Ah, such elegance! A consummate pianist playing her fingers over
the keyboard as beams of light flash through spinning disks to produce
sweet music through honking great horns that look as if they've been
nicked off a steamship. It's a pity that Herr E. Welte's of
Germany's 1936 Light-Tone or Light-Beam Piano never became a mainstay
of the classical music scene. It's such a monster of an
instrument that I'd go to a concert just for the curiosity value.
Hook this baby up with a couple of kettle drums and a Chinese gong and
it would carry all before it at any Battle of the Bands.
The principle behind the light-beam piano is rather interesting and up until 1963 you could have found a perfect example of it
anywhere in Britain just by ringing up the
Speaking Clock.
When I first heard the Speaking Clock as a boy I thought that it must
have been the most thankless job on the face of the Earth. I
imagined that there
was some woman with a voice box like leather stuck in an office day and night reading off the time.
Maybe, I thought, they gave her time off, but I couldn't see how.
I could never even detect when she got a chance to take a sip of
water, much less get her head down for some sleep. Later on,
someone in a fit of exasperation explained to me that the Speaking
Clock was, in fact, a recording. That made sense, except that I
still could not imagine how anyone could have the stamina to manage to read out the time
even for a record at ten second intervals to fill up twelve
hours worth of time signals. Besides, how do you make sure
the pips sound in the right place? What happens if the record
wears out, as it was sure to do?
It turns out
that the lads at the GPO used the same dodge that made the light-beam
piano tinkle out notes. The Speaking Clock, in fact, consisted
of four motorised glass disks with a beam of light shining through
each one. One disk had a recording of the woman reading out the
hours, the second had her reading out the minutes, the third the
seconds, and the fourth had the pips.
That saved a lot of recording of a lot of very dull
lines about "Ten twenty-one and 30 seconds" and all that. Just
read read out the hours, then the minutes, then the ten-second
intervals and you're laughing.
But why glass
disks? And what has that to do with pianos?
That's
where the clever bit comes in. If you take a magnifying glass
and look at a piece of sound motion picture film you'll see a squiggly
line running down one side between the picture and the sprocket holes.
This is the soundtrack of the film. The sound is recorded and
printed on to the film as this line, much as sound is recorded on a
phonograph record as a squiggly line cut into the vinyl. And if
you don't know what a phonograph record is, I shall hit you with my
cane. As the film runs, a light shines through the strip on to a
photoelectric cell and turns the squiggles back into sound.
The glass disks of the Speaking Clock and the
light-beam piano do exactly the same thing. On the Speaking
Clock the woman's recorded voice is printed the same as is the
soundtrack of a motion picture, but on the light-beam piano, it is
musical tones that are printed so that when the pianist strikes a key
a light shines through a track and produces the desired tone.
In
this close up of one of the light-beam piano disks you can see the
tone tracks. One thing you may have noticed is that the tracks
don't look like the sort of continuous, irregular squiggles that you
see on a film soundtrack. Instead, you'll see that they are
quite regular, even geometric in shape. That is because the tone
tracks for the light-beam piano aren't made by recording real sounds,
but by etching the shapes directly on to the disks so that the piano
maker can get exactly the tone he wants. Call it
custom-tailored sound to order.
At the end of the day, though it's all terribly
technical and complicated and you have to plug it into the mains to
get it to work anyway, so maybe it's best to just stick with the
banjo.
It turns out
that the lads at the GPO used the same dodge that made the light-beam
piano tinkle out notes. The Speaking Clock, in fact, consisted
of four motorised glass disks with a beam of light shining through
each one. One disk had a recording of the woman reading out the
hours, the second had her reading out the minutes, the third the
seconds, and the fourth had the pips. 
But why glass
disks? And what has that to do with pianos?
That's
where the clever bit comes in. If you take a magnifying glass
and look at a piece of sound motion picture film you'll see a squiggly
line running down one side between the picture and the sprocket holes.
This is the soundtrack of the film. The sound is recorded and
printed on to the film as this line, much as sound is recorded on a
phonograph record as a squiggly line cut into the vinyl. And if
you don't know what a phonograph record is, I shall hit you with my
cane. As the film runs, a light shines through the strip on to a
photoelectric cell and turns the squiggles back into sound.
In
this close up of one of the light-beam piano disks you can see the
tone tracks. One thing you may have noticed is that the tracks
don't look like the sort of continuous, irregular squiggles that you
see on a film soundtrack. Instead, you'll see that they are
quite regular, even geometric in shape. That is because the tone
tracks for the light-beam piano aren't made by recording real sounds,
but by etching the shapes directly on to the disks so that the piano
maker can get exactly the tone he wants. Call it
custom-tailored sound to order.