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The First Streaming Music Service











Imagine a subscription service, in 1897, for delivering live music to homes over telephone lines. Well, this was just the idea of Dr. Thaddeus Cahill (1867 - 1934). A licensed attorney, he is credited with the invention of the first electromechanical musical instrument, which he called the Telharmonium.

He proposed that Telharmonium music be “streamed” into hotels, restaurants, theaters, and homes via telephone lines.  Mark Twain, a fan, said “I couldn’t possibly leave the world until I have heard this again and again.”  Keyboard musicians mostly played classics by Bach, Chopin, Grieg, and Rossini.

The device was an electronic music synthesizer and the most complex musical instrument ever produced. In some ways it mimicked the air driven pipe organ, but its output was an electrical signal over a pair of wires – no air supply needed.

In 1906 the Mark2 (or MkII) model was installed at the ‘Telharmonic Hall’ on 39th Street and Broadway, New York City. Moving the finished Telharmonium equipment to NYC from Holyoke Mass. required more than 30 railroad flatcars. It was previewed to an audience of ~900 people. The Telharmonium remained in NYC for another four years giving regular concerts and ‘broadcasts’ at the Telharmonic Hall and other venues. The audience listened by means of a variety of rudimentary speakers including large, six-foot acoustic horns designed by Cahill.

An early version of the keyboard with two performers and horn speaker
It was a touch-sensitive keyboard

“A skillful performer upon the Telharmonium can make it blare like a trumpet, snarl like a bassoon, warble like a flute, or sing like a violin. Four or five performers, playing in concert, will ultimately be able, it is believed, to produce an effect closely approaching that of a full orchestra; for each bank of keys is furnished with a set of stops somewhat like those of an organ, by means of which it can be made to produce tones almost if not quite identical with those of any family of instruments.”  

                             -- "The Telharmonium", Outlook, May 5, 1906

An official 1906 brochure from the New York Electric Music Company stated:

“With the first plant producing such beautiful music as it does, what may we not expect when three hundred dynamos (alternators) and a dozen keyboards shall be installed?” 

Ads for Telharmonic Hall performances ran in the NYC Sunday papers. "The Music of 2000 AD" was one ad’s amazingly prophetic title. Admission was 50¢ and some Broadway theatre seats went for $1.50.

The Telharmonium must have been the most terrifyingly difficult instrument to play in all the history of music, a performer's worst nightmare.  It required two musicians to control its 3 keyboards and foot pedals.

Construction of the Music Machine

In his youth, Cahill had read physicist Hermann von Helmholtz’s famous book “On the Sensation of Tone” (1862), a magnum opus on the analysis of musical timbre (sonic quality) as mixtures of pure tones. The ideas inspired Cahill's design of the electromechanical music machine.

The Telharmonium was the first additive electronic music synthesizer; creating instrumental timbres (or notes) by adding/mixing the fundamental frequencies with select harmonics. The basics of additive synthesis are explained in a later section.

In its most basic form, the device was composed of ~145 AC alternators. An alternator is an electrical generator that converts mechanical energy to alternating current (AC) sine waves. Think of each alternator as a single pure tone source. These tones could be additively mixed to create any desired single note or several notes at once. In total, it supported ~7 musical octaves, from 40 to ~4,000 cycles-per-second.  As an aside, your house wall socket provides an AC sine wave at 60 cycles-per-second (in North America).

Switchboards and Tone Mixer Transformers in the basement of Telharmonic Hall  
(New York Electric Music Co. brochure, 1906)

Constructing the Mark2 Telharmonium was a massive effort. It consisted of eight 11” steel shafts carrying a total of 145 alternators. The 60-foot mainframe was built of 18” steel girders set on brick foundations. Ten switchboard panels contained ~2,000 switches. The switchboards configured all aspects of the system. The whole apparatus weighed ~200 tons and cost ~$5,514,000 (2022 $) to build. It had the proportions and appearance (and noise level!) of a power generation station. Cahill had a 50-man machine shop for building the components.

The musician’s console had 153 keys and several foot pedals. With 60 alternators (for multiple concurrent notes) online at once, the instantaneous available power output was a staggering 671 Kilowatts.  With all 145 online, ~1.60 Megawatts available output. Stand aside Bösendorfer, make way for the Telharmonium.  But why this astonishing power level?

Cahill’s bold intent was to generate the music signal at a sufficiently large power to supply up to 5,000 remote listeners over wires (using receivers without amplifiers) in Manhattan and beyond from a single musical instrument system. It was a music power plant. This was done before the vacuum tube amplifier was invented in 1906. It was essentially a Muzak service for the telephone.

Alternators of the Telharmonium, McClure's Magazine, July 1906

Listeners at home used a regular telephone receiver and attached a large passive paper horn to spread the sound waves. The electrically driven loudspeaker was not invented until 1925 so Cahill did his best without it.

