what determines how a sub works?

for example place one sub of any size with a board over the rear well area and it works decent compared to placing the same sub with equal cubic feet in a box in the rear seat?


if the box and sub are equal shouldn't it work the same anywhere in the car, what causes this difference?

 

as far as I can tell/have noticed, is that the further the speaker is from your ear, it has time to "fully develop"... My friend has a ford ranger with two 15"s instead of a back seat... the box is big, and I'd say the two 15"s in my truck are MUCH louder... (his are Kicker VRComps)...

at least if you are further away from the speaker, the bass 'sounds' deeper to me.

it can also be that more of the sound is being channeled towards you.

if the box is in the back seat, most of the sound will flow past you, or into the body of the car... put it in the rear well and it will reflect off the glass and into your ears.

just some food for thought.

 

yea i agree the farther away the sub is from your ear the better bass or loudness you get from it. the same sort of thing works in a home audio subwoofer the farther you from it the more bass you hear.

 

It has nothing to do with how far the sub is from your ears. In fact, sound waves diminish at a rate of 6dB for every doubling of the distance from the source.

The reason that subs sound better farther back as compared to in the center of the car is due to cancellation of the direct and reflected sound waves.

Read this:
http://www.installer.com/tech/aiming.html

I don't know how accurate he is with his pictures, but the fundamental idea that he's attempting to show is good.

 

I hit 140 db with a small box with 2 16kv.2 elemental design subs with a RF1000bd amp. That **** rocked. And that was in a sealed box in the back. Lol i blew it all up so warrenty still has to get my new stuff back.

 

thanks jim. by the way found some more kickpannels if you need them let me know.

 

Thanks, I'll keep that in mind. I've got 3 spare sets right now, so hopefully that'll be enough.

 

That is a pretty good website - makes me think about designing a box that is rear facing and fires towards the rear of the hatch.
I was looking at Disturbthepeace's design, and think it looks pretty good. Anybody see any problems with it? I was thinking that it might be hard for the sound off the speaker cone to escape, since it will have to reflect off the rear and then filter through the small hole in the top mdf panel to get to the front of the car.

https://www.thirdgen.org/techbb2/sho...hreadid=146179

 

I installed a 12W0 into an 86 Trans Am in a similar way. I had the sub facing straight back, and I built a flush mount panel to conceal the box and flush the amp. I left a little bit of open space around the hatch motor for the sound to get through.

The box worked great, and pounded a lot harder than I expected considering it was an 8 ohm woofer and a small Kicker Impulse amp. I don't think you'll be disappointed if you go this route.

 

Sorry for the double post, but I put some of the same information in the thread that I started. You have pics of that box, Jim? I'm interested to see how the amp is mounted.
I did the calculations on Disturbthepeace's box, and it looks like it's around 1.3 ft^3, which should be good according to JL Audio and the WinISD program.

 

The website I used to have the pics on is no longer around. If I get a chance, I'll throw the pics onto a cd and upload them at work. It was a pretty clean install overall, but the cosmetics weren't quite up to my linking because I finished the job with a wood chip in my eye.

 

Ouch! I'll keep protective eyewear in mind.
What do you have back there now? A 2 sub setup firing into the hatch window?
Where did your website go?

 

I had a couple websites. One was my college website, and 4 years after graduating, they finally realized I wasn't there anymore and removed the account.

My other site was an fbody.com site, which now requires a monthly fee that I don't want to pay, so it's gone too.

Anyway... in my IROC I've got the same pair of Oz 300L "Superman" subs that I've had since I bought them back almost 10 years ago. They're in a sealed box, facing straight up. It's the same box that I sell, except that I never got around to making the carpeted cover piece, so mine's a nice big old plain piece of MDF.

I've got a sounddomain site, but I don't have any pics of my sub enclosure on there yet:

http://www.sounddomain.com/id/jim85iroc

 

Pics of both boxes are greatly anticipated...

 

hmmm.... I don't think I've even got pics of the box in the IROC. It's really a mess... the box is bare and the amps are just sitting in front of it.

You know how it goes... your own stuff is always the last thing to get done.

I never finished the cosmetics because I've been saying over and over that I'm going to yank those subs for a single 12", but who knows when that'll ever happen.

The box looks the same as this though:

 

hey Jim, have you ever thought of hooking up a PC or Xbox to your LCD and have some tunes/movies while driving? then you could get rid of that dvd player under the dash.

 

Then he would have a PC/Xbox under the dash hehe
In all seriousness, I'm still thinking about going that route some time in the future. I'd be surprised if Microsoft didn't start making something like that specifically for cars. They could sell a bundle of 'em.

The problem with finishing your own stuff is that you take so long to make it "perfect" that there is always work to do!

 

I thought about it but decided on a DVD player instead. I don't want the complexity of booting a PC every time I use the car, nor do I want to take up the real estate for it. I'd thought about using a PS2, but using one as a dvd player sucks. They are also so cheaply made that it's unlikely that it would hold up to the abuse that a car environment would subject it to.

 

i don't know about movies but with games it isn't bad at all however most of it is stored in the memory with the games. i'm sure movies would be a different story with the ps2 and the road.

 

Environment notwithstanding, watching a movie on a PS2 is inconvenient at best.

 

The two different boxes and locations you are proposing (box where rear seats are and a plate in trunk area) are differrent for a few reasons. The box configuration is a true box and will have different characteristics than the plate configuration in the rear well that is using the trunk as part of the enclosure. Differrent box shapes will affect the sound characteristics.

As for the location of the box. Low frequencies (bass) are omni-directional meaning that you don't need to direct the speaker towards the listen (unlike a tweeter) Frequencies have certain wave lengths. Higher frequencies have short wave length and lower frequencies have longer wave lengths. That is why bass is omni-directional with low frequencies having wave lengths greater than 10 feet. When it comes to subwoofers speaker box location can be important for hearing certain frequencies at the listeners location. A wave length is like a sine wave and if your location is not at the correct portion of the the sine wave it will be out of phase to the listener. You can do one of three things to try and correct this. Move the box, move the listener, or change the phase (polarity) of the subwoofer.