# Sub firing direction make difference on db meter?



## trunks9_us (Oct 25, 2007)

If I was to want to get my car metered would it give me different results to have the subs fire to the trunk or fire forward or does it not matter at all?


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## lovenlife (Feb 3, 2008)

Hope this helps


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## MadMaxSE-L (Oct 19, 2006)

It has been my experience that, in a trunk car with back seats, subs facing rear as far rearward as possible seems to get the most output in the front seats. If you start taking out backseats or putting the rear of the subs in the trunk and the fronts in the cabin and sealing the two off, that is a different story.


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## JoshHefnerX (Jun 13, 2008)

Yes it probably will. My experience has been that w/ sedans you want to fire fwd and thoroughly seal the cabin from the trunk.


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## goodstuff (Jan 9, 2008)

My sub is louder in the trunk facing away from me than facing foward, eithre in the back seat or in the trunk. My guess is it has something to do with cabin gain but I can't explain the science behind it.


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## cubdenno (Nov 10, 2007)

There is the potential to have wave cacellation. So the orientation of the box can make a huge difference. Even from one car to another or sub to sub or enclosure type. The way I did it cheap was a radio shack SPL meter and a 8p0 hertz to 20 hertz sweep. Set your radio to a specific medium volume to be tried again and again. 

Set your subs in the first orientation get in the car and play the sweep a couple of times. Write down your max reading.

Switch your subs to the next possible orientation. Again run your sweep Write down the results.

This is an oversimplified way to find out which orientation play loudest in your car. It's not 100 % but gets you close.


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## MCarmer (Apr 6, 2009)

old thread im bringing back to life only because of certain things said above about it being in your experience louder facing forward with seats down and sealed off from the trunk.

What kind of experience do you have in this? Has anyone seen tests proving this?

Im debating to aim sub forward fold the rear seats down and have Aero ports firing through the 6x9 holes above the box so they fire off the rear glass of the car. 

Do you think that will yeild better results then aiming the box to the rear of the trunk?

Id love to see a write up on someone testing that, or id love to see someones setup they are running like what i described im thinking of doing.


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## cubdenno (Nov 10, 2007)

What you are asking is truly dependent on your car. It really is a trial and error test. You can sometime often gain output if you have the sub facing toward the rear of the car. Also distance from the rear can help or hinder. All this is due to wave cancellation. Having the port on the right or the left can have differing results at a specific point in the car. I have a bandpass enclosure that if the port is on the right, it is louder at the driver side headrest than at the passenger and vice-versa. the key to remember is you are placing an enclosure inside an enclosure (your car). my set up obviously moves more air when the seats are down. It is louder as well. But only by a bit. Hope this helps.


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## JoshHefnerX (Jun 13, 2008)

When you seal the trunk from the cabin, you're making a smaller pressure chamber. When you seal the trunk from the cabin, you're also taking that energy that would normally be shaking the trunklid, spoiler, license plate ect and directing that into compressing the cabin space. But it really does have to be sealed if you go that way. As always each car is different and you'll really need to experiment to get the optimal position.


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## chad (Jun 30, 2005)

Search sub facing.


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## ChrisB (Jul 3, 2008)

There was an SPL competitor on one of the other forums that I am a member of who lost just over 3dB by going direct fire into the cabin versus facing it backwards. He also complained that he lost the bass you can feel.

Oddly, since his Civic coupe resonated in the 50 Hz range, I wouldn't have thought the lower sub bass frequencies would have been lost.


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## MCarmer (Apr 6, 2009)

so you saying he sealed it off from the trunk? or that he had it facing forward with seats down and not sealed off from trunk?

If it wasnt sealed off from the trunk i would think that wouldve been obvious, i think so many people know the general aim to rear when not sealed off but im wondering about sealing off from the trunk aiming forward and aiming ports either forward with sub or aiming through the rear deck, and sealing the rear deck off so no air can go around the ports or other areas of the deck.


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## Oliver (Jun 25, 2007)

trunks9_us said:


> If I was to want to get my car metered would it give me different results to have the subs fire to the trunk or fire forward or does it not matter at all?


Meter it and then turn the sub and meter it again


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## ChrisB (Jul 3, 2008)

MCarmer said:


> so you saying he sealed it off from the trunk? or that he had it facing forward with seats down and not sealed off from trunk?
> 
> If it wasnt sealed off from the trunk i would think that wouldve been obvious, i think so many people know the general aim to rear when not sealed off but im wondering about sealing off from the trunk aiming forward and aiming ports either forward with sub or aiming through the rear deck, and sealing the rear deck off so no air can go around the ports or other areas of the deck.


Nope, he completely sealed it off from the trunk via a baffle board AND he went through great pains to seal the deck and wheel wells. He was extremely disappointed to lose over 3dB on the termlab with the same exact setup with the only difference being his direct cabin fire with the rear seat backs down versus facing the trunk.

On the other hand, the direct fire method into the cabin eliminated the trunk, spoiler, license plate, and rear deck plastic rattle that he had when the subwoofer was facing the rear of the car.


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## MCarmer (Apr 6, 2009)

06BLMUSTANGGT said:


> Nope, he completely sealed it off from the trunk via a baffle board AND he went through great pains to seal the deck and wheel wells. He was extremely disappointed to lose over 3dB on the termlab with the same exact setup with the only difference being his direct cabin fire with the rear seat backs down versus facing the trunk.
> 
> On the other hand, the direct fire method into the cabin eliminated the trunk, spoiler, license plate, and rear deck plastic rattle that he had when the subwoofer was facing the rear of the car.


Yea youd think that sealing it off from the cab would only make it louder and more pressure but it doesnt always work that way, and its probably alot more trouble than its worth doing that.

Guess i gotta mount my amp behind the box behind between the back seats and the back of the box.

Thanks for the information i appreciate it. Ive heard mixed reviews on aiming forward but mostly because i dont think that half the people when aiming forward seal the trunk off.


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## Stryker27 (Jul 10, 2009)

I have mine forward facing in a 96 tbird. Completely sealed 4.2 cuFT ported box at 37.5 Hz using 15's. it's sealed off from trunk using expanding foam, fatmat and sounds great. I've never had the chance to have it metered but the same setup idid 146.3 years ago at a contest with less total watts. I would have to say it's louder than when the subs faced backwards toward rear of the car.


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