One of my goals with the projects in Snip, Burn, Solder, Shred was to present designs that–both in terms of the functional guts and the finish aesthetics–could be adapted to suit both your own tastes and the supplies you could easily get. For example, the grill on the Dirt-Cheap Amp is an old computer power supply fan cover–which just happened to be the perfect size to secure my 8 ohm speaker (itself torn out of a broken Barbie boom box). I’ve also had good luck pulling grills off of old/broken small appliances I’ve gotten for free as resale shop rejects or garage sale leftovers. As far as new sources, check out your local hardware store, where there are many neat vent, drain, and recessed-lighting covers (the plumbing, electrical, and HVAC aisles are always profitable places to search for neat fittings, in my experience).
Upholstering Your Amp
Failing all else, you can cover the front of the amp in fabric (as is standard in the old school Fender guitar amps). When doing a fabric cover, I like to start with a double-layer of nylon window-screen mesh, which protects the paper cone of the speaker from getting dinged. Double up the mesh, then cut a square at least a few inches bigger than your speaker hole and staple it in place around the perimeter of the screen (you can, of course, cover the entire front of your speaker cabinet in screen, which will make your amp look a bit more pro. I sort of like the look of the doubled mesh, but if it doesn’t work for you aesthetically, you can recover it with basically any single layer of fabric (going the Fender Tweed Amp road, for example). In terms of finish, you can pull the fabric all the way around the lid and staple it from behind (thin fabric won’t usually cause you much grief in terms of getting the cigar box to close once you finish). A few brass-headed furniture tacks added to the edging of the front of the fabric cover, or framing it out in thin strips of wood or brass, will give the amp really slick look.
Using Weird Speakers
Folks occasionally ask me if this design–which calls for an 8 ohm speaker–will work with lower impedance speakers. I’ve tested this out, and had the amp work perfectly with 3 and 4 ohm speakers I’ve scrounged out of old boom boxes. I’ve also had decent results with speakers as high as 16 ohms. So, if you’re salvaging parts, feel free to grab those 3, 4, and 6 ohm speakers as well as the 8s. If you find your non-standard speaker distorting, you might wanna monkey around with the pin 1 to pin 8 jumper: some amps built around “non-8” speakers work better with pin 1 and pin 8 connect with plain old wire (as in the base design shown in the book), others work better with that connection omitted altogether, and some need the gain-boost that comes with connecting pins 1 and 8 using an electrolytic capacitor (as described in the “Tweaking the Amp” section of that project).
DIY Music Freebies
UPDATE: You can now get a free “Jam Pack” of musical projects from my first two books!