Yamaha TG500 Owner's Manual page 135

Higher resonance values produce a higher resonant peak and reduce the
overall bandwidth of the filter, passing a narrow band of frequencies at the
filter's cutoff.
Band (BPF & BEF bandwidth)
Determines the width of the frequency pass or elimination band for the BPF
and BEF filter types, respectively. The minimum setting of "0" produces an
extremely narrow pass or elimination band, while the maximum setting of
"127" produces a wide band.
Ctrl (Filter control)
Determines whether the cutoff frequency of the selected filter will be con-
trolled by the LFO or by the filter envelope generator (EG).
Varying the filter cutoff frequency can create "sweep" or "wah-wah" type
effects. If the cutoff is controlled via the LFO a cyclic variation based on the
"shape" of the selected LFO waveform is produced. If EG control is selected,
the filter envelope generator (see "FILTER EG LEVEL & RATE" below) can
be set up to produce a wide range of time-based variations.
Please note that if "LFO" is selected, the filter cutoff envelope generator
parameters have no effect on the sound. If "EG" is selected, any controller
assigned to filter cutoff control will not function while a note is being played.
VOICE EDIT MODE / 3: Full Edit. 3-3: Filter
3-3-01: PARAMETER 123