9

In the second approach to polyphonic sound generation, a synthesizer was assigned to
a key only when the key was pressed—in effect, semi-polyphony. As early as 1973,
American company E-MU Systems introduced the Modular Keyboard System Series 4050,
a digital keyboard that could be connected to up to ten monophonic synthesizers, and
thus had ten-voice polyphony. The problems with this approach are obvious—very few
people owned ten synthesizers, and the amount of time and effort involved in
programming the settings for a new sound were an overwhelming deterrent. Digital
memory was still waiting to be developed and, once again, the evolution of
semi-polyphonic synthesizers required the desirable qualities that only digital keyboards
could provide.
The same prerequisite-digital engineering—eventually led to synthesizers that allowed
sounds to be stored. Without the benefit of digital technology, early attempts at storing
sounds included some unwieldy solutions. As an example, a synthesizer with analog
programmability required a dedicated row featuring all of the instrument’s control
elements, for every “memory” slot! In this case, a selector switch accessed one of the
many identical control panels and connected it to the sound generator.
The first synthesizer featuring storage slots implemented in this manner was the GX1,
which Yamaha released in 1975. The control elements for the system’s storage slots were
so small that they could only be adjusted using jeweller’s screwdrivers and complicated
tools—called programmers and comparators.
It was not until 1978 that the problem was resolved satisfactorily. The five-voice polyphonic
Prophet-5, released by American company Sequential Circuits, was the world’s first
synthesizer with a global storage facility. All settings for each of its five onboard
monophonic synthesizers were stored in memory slots—40 in the debut model. Moreover,
all five synthesizers shared a single user interface, which simplified matters considerably.
In spite of its initially steep price, this instrument proved extremely popular and
approximately 8,000 were built, up until 1985. In addition to its digitally implemented
polyphony and memory, the success of the Prophet-5 is attributable to the outstanding
quality of its analog sound generation system.
Digital Synthesizers
Even modern digital synthesizers featuring variable polyphony, memory, and completely
digital sound generation systems follow this semi-polyphonic approach. The number of
voices that these instruments are able to generate, however, is no longer dependent on
the number of built-in monophonic synthesizers. Rather, polyphony depends entirely on
the performance capability of the computers that power them.
375Appendix Synthesizer Basics