525iSE

Please help on getting sound from the "soundproof" trunk in to the car more. I have no rear folding seats or anything. Please help me.. I'm going crazy..

ronald_adi

What kind of base system do u have in the trunk? Size? Make? Does it have a AIR PORT or fully insulated box?

525iSE

My subs are Kicker CVR 12. and my amp is rockford fosgate 800-2. Its a fully insulated box.

ronald_adi

ok, well kicker and RF's are good. i dont know the CVR 12, but i assume its a 12inch? Thats rather big.

In ex my e39 (previous 5 series), I had a kicker Solo baric 8inch (and later changed to 10inch) placed inbetween the rear armrests.

The pic above shows the 8inch sub. I played it at 1ohm and the sound was truly wicked! Base rocked the whole car!

i changed later to a 10inch at 2ohm (the lower the ohm the more power). Sound was also very good but not as good as the 8inch at 1ohm.

My feeling is that your 12inch will not fit inbetween the arm rests, but please check. You may need to get a 10inch or an 8inch sub. If supplied by the right amp, the smaller subs give deeper more direct base that the bigger ones - which give lower flatter responses.

Your car - if like mine without the foldable seats - doesnt have a metal frame behind the rear seats. Its some form of hardened cardboard type thing. u would need to make a hole in this and strengthen it with wood. Your local stereo installation shop can do this for u within an hour. Dont try to do it yourself unless u really know what u r doing.

Good luck and let us know how it goes.

Ronald

525iSE

Problem solved today!! Shop called, "The Voice" in thailand, one of the greatest shop i've been to. The owner knew some reali good tricks. Well he reversed positive and negative outputs into the subs which shifted the sound forward reali well. He also tuned my amp, and now i'm satisfied with the sound. He recommended a "Phase Shifter" which will accurately direct the sound. I'm giving the phase shifter a try this weekend, he guarantees that i'll be reali satisfied with the shifter. So i'll give this phase shift thing a try because i've never even seen it before.

subterFUSE

Your problem sounds like it was being caused by phase cancellation. Essentially your subs were creating a dead spot where you were sitting. By wiring your subs in reverse, he effectively flipped the phase by 180 degrees.... and moved this dead spot.

A phase shift controller is a signal processor which gives you even more control over this same concept. It is designed to help correct "less-than-perfect" speaker placements. For example, a tweeter mounted near the side view mirror, and a midrange mounted low in the door. Typically, this type of setup is not ideal, and phase alignment helps improve the sound.

525iSE

With the phase shift, will it tremendously make the sound come into the car more? I have a feeling that its not the imperfection of the sound, its more of it not getting into the cabin. Please comment, subterFuse. TIA. To me even with the phase shift, the sound will still remain in the trunk whether its pointing the sound anywhere. Hope you know what i'm trying to get at here. thanks.

subterFUSE

If phase cancellation is not the problem, then the problem might be improper venting in the trunk.

Check out my post in this thread: HERE


I would like for you to conduct a simple test for me. It may help distinguish what the problem is.


Please go to your car, and open the trunk lid. Then go in the car and start the stereo. Play the stereo at a loud, but comfortable listening level. Pay attention to the bass response, in particular.

Next, close the trunk lid.... and continue listening to the same music at the same volume. (It is best to have someone else close the trunk while you remain in the car) If the trunk venting is the problem, you will notice a huge drop in bass response when the trunk lid is closed.

Do that test when you get the chance, and let us know what happens.

525iSE

I did the test for ya subterFuse. When i open the trunk, the bass sounded less deep, but when I close the trunk, it sounded deeper and "boomy". I think its beacuse of the phase cancellation tho, thats the reason I can hear the subs.

subterFUSE

OK.... thanks for doing that.


If you are getting more bass when the trunklid is closed, then the problem is not air pressure inside the trunk.

What is happening is that you are getting some wave interference patterns which develop when the bass is reflecting off the rear panel of the trunk and back towards the front of the car.

This supports the phase cancellation theory.


There are a few things you can do to improve the bass response in your car:


1. The phase shift controller as recommended before can be used to help tune your setup.

2. An equalizer would also be helpful.... or a bass enhancement controller like the AudioControl Epicenter.

3. I would also recommend installing a lot of dynamat material in the trunk, to reduce rattles and improve the sound dampening.

4. I would also look into your crossover settings. If your bass is boomy, sometimes this can be improved by lowering the high-pass filter setting. Personally, I prefer my subwoofers to play only very deep bass... 80 Hz is about where I like my high-pass to be set.

5. Ask your install shop if they have an RTA meter. They should be able to run some test signals and determine which frequencies are cancelling out, and then tune the system accordingly. Tuning of this type requires a high-end equalizer... like a 30-band 1/3 octave EQ.