of SQ as you will have less reflections and rattles. However, the output will also be less. That is, unless you have a ski hole in which case you can slide the box against the back of the seats and have the subs "firing" through the the ski hole. I have personally tried this but it sounded better facing the subs toward the rear. To take it a step further, you could seal off the sub box against the back of the seats, so that the subs would directly pressurize the cabin. In that case you are virtually eliminating any back waves from bouncing around in the trunk and you can have the front waves going directly into the cabin. While such a set-up will probably sound better in terms of having a cleaner sound with less vibrations, I still think that in most cases a rear-facing set-up will produce more SPL.
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