subs facing boot or cabin?

[Stoosh]

hey ive got 2 x 12" kicker COMP subs, usually i have them setup facing the boot, but when i re-arranged my amp i had to face them inside the cabin because of lack of wiring. now i found that at the same level facing inside the cabin it starts to distort for some reason, it maybe something rattling but i took everything out and it still sounds the same, so im not sure about that.

would you feel the bass more from the outside if the subs were facing the cabin or the boot?

i havent tuned the audio setup atm, im gonna get my audio mate to come see what he can do.

[vtec_jet]

face to the boot..
betta sound quality.. the bass bounces back and fourth giving the passengers the better quality end of bass...

[ICACHA]

vtec jet, can i ask who told you that crap?

didnt know bass can bounce back and forth inside a car :confused:

Stoosh, facing towards the boot will give you some cabin gain and a longer wave length, which isnt a bad thing, but you really want the subs going bang at the same time the front mids go bang with the bass note, facing them backwards will delay the subs from the front. having them facing forwards and if you have a deck with time alignment you are able to delay the front using the time alignment to allow the sub to catch up in a sense and the whole bass experience becomes more in time and the way it should be.

if you arent sure shoot me a PM and i can explain a bit more.

[Slow96GSR]

^^What he said. The only time I face them back is for competitions. It allows the waves to hit the mic point just right and the pressure seems better too. Don't know why as I am not a physics major or anything it just seems to work that way. We also do it in most cars because it's done for cosmetic reasons. If the customer is spending money we can get hardware that can delay the signal or change it in a way that it wont effect the mids/highs also can be done with a good tune. Everything to do with a car seems to work best with a good tune! I guess face them what ever way is most convenient for you and then listen to it. If you don't like it move the box around. Unless you want to spend time researching and testing configurations just put it in and take a listen, your ears will be the true testers.

[Fhrx]

The aiming of subwoofers has been quite a topic of speculation for years now in car audio. Through experimenting many people have found that their subwoofers sound much better when aimed backwards. Many people realise that there seems to be much more bass with the boot open than with the boot closed. We've heard a great deal of strange and utterly incorrect theories to explain this phenomenon.

The main reason this phenomenon occurs is all about sound waves (direct and reflected) and more importantly the cancellation of these waves. The diagrams below assist in showing the sine waves and their phase relationships between the direct sound wave entering the car and the reflected wave that hits the back of the boot and reflects forward. Since the reflection is bounced into the listening area one can treat them much the same as having two sources.

http://www.fastfoursforumscarclub.com/temp/fhrxstudios/images/aiming_1.jpg

In the above picture the vertical black line at the left of the picture is the boot rear panel (the beaver panel the tail lights are mounted on). This picture is an illustration of what happens when sound comes out of the front side of the subwoofer enclosure. Sound travels forward into the car (the purple wave) and also backwards to reflect off of the back of the boot (the red wave). Both the direct wave and reflected wave get to the listener but they are slightly out of phase causing a variable amount of cancellation in the listening area. At this stage if you opened the boot the reflected wave would disappear and not reflect back into the car, thus resulting in no cancellation.

http://www.fastfoursforumscarclub.com/temp/fhrxstudios/images/aiming_2.jpg

In the picture above picture the speaker box has been aimed at the boot instead of the rear seat and you can clearly see the direct and reflected waves are not nearly as much out of phase as in the first example. This resulting in much better bass reproduction.

http://www.fastfoursforumscarclub.com/temp/fhrxstudios/images/aiming_3.jpg

This picture above represents the subwoofer enclosure being moved to the rear of the trunk with the subwoofer aiming forward. The waves are a little closer to being in phase with each other.

http://www.fastfoursforumscarclub.com/temp/fhrxstudios/images/aiming_4.jpg

In this picture (above) we're aiming the rear mounted subwoofer enclosure at the rear so the direct and reflected wave are very close to being in perfect phase from the start and hence they reinforcing each other quite well.

