Several manufacturers offer complete packages
of power amplifier, microphones, loop cable with all the technical details worked out. One very significant development in power amplifiers for loop systems is that they are able to drive high current around a
single turn of wire around the room. A single turn loop will have a very low impedance so conventional power amplifiers cannot be used with single turn loops. The advantage of single turn loops is that it makes installation of the loop cable relatively easy since the cable is just one small wire and no connectors are needed. Each end of the wire just plugs into the amplifier. By contrast, a multi-turn loop must have a connector that places each turn in series so the signal circles the room several times.
These sources offer several sizes of audio loop packages to accommodate small rooms or big auditoriums. Also some models operate on power systems found in automobiles, busses, boats, etc. as well as standard household current. The small loop cable plus operating on automobile power makes them ideal to install in cars.