OK I have searched the forums here and I am still confused about the best way to go for putting a sub under the tray next to the fuel tank. I have seen the article on it in the past Street Commodores magazine but I was going to use a slimline Pioneer sub so the design they give there wouldnt suit.
The guy at the car stereo shop said the boxes they use are a type of bandpass design but they dont fit a port on the output but just use the existing holes in the bulkhead to pass the sound through. I thought that the port length was a critical factor! I want to build the box myself and they wont give me their design and want $450 for the custom box.
I have also seen people use sealed boxes?? with the driver pointing upwards?? next to the fuel tank and use the existing holes in the bulkhead for the sound to come through?? Wouldnt this be inefficient and make the tray rattle??

I know heaps of people have put subs in this spot in utes so could anyone who has done it please give some advice on what works best?


Cheers

Let me guess, youv'e been to Audiocom???

There are lots of ways to do this, if you want to use the Pioneer shallow sub (which are a bloody decent option IMO for a shallow woofer) don't bother with putting the woofer in the tray.

A couple of 8 inch woofers will work no problems, a shallow 12 or a single ten, you can do a cut through and have 4 15s in the tray in a bandpass...

There are a LOT of different options, what is your budget? this will be the biggest factor to an extent.

Nah it wasn't Audiocom ... I wont mention the name of the place as I have used them a bit and they are generally fairly good.
I dont really have a budget in mind but I am only after a reasonable system with good sound quality.
I have the seats pushed all the way back so there is absolutely no room behind the seats and I dont want to cut away any of the metalwork. As far as I can see that limits me to using a bandpass box or similar ported through the existing holes.

Yes it does, it really isn't that hard to do.

Pull the cover out in the tray, measure the space you have and then go from there.

I think you will probably have about 40 litres IIRC, but haven't done a box in that part of a ute very often so am going from a long term memory of it.

I would be keen to hear from someone who has built a box in that position that has the sub firing upwards into the fuel tank cavity.

It seems like some people have built sealed boxes and put them into the fuel tank cavity but that sounds like it wouldn't be very efficient if you only have two small hole connecting this cavity into the cab space.
Please, somebody help me!!

most people build the box in the cavity and then join it up against the wall, them mount the sub from inside through the wall into the box

Doing it that way means cuttng a big hole in the bulkhead which is supposively illegal. A lot of people utilise the inspection holes that are already there but normally have covers on them. Thats what I would prefer to do but I cant seem to get agreement on the best design method to do it.

It sounds fine with the sub firing forwards through those holes.

Agreed, and you dont need to use slimline subs to fit.
During work experience at the local car audio shop we done one... We used the old series vdo/dayton 10 inch ported run from 250w RMS and only had the two service holes bringing the bass into the cabin. It sounded great. BTW cutting front or rear fire-walls is illegal.
A couple of notes if you are going to do it.....
- Inside the cavity, there may be other holes or grommets which is open to the outside of the car... These allow dust in but not out.
- The access cover will need some kind of sealant/rubber to preven water seeping through (if you have a tub liner this isnt a problem)

1. Silicone some metal or painted MDF over the drain holes in the bottom of the cavity.
2. Make sure the drain pipes from the gutter around the access cover are clean, and also waterproof your box by painting it with something (fibreglass resin works well)

What I think I will try is to build a sealed box with the sub facing forwards and have a small chamber in front of the sub that seals up against the rear bulkhead behind the two inspection holes. That way all of the sound will be directed into the cab and I wont have to worry about dust and fumes entering the cab.

Any thoughts on that idea?