Positive-Negative On BInding Posts

I haven't been able o listen to my stereo due to my parents being ill.About 2 years ago I remove the speaker that was being used and I just went to set my system back up and there aren't any indicators showing which post is positive or negative. No red ring etc.
I have a pair of IMF 80'S. I sent my amps away a month ago to get upgraded and didn't notice the problem with until I went to hookup the new speaker cables.I checked On Line but no info or pictures of the rear of the speakers. Can someone help me ?

Thanks
Bill