this is my first post here and i'm looking for some help.

my old neighbor moved and gave me a set of two speakers. they are large: 33 3/4 in. H - 23 3/4 in W - 21 3/4 in D. they are also sealed so i have no idea what kind of speakers are actually inside. it looks as though they may have 15 in. speakers. each enclosure has a single knob near the bottom and i am not exactlty sure what it does (i haven't had them hooked up for over a year and i just now noticed the knobs).

the only thing i know about the speakers is that they were considered nice for their time and they were purchased sometime between 1977 and 1980. i know this is very vague but that's all i know and i'd like to find out what they are. if anyone has any suggestions about where i can find more info on these speakers or if you might have an idea about them yourself, i would really appreciate hearing them.

thanks for your time,
erik