Yamaha Electone EL-87 Owner's Manual page 101

(3) AWM Operators
Each algorithm also has a special AWM (Advanced Wave Memory)
Operator. AWM Operators are not sine waves like the other Operators,
but are digital recordings of actual instrument sounds, such as piano,
violin, guitar, and so on. The AWM Operator's sound is mixed with
the sounds of the other Operators in the algorithm to create realistic
voices.
AWM Operator
OL (Output Level)
1
Determines the level of the AWM sound. Range: 0-127
C-OFF (Cut-off)
2
Determines the cut-off frequency filter, or the frequency point
to filter out the specific frequency range. See diagram below.
Range: -128- +127
The filter removes a specified range of frequencies from the
sound and allows the rest to pass through, thus giving you
powerful control over the sound's characteristics. The EL-87
has three types of filters: High Pass Filter which passes the
frequencies above the cut-off point, Low Pass Filter which passes
the frequencies below the cut-off point and Band Pass Filter
which passes only the specified range of the frequencies.
The filter type used and the effective cut-off point depend on
the selected voice.
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