Marshall 2x12 speaker cab wiring?

[joepete]

I just wired my 2x12 cab up from diagrams off of the celestion website. I have 2 8ohm speakers wired for 16ohm total, i have noticed some squeeling feedback and was wondering if it could be the cab, my question is = does it matter which terminal on the input jack is used for the positive or neg as they arent labeled on the back of the input jack like they are on the speakers themselves??

[Scumback Speakers]

It makes a difference. If you have the Cliff jack, the neg terminal is the one closest to the back panel, the front one (nearest the speakers) is the positive terminal. Wiring them wrong produces potential out of phase tones.