Electromagnets had been generally Employed in musical instrument amplifiers cabinets nicely in the fifties; there have been economic discounts in Individuals working with tube amplifiers as the field coil could, and typically did, do double duty as an influence provide choke. A transmission line loudspeaker is really a loudspeaker enclosure https://claytondfatm.spintheblog.com/30096718/speaker-fundamentals-explained