As far as the outputs, there would be numerous impedance taps to match the speaker to the amp, so you should have 0 (gnd/-), 2, 4, 8, and 16 (most common).
On the input side of things, whatever you want to hook up that has a "line level" output (about 1-1.5 volts p-p is typical). So, any of todays equipment, but you will have to settle for "Mono" unless you can find another amp.
While crystal radios are typically about 30 years older than your amp, purists in the high falutin realms of "audiophile" (audiopile, If you really wanted to be unique, get one of the project books from the Crystal set society to construct an FM crystal radio (uses slope detection) for that "pure" FM sound. It is a decent amp, but I believe right now Emerson holds the rights to the product name. If I recall correctly, it was the economy line of Grommes, which is also held by Emerson. Which you can verify on the "Photofact". : I have this old Bell model 2122-A Hi Fi amp that I have had laying around for over 20 years and finally I want to do something with it. It is in mint condition, I got it from a lady I did odd jobs for and she paid me by giving me old electronics. It works fine, however, I would like to know how to set it up. It is just a chassis with the volume and tone knobs on the front with various inputs and speaker outputs on the back. How were these originally used? I mean what kind of speaker and radio (crystal set?) input was used. And also was the amp just setting on a shelf or was it installed into a cabinet. The way it looks to me I would think the former. Anyway any help in getting it set up in a original type fashion would be appreciated. Thanks.
: Hap