The most famous, early use of an Electro-Magnetic coil for sound reproduction was Tested in London in 1877 by Alexander Graham Bell with the ear-piece in his Telephone. This Pickup was crudely made from an Iron horseshoe form Magnet, typical of the period, wrapped with 2 coils of Copper wire & using an Iron diaphragm to reproduce the sound of the Inventor's voice. Although Graham Bell was credited with the design of this technology, earlier, in 1860 Phillip Reis was the first to convert Human speech into an Electrical signal by way of his much earlier attempt at a Telephone. This technology was improved upon over the following years & using this original Horseshoe form magnet as a basis, many types of loud speaker drivers were produced & used by the Wireless Fraternity. Around 1925 this Speaker driver technology was inverted to "pick-up" an analogue signal from a Shellac record on a wind-up Gramophone player, which created a tonal revolution. Previous to the Electro-Magnetic pickup, there were crude mechanical diaphragm Reproducers that lacked a decent Bass response. With 1 of these new Electrical reproducers, or "Pick-up", 1920's Audiophiles heard their record collections like never before & the Electro-Magnetic Pick-up period was born. Spanning around 7 years, it was during this transitional period that some of the most interesting audio Pickup designs ever made were offered for sale. These early Pick-up's were Cutting edge technology, relatively expensive & purchased by only the most enthusiastic Audiophiles of the day.
Popular magazine articles started appearing around 1927 & onwards, instructing "Readers" how to build Pick-Ups themselves, re-using old Telephone receivers & Headphones of the type utilizing Electro-Magnetic coils to create something affordable. These incredibly crude devices give a decent tone & were probably constructed by many audiophiles of the day in an attempt to "catch up" . Me & Dredzik decided to attempt to build the Headphones type & the hardest thing in the 21st Century is finding the original parts that were needed to build on. Simple hand tools are enough to make the custom bits to turn a headphones ear piece into a Pick-up & the one we built from a pair of archaic "Brown" type A headphones, actually sounds surprisingly good.
In Russia, in 1920 an Electric Musical Instrument operating on radio frequencies was Invented by Leon Theremin which caused International interest, 9 years later, In Germany, the electrification of a type of keyless Piano, was achieved by a Dr. Trautwein of the Radio Research section of the "Berlin Akademische Hoch-Schule fur Musik" by means of a "Neon musical Oscillator" which used the natural electrical resonance of the musician to generate an electrical tonal signal over a set of strings ,This Instrument was known as the Trautonium & is still used today by some Avant Garde musicians, as is the Theramin, 100+ years later....... However,
One of The earliest Electro-Magnetic pickups fitted to a stringed Instrument was possibly made a year or two later, at the beginning of the 1930's & at least one of these designs utilized the electro-Magnetic type headphones technology as it's basis & compared to the earlier Trautorium & Theramin, was a logical progression from the already available Electro-Magnetic technology. On one early design, a pair of headphones were used on an Electric Cello & overlaid with a piece of a Cigar box lid which acted as the resonant communication with the Bridge. Although it utilized the Electro-Magnetic coil technology, it may have behaved more like a Piezo Pick-up, relying on pressure variations through the Aluminium headphone Diaphragms to generate the Electric signal & reproduce the Tonal characteristics of the Instrument.
For a Gramophone Pick-up with a very low output, 1-2 K Ohms D.C typically,
the performance from the Pick-up's in the 1925-32 era, is varied.
There were, however, 2 outstanding examples. In 1927 a Designer from Fulham, in London named John Baden Woodroffe built a Horseshoe magnet type Electro-Magnetic Pickup for Celestion, A well known manufacturer from Kingston Upon Thames, that is still in existence. This Woodroffe / Celestion Pick-up is regarded by many Audiophiles as the pinnacle of The Horseshoe magnet type. Woodroffe was originally approached by another designer H.J.Round in 1925, who had already developed the first Electro-Magnetic Pick-up that was already in use by the B.B.C to broadcast Records over the airwaves from the summer of that year . It was the collaboration of Round & Woodroffe that led to some very interesting design concepts & eventually with Woodroffe's involvement with the Celestion Company . The 2nd notable Horseshoe magnet type Pick-up was manufactured by the "Varley" company, Located in Holborn, London & was first offered for sale around 1929. Visually, very similar to the Woodroffe, but with a different type of needle holder which rested on a slab of Rubber in front of the twin Electro-Magnetic coils, rather than a metal pivot that was used on the Woodroffe type. This "Varley" Rubber suspension created a more natural Tone than the Woodroffe. Percy Wilson, an Audio authority of the era regarded the "Varley" Pick-up as the better sounding of the 2 types, although not as visually attractive. A manufacturer of Electro-Magnetic type headphones "Brown" of North Acton, London, produced a Gramophone Pick-up in 1929 which internally replicated the layout of their own Headphone design features & shows the progression, or re-appropriation of the technology. Interestingly with this Pick-up, the cover is held on with a knurled button screw which looks like the manufacturers were eager to show off the internal mechanism.