The Early Electronic Orchestra
The Analogue Circuits Behind Polyphonic Electronic Keyboards Before Digital and MIDI Came Along
Before digital signal processing took over electronic keyboard instruments, they were implemented using analogue circuits that used tubes/valves, transistors, and even neon lightbulbs! Yet using these components keyboards were developed that could mimic string and brass ensembles, pianos and harpsichords and many other instruments. How did they do it?
The purpose of this talk is to look at both the architecture and the circuitry of these instruments. And show how amazing results could be achieved using comparatively simple electronic circuitry. It will look at:
1. The basic architecture of these instruments
2. How they generated the right notes,
3. How they generated the desired envelope,
4. And imposed them on the waveform,
5. How they simulated the effect of many instruments playing together.
6. Some of the limitations of the circuitry, and ways of mitigating them.
It will also look at how, if it was required, touch sensitivity could be achieved, such as in electronic pianos. Where possible there will be audio examples demonstrating the sounds that could be achieved.
For many people who have only ever experienced the digital world it will be illuminating to see just how much could be achieved by comparatively simple circuits. In those days electronic components were expensive so considerable ingenuity was expended in minimising the total number of components required.
These instruments are part of our musical and audio heritage and the circuit techniques they used are in danger of being forgotten so this tutorial will be a timely reminder of what used to be done.
It may also provide useful information to people who are attempting to model these instruments using modern digital methods.
The talk will be accessible to everyone, you will not have to be an electronic engineer to understand the principles behind these unique pieces of audio engineering history.
Jamie Angus-Whiteoak
Emerita Professor of Audio Technology
University of Salford
Jamie Angus-Whiteoak is Professor Emerita of Audio Technology at the University of Salford. Her
career in industry and academia has spanned integrated optics, acoustics, analogue and
digital signal processing, and her expertise ranges from valve (tube) circuits to the applications
of esoteric number theory in signal processing. Jamie has invented modulated, wideband, and
absorbing diffusers, direct processing of Super Audio CD signals, and one of the first 4-
channel digital tape recorders. She worked in signal processing, analogue circuit design, and
numerous other audio technology topics, and has been active throughout the AES for 30
years. Aside from pioneering degree-level courses in both music technology and electronic
engineering in the UK, Jamie has been awarded an AES fellowship, the IoA Peter Barnett
Memorial Award, and the AES Silver and Gold Medal Awards "For extraordinary contributions as an innovator and inventor in the fields of audio science, acoustics, and signal processing".
She is also an honorary fellow of the IOA and ISCVE and is currently AES VP for Northern Europe.