User Guide

23
MODULATION
Modulation is an important aspect of programming and playing
synthesizers. In short, whenever one signal is used to change the value
of another – it is known as modulation. Grandmother has a dedicated
Modulation section that can apply modulation to multiple destinations
at once, and in varying amounts. This Modulation section is based
around an analog oscillator that operates in the low-frequency range,
and is commonly known as an LFO (Low Frequency Oscillator).
NOTE: The PITCH AMT, CUTOFF AMT, and PULSE WIDTH AMT knobs
are used to specify the maximum amount of modulation to be applied to
specic parameters. In order to actually apply the modulation and hear the
effect, the MOD wheel must be set to a greater than minimum position.
RATE
The R ATE knob sets the frequency of the LFO from .07 Hz to 1.3 kHz. The
accompanying LED will ash at the current Rate setting.
TIP: Patching from the KB OUT in the ARP / SEQ section, into the RATE IN
jack will cause the LFO to track the pitch of the keyboard just as Oscillator 1 and
2. This will also allow the LFO to exceed the range of the panel RATE control.
TIP: Holding the SHIFT button while adjusting the Modulation RATE knob allows
ne-tuning of the LFO rate, which is useful when utilizing the Modulation LFO as
an audio oscillator.
WAVEFORM
This four-position knob is used to select the Waveform for the Modulation LFO.
The choices are Sine, Sawtooth, Ramp, and Square.
PITCH AMT (AMOUNT)
The PITCH AMT knob determines the maximum depth of modulation that will
be applied to the Pitch of Oscillators 1 and 2 when the MOD wheel is at its
maximum position.
CUTOFF AMT (AMOUNT)
The CUTOFF AMT knob determines the maximum depth of modulation that
will be applied to the Cutoff frequency of the Low Pass Filter when the MOD
wheel is at its maximum position.