TJM12

That is really wierd. I would maybe test out another sub setup, like maybe a friends, to see if it is definatley the subs and not some other issue. Maybe the amp is getting to hot and decreasing output or going into thermal shutdown?

medic_23387

Ok it's not the phase and not getting hot. It will do it as soon as you turn it on with cold amp. It has to be some sort of electrical prob I just don't know what. The speakers are loosing power. I can put down the back seat and it still does the same thing. I can sit in the car and watch the subs pounding. As soon as the trunk is shut I can see the speakers stop moving.

TJM12

Maybe somehow the closed trunk is causing it to be like pressurized and stopping the speaker cones movement?

medic_23387

Can't be with the back seat folded down it is not pressurized. Man I was hoping someone had had this prob.

TJM12

Very curious about this? What if you close the trunk but roll down the windows?

Trickedjk

No it's something to do with the frequency the amp is sending the subs. I know that much. U sure a wire is not pinched or a sub isn't blown? Sometimes a wire can fold itself if it's not pulled tight and a sub can partially blow and work in certain situations and not work in others. Do u know how to check your subs to see if they're blown?

Also your front cone of your sub can come unglued making a very loud vibrating noise when it's in an open area, and a very faint booming when it's in a closed area. Do u know how to check that too?

EagleJeeps

Hmmm, maybe you just need more vented space. Speakers don't work well in concealed spaces, its like the difference between a sealed box and a ported box. Idk can you post some pictures of the setup, I would love to see how there positioned that could also play a big part in this. I have done research back when I was is college and when two speakers facing eachother out of phase not only did you not hear anything but made the woofers move very little because of contradicting forces. If you checked for phase and say its not that, it leads me to space volume and placement. Which can maybe cause the same type of effect. I could be completely wrong just trying to think of every possible sinareo.

imedic31

I'm no expert on wave pressures created by subwoofers (Paramedic by trade) but I've installed dozens of systems in all types of vehicles. You may have mentioned this before in a post, but I'm on my last night shift & I can't remember crap...lol

Newer vehicles have more damping material and / or better door gasket seals, which reduce wind noise, road noise, and drivetrain noise, giving the consumer the 'Impression' of a higher quality vehicle. Every opening in the vehicle, right down to the wire gromets thru the fire wall, down to the rear tail light access will probably have some sort of rubber gasket to reduce the noise that reaches the operators
cabin.

Audio is reproduced by the movement of air waves at certain frequencies. (I'm positive you all know this already..lol)
Bass specifically operates in the lower frequency spectrum, with an elongated sine wave pattern. In order to create the long
flowing airwave, the sub cone pulses to move adjacent air. If the air has no where go, (as in a sealed compartment in the vehicle), it cannot propagate the correct amplitude (loudness). Anything that does move, will immediately be hindered by the closed
environment (causing your sub cones to be restricted in their movement), causing a severe dampening of the sub output.

By opening the trunk / hatchback, you are immediately removing a large barrier, allowing a lot more air to move freely, which allows
a greater efficiency from the subwoofer to reproduce the waveforms. (Your cones are free to move more, which increases the loudness of the signal reaching your ears.

This can be overcome by stronger amp/sub combo (basically using brute force to propagate the sound wave), ensuring the box is the
correct dimensions for the subs utilized (making it more efficient to operate, which makes it louder), or by utilizing a different type of sub enclosure (sealed, ported, bandpass, etc).

Easy way to test this:
Select a good tune to listen too with some good rolling bass.
Start at moderate sound level, all windows and doors, etc closed.
Increase the airspace by first opening all the windows. (you stay in the same spot - have a friend perform the opening, etc)
You should notice an increase in the volume and depth of the bass.
open both (or all) passenger doors. Again, this increases the available airspace for the waves to propagate without them competing with other waves. Things should get louder / deeper again.
Now have them open the trunk/hatch. This will completely free the generated waveforms (from the subs) to propagate without
impedance / cancellation from other waves.

This air movement is the reason your stereo sounds better in the summer, with the windows rolled down (more airspace).

Hopefully that helps somewhat. There is a really good explanation of this on the net somewhere. I'll try to track it down and post in this thread.

---adding URL
OK. This isn't the one I wanted to find, but it should work. Hope something helps

2nd Edit---------
OK I think I found the right one. Cheesy site, but good info.
http://www.mobileinformationlabs.com...s_cancel_1.htm

Cheers!

grandpa jeep

Are the subs facing Toward the driver ?

Jnicewvu

I have heard of this happening when the box is too small for the woofers.