Box positioning in trunk?

You are correct for your car and most sedans on the direction and location of your box. The window thing is kind of quirky. I've got much better bass on some cars when you crack a window open and on other cars it doesn't seem to make a differance. I always thought it had something to do with how airtight the car is. Any ideas guys?There is no such thing as free installation!

stevdart wrote: Does that make sense?

Yeah. But there have been times when I've been in my car and, with the windows rolled up, the bass sounds more compacted, and when they are rolled down, the bass seems to smooth out a bit (this is with the car parked, btw). I wouldn't say hit harder, just a bit cleaner, it seemed. Granted, since moving the box further back, this doesn't seem as noticable...maybe I was just lacking in trunk airspace, I don't know. Or maybe I'm losing my mind...

There are variables that must be factored in to understand why things happen. The reason that there seems to be more bass if the box if faced towards the rear of the car is that there is less cancellation of the sound waves. The sound wave bounced off the back of the car is different in length than the sound wave which travels from the box to the front of the car. If you flip the box to aim forward the length of the sound waves are nearly the same and tend to cancel each other out more. You would get the same affect if you hooked up a sub box and stuck it in the center of a room. If you moved the box to a wall the bass output will seem to increase. If you move to a corner it will increase it further. All you are doing is changing the wavelength of the reflected sound waves. Equal wavelenghts cancel each other out.   The next factor is that by turning the sub box to face a wall or back of the car, you load the front of the woofer. It is similar to putting the sub in a box. The box loads the rear sound wave from the woofer and acts like a spring. Loading causes the sound wave to be compressed.   The other large factor is the design of the box. Depending on whether or not the box is sealed, ported or a bandpass will affect the bass. Certain designs are better suited for different vehicles. There is a lot of physics involved in understanding how a box will sound in a vehicle. The size, porting, and tuning are all critical to performance. In short, box building is one science and applying it to a car is the job of a good and knowledgable installer. sparky

But why, when sitting in the install bay with the motor off, does the bass get better, deeper, louder which ever you want to use in "some" cars when you crack open a window. Ham, Dyohn, Sedate? There is no such thing as free installation!

It would seem logical to me for the same reason as stated above- less cancellation.  That's why sometimes when you open the trunk on some cars the bass response seems to improve.  I've been fortunate enough to not have this dilemma in my cars, though.My ex once told me I have a perfect face for radio.

To clarify.. Equal wavelengths in-phase with one another will increase output Equal wavelengths out-of-phase with one another will cancel each other, thus decrease output

Did I hear my name? Okay tcss, I'll see what I can do for you guys...but ehh.. no one get mad at me all you guys are barking up weirdo trees and last time I set ya'll straight the thread got locked... sooo... ehh... don't shoot the messenger ya? I don't know how to address this thread without addressing the individual statements made herein... soo... THIS IS NOT A PERSONAL ATTACK .... here we go:

tcss wrote: I always thought it had something to do with how airtight the car is.

Not at all. "Airtight" as a function of system design exists only in relation to the suspension air provides the movement of a woofer cone... for actual sound propagation... 'airtight' is extraordinarily bad.

stevdart wrote: The air that comes off a sub cone...or off a port, too....is a wave of air created by the movement of the cone. It's not an exchange of air from one place to another, that is, it's not coming out of the box or out of the trunk or wherever the sub is located. It's a sound wave that travels through the air, moving the air as it goes. It's wake is refilled with air from the same car enclosure; the air just recirculates back to where the wave displaced it.

The most careful, probing examination of this prose from the most legalistic intrepretation proves it completely correct. But to clarify, stevdart did not use a key word I would have been far more comfortable with.. 'medium' ...... the air is a *medium* through which the wave moves, air itself however, is *not* the wave. This is a *very* important distinction, especially when getting back to the whole "airtight" idea..

A12Volter wrote: The reason that there seems to be more bass if the box if faced towards the rear of the car is that there is less cancellation of the sound waves.

This, and the remainder of the meandering post is categorically wrong. For any other math hobbyists in the room, we've all noticed how Wavelength = Speed of Sound/Frequency. and of course how Speed of Sound = 1100/ft/sec/sea level.. give or take .. well.. alot.. depending on temperature. But we can at least arrive at the acceptable conclusion of Wavelength = 1100/60 or, 18.3 feet. So.... the wavelength of a 60hz tone is about 18 feet. Now, to generate a wave that will CANCEL this one, we *MUST* have half distance of the wavelength between the cone and reflective surface... that is, the trunk lid. Ya know... NINE feet. Herses don't have trunks that big.

tcss wrote: But why, when sitting in the install bay with the motor off, does the bass get better, deeper, louder which ever you want to use in "some" cars when you crack open a window. Ham, Dyohn, Sedate?

First off, I just want to express my humble appreciation at being mentioned in the same breath as heamph and our stalwart administrator. Smart guys. As simply as I can express it, sound really likes space. The *louder* the sound, the *higher* the amplitude... the 'bigger' the wave. Bigger spaces = bigger sound, period. How many of us have moved that crap 40x4 with the coaxials and the 12" from the Civic to the Explorer and suddenly went from "what system?" to "whoa I'm deaf" ? *SAME* exact phenomenon with opening the windows. *Everyone* knows their system sounds wayyy louder that way.. and indeed, that is why... by expanding the airspace you allow your woofers.. or cabin speakers for that matter, you can drastically alter the amplitude, and ensuing volume, you allow the sound in your vehicle. As such, to the *original* question:

A12Volter wrote: Am I crazy, or does the extra air space in the trunk make for better bass? seats - \box = better bass. seats - \   box = not so great bass.

Buddy, your not crazy at all. Same thing everyone else finds. Without all that goofy 'cancelation' logic ppl are spewing, the airspace of the trunk *is* effectively increased the further away from the trunk the woofer cone is moved.. here, the trunk lid DOES serve as a reflective surface for the sound waves... and this is sort of the crux of the whole thing... like I was saying, the wavelength of frequencies so low into the sub-bass region have inordinately huge measurements... to actually HEAR the sound you are listening to, like the standing wave thing, you *must* have half the distance of the wavelength between the ear and the cone.. By flipping around the woofer you allow the sound just a few more feet to travel before it hits your ears, providing that audible bass extention ... To be honest, I find this answer only half-complete. The dynamics of sound waves in enclosed spaces are ruthlessly unpredictable, as well as dynamic vehicle to vehicle acoustics, really makes this thread something of a nonsense "what-if" thread.... In the end, the proper orentation of woofer and box rely far more on individual preference and individual vehicle acoustics than simplistic deductions like "Pointing backwards is less cancelation" or whatever.. "I'm finished!" - Daniel Plainview