Note; these pictures are simulated using a 60Hz note with the rear of the box mounted approximately 3 feet from the back of the boot. Keep in mind we're only discussing the direct and rear reflected sound in an effort to try to simplify this. The reflecting sound waves in a car are much more complex than these drawings indicate but we must start simple before getting too carried away. For example, remember that placing the subwoofer cone face too close to any panel can load it (resulting in a similar effect to that achieved by a bandpass enclosure) but we'll worry about that another day. This explanation should be a nice foundation for those of you who wish to study this phenomenon further. One other thing we should mention is that before people comment that this cannot be true because the interior of cars being small in relation to bass wavelengths, the full wavelength does not have to completely develop to be in or out of phase with its own reflected sound. The pictures above are showing a 60Hz wavelength and the bounce distance to reflect back out of phase a complete 180 degrees is just over 4 foot. At higher frequencies the distance is less (120Hz is 2.3ft for example). Remember, the key is to experiment and see what works best for you and your vehicle.

[Fhrx]

Can I just say also that this WYSISYG editor is not the easiest to use.:(

[mj3610]

i've got a EG hatch, i face it towards the boot and im running the sub off phase and it sounds alot better than running in phase facing the front. also regarding outside the car mine sound 2x as loud from the front of the car compared to if u stand at the bak of the car...
i think its a good setup for hatchbaks.

[Slow96GSR]

Can I just say also that this WYSISYG editor is not the easiest to use.:(

I'm sorry. Try Termpro or Bassbox Pro. Both are good to use. Termpro is a little more expensive but if you need a RTA it makes the package a great deal.

[ctn]

[QUOTE=mj3610]i've got a EG hatch, i face it towards the boot and im running the sub off phase and it sounds alot better than running in phase facing the front.QUOTE]

I find the exact opposite.
Facing back is way too boomy.

[mj3610]

^^^ are u running it off phase? i found it abit weird when i faced it towards the bak it didnt sound that good but when i ran it off phase it sounded alot better :)

[Fhrx]

I'm sorry. Try Termpro or Bassbox Pro. Both are good to use. Termpro is a little more expensive but if you need a RTA it makes the package a great deal.

Dude, the WYSIWYG (What You See Is What You Get) system is the type of user interface used with this forum software. Nothing to do with what we're talking about.

[AmmoJammo]

face to the boot..
betta sound quality.. the bass bounces back and fourth giving the passengers the better quality end of bass...

face forward, better sound quality, rear may sound better, but its only cos the distortion from the sub is being muffled by the boot.

if its distorting facing forward, it was already distorting facing backward. :thumbsup:

[Fhrx]

face forward, better sound quality, rear may sound better, but its only cos the distortion from the sub is being muffled by the boot.

if its distorting facing forward, it was already distorting facing backward. :thumbsup:

Just go up a little and read my first post champ. :)

[Stoosh]

ok now i face my other problem when the subs are turned up the hatch rattles it thinks its the plastic that covers the wiperblade motor n such, what should i do to try and secure it, i dont want to be drilling holes into the body if it is not necessary :)

[Fhrx]

That issue is also faced by everyone with a system. It is resolved by using a careful blend of foam (to stop light panels rattling), sound deadening (to stop the larger panels flexing and letting sound through) and patience (to stop you going insane whilst rattle chasing).;)

[ICACHA]

hey marty, expanding foam (dont try this at home kids) works a treat hahahaha just buckles a few panels in the proxess thou :p

[marte]

ur number plates might be rattling also check for that

[Slow96GSR]

hey marty, expanding foam (dont try this at home kids) works a treat hahahaha just buckles a few panels in the proxess thou :p

Did that in our competition van, just do it little by little. Don't try filling the whole section at once. As long as the foam can expand somewhere you should be fine. It improved spl and made it quieter outside quite a bit.

Do you all have a Home Depot or a big home repair place down there? If so you can use the gutter repair kit instead of the dynamat. It's the same thing just that it is 10" wide by 15 feet long for $16USD. I used that because it cost me 50 bucks to do a whole car where as the Dynamat was going to cost well over $200USD.

[newmski]

gutter repair kit info is very very interesting