Print Page | Close Window

Sound is better when trunk is open

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=35416
Printed Date: June 10, 2024 at 11:16 PM


Topic: Sound is better when trunk is open

Posted By: pimpincavy
Subject: Sound is better when trunk is open
Date Posted: July 11, 2004 at 4:42 PM

I just installed my system yesterday. When the trunk is open the bass inside the car is much louder and clearer then when the trunk is closed. Is this normal?? The subs are in a sealed enclosure and they are facing towards the front of the car. Should I turn the subs around??

-------------



Replies:

Posted By: Teamrf
Date Posted: July 11, 2004 at 5:04 PM
Turn the subs towards the trunk not the inside.

-------------
~The Rookie~
Rookie of the year that is...
Don't let the smoke out of your equiptment..it doesn't go back in.




Posted By: lensam69
Date Posted: July 11, 2004 at 5:48 PM
Could it be that when it's closed the metal and other parts rattle too much?

If that's the case you need some dampner.

-------------
forbidden wrote:
Wrong advice young grasshopper, go back to square one and do not pass go.




Posted By: stevdart
Date Posted: July 11, 2004 at 6:14 PM

I just installed a pass-through opening to the cabin in my rear deck today.  I get a harder hit from the sub now inside the car.  My bet is that the trunk is a bit too isolated from the cabin in your car, and that you are just feeling the frequencies instead of hearing them.  It depends on your crossover settings and what you are expecting out of the sub range.  If it is set fairly high, up to about 120 to 150 Hz, you will want to have a pass-through type of opening into the car.  If the sub, though, is set to about 80 Hz, and your mid-bass drivers in the car pick up from that point, there should be no difference, as all you will hear are the frequencies that you feel more than you hear.

I will also guess that you are hearing reflective sounds with the trunk open, the sound waves reflecting off of nearby surfaces and then sounding louder as the long sound waves develop to their strongest point, which is several feet.  The sound then enters through the open windows.  Some repositioning of the sub box in the trunk might help the waves develop into longer waves, maybe bouncing a little differently in the trunk.  When I built my sub box, I designed it to fit into the trunk only one way, firing toward the middle of the trunk and towards the far side.  I got lucky, because it sounds good and loud.  If I were having the situation you are, I would have to build a different enclosure.

Also, try using some polyfil in the enclosure, as it will change the waves somewhat.



-------------
Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: xtreamcc
Date Posted: July 11, 2004 at 7:45 PM
dig, the crossover should have nothing to do with that unless its just totally off for the subs. TeamRF is right, I know for a fact that back waves will cancel out frontwaves if the waves are too far out of phase. You need to face the subs back into the trunk in order to better align the phase of the sound waves.

This website will better explain and show you exactly what I'm talking about

Aiming a Sub

-------------
"Shiny chrome when used in conjunction with bikini models is particularly effective in inducing brain deficit disorder"

02 Jeep Grand Cherokee

Monster System on its way.




Posted By: aggie altima
Date Posted: July 12, 2004 at 5:06 AM
Referring to the link suggested by xtreamcc (which I have read numerous times before and influenced me to place my subs where they are now), with the trunk closed, the rear waves were interacting with the front waves, which most likely was causing cancellation. The bass more than likely sounded louder when you opened the trunk because it let the rear waves escape out of the trunk, preventing the interaction with the front waves, and thus preventing cancellation.

If you wanted to properly have the enclosure facing forward, your best bet would be to completely isolate the face of the enclosure (just to be exact, the face with the subs) from the trunk. That is, have the face of the box directly behind the seats, and create a wall (usually using fiberglass) which meets the face of the enclosure around the subs, and blocks any air from the trunk behind the face from entering the cabin (including any holes in the rear deck). With this type of enclosure, opening and closing the trunk will have no affect on the sound inside the cabin.

Any corrections, please make them, I haven't got much sleep and I feel a tad bit delirious.

-------------
Jon
Don't like rockford subs? Then don't look at my car =)





Print Page | Close Window