Loss of bass with reversing of box. HELP

Qpizzle
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94 civic sedan

alright, heres a summary of whats goin on. I got a nice mdf dual 12" box, and when i initially set up the system, i had the box facing the rear. (the subs and port were facing the back of the car)

i kept it like this for several months, and i was satisified with the "loudness". bass would lessen when the back seats were up, and when i would fold them down, it got real loud and i understood it had more room to vent, making it louder.)

so i figured, if i was to turn my box 180 degrees, facing the back seat, and facing me... it would be much louder, as i would now be in the direct path of the subs. turns out this isnt true at all.. it sounds like ass now, and has no bass whatsoever. almost as if the subs arent even on (they are, and yes, everything is working properly) so i am basically in need of an explanation as to why there is practically 60% less bass/loudness as before. I think using the trunk as a convection for air or something may effect it. but please, explain this... as i am pissed off that i now have to spend another 2 hours, disconnecting/draining cap, unscrewing amps, unconnecting everything else, taking box out,and rotating it back to normal... then replacing everytihng. :x

 
Almost always the bass will be amplified with the reflection off another surface, which in your case would be the inside of the trunk lid. This is why hatchbacks are usually louder, because they have a window on a good angle to reflect the bass off of. Now, in some cases, though, such as mine, I lost a LOT of output when I had my box facing rearward, simply because I lost so much air out of my non-deadened trunk. (5 dBs JUST from turning the box around was gained.) This is why you see many cars with the subs facing the rear, as it usually is louder, unless the output is too great for the trunk to contain it well enough.

And also, if you do not have fold-down rear seats facing the box forward usually is not a good idea.

 
Bass is all about air pressure. When the sub moves, it only displaces a certain ammount of air, so in order for the pressure around the box to be increased, it needs to be in a place w/ a smaller volume (i.e. trunk). When it is facing you in the cabin, the sub is unable to pressurize the air as well because there is much more volume.

 
my rear seats DO fold down. and i just tried it with them down, subs firing forward and it sounded like ass... i guess i just gotta turn the big ass box around again :X.

 
When a sub hits the lower Hz (bass) tend to sneak around the back of the sub. That is why subs are normally facing the back of a car. The upper Hz tend to go stright out of the sub. This may not be completly right but it is what I understand about the actual phisics of subs.

Hope this helps explain some things...

Jon

 
would it sound like ass if the sub was facing up inside of the trunk???
It completely depends on the car, generally up in a trunk sounds like ass and causes everything to rattle. You have to just try all different setups in you car till you find the one that sounds best.

my rear seats DO fold down. and i just tried it with them down, subs firing forward and it sounded like ass... i guess i just gotta turn the big ass box around again :X.
Yes I know, that was my point. W/ the subs firing forward into the large cabin, there is too much air volume for the subs to pressurize to get good bass. Have them fire into the trunk where there is less air volume and the subs will have an easier time pressurizing it and making bass

 
my rear seats DO fold down. and i just tried it with them down, subs firing forward and it sounded like ass... i guess i just gotta turn the big ass box around again :X.
Sheeeeit. Put your back seat down and face the box backwards, you'll go deaf. I've done it like that plenty of times, it's is RIDICULOUS.

Though it is still more than enough faced backwards with my backseat up.

 
Bass is all about air pressure. When the sub moves, it only displaces a certain ammount of air, so in order for the pressure around the box to be increased, it needs to be in a place w/ a smaller volume (i.e. trunk). When it is facing you in the cabin, the sub is unable to pressurize the air as well because there is much more volume.
This would make sense if he were listening from the trunk, but since he is in the cabin of the car, the only pressure change he will hear is that which takes place in the cabin.

Rear firing the subs allows the subs to basically corner load off the rear wall of the trunk. Since every model car and every sub system are different you can't make a blanket statement that addresses all cases of which way to aim the subs. Results of corner loading vary greatly depending on the sub and box and the environment they are playing in.

 
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Qpizzle

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