As for a diagram, this one should work for any standard Economy board since 2010:
While it specs a 4.5v battery pack, anything from a 3.6v Lithium-ion to a 5v USB bank should work, though the lithium-ion is probably what you're interested in. The board will only pull
The recommended transistor is a Tip42C since it can handle up to 6A. I've personally tested it with one-up Crees, Tri-Crees, and a SF 6W+. It should work fine with a 12W+.
The board will function just fine without an LED connected. If you want to disable light while keeping sound, you could install a latching switch on one of the LED wires - it doesn't matter if it's the positive or negative wire. Alternatively, you can wire in a quick-connect after the transistor and unplug the LED at any time.