I found this interesting...

[Bryson]

I thought maybe some of you might enjoy reading this, or learning something from it

http://installer.com/tech/aiming.html

edit: it's about box positioning and firing direction

[808BMW]

Seen it before, just made me say "So, basically choose what sounds best" :P
At least I can laugh at people who tell me that it lets the wave develop, with the extra 2 feet :P

[BMW BMXER]

Ive posted that here a few times.

[Bryson]

:oops:

[C ///M]

So subs facing toward the rear of the car really is better? Interesting.

I read a lot of that, but could someone explain to me in short why exactly a sub facing towards the rear of the car performs better?

[DSchultz325e]

In summary I found:

1. box at front of trunk speakers aiming forward or up through the rear deck = poor in car bass response, much better with trunk open.
2. box at front of trunk speakers aiming backward = better in car bass response by far, slightly better with trunk open.
3. box at back of trunk with speakers aiming forward = better in car bass, no difference with trunk open.
4. box at back of trunk with speakers aiming backward = best in car bass response and gets less bass with trunk open.
Kiss my ass, bitch!

If you want to understand it, you've gotta read the diagrams. He shows how the sub at the rear facing the rear produces the sine waves that don't phase cancel each other out. They actually reinforce each other.


This shows that if you continue past the trunk, the waves are pretty much exactly in phase, resulting in a better open-trunk bass response. However, the waves inside the vehicle are almost directly cancelling each other out.


This one shows the waves are nearly overlapped in perfect phase, thus they reinforce each other very well inside the vehicle. It's kind of hard to see, but if the waves continue past the trunk, they are about as much out of phase as the in-car waves on the upper diagram. That's why the open trunk bass response is shitty.

He doesn't end up with "Do this", he just explains what method will produce what kind of results, depending on how you want to demo your bass.

[StereoInstaller1]

oh boy, here we go again...

Ok, kids, lets consider one thing. None of those installs has the one nesessary ingredient

I will say this again....THE ENTIRE OUTPUT OF THE BOX MUST BE SEALED INTO THE CABIN!

This is what makes mine, Jordans, and ALL other good sounding boxes perform (especially in e30's), the fact that there is no practical difference between the primary wave and the reflected wave. he also has not taken into account corner loading, a well known acoustic principal that has been documented since the 1940's.

On the test in the SUV, ALL of the gain he saw was caused by corner loading. Read Allison's work on this phenom if you can find it. I did, but that was 25 years ago, back when I was a member of the AES, Audio Engeneering Society.

Once again...firing backwards is better for boom. This is also the domain of lazy fuck installers, unwilling to properly seal the box into the car. The Neon install certainly wasn't sealed into the car!

Richard Clarke and David Navonne did TONS of research into this shit back in 1983...none of the shit on that guys page is even kind of new, nor is it even remotely complete. Ever hear of "Trasnfer Function"? Those guys invented it!
This phenomenon is well documented, far past what a couple of spectrum analysers and a cheap ass PC. To properly analyze this phase reversal, FFt woulld be necessary. FFt is damn expensive, an adequate mic can run $10,000.

If you want the best sound AND the biggest boom, you must do the necessary work to seal the output into the car. If you drive a Jetta, or some other 2 door car with a sloppy ass rear deck, you must seal the rear deck AND the side panels (thus 4 doors, having no side panels don't need this)

If ANY bass energy makes it into the trunk, phase reversal causes cancellation, then corner loading causes a 6db gain, making the cancellation worse. Often the reflected wave is actually louder than the primary wave.

So yes, lazy fuck installers, for your shitty work, firing the box backwards is better.
IF you get some skills, and build HUNDREDS of boxes, you may some day understand.

In the meantime, have fun!
Luke

[C ///M]

oh boy, here we go again...

Ok, kids, lets consider one thing. None of those installs has the one nesessary ingredient

I will say this again....THE ENTIRE OUTPUT OF THE BOX MUST BE SEALED INTO THE CABIN!

This is what makes mine, Jordans, and ALL other good sounding boxes perform (especially in e30's), the fact that there is no practical difference between the primary wave and the reflected wave. he also has not taken into account corner loading, a well known acoustic principal that has been documented since the 1940's.

On the test in the SUV, ALL of the gain he saw was caused by corner loading. Read Allison's work on this phenom if you can find it. I did, but that was 25 years ago, back when I was a member of the AES, Audio Engeneering Society.

Once again...firing backwards is better for boom. This is also the domain of lazy fuck installers, unwilling to properly seal the box into the car. The Neon install certainly wasn't sealed into the car!

Richard Clarke and David Navonne did TONS of research into this shit back in 1983...none of the shit on that guys page is even kind of new, nor is it even remotely complete. Ever hear of "Trasnfer Function"? Those guys invented it!
This phenomenon is well documented, far past what a couple of spectrum analysers and a cheap ass PC. To properly analyze this phase reversal, FFt woulld be necessary. FFt is damn expensive, an adequate mic can run $10,000.

If you want the best sound AND the biggest boom, you must do the necessary work to seal the output into the car. If you drive a Jetta, or some other 2 door car with a sloppy ass rear deck, you must seal the rear deck AND the side panels (thus 4 doors, having no side panels don't need this)

If ANY bass energy makes it into the trunk, phase reversal causes cancellation, then corner loading causes a 6db gain, making the cancellation worse. Often the reflected wave is actually louder than the primary wave.

So yes, lazy fuck installers, for your shitty work, firing the box backwards is better.
IF you get some skills, and build HUNDREDS of boxes, you may some day understand.

In the meantime, have fun!
Luke

Ah thanks!! I remember a lot of your posts but I just plain forgot when i was reading all that stuff.

[Bryson]

I think that he did mention that you need to seal off the box from the trunk completely at some point, but he was merely documenting the general idea for people who have sealed enclosures that they just tossed in their trunk.
Most people don't have the time/money to put into their car to completely seal the woofer/port into the cabin of the car, so I think that this article applies to a greater percentage of the people with aftermarket woofer systems.
In no way am I undermining what you said, but the level that you are speaking on is much greater than the level that most people are playing on

[DSchultz325e]

Yea this article kinda only applied to sealed boxes...I don't see what is "lazy" about wanting a sealed box, either. :? It's a much more cost-effective solution that anyone with half a brain for woodshop can do.

[StereoInstaller1]

Dshultz, the discussion was NOT about sealed vs. ported or any other box design issue, it was about getting all of the bass into the car...sealing the entire output into the cabin of the vehicle.
cool? nothing to do with either sealed or vented, but just so you know, vented is far more diffucult to design and build, but that is another issue for another post.
Luke

[ryan_george]

What about bandpass boxes? It seems like it would be much easier to ensure that all the output would get to where you wanted it. I'm far from being an audio expert, but I was just curious.