Yamaha DX27, Owner'S Manual

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Most algorithms have multiple modulators and carriers. In one algorithm a given
operator may be a carrier, while in the next it might function as a modulator—the
only difference being how it is connected. In algorithm number 5 for example, there
are two vertical stacks of two operators, and the outputs of the carriers in these
stacks are connected in parallel (horizontally). Algorithm 5 has an equal number
of modulators and carriers—two modulators and two carriers.
On the other hand, all operators in algorithm 8 function as carriers. Note that no
modulation can occur in this algorithm (except for the feedback loop on operator
4—we’ll discuss that later). But algorithm 8 is ideal for creating rich organ voices—
think of each operator as different organ “stops,” which can be mixed together
as desired.
The algorithm alone, however, does not determine the actual sound of the voice.
The vital characteristics of the voice you create depend mostly on the frequencies
and levels you program into each operator. The 8 algorithms provided in the DX27
were specially selected because they offer the broadest range of voice programming
possibilities.
The results of using different frequency ratios, as well as different algorithms, are
shown graphically in the accompanying illustration. In the left column, you see the
waveforms created by 1:1, 2:1 and 3:1 ratios between one modulator and one carrier.
In the right column, you see the waveforms which result from the same three ratios,
but when the two operators used are both carriers (connected horizontally, this
is known as additive synthesis).
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