Sequential Split-Eight - Filter Parameter Details

FILTER MOD BY LFO
Value Ranges 00/01
00= Off
OUOn
This parameter switches LFO-modulation to the filter, which
normally produces a vibrato effect.
FILTER
The FILTER section contains parameters of the filter itself and of its
ADSR envelope generator.
CUTOFF FREQUENCY
Value Range: 00-127
(The "hundreds" digit is not displayed. For example, value 127 is
displayed as 27.)
Adjusts cutoff frequency of the 24 dD/octave (4-pole) low-pass filter.
This parameter is rather like a tone control. "Cutoff" is the
frequency below which all elements of the mixer's output signal are
let through. The higher-frequency components of the input signal
(that is, all those above the cutoff frequency) are suppressed. The
higher the parameter value, the higher the frequencies are which pass
through the filter. Thus, the "brighter" the sound.
In addition to this parameter, overall cutoff frequency is the result of
all the filter modulation parameters.
RESONANCE
Value Range: 00-31
26s approximate oscillation point (may vary by voice)
Adjusts the amount of filter resonance. As the value is increased
from 0, the amount of resonance ("emphasis," "regeneration," or "Q")
applied to those signal components at the cutoff frequency will
increase. As resonance increases, frequencies lower than the cutoff
will become decreasingly audible in comparison with those nearer the
cutoff. As the parameter value is increased, the filter breaks into
oscillation, acting like a sine-wave audio source whose pitch is
determined by CUTOFF FREQUENCY (and the various filter
modulation sources). . :
ENVELOPE AMOUNT
Value Range: 00-15
00s no envelope modulation
The filter cutoff may be varied over time by the filter envelope
generator. This parameter adjusts the depth of filter envelope
modulation.
Each voice contains two independent ADSR envelope generators: one
controls filter cutoff frequency, and one controls the amplifier gain.
The following comments on the ADSR envelope generators are valid
for both.
An "envelope" changes value over time at a rate adjusted by the
ATTACK, DECAY, and RELEASE parameters. As the envelopes are
generated with each keystroke, they "contour" the voice intonation,
timbre, and dynamics, animating the otherwise raw waveshapes which
come from the mixer.
The contour pattern is initiated when a key is struck. This "triggers"
the envelope generator(s) to proceed through their attack and decay
periods. These periods can each range from zero to about 11 seconds.
The envelope voltage rises to its full value, then falls (decays) to the
level set by the sustain parameter, where it remains until the key is
released. When the key is released, the gate goes off and the
envelope voltage drops to zero at a rate set by the release
parameter.
ATTACK
Value Range: 00-15
8= 1 second
15s U seconds
Adjusts the length of time for the envelope to go from zero level
(when key is initially depressed) to maximum level.
DECAY
Value Range: 00-15
8s 1 second
I5s 11 seconds
Adjusts the length of time for the envelope to go from maximum
level to sustain level. If sustain is set at maximum then the decay
parameter value is irrelevant, because level is already maximum.
SUSTAIN
Value Range: 00-15
Adjusts the sustain level from zero to maximum. This is a level
control, not a time control. Sustain time is the period between the
end of the decay period and the beginning of the release period. This
is the length of time the key is held after attack and decay.
CM608A
15
CM608A
16