Gallery opened 19 May 2018
|Distributing audio on paper
The Fotoliptofono was a method of printing sound on paper, for reproduction by a photocell. It was an example of optical recording, like the Duotrac system which used photographic recording on plastic tape. A complete article on the system is reproduced here; it is largely self-explanetary.
Left: The article on the Fotoliptophone in Newnes Popular Mechanic
The distinguishing feature of the Fotoliptofono from other optical/paper systems was the way it used a flat sheet of paper (presumably the audio track was in the form of a spiral) rather than a long paper tape. It would appear that the two edges of the paper would have to be aligned very accurately indeed when it was being wrapped around the cylinder.
The advantage of the format is that a simple sheet of paper could be printed very quickly and cheaply, while printing long paper tapes would have been difficult and expensive, requiring specialised machinery.
The article is regrettably short on technical detail; I would like to know how fast the audio track moved past the photocell. The lower photograph suggests that variable-width optical recording was used, variable-density being impractical with a printing process.
It is suggested that the Fotoliptofono had a frequency response of 16 Hz - 7 kHz, which would have been very respectable for its day. The lower limit is set by the electronics as the recording process could go down to DC. As playback was optical there was no wear on the recording.
Info from Newnes Practical Mechanics Jan 1936