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Flipx99
10-27-2005, 10:34 AM
I was driving to school today and I got the the thought of taking my backseat compelete out and building a wall of 2 18s (XXX, probably). Of course I would have to upgrade electrical, amps, etc

I was wondering how does one calculate volume for walls? I mean do I just use total volume for the trunk? Also, I have seen walls in action many times but won't they sound like a sealed box with a leak? I have a 89 cutlass ciera with about 6 ft of trunk space. But that is not including nooks and crannies and space around wheel well which I couldn't use, but is part of the volume of the trunk.

What other considerations must be made when building a wall in a car, other than lack of back seat?

NhustlaR
10-27-2005, 11:32 AM
the ******* that redid my gas tank put new harness bolts on, and never welded them to my floor, so i had to take out my back seat to drop my tank a couple weeks ago, and im thinkin about the same with 2 15's but thats as far as ive gotten to :laugh:

Flipx99
10-27-2005, 02:06 PM
If you find something out, let me know. I am pretty sure Jack Frost has some insight on this.

hoss
10-27-2005, 02:11 PM
search on SIN, loyd has a good write up of how to build a wall in a car. it should be able to help you out a whole lot, answer a bunch of questions, and gives you a step by step of what all you need to do.

Flipx99
10-27-2005, 02:13 PM
what is SIN?
I appreciate the help.

avs20
10-27-2005, 02:17 PM
http://forum.soundillusions.net/index.php?

80INCHES
10-27-2005, 02:18 PM
i think its bigbadbass or something like that
he's always on soundillusions forum

80

hoss
10-27-2005, 05:36 PM
what is SIN?
I appreciate the help.
www.soundillusions.net . its another stereo forum, i used to post there primarily, but i left because of cloed minded self absorbed admin. there is still some good info and stuff over there though.


i think its bigbadbass or something like that
he's always on soundillusions forum
bigbassman is loyds name on there. loyd = smart guy. he can be a very helpful person to be involved with.

jellyfish420
10-27-2005, 07:06 PM
I was driving to school today and I got the the thought of taking my backseat compelete out and building a wall of 2 18s (XXX, probably). Of course I would have to upgrade electrical, amps, etc

I was wondering how does one calculate volume for walls? I mean do I just use total volume for the trunk? Also, I have seen walls in action many times but won't they sound like a sealed box with a leak? I have a 89 cutlass ciera with about 6 ft of trunk space. But that is not including nooks and crannies and space around wheel well which I couldn't use, but is part of the volume of the trunk.

What other considerations must be made when building a wall in a car, other than lack of back seat?
are you talking a wall at the b-pillar or at the back of the backseat? its basiclly just a box with a front that extends all the way to the sides. or "filler" panels on all the sides to make it look like a wall. nooks and crannies of the trunk? are you wanting to do IB?
take a look at this. plenty of pics of my wall i just did ;)
http://forums.caraudio.com/vb/showthread.php?t=118151

Flipx99
10-28-2005, 12:07 AM
What I am trying to do is remove the seatback (the area that your back is on in the rear seat) and screw up a thick piece of MDF and put some subs there. Like if you were to sit in the rear seat your back would be subs. A better illustration would be at the C-pillar (it is a sedan). I don't think it would work because it would be like a sealed box that leaked unless there are subs that work in this type of situation. I am thinking it is like IB.

Flipx99
10-28-2005, 12:39 AM
or if I use a free air sub, it would also work?

What is some popular free air subs, are any 18"?

Flipx99
10-28-2005, 01:01 AM
The SIN link doesn't have pics and that is not what I am trying to do based on description. I think it is more like what rukus what mentioning about people in Miami put a piece of plywood and play subs free air.

Thing I guess I need to understand is what is the difference between IB and free-air.
I learned from searching I need a sub with qts >.7, although it seems difficult to find these in 18s.

Flipx99
10-28-2005, 09:28 AM
are you talking a wall at the b-pillar or at the back of the backseat? its basiclly just a box with a front that extends all the way to the sides. or "filler" panels on all the sides to make it look like a wall. nooks and crannies of the trunk? are you wanting to do IB?
take a look at this. plenty of pics of my wall i just did ;)
http://forums.caraudio.com/vb/showthread.php?t=118151


Nice box, I was trying to do something without a box at all if that is more clear.

hoss
10-28-2005, 12:39 PM
Thing I guess I need to understand is what is the difference between IB and free-air.
I learned from searching I need a sub with qts >.7, although it seems difficult to find these in 18s.
the difference is this... in an IB set up, there is a baffle that the woofer mounts to, this baffle is what seperates the woofers front wave from the back wave. the theory behind infinite baffle isnt that there is no enclosure, more so that the woofer hasan amount of air equal to or greater than the Vas, which is in simplified matters, the amount of air in a sealed application that is equal to the Qts.

in a free air set up, there is no baffle to seperate the front and back waves. the woofer is simply suspended in place, or sitting there. there is alot of cancellation, and in general, it is a VERY bad idea...

it looks like you are more interested in an IB set up as opposed to the wall you originally were asking about. a wall is a different concept than both of these.

PhatTonyDeMarco
10-28-2005, 12:46 PM
the difference is this... in an IB set up, there is a baffle that the woofer mounts to, this baffle is what seperates the woofers front wave from the back wave. the theory behind infinite baffle isnt that there is no enclosure, more so that the woofer hasan amount of air equal to or greater than the Vas, which is in simplified matters, the amount of air in a sealed application that is equal to the Qts.

in a free air set up, there is no baffle to seperate the front and back waves. the woofer is simply suspended in place, or sitting there. there is alot of cancellation, and in general, it is a VERY bad idea...

it looks like you are more interested in an IB set up as opposed to the wall you originally were asking about. a wall is a different concept than both of these.


That is just about the best post I have ever seen ...

hoss
10-28-2005, 01:00 PM
That is just about the best post I have ever seen ...
thank you :) .

Flipx99
10-28-2005, 05:48 PM
it looks like you are more interested in an IB set up as opposed to the wall you originally were asking about. a wall is a different concept than both of these.

You are exactly correct. I appreciate you deciphering my random comments into a precise phase.

I did a little searching and have discovered that IB is no good for SPL comps. If this is correct, then I suppose IB isn't for me.

Thanks hoss.

hoss
10-29-2005, 10:18 AM
yeah, IB is pretty far from good for SPL. im fact, a small sealed box would yield better SPL than an IB set up.

if youre after SPL, id suggest a large ported application. since your obviously willing to sacrifice all your trunk space, then this shouldnt be a problem, and since you have an old car with a beast of a trunk, you should be able to fit one in there. try a CRX style box, those are easy to build, and they wang pretty good. you should be able to net 5 cubes or more back there with one of those.

jellyfish420
10-29-2005, 02:00 PM
if your going for high SPL i might go out on a limb and suggest bandpass....
very high spl gains, but difficult to design and build...some even have the ability to sound quite good, mine for example ;)

hoss
10-29-2005, 03:23 PM
if your going for high SPL i might go out on a limb and suggest bandpass....
very high spl gains, but difficult to design and build...some even have the ability to sound quite good, mine for example ;)
x2

only reason i didnt suggest that, is because of the level of question asked ( no offense here flip, so dont get mad at me :) ) i didnt think he would have the adequate knowledge to design/build a bandpass of that nature. BP boxes can be pretty tricky to get right often times, and for a novice box builder, they might not be the best route to go with.

but if you feel like your capable of putting one together, they can get nasty :)