Yamaha MU90R Owner's Manual page 67

MULTI MODE
EQ Low Frequency (Low Freq)
This determines the frequency which is boosted or cut (in the Low Gain
parameter below) for each Part.
EQ Low Gain
This determines the level of the selected frequency (in Low Freq
above). Positive values boost the level of the selected frequency and
negative values attenuate it.
EQ High Frequency (High Freq)
This determines the frequency which is boosted or cut (in the High
Gain parameter below) for each Part.
5 8
Graphically shows the Low Frequency setting for each Part.
Selected Part and MIDI channel
Graphically shows the Low Gain setting for each Part.
Selected Part and MIDI channel
Graphically shows the High Frequency setting for each Part.
Selected Part and MIDI channel