I think this sounds like a great project. It seems like you need to do some research first though, because you're not just talking about
speaker building (as in woodworking) but
system design at both the
system and component
level.
Here's a couple thoughts:
A 4/12 cabinet makes a good guitar rig. As a
portable SR rig, it'll suck. using 12s as subs only works well with some of the more advanced designs, think folded horns. That's computer program design stuff. with four of them in a box you'd be looking at a baby version of the old EV MT4 rig or something. If you're going to go that route, 4 single 12 scoops may be a more flexible approach. With 4 12s as mids you're going to need a lot subs to keep up with them, or you will be turning them way back so they don't overpower your existing sub, which becomes a waste of the drivers and a lot of extra weight to carry around. I worked for a guy who had 12s as low mid drivers in a homebrew
system and it sounded good but each 12 was in a box with 2 horns and an 8, I'm not sure 4 12s in a single box would
play well together. Off the top of my head, it seems like there could be some potential for some interference between the drivers.
A four
ohm load on a single cabinet is too low of a goal
IMO. If you are thinking outdoor gigs, you'll be hooking a lot of cabinets up. If you design 4
Ohm cabs, and you put two on an amp
channel, you're already at a 2
Ohm load. That's as low as any amp I've worked with will go. For that matter, most entry
level amps will only go to 4 Ohms. If yours amps only go to 4 Ohms, and you
build multiple 4
ohm speakers, how are you going to
power them? I'd look at an 8
ohm speaker at least.
How are your woodworking skills? Do you have access to your schools shop and shop teacher? This would have been a great Woods 1 project when I was in high school. To do it right, I would suggest you would need access to a table saw for cutting side panels, chop saw for cutting interior support members,
hand drill,
router, and an assortment of finishing tools. Good fasteners and wood glue is a must. Soldering gun,
shrink tube for the electronics. Sturdy handle and casters hardware.
Speaker cabs are subject to a lot of abuse and vibration, you'll want to overbuild everything.
As for matching speakers to enclosures, this is the most important part of the design after you figure out what you want the speakers to do. Google Thiele-Small Parameters. The T/S parameters are the measurements that get used to match boxes with drivers and include things like box volume, excursion distance and a host of other things. If you don't put the right
speaker in the right enclosure, at best things will sound like crap, at worst you can ruin speakers. I did that once. I put a pair of 12s in a home built box with no regard to box volume. Things sounded good for about 6 months. Then the speakers slowly got quieter and quieter until they stopped a together. Turns out the weren't designed to be used in a sealed box of less than 1 cubic
foot. I wish I knew then what I know now.
I did learn a lot from that experience, and a few others since. Mostly I appreciate what
speaker designers and manufactures go through.
Go for it, have fun
Matt