2 STEEL TAPE
3 OPTICAL FILM
4 DIRECTLY-CUT DISKS
5 MAGNETIC TAPE
6 PORTABLE RECORDING
7 CARTS AND DARTS
8 DIGITAL RECORDING
were made with sound from the end of the 1920s; disk and optical
recording ran side-by-side for a time, but the advantages of optical
were considerable, particularly in editing, and in that the track was
on the projection print alongside the picture and so couldn't get lost
or out of synchronization. Though the quality could be noisy at first,
it was rapidly improved.
There were a few stand-alone optical recorders, such as the Selenophone
which used 35mm film sliced to leave just the sound-track and adjacent
and was used for recording the 1937 Salzburg Festival opera
performances (not by the BBC). However the system was not really
suitable for broadcasting as the film
had to be developed, causing delays, and the quality was mediocre.
The BBC became interested
in a development by the Dutch Philips company, the Philips-Miller
optical recorder. Instead of using photographic techniques, this used
film stock coated with a clear layer of gelatine with a thin opaque
covering. A stylus with a wide angle moved vertically and cut away the
opaque layer to make a variable-area soundtrack; this could be played
back immediately using a light beam and a photoelectric cell (the same
as for a photo-optical recording). The film travelled at 32 cm/second
(fractionally over 12½ inches/second).
the machines and the reels of film were a much more practicable size
than the Marconi-Stille, the film could be easily edited (using film
cement, as with cinema film), and though there was still some
background noise the quality was quite good. The BBC started
experimenting with this system in 1935 and it gradually came into use.
the onset of the war in 1939 the ability to make recordings suddenly
became much more important. The concept of a programme appearing on the
same day of the week became normal for the first time, because of the
expected difficulty in distributing the Radio Times
Programmes such as the immensely popular ITMA
were performed live but recorded on Philips-Miller for subsequent
repeat - up to then Variety and similar programmes had not normally
been repeated, and with the difficulties caused by the war a second
chance to hear a programme became important.
were difficulties in obtaining the film stock during wartime, and two
methods were used to eke it out - programmes where a lower quality
could be accepted were recorded at 20 cm/sec; and there was enough
space to record two tracks (separately) side-by-side. I believe some
were even made with three, though this would pose a danger of peaks on
one track breaking through into the adjacent one (and I've heard
something suspiciously like this on recordings).
The surviving wartime ITMA
were all recorded on (and have since been transferred from)
Philips-Miller, as was the very ambitious Louis MacNeice play Christopher Columbus
performed live in 1942 and involving multiple studios, a huge cast, a
chorus and the BBC Symphony Orchestra.
reasonably reliable the machines did require skilled handling; because
the cutting stylus had to be exactly made, when engineers found one
that worked well they tended to appropriate it and carry it for their
own use. The system continued through into the post-war period but fell
out of use by the end of the 1940s.
At the same time as the Philips-Miller was coming into
use, a new method of disk recording was developed, and this will be
covered on the next page