Those speakers are generally used with a PA system to deliver whole building sound, such as Muzak. Basically there is a 70 volt feed to each such speaker, that is attached thru a transformer to the actual driver. The transformer provides a high impedance load (not the 4-8 ohm load of stereo speakers. If you bypass the transformer, then you could use the speaker with your stereo, but don't expect high quality sound from it.