Multi-purpose cabinet

[ViolinMagick]

Greetings all,

I have a rather odd cabinet to build that will take some thinking through before I start cutting. It will be occupying the area behind the front seats of my newly acquired 2002 Ford Ranger Extended cab pickup. Here are the requirements:

1) Provide a ported enclosure for an alpine 12" sub.

2) sit high enough off the floor so that 10- 1.5" diameter poles 4' long can be stored under it.

3) provide a mounting surface on the front for two amplifiers.

4) Have 4 drawers which exit sideways to store stuff in like tools, medical kit, etc.

5) covered in carpet to match the interior of the truck.

6) not take up the whole back area of the cab.

I am thinking of using 3/4" mdf for the main box and 1/2" birch ply for the drawers with 1/4" bottoms in them. Perhaps leave the wood bare on the drawer fronts and finish with a poly coat.

To mount the sub, use 3/16" bolts with t-nuts on the back side of the mdf. Same with the amps. and drawer slides.

Mount the amps such that the wiring can pass through the MDF to the interior of the box to hide them. I think I will need to consider where the drawer slides are going for this.

All components will be mounted on the front of the cabinet leaving the top free to carry things like groceries. Maybe incorporate a 2" lip around the top to help keep stuff from falling off it.

Note: my truck has the kind of half doors that open up to get to the rear area behind the seats.

Anyone have any thoughts on how to improve this design? I will be mocking it up in Sketchup once I get some measurements and post the image here as well.

Cheers,

VM

[Bombarde16]

Anyone have any thoughts on how to improve this design? I will be mocking it up in Sketchup once I get some measurements and post the image here as well.

For the moment, only that 3/4" MDF may be overkill. Beyond that, we need some pictures of the inside plus at the least a pencil & napkin sketch of what you want to do.

[Darnell Hagen]

3/4" MDF is an ideal material for sub boxes. I'd seal it, porting requires a knowledge of physics beyond me.

Carpeting a box is tough, I've used hammertone and fleck spray paints to good effect.

The drawers may be undesireable. They'll take away from your subs cubic footage, and I'll bet they'll rattle when the bass hits.

[jHop]

Start by going to an aftermarket sound shop, and checking out their sub boxes. Most of them already have some allowance for amps built in. Plus, many of them are already covered with a basic carpet, so that clears two of your requirements.

The majority of the boxes I have seen have been 1/2" or 3/4" MDF: this is a dense, stable material that has so few vibration points that the material will not rip apart from the vibrations of the subs. However, since it's basically compressed sawdust and glue, it does not have the long grain stability that is preferred (but not required) for weight distribution.

Admittedly, I'm not a sound engineer. (Check with Sonic Fedora before doing a lot more.) But I believe you would need to mount the subs firmly in the truck: having them be free floating would not be good. Not just with vibrations rattling components apart, but for the stability of the speakers themselves. Drawer units are available, but they do not handle tools. they are your basic small parts drawers. having loose metal around will simply allow them to resonate with the waves from the speakers. This causes some of the distortion you might hear.

there are sites on the internet that will help you determine the size of the cabinet you need, based partially on the size of the speakers, the desired amperage and wattage of the system, the number of speakers, whether you want it ported or not, and a whole host of other considerations. I'd also recommend perusing either the library or your local Radio Shack: there are two speaker books that are definitely worth purchasing if you are going to build your own boxes. (I'd loan you mine, but I need to replace it after my basement shop flooded.)

You can purchase the pre-made boxes for ridiculously low prices, comparatively speaking. From there, it's a simple process of adapting it to suit your needs. I've heard of people mounting the amps between their subs, inside the sub boxes, and behind them. remember, the amps will heat up when in use, so you need to keep air flow around them, and keep things that are sensitive to heat further away. And drawers inside the box itself (if you haven't figured this out) are an absolute no-no. This is a leak of air, no matter how well made the drawers are, that will ruin the quality of the sound created.

A final thought: a friend of mine once built a speaker box for some 10" subs out of OSB. He didn't follow a plan, didn't seal the box with silicone, and simply stripped pieces of foam out of his couch to line the box with. Needless to say, the box was not that good. But it looked pretty cool, since he used that flecked / faux stone spray paint system (two can system: first is a base coat, second is a textured "flocking" style over coat) that got more compliments. Until he turned it on. Admittedly, your ride has more coolness factor going for it than an 89 Ford Topaz...

[ViolinMagick]

Buying a pre-made box is out of the question. I have been engineering sonic enclosures for over 20 years and know what I am doing there. Yes, I can do the Thiele/Small calculations though not in my head anymore.

I was looking for ideas on the usability/layout of the thing in general. I will be taking measurements tomorrow so I can do a sketchup drawing of what I have in my head.

Cheers,

VM

[ViolinMagick]

Ok, change of plan. I went out and measured the truck this morning. There is not enough room for the poles to live under the box. So, that just made things a bit easier.