Modulation And The Spectrum Bass Ii - Peavey Spectrum Bass II Operation Manual

Chapter 5 Beyond the Basics
MODULATION AND THE SPECTRUM BASS II
Modulation modifies some aspect of a sound over a period of time. Since synthesizers inherently make static sounds
(unlike acoustic instruments, whose timbre and dynamics change—often radically—over the duration of a note),
modulation can be the key to making rich and expressive sounds. The Bass II has a variety of modulation sources,
shown in the chart on page 22. Here's an overview of the main modulation categories.
«•* Modulation signals generated by the way you play the keyboard or other controller driving the Bass II (velocity,
note position, and pressure)
Envelope generators (these produce a programmable modulation change over time)
LFOs (these produce periodic, cyclic modulation changes over time, such as vibrato or tremolo)
Performance controls (modulation wheel, foot pedal, and data slider, which are designed to be manipulated
in real time, as you play)
*•" External MIDI control. This allows external MIDI control signals (e.g., from a sequencer) to control some aspect
of die Bass IPs sound.
The Bass II arranges its modulation source outputs and modulation destination inputs into a "matrix" so that virtually
any output can feed virtually any input. The Wave, DCA, Filter, and Pan modules have two independent inputs that
can be assigned to any modulation source. The LFO has one independent input that controls modulation amplitude
(depth), an input that controls modulation rate, plus a separate modulation wheel control for LFO depth and rate.
Each non-normed modulation input includes two parameters: modulation source (including OFF if no modulation
is desired) which lets you choose from die various modulation sources mentioned above, and modulation amount.
The modulation amount can be positive or negative. With positive amounts, an increasing control signal increases
the value of the parameter being controlled. With negative amounts, an increasing control signal decreases the value
of the parameter being controlled. A setting of 00 is equivalent to turning off the modulation source.
Note that having two modulation inputs available allows for interaction between two modulation signals. Example:
If a parameter responds to keyboard velocity and an envelope generator, the parameter will follow the general
envelope shape but also be influenced by the velocity.
If a "baseline" setting exists, modulation amounts add or subtract values from that setting. Example 1: If the filter cutoff
is set to a certain frequency, positive modulation amounts will increase that frequency, and negative modulation
amounts will decrease that frequency. However, modulation cannot force a value beyond its maximum range.
Example 2: If die filter cutoff is at die lowest possible frequency, then maximum positive modulation will vary the
filter cutofffrom the lowest to the highest frequency. Applying negative modulation will not affect the filter frequency
because if it's at its lowest value, it cannot go any more negative.
To achieve modulation, you must first assign a source. This source can be something you physically move
(Modulation Wheel, Aftertouch (pressure), Foot Pedal, Velocity (how hard you play a note), Pitch wheel, keyboard
(specific notes) etc., or synthesizer parameters such as the Envelopes, LFO, Sample & Hold, Key Scalar, etc. Next,
the source must be assigned To a DESTINATION (die parameter that is actually going to be modulated).
18 Specrtum
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Bass II