Tools for building cab

You really need to make your board cuts on a table saw. The edges should be dead square and straight which is just about impossible with a jig saw and still hard but easier with a circular saw. You need a router if your going to round the corners or do any kind of joinery and the appropriate jigs. Unless you can justify buying tools for other projects it doesn't make sense to me to do it only for a couple of cabs. I recently found a True Tone cab at a local music store 2x12 fender copy for $175 in mint condition empty. Very well made and after I put on a Fender logo looks like a million under my old black face Bassman head.

 

Using a quality jig saw to make square cuts even with a straight edge is next to impossible.You won't get the job done with a B&D jigsaw for sure.
It is possible to cut the edges square,round over the corners and do perfect speaker cutouts with a router and straight edge.
For a straight edge I would suggest what is called a back to back
clamp.
A router and a straight bit can cut very well and true if you only cut 1/4"-3/8" each pass .You could also use the router and straight bit to make rabbeted corners although finger joints would be stronger.
A router and a hom made circle cutting jig will cut perfect speaker holes.
The down side here is you will be cleaning up saw dust for months.

 

Square corners and straight lines are possible with a good circular saw and precise jigs/guides. I recently built a solid oak head cab using a table improvised from saw horses and a slab of 1 inch particle board as a table top. Also used my standard garage shop work table. Used large c clamps and 24 inch bar clamps. Used a high quality blade on my circular saw and took my time on all cuts. Had to use a cheapie B&D jig saw on one cut, that was the messiest cut of all, but with a little hand filing and sanding, it's not too bad. Of course, couldn't make finger joints and such, so I used glue and dowel construction on all corners. Re glue, I had good success with "Gorilla" glue, available at Home Depot. Rounded corners when needed with a hand file and sand paper (no router). It's a good looking cab, and very solid to boot.

 

Somewhere on every home-building site I've seen there's a poor man's table saw.

Clamp your circular saw to something flat and stable (I've seen 2x4s, plywood, you name it) and invert. Another 2x4 (or better, the 4' level) gets clamped down for a rip fence.

 

I used a piece of 1/4" Lucite with the saw screwed to it underneath and then screwed the lucite down on my workmate and plugged the saw into a momentary footswitch . YMMV , and your fingers are your own .

 

Mild dain bramage earlier -- you may not like the results you get if you use a carpenter's level (the 4' things) as a saw guide/rip fence.

The problem is that most of them are not a true straight edge, but instead have a slight inward bow to them (think hourglass). The idea is that for a level/plumb reading the device is resting on its ends, not its center. The curve is slight, but definitely there.

 

there is also a hi-end circular saw by Festool that will not take up a lot of space (i sense your main limitation in not buying a a table saw...?) though will cost about as much as a decent non-cabinet table saw. It comes with its own custom guide/fence and woodworking magazine reviews rated it VERY highly.

baald