I came up with a cheaper way to increase bass response from my rear sub ... by adding some foam padding behind my rear panel speakers.

Although I had originally set my high pass filter to 150HZ, I did not realize that there was still some minor phase cancellation occuring between the rear panels and my sub.

I placed some foam padding in the cavity behind the speakers in the panel and a small strip of foam between the edge of the cavity and the vent area alongside.

This does two things, first, it absorbs the back waves and second, partially seals the cavity from the rest of the compartment.

When I powered up the system I thought that I had turned up the BBE one more notch on the Alpine headunit. But that was not the case at all.

Inexpensive solution that yields more bass.

 

Thanks for the heads-up. I am planning on putting in some panel speakers over the next couple of weekends.

 

I guess I am the only one who has experienced bass phase cancellation?

 

I think most of us have no idea what you just said

I was kinda mad this morning when my particle flow was 0.003 delta off from the flux field but I compensated properly.

 

It's particles of a sort, really sound waves. If the bass waves from your panel speakers are not in phase with the bass waves coming from your sub, you will experienced decreased bass. The two will create sound waves that cancel each other out.

The term as I learned it is phase cancellation. You can manipulate your high pass filters to try an eliminate overlapping frequencies, which is one way. That is what I did with my system.

Another way is to isolate the two, which is what was done using the foam. If you want to get fancy and have some cash you can do this with dynamat, too.

By eliminating virtually all of the cancellation you will experience louder and deeper bass.


So I would say don't get mad. Just isolate.

 

No, we all experience it every day we listen to music, but most of the time never realize it. For example, in SUVs and cars, the ideal position of the subwoofer is as far back against the rear hatch as you can get it. It will net you the most amount of bass because of the least amount of phase cancellation.
http://www.teamrocs.com/technical/pages/aiming.htm

We experience them at home too on our stereos. There will be nulls and standing waves that usually go unnoticed because it's always done it. Not until you eliminate them do people realize they ever existed.

 

Interesting... I might have to try that!

I did notice that my bass response was significantly improved when I set my sub to reverse phase using my HU settings. I never thought my tiny rear speakers had that much of an effect...

A question: Will placing padding there decrease airflow going across amps mounted in the spare tire area?

 

I did not think that air flow would be a problem, because I keep the main vents, on the other side clear.

I have both my amps in the gas tank area and have not experience any heat related problems in almost two years.