#1
The speaker in my cab is unlabled. How do I know which side is positive and which side is negative on a 10 inch speaker?

The speaker clips are at 12 o'clock in the cab
#2
If it's a single speaker cab then it doesn't matter which side is which. The only time you really need to worry about specific poles is when you're wiring multiple speakers together so they're in phase with each other.
Endorsed by Dean Guitars 07-10
2003 Gibson Flying V w/ Moon Inlay
2006 Fender All-American Partscaster
SVK ELP-C500 Custom

1964 Fender Vibro Champ
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[thread="1166208"]Gibsons Historic Designs[/thread]