Subs in the back

[gsgoingturbo]

Hi, I recently cleaned up my car and at that time I decided to mount my speakers to the back of the rear seats. They work but they are not getting much punch out of them...now I know they are getting deadened by the seats but I was wondering if anyone else has done this or has any advice on how to finish this project?

 

[Shadowofoblivio]

first things first,

What brand and type speakers are you using? Size? How many? and what do you want them to do? Are they in a box if so what kind of box? what type of amp are you using?

 

[Microrcdude]

Is it pretty sealed under the seats? Is air able to easily get to them and get away from them? That may be your problem.

 

[gsgoingturbo]

I'll be more detailed in what I did.

First I took the rear seats out and placed a piece of 3/4" board to the back of them, underneath the fabric.

Secondly I have older subs that I know aren't the best, but when in a box they hit pretty well. I mounted them forwards to the back of the seats. They are 2 - 12" subs.


I attached pictures that I recently took. It's dark, but hopefully you can tell what I'm doing. The pictures are from the hatch, that is the back of the seats you are seeing and the subs are mounted to them.

 

[zachakagoat]

did you cut a hole in front of the subs or just mount them to the board WTF if not then that would definately be your problem. Are they even open air subs?

 

[Shadowofoblivio]

theres your problem right there, make some sort of enclosure behind them and that should fix all of your problems. subs need to be enclosed in a certain enviroment to sound right. just make 2 boxes to go around them and seal them off but make sure you have some room for excursion in the front or you could damage the cones.

 

[gsgoingturbo]

did you cut a hole in front of the subs or just mount them to the board WTF if not then that would definately be your problem. Are they even open air subs?

No there isn't a hole cut in front of them, which brings me to ask how much spacing from the front should I have? Could I just mount them the same way but with a spacer between them and the seat?

As for open air, I don't believe they are. But I'll be buying some since I don't really have any way of making an eclosure for it there.

 

[zachakagoat]

You must have NEVER had a subwoofer before. These subs are NEVER going to sound good if they arent meant to be open air subs. You have to have room for the air to travel through. No a spacer I don't think will help that much because you will have air cancellation and you arent even giving your subs room to move. Cut out a circle the size of the sub and then mount it and it MIGHT work alittle better being able to suck air through the seat.

 

[gsgoingturbo]

You must have NEVER had a subwoofer before. These subs are NEVER going to sound good if they arent meant to be open air subs. You have to have room for the air to travel through. No a spacer I don't think will help that much because you will have air cancellation and you arent even giving your subs room to move. Cut out a circle the size of the sub and then mount it and it MIGHT work alittle better being able to suck air through the seat.

I've had subs before, always enclosed in some kind of box, and I've never cared enough to learn about subs and the correct way of installing them. These subs were given to me a few years ago and work good. I was only looking for a way to conserve space since boxes take up so much room.

I will cut a hole in the back of the seats, get some open air subs, and see what happens from there. Maybe I'll find a way to reconstruct the seats so there would be a hole all the way through the seat and still be useable to sit on.

 

[Jason84]

uhhh this is a joke right?

 

[gsgoingturbo]

uhhh this is a joke right?

Fine everybody. Just screw it, forget I even asked for help. So what if I know nothing about subs or speakers. That's why there is a forum, for people that have no clue to ask questions. I'm just bothering you.

Forget it.

 

[Jason84]

well if you didnt know that sorry... but subwoofers do have to be in a box to sound decent..

you cant just mount them like a front/rear speaker open air like that..

 

[Attack Eagle]

ok, if you seal the sub to a board how do you expect it to move any air? Sure they are designed to have a sealed volume of air on one side, but not .05 cu ft.

you need an enclosure so "either give up the space or give up the bass".

 

[95RedRS]

I've seen it done...Don't knock the kid.

Technically he is trying to use the hatch area as one big box...Subwoofers come with certain cubic inches of space to have the best quality sounds...the subs i have need .7 cubic ft of space per sub...i have two so 1.4 cubic ft totall...bunch of equations and whatnot some Measuring and cutting...and i made myself a box...read up on it it won't take long...But they are right you normally need something for the sub to hit against...and having that much open space is a wee bit for your subwoofer

 

[DGajre777]

Thats a very good and original idea, IF they were open air subs.

All subwoofer companies give you a sealed box range, for example between 0.7 cubic feet and 1.2 cubic feet. Anything more or less than this, and your subs will sound like crap and they won't hit any bass. Mainly because if is less than 0.7 (for example), there is not enough space for the sub to bounce off sound waves, and if the box is more than 1.2, then the subwoofer "thinks" that it is in a free air application (like the one you have). This is why you are not putting out enough bass - they are operating out of specs.

Here is what you can do:
1) If you don't want to get rid of the subs and buy open air subs, cut a hole in front of them. You need space for the air to come out of the front. Subs breathe like people, they need to breathe in and breathe out. Right now, your subs are just breathing out.
Make a sealed box around them - one box for each sub, or one big box with a partition to keep the chambers separate.

Build a box out of 3/4" MDF (medium density fiberboard). The Height x Width x Depth = Cubic Volume of the enclosure. You need to divide the Cubic volume by 1728 to get cubic feet. For a subwoofer that is not designed to operate in a open air/free air application, you need to build a box within the specs designed by the subwoofer manufacturer.

OR

2) If you don't want to build a box, just buy a sealed enclosure, put the subs in them and leave it in the trunk.

Another thing: Open air applications reduce subwoofer efficiency. A sub that has an output of 175 watts in an open air application will have about 300-350 watts output in a sealed box. Open air applications are good, if you get 1000 watt subs, mount them in an open air system and give them 300 watts cause you want to show off the chrome from the subs (talking about Audiobahn here) Just to clarify - I'm dissing open air applications here, not Audiobahn.

 

[timm98gst]

to learn exactly how to do it, look for a book called 'the loudspeaker design cookbook' by vance dickason

 

[Attack Eagle]

ifyou have the front sealed against a board you are NOT running them as free air subs... you are running them sealed with the space between the cone and board being the sealed enclosure.

if you cut a hole in the board you still are not running them as free air subs since hatch is not sealed from the cabin.

Free air subs used the sealed off trunk as an extremely large sealed enclosure... it must be sealed or else you will get cancellation from the rear wave which is 180 out from the front wave reducing the out put.


N/A in a hatchback


In short: build a box before you destroy the poor things.
If you are really technical build a small aperidonic (sp?) enclosure