I am thinking about building a new rear deck for my car. I would build two boxes for the subs and mount them into the middle of the deck. The 6x9s would be flanking on either side. Does anyone see any problems with this?

Sorry for the pic, I made it in paint a second ago. Would this sound better than having the subs in a normal sealed box in the trunk? Right now there is enough pressure in the trunk that the rear deck flexes about an inch in and out when the stereo is cranked.
The subs are 12" JBL GT series 8 ohm. They are currently running in a 1.25 cf q-logic box off of a Profile 600sx. I would make the deck and boxes from 3/4 mdf.


[Modified by TheWacoKid, 1:45 PM 11/23/2002]

 

Anyone?

 

It could work.
Problems:The bars that cross the car under the deck. These are the springs for the trunk. If your car has these, and I think it does, this would be a problem. You could solve this by installing piston type springs on either side. Lots of work. Or just loose the springs and prop it open like a hood with a metal proper.
Second, I'd loose the 6x9s. They are good to have if they are your source of bass. The car would sound better if you are using subs with 6 1/2" in place of the 6x9s.

Last, a possible solution we'd done often in car installs, build the boxes in the trunk, make them a ported enclosure, and have the port tube go from the box to the rear deck. This avoids the springs and pumps all the bass directly into the cabin. We used to do this on Porsche 911 as their trunk was the hood. We would steal a vent or two and pump the bass from the front out the dash.
:yesnod:

 

Another alternative if you run into clearance issues is to point the subs down into the trunk. Subs can play either way, just remember to flip plus and minus if you do that. A friend of mine has a ported box in his trunk where the ports are lined up with the 6x9 holes in his rear deck. It sounds really good. The only problem there is that your subs might not be designed for a ported enclosure.

I'd try to avoid building a new rear deck if I were you. Getting it to fit right will be a pain in the butt.

 

Thanks for all the suggestions.

I looked at the trunk and the way it opened...the hinges just bolt on to the sides of the trunk, right next to the rear deck attachments. They wouldn't be in the way of the boxes.

A vented box isn't an option...the subs aren't designed for it, and I don't want to deal with them unloading below the tuning frequency. I would like not to add a subsonic filter either...I like subsonics (vented would suck with the amount of subsonic stuff in my music).

I would rather not go buy new speakers right now. The 6x9s in question are Blaupunkt (the transparent blue cone model) 3-ways. I have a seperate amp driving them for rear fill.

I will take another look tommorrow as to how to go about this, I'm not sure yet whether I want to go ahead with this yet. It will be a ton of work, and I'm not sure I want my back seat or out of commission for a week or so.

How different would it sound? Right now the subs have to drive through about 8 inches of foam from the back seat. I assume if that was out of the way it would be tighter and cleaner, but not necessarily louder.

Again, thanks for the suggestions. :cheers:

 

This idea just got scrapped...the rear window needs to be taken out to take out the rear deck... :mad

Thanks anyway for all the replies. :seeya

 

Depends on what kind of subs you had anyway to know if it would sound better than the sealed box inside the trunk. If your subs are designed for a boxed closure then it would sound like crap mounted up on the deck, the reason is, the trunk space is to large for the speakers, therefore they would flop in the wind when volume is increased. They do make subs that are for open air configurations, however they are limited on how low they can go in freq.

 

I was going to build the box into the rear deck...it won't work anyway because I'd have to take out the rear window to take out the rear deck.

 

You say your subs are currently in a sealed enclosure in the trunk right? Where are the subs firing? It's hard to tell from your sig pic.

You may already be doing this but they should be firing toward the back taillights of the car. You will have to play with the distance from the back that the box is sitting for best bass response, i.e. back by the seats, in the middle of the trunk, or up against the tail section. Wherever the box sits, fire the subs toward the taillights of the car.

If the rear deck flexes when the bass hits and you can't remove it to build a new one from MDF then try bracing it from underneath. You could place a piece of MDF underneath the deck to support the pressure from the trunk and/or brace it with 1x4's. It may take using liquid nails (construction adhesive) to mount it. You would in essence be sealing off the trunk from the cabin from underneath the stock deck. That should drastically reduce the amount of air pressure hitting the stock deck if not all of it. Of course, it would be nice to see how the deck is designed.

 

They are firing to the rear of the car...sitting under the rear deck.
If I kept the rear deck from flexing, the pressure would end up going into either the trunk lid (not good, it already flexes a lot) or into the cabin (very good :D ). I really need to reinforce the entire trunk and the rear deck.

 

oops, gotcha. Sorry if i didn't catch that, I thought you were wanting to just mount them on the deck lid and use the trunk as the box so to speak. As far as taking out the glass, if you knew somebody that does auto glass replacement work, they could take it out and put it back in for about 20 bucks, I would think. Its not much to it really, I've seen guys take one out and re-install a new one in less than 30 mins.

 

The problem with this window is that they have to cut it out. The seals are then wasted and new ones are needed...expensive to put it bluntly. I think I will just leave it as it is until I come up with a better way to put the subs in (maybe take out the passenger seat?). :cheers: