The First Commercial FM Receiver

The following photos show the first FM (Frequency Modulation) receiver, and its rather large accompanying speaker, commercially produced by REL (Radio Engineering Laboratories). This was apparently intended to be used as a "Station Monitor" for the first FM stations, but it also was used for the famous stage demonstrations in which an audience would be challenged to hear any difference between a live piano and one broadcast over FM and played on this system.

This particular unit belonged to my Dad, Henry George Dietz, who played a major role in bringing the concepts from Major Armstrong into products at REL. My Dad's notes say this unit was built in 1935.

The System

More About The FM Receiver

A fairly hefty gray metal cabinet, with a heavy chassis construction. My brother recalls my Dad saying that he had used the amplifier within this unit with an external FM tuner for a while after the frequency assignment changed. The missing tubes were probably removed for testing and never returned.

More About The Speaker

In the 1970s, I came upon this in our basement. It was externally in pretty sad shape, however, I was able to clean it up without refinishing it. I needed to replace the cord to plug it into an audio source to try it out, and I did that with a rather obviously not original cable that could be trivially removed if needed for future resoration efforts. The speaker worked remarkably well, with sound quality typical of a high-end theater speaker system. It is an amazingly efficient speaker, able to be painfully loud with less than a watt driving it. The price for the efficiency seems to be directionality: this speaker has a very narrow "sweet spot." Or at least it did 20+ years ago when it was last tried....