There is a doubleback tape transducer pickup about one inch square made by Barcus Berry. I have one installed on the treble side of the bridgeplate in my 40's Silvertone. It sounded OK but I didn't want to be teathered to a wire a'la monkey so i built a small preamp with 9v bat. for it, then a small 10 watt amp with another 9v bat. Each amp on separate pc boards. Added a two pole off/on switch to a volume pot, cut a hole in the back big enough to mount a 4ohm outdoor speaker and let the horn stick thru the sound hole. The horn is a bit raspy like an old wind up phonograph and when turned up produces feed back a'la Hendrix, otherwise it's rather pleasant and self contained. Its covert useage is rather well received as a curiosity but it is much appreciated at about half throttle where it will cancel the racket of three five strings. I call it my banjo killer. The preamp batt. lasts about three years. The amp batt. lasts about a year. The BB pickup was about $20.oo. I have played at indoor and outdoor concerts sans sound equipment, and over/thru sound reinforcement systems. The volume range is more than ample in all situations. I doubt if you can come up with any snide comments I have not already heard but hey, entertainment is where you find it.