When I used to play in a band, I quickly learned that carrying a decent cable tester made the difference between wondering whether the PA system would work — or whether it’d cut out in the middle of the second set and make me look like a complete ass.
This is the one I ended up carrying, mainly because it’s cheap and effective. As you can see from the picture, it can handle balanced and unbalanced mic cables, 1/4″ and 1/8″ cables — or best yet, any combination thereof. For example, if you’ve got a balanced 1/4″ to XLR, just plug each end into the appropriate hole and you’re good to go.
The small lights next to the LED grid (at the right of the photo) turn on whenever continuity breaks, making it easy to diagnose cable problems by yourself; you just plug it in, hit the reset button to extinguish the “intermittant” LEDs, then run around and wiggle the cable. If they’re on when you come back, the cable’s screwed.
Best yet, the LED grid shows you the wiring of the cable, so you can tell the difference between when the cable itself has failed and when the guitarist just installed the wrong one. (It’s also great if you build your own cables ’cause you can troubleshoot them.)
It runs on a 9V — which you’re carrying for when the guitarist all of a sudden can’t perform because he’s still running one of his pedals on battery power and it’s dead anyway, right? — and is durable enough to a roadie’s beating.
You can find it at Guitar Center or other large music stores for around $50, but Froogle’s turning up one for $30 right now. Trust me — if you’re gigging, you’ll wonder how you ever got by without one.
One last piece of advice: When you find a bad mic cable, cut the damn thing in half and throw it away. Sure, you could recover the parts or “repair” it, but here’s what’ll really happen: It’ll lay around with the other cables waiting for you to find some “spare time,” then eventually get mixed back in and screw you publicly at a future show. Count on it!