My father is back to playing with his trains (N scale I believe)! He bought the attached Big Sound round speaker - says it is an engine whistle. However, he doesn't know how to hook it up (do you attach 2 wires, 4 wires). I tried searching internet but can't find anything. I noticed there is one small hole on the side of the speaker, but he thinks you attach the wires to the nubs that sit on the top of the speaker.
Speakers operate with two wires. I vote for the two nubs.A little out of focus but appear to be connectors. A side hole may be for an air hole because it has to vibrate to make a sound and it is encased with a metal back.