In 1906, Cahill and his business partners struck an exploratory deal with AT&T to install their own wires in AT&T’s conduits. They started out by creating a small web of wiring for subscribers living near the Telharmonic Hall along Broadway from 23rd to 45th streets. The experiment did not last long.

It became apparent that the high-power output signal could cause severe crosstalk interference on AT&T’s New York telephone network. So, they prevented Cahill from using their wires or conduit to reach remote audiences.  Just imagine the strong music signal leaking onto 1,000’s of NYC calls. This dealt a critical blow to Cahill’s business plan.

Two Mark2 tone rotors in the basement of Telharmonic Hall.
Image from McClure’s Magazine 1906

“Music Plant” signal routing system

Switchboards during installation

Alternators of the Mark3 Telharmonium
Electrical World, April 28, 1910

Before each program began at the Telharmonic Hall, select audience members were treated to a tour of this extraordinary machine in the basement. Seeing the massive machinery, switchboards and wiring must have enhanced their appreciation of what they were about to hear.  

Generating the Notes

Cahill’s 1897 electronic music synthesizer design was an engineering masterpiece.  Modern synthesizers often use the same basic idea of building a single note composed of its fundamental frequency plus mixing in its many harmonics, usually with decreasing amplitudes.






The principles behind additive music synthesis

This figure shows N pure analog sinewave oscillators summed to create one output. Osc 1 is set to the fundamental frequency f1 (say, 128 cycles-per-second, CPS, for C3 on a piano) and amplitude a1. The other oscillator frequencies are typically integer multiple harmonics of Osc 1. The amplitude of each higher frequency typically ramps down.  The unit Hertz (Hz) is the same as CPS.

To create a realistic sound of a C3 piano key, set f1= 128 Hz, N=12, with a roughly falling amplitude envelope. Note that for some timbres not all higher frequencies are integer harmonics, and the individual amplitudes may be somewhat irregular.  Cahill knew this.

The biggest technical influence on Cahill was Elisha Gray’s ‘Musical Telegraph’ of 1874. Gray (a competitor of Alexander Bell for inventing the telephone) had developed a way of transmitting pitched tones over a telegraph network using electromagnetically controlled vibrating metal reeds (sinewave generators).

Cahill took a very different approach. His oscillators were the 145 AC alternators previously discussed. Each alternator has a rotating iron “gear” with the teeth spacing directly related to the desired sinusoidal frequency to be generated.  Very clever.

The video below demonstrates the simplified workings of an alternator. The gear rotates continuously and the iron teeth interact with the magnet and coil windings to create an approximately sinusoidal voltage at the coil’s output. The vertical black stripe with white lines represents the sinewave being generated as the gear turns. Press play to see operation in slow motion (264 Hz tone generated). 

 Source: Moog Foundation (with tone added)


At 11 RPS and with 24 teeth, the generated tone frequency is 264 Hz. Alternators had a varying number of teeth and rotation speeds for creating 145 distinct frequencies.

Young mill worker with one rotor for eight alternators (fundamental and 7 partials)
There were 145 “geared tone wheels” in the Mark2

All the 145 alternators were running in sync. When the keyboardist pressed a key, the system caused the desired alternators’ outputs to be combined (with appropriate amplitude per tone) to generate the note. It was typical to have ~10 alternators’ output summed per chromatic pitch (note).

The keys were touch sensitive thereby varying the output tone amplitudes depending on the pressure. So, it had elementary ADSR (Attack, Decay, Sustain and Release) amplitude envelope control.

The figure below is a simplified example of how the Telharmonium would generate a C3 piano note (with a 128 Hz fundamental) using additive synthesis.


See Appendix A for a deeper dive and two recorded sound demos.

Example details of Cahill’s alternator patent
The central rotating rotor has 24 teeth
The signal output is a 600 Hz near sinewave when turning at 25 RPS


There were three Telharmonium versions spread over about 20 years, so called Mark 1, 2 and 3. Cahill was granted the first US patents for electronic music. The Cahill Music Machinery Manufacturing Company (what a wonderful name) built the expensive machines. In the end, Cahill’s New York Electric Music Company didn't have sufficient subscribers to make the business profitable.  Advances in vacuum tube amplifiers made the Mark3 design outdated soon after completion.  Also, AT&T’s reluctance to transport the high-powered signals was a major obstacle for success.


Arthur T. Cahill (brother) with a Final Tone Mixer

Cahill filed for bankruptcy in 1914. Eventually, the last existing version was sold for scrap after brother Arthur died in 1962.  No sound recordings of it exist today.

Cahill’s historical status as the inventor of the first electronic musical instrument is irrefutable. His ideas paved the way for loudspeakers and eventually portable electronic organs. Following the master Cahill, the first modest size electronic organ was developed in 1929 in France by organ builder Edouard Coupleux and radio engineer Armand Givelet. The organ had about 1,000 vacuum tubes (~300 amplifiers and ~700 oscillators) for a pitch range of 70 notes with ten different timbres.

American inventor Laurens Hammond produced the Hammond Organ in 1934. This organ generated tones and notes in a similar fashion to the Telharmonium. Individual tones were derived from rotating metal tone wheels with pickup coils.  Hammond organs used this electromechanical method until 1975. By using vacuum tubes to amplify, Hammond’s tone wheels were substantially smaller than Cahill’s. Plus, the organ’s electrical output was not directly streaming to 1,000’s of homes.

Casting a long shadow

A 1907 article in Scientific American speaks about the potential for the Telharmonium.

Clearly the world has, through the wonderful powers of the electrical forces and the skillful use made of them by Dr. Cahill, a new music, a music which can be produced in many thousands of places simultaneously, and which in its very infancy seems destined to surpass in sympathy and responsiveness-in artistic worth-the existing music of pipe and string, the evolution of many centuries.”


                          --Scientific American Vol 96 #10, 9 March 1907

Regrettably, it never lived up to its promise. Nonetheless, the Telharmonium was a tour de force in concept, engineering, and manufacturing. It's rare to find a person who has both an expansive vision and ground-breaking engineering and manufacturing talents. His designs and visions paved the way for the future of electronic music.  

Cover of Scientific American, March 9, 1907

Thaddeus Cahill, Inventor

Appendix A
Simulating an Additive Music Synthesizer

Additive synthesis is a sound creation technique that creates timbre (notes) by adding sine waves together (1). There are several methods to simulate an additive synthesizer. One common technique uses computer programs to build the notes. Another path is to use a tool like the Audacity audio editor (PC, Mac, Linux) and lay down tracks of sine waves.  This approach is used here. This means is not useful for a live performance but is perfect for experimenting with note composition. 

Each tract is a sine component of the desired note. In the example below, the first track is the fundamental tone (131 Hz) for a C3 key on a piano. The other 5 tracks are all integer harmonics of Fund each with lower volumes. The bottom track is the mixed result of all upper tracks with a falling amplitude envelope over time, as when a piano key is hit.  Telharmonium alternators are shown associated with each tone track since, in a parallel way, they generate nearly identical sinewaves for the same C3 piano note.  


A real piano may have > 20 components including some fractional harmonics (not integer). So, this simulated example won’t sound identical to a real piano. For sure, a professional synthesizer will sound better. Nonetheless, this simulation is a proof-of-concept example.  

Using Audacity summed tracks to simulate a piano C3 timbre (sums of sines)

Here is an audio sample of the C3 key being pressed on a modern professional synthesizer.

Here is the simulated audio result (bottom track in figure above).  By adding more tracks and amplitude-envelope features this simulated sound could be noticeably improved. 



Note that a single alternator may be the source of more than one harmonic tone. For example, 1024 Hz is the 8th harmonic of 128 Hz, the 4th harmonic of 256 Hz and so on. Cahill’s signal routing network reused alternator frequencies as often as possible when constructing notes based on what keys were pressed and what timbres were desired.  

Bottom line, additive music synthesis is a viable way to create a practical musical instrument and Cahill proved this with his Telharmonium. State of the art professional synths can emulate 100’s of instruments. For example, the Korg EK-50 can emulate anything from an Alto Sax to a Xylophone, all together 744 “voices”.

It should be noted, pro synths also use other methods to generate complex timbre. One example is “sample-based synthesis”.  This technique uses the sampled sounds of real instruments instead of fundamental sine and triangular waveforms. Other techniques not described here are also used.

We are now on the threshold of neural networks generating music. See for example,  


Thaddeus Cahill would be amazed at how his vision has blossomed over the past 120 years.  

Piano C3 note pro synthesizer
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Piano C3 note Audacity synth V2
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  1. Sine waves are common in everyday life. The alternating current (AC) available from your home wall socket is a sine wave at 60 Hz (Hertz, cycles per second) and 117 volts (domestic US).


The book, Music from The Telharmonium by Reynold Weidenaar, 1995, provided some pictures used herein and many insights into the workings of the Telharmonium. Hats off to Mr. Weidenaar.


Other Reference sources

  1.  (short tutorial)



  4.      (Hammond organ tone wheels breakout)

  5. Cahill patent US 1,295,691, beautifully illustrated

  6. Stanford University, Music 256a class notes, Romain Michon

  7. “The Telharmonium: A History of the First Music Synthesizer,” review by Thomas L Rhea. Computer Music Journal, vol. 12 #3, 1988



Al Kovalick, Santa Clara, Jan 2023

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