Hard Sync Functions - Kurzweil K2661 Musician's Manual

DSP Functions
The DSP Functions
Amplitude Modulation (AMP MOD)
The AMP MOD function multiplies its two input signals, and the result is multiplied by a gain
value that is determined by the parameters on the AMPMOD's control-input page. This result
determines the balance between the upper and lower wires. AMP MOD can clip the signal, so
you may need to use the Pad parameter.

Hard Sync Functions

SYNC M AND SYNC S
These two functions appear in Algorithms 26–31, and always work in tandem. Each is a rising
sawtooth oscillator. SYNC M is the "master" waveform, and SYNC S is the "slave." These terms
stem from the fact that the pitch (frequency) of the master waveform determines the repetition
rate, and thus the shape, of the slave's waveform. These functions generate their own
waveforms, and do not pass the sample input through the algorithm. Consequently the PITCH
function does not appear for these algorithms.
Every time the master waveform falls from positive full scale to negative full scale, the slave
waveform is forced to negative full scale. You can create a wide variety of timbres by adjusting
the pitches of the waveforms relative to each other. This is done with the parameters on the F1
PCH and F2 PCH control-input pages. F1 is for the master, and F2 is for the slave. Pitch control is
really a bit of a misnomer for the slave waveform, because its pitch is determined by the pitch of
the master waveform. The fundamental of the slave waveform is forced to be the same as that of
the master, since they always have the same frequencies, although the shapes of their
waveforms differ.
To clarify this, assume for now that the pitch of the master waveform remains constant. When
you trigger a note, both waveforms start at negative full scale. If the slave's "pitch" control is set
to a much lower value than that of the master, the master waveform will reach positive full scale
before the slave. So the shape of the slave waveform will be that of a more slowly rising
sawtooth wave with a relatively large negative DC offset (most of the waveform will be in the
negative portion of the scale).
If the slave's "pitch" control is set to a value only slightly lower than that of the master, the
waveforms will be very similar, and the slave waveform will have a small negative DC offset.
When the pitch settings are identical, the waveforms are identical.
If the slave's pitch setting is higher than that of the master (which usually gives more interesting
results), the slave's waveform will alternate between a complete sawtooth cycle and a fraction of
the subsequent cycle. At twice the frequency of the master, the waveform will have twice the
frequency, and only the even harmonics of the master frequency will be pronounced. When the
slave/master frequency ratio is nearly, but not exactly three, all harmonics will be present, but
the 3rd, 6th, 9th (all multiples of 3) harmonics will be much louder than the others. This will
sound like a resonant filter with multiple resonance peaks.
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