Type, DB LPF Figure, CUTOFF0...127, Resonance

6.FILTER — SYNTH

The filter controls the tonal character of the sound produced by the oscillator. It determines the tone by allowing only the desired portion of the sound to pass. "TYPE" (knob 1) selects the type of filter (i.e., the way in which it will cut the frequency). "CUTOFF" (knob 2) sets the frequency at which the cut will occur. Normally, turning this knob toward the right will brighten the sound, and turning it toward the left will darken the sound. "RESONANCE" (knob 3) emphasizes the frequency region near the cutoff frequency, adding a distinctive character to the sound. Other parameters in this section let you specify the depth of the modulation applied by the filter EG, and the way in which keyboard tracking will affect the cutoff frequency.

TYPE	[-24dB LPF, -12dB LPF,
	-12dB BPF, -12dB HPF]

Selects the type of filter

-24dB LPF ():

The -24 dB LPF (-24 dB/octave Low Pass Filter) is the most common type of filter; it passes the frequen- cies that are below the cutoff fre- quency, and cuts the frequencies that are above (➝ Figure 6-1). Low- ering the cutoff frequency will make the tone darker and more mellow.

-12dB LPF ():

The