The Pianorad, designed by Hugo Gernsback and built by Clyde Finch at the Radio News Laboratories in New York was a development of Gernsback’s Staccatone of 1923. the Pianorad had 25 single vacuum tube oscillators, one for every key for its two octave keyboard making the instrument the first valve based electronic instrument to achieve full polyphony*. The sound from the tubes was passed through a rudimentary mechanical filter that removed harmonic distortion producing virtually pure sine tones. The instrument played sound through a top mounted speaker or could be connected directly for radio broadcast.
Theory of the Instrument
The Pianorad has a keyboard like an ordinary piano, and there is a radio vacuum tube for each one of the piano keys. Every time a key is depressed, there is energized a radio-oscillator circuit which gives rise to a pure, flutelike note through the loud-speaker connected to the device. It is possible to connect any number of loud-speakers to the Pianorad if it is desired to flood an auditorium with its tones. Also, by arranging suitable outlets for loud-speakers on different floors or different rooms, the sounds of the Pianorad can be heard all over any large building.
The musical notes produced by the vacuum tubes in this manner have practically no overtones. For this reason the music produced on the Pianorad is of an exquisite pureness of tone not realised in any other musical instrument. The quality is better than that of a flute and much purer. the sound however does not resemble that of any known musical instrument. The notes are quite sharp and distinct, and the Pianorad can be readily distinguished by its music from any other musical instrument in existence.
Electric, Not Sound Waves
The loud-speaker arrangement makes it possible for an artist to play the keyboard while the music emerges, perhaps miles away from the Pianorad. It is thus possible for the pianist to play the instrument in absolute silence while the music is produced at a distance. This requires simply that a wire line must connect the output end of the Pianorad instrument with the loud-speaker at some distance away. It is quite feasible for the Pianorad to be played in New York while the music will be heard at the Chicago end, with any number of loudspeakers connected by amplifiers to a long-distance telephone wire line.
A novel idea is the connection of the Pianorad direct to the broadcast-station transmitter. In this case, instead of using a loud-speaker in the studio, the Pianorad is connected electrically to the broadcast transmitter. The artist now plays the Pianorad in the studio in absolute silence. No sound is heard. The radio audience, however, will enjoy the music, although no one in the studio can hear it. In order that the pianist may hear what he is playing, he will wear a set of head receivers attached to an ordinary radio set. The music, therefore, is picked out from the air by the receiver and thus only the artist hears it. In the studio itself, no sound is audible for the Pianorad itself is silent.
Developments Still Continuing
The Pianorad has as yet not entered the commercial stage. The instrument illustrated in this article has 25 keys and therefore, 25 notes. A full 88-note Pianorad has as yet not been constructed, but will be built in a short time. The larger instrument could have been built at once, but it would occupy almost as much space as a piano; and as this amount of room was not then available in the studio of WRNY, for which the first Pianorad was especially constructed, the smaller instrument was built instead.
The Pianorad at WRNY is usually accompanied by piano or violin or both; very pleasing combinations are produced in this manner. At present it uses a single stage of amplification, giving volume enough, in connection with one loud-speaker, to more than fill a fair sized room. By adding several stages of audio-frequency amplification, sufficient volume can be obtained to fill a large church or auditorium.
The Pianorad was first demonstrated publicly Saturday, June 12 at 9 P.M., with a number of brilliant selections played on it by Mr. Ralph Christman; the concert being broadcast over WRNY at The Roosevelt, New York.
The principle embodied in this instrument was first demonstrated in 1915 by Dr. Lee de Forest, inventor of the Audion. At that time Dr. de Forest was able to produce musical tones by means of vacuum tubes, but the radio art at that time had not progressed sufficiently to make possible the Pianorad.
An article by Clyde J. Fitch describing the construction of the Pianorad will appear in the December issue of Radio News.
Each one of the twenty five oscillators had its own independent speaker, mounted in a large loudspeaker horn on top of the keyboard and the whole ensemble was housed in a housing resembling a harmonium. A larger 88 non keyboard version was planned but not put into production. The Pianorad was first demonstrated on june 12, 1926 at Gernsback’s own radio station WRNY in New York City performed by Ralph Christman. The Pianorad continued to be used at the radio station for some time, accompanying piano and violin concerts.
*The Telharmonium at the beginning of the 20th century earlier was a polyphonic electronic instrument but, because it generated sound using tone-wheels, it can be considered an eletro-acoustic instrument.
Hugo Gernsback: “The ‘Pianorad’ a New Musical Instrument which combines Piano and Radio Principles” Radio News, vol. 8, no. 5, November 1926