| | asere
I have looked into building a sub myself however I do not know where to begin.
You've already begun here
Well, you'll need
- A driver or two
- An Amplifier (some amps will drive two drivers)
- probably 2 sheets of MDF (or Plywood though it's more expensive), maybe 4 if you do dual subs off one amp
- miscillaneous wood-working tools, screws, adhesives, etc. A router and a table saw are most useful, though some skill with a jigsaw might cut it (no pun intended! lol). large clamps never hurt anyone. And of course, there's a matter of finishing... do you want a wood veneer, vinyl laminate wrap, or a spray paint finish?
What will make it have a low frequency etc.
Three major factors
1) Amplifier power will move the driver
2) The driver as a piston will move air
3) A resonator may reduce the driver's motion and "substitute" itself, and thus also move air.
An example of a resonator is a vent. It's a mass of air. It's "tuned" to a given frequency band. So when the driver is stimulated by the amplifier, the resonator will create the lowest frequencies.
There are two main types of resonators...
- Helmholtz Resonators
- Quarter-wave resonators
and there are also speakers with no resonator (sealed). Sealed will have the smallest box size requirements, but you'll sacrifice some output/extension.
Of Helmholz resonators, the main types are Vents/Ports and Passive Radiators. They're both masses of air loaded by internal box pressure.
Of Quarter-wave resonators, the main types would be Quarter Wave Tubes, Tapped Horn, Front Loaded Horn, Backloaded Horn. They use internal standing waves and impedance matching to produce deep output. The QWTs (and Tapered-QWTs) will be about the size of a large vented or passive radiator alignment, and the horns will be notably larger.
Never mind the details of HOW they work, though. What you need to figure out is what you're willing to live with from a size and weight perspective, for the budget you've got. In a perfect world, you could just get eight high-end 18" drivers, seal them, EQ them, and call it a day but that's not cheap. So first you need to figure out your total budget. Second you need to figure out how big you're willing to go. That will help us decide on appropriate driver/alignment combinations.
Also by the time I am done with buying parts to build won't I have spent around the same as buying a commercial sub?
For the cost of a single (well-chosen) 12" DIY driver ($150-200) and a 300 or 500w amp you can effectively make something that can run with a $1000 commercial sub. Will there be a lot of small costs? Yes. But I'd still wager on the DIY build.
The #1 reason for this, is that it's not economical for manufacturers to make large, heavy subwoofers.