Dolby A 1

Ray Dolby's 'A' type noise reduction system was one of the most important technical
developments in the production of recorded music.

Most people will be aware some sort of of Dolby 'technology' lurking in their cassette decks and
home cinema systems, but the professional 'A' type audio noise reduction system was probably
their most significant product in terms of impact in how the recording industry went about its
business and in the actual sound of popular music.

This simple looking instrument revolutionized the recording of popular music during the 1970's
because it allowed effective use to be made of multitrack tape recording.

And what is so special about multitrack recording? Well, it allows recorded music to be put
together or assembled rather like building a jigsaw puzzle. With multitrack, instead of attempting
to 'capture' a real performance or musical event as it is being played, each performer and
instrument is separated out by means of directional microphones and accoustic screens, and is
then recorded onto their own particular 'slice' of the master tape. This tape 'layer cake' (to mix my
metaphors) is usually built up by 'laying down' a 'backing track' first and then adding various other
instruments, performers or effects until the producer is happy.

To this many layered cake of mono recorded tracks and instruments other stuff or effects may be
added to 'improve' the mix. This can be done at various 'future' times and indeed at various
locations around the World. The layers are then mixed down onto another machine (or back to the
same machine) and the various (mono) tracks are panned to make a 'stereo' mix. Various types of
synthetic echo, volume compression and lord knows what else are all employed to 'improve' the
sound. All very fine and clever, but each of those analog tracks will actually double the amount of
tape noise added to the final recording. During track 'bouncing' and mixdown (we used to call
them reductions) noise could build up to such an extent to make acceptable recordings impossible.

But just at the right time this clever piece of electronics arrived and effectively fixed the problem.
And while many other 'wonder' noise reducing boxes came and went over the years (including
those by DBX and Telex), Dolby A was by far the most successful and probably the best (er,
least) 'sounding'.

This particular example is a 2nd generation Dolby A type 361, and it spent its working life at the
BBC Maida Vale studios in London.

Click on the pictures for further information.