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2009/83/2 Transient waveform modifier (envelope shaper), custom built, metal / plastic / electronic components / glass, probably made by Tristram Cary, England, 1958-1962. Click to enlarge.

Transient waveform modifier

This object is an example of a piece of electronic equipment built (probably in the early 1960s) specifically for audio synthesis. It is custom built, possibly by Tristram Cary and was used in his early studios established in London in the mid-1960s. It uses valve technology and was hand built, suggesting that it was built in the very early 1960s. It may have been used in the construction of sounds for the Daleks in early episodes of the BBC's ground breaking science fiction series Dr. Who. It …


Object No.


Object Statement

Transient waveform modifier (envelope shaper), custom built, metal / plastic / electronic components / glass, probably made by Tristram Cary, England, 1958-1962

Physical Description

This is a hand-built device known as a Transient Waveform Modifier. A transient is a voltage waveform that is generated to trigger the envelope of a sound. The envelope shapes the amplification of an oscillator over a short period of time so that it sounds like it has been produced as a musical sound. This is the contour of the sound and is normally thought of as having an attack, decay, sustain and release period (ADSR).

It appears to have been custom built either by or for Tristram Cary and was used in his early studios back as far as, at least, the Fressingfield studio in Suffolk in the UK. It is a black metal panel with sixteen control knobs arranged in four rows of four, with a set of labels between the upper and lower pairs of rows.

Electronically, it consists of four independent channels each of which utilises one row of control knobs. Each row consists of two multi-pole switches and two potentiometers. Each row is numbered, in cream paint, from 1 at the top to 4 at the bottom. In the back of the metal plate are the electronics for the four channels. These consist of the body of the switches and the potentiometers, an EF40 pentode audio amplifier valve, and the necessary passive electronic components to connect everything up and shape the currents so that the device works.

Functionally, this device is a version of the envelope generator used in most analogue audio synthesisers. It has controls:

The left most control is a 6 position switch that sets the degree of differentiation performed on the signal. Differentiation causes the signal to be sharpened up and may be thought of as the "attack" rate (slew rate) of the control voltage envelope. This control sets the rise time or 'attack' of the envelope.

The second control is a three position switch which determines whether the envelope waveform triggered by the transient continues to 'grow' (or rise) or 'die' and drop away (or releases).

The third control is a variable potentiometer that sets the duration of the active period of the envelope, that is, it sets the hold period of the note being shaped by this signal.

The right most control is a potentiometer labelled Low Level Set and is the level of the voltage held during its interim period or the voltage that it remains at between transient events.


Handwritten label: Transient Waveform Modifier



370 mm


320 mm


147 mm




Tristram Cary (b. Oxford, UK, 1925 - d. Adelaide, 2008) was a pioneering English composer who worked in electronic music. His first studio was set up in the UK about 1965. He was instrumental in the development of the audio synthesiser being at least in art the impetus behind the development of the Electronic Music Studios' (EMS) Synthi A, and VCS3. In 1974 he moved to Australia, first to Melbourne University to teach electronic music using the EMS Synthi 100 at Melbourne University and subsequently to Adelaide to teach composition and electronic musk at the Elder Conservatorium, University of Adelaide.

He gained his knowledge of electronics as a Naval radar operator during WWII. During this period he heard of the development of tape recording and he realised that he could edit and make musical works by cutting up the tape with a razor blade and re-splicing it. As he later said:
"It occurred to me that … here was a chance to have a new sort of music altogether. The editing capacity meant that you could cut sounds together that were not normally together." [David Ellis, "Music pioneer celebrates milestone", Lumen, The University of Adelaide Magazine, winter, 2005, ]

After the war he returned to university at Oxford and then went on to Trinity College of Music in London. He began to experiment with electronic sound in 1949, bought his first tape recorder in 1952 and began composing electronic and orchestral music. His first great success was the score for the film The Ladykillers (1955) starring Alec Guinness and Peter Sellers. He continued to write film and television music and is famous for producing the music for several episodes featuring the Daleks in the BBC's Dr. Who.

Around 1965 Bob Moog began selling his early synthesisers in America. In 1967, Cary established an electronic music studio for the Royal College of Music and assembled his own studio in his London house. Up until this time most electronic music had been produced within large workshop style studios using an assemblage of electronic workshop test equipment (function generators and filters and the like) and hand built special purpose devices.

Cary met and consulted for Peter Zinovieff who had established a private electronic music studio in Putney (on the south bank of the Thames in London). Zinovieff had purchased a DEC PDP-8 minicomputer to explore computer music and established it in the studio. David Cockerell was an experienced electronic designer who built a ring modulator that gave the distinctive sound to the Dalek's voices in Dr. Who. He became Zinovieff's engineer in 1968. Cary, Zinovieff and Cockerell, through their common interest in electronic sound, worked together to come up with an audio synthesiser that would be more portable and a lot cheaper than existing devices such as the Moog synthesisers.

Legend has it that the Australian composer Don Banks who, in the 1960s was resident in London, also wrote film music and was interested in incorporating jazz into his compositional repertoire, had asked Zinovieff and Cary to make him a small voltage controlled synthesiser. With Cockerell as the main electronic designer, they mapped out how to build what became the VCS1, of which two were built. One of those two is in the collection of the Powerhouse Museum [H9953-13]. By 1969 they had established the company Electronic Music Studios and began marketing the VCS3 (a larger version of the VCS1) with 3 VCOs, a VCFilter, an envelope generator and other interesting modules. Again the electronics were designed by David Cockerell, the case was designed by Cary and the whole project was supported by Zinovieff. Apart from its small size the most interesting aspect of the VCS3 as against the American synthesisers of the period was that it used a small plug settable patching matrix to connect outputs of sources to inputs for control of audio signals.


Credit Line

Gift of John Cary, 2009

Acquisition Date

15 October 2009

Cite this Object


Transient waveform modifier 2021, Museum of Applied Arts & Sciences, accessed 19 January 2022, <>


{{cite web |url= |title=Transient waveform modifier |author=Museum of Applied Arts & Sciences |access-date=19 January 2022 |publisher=Museum of Applied Arts & Sciences, Australia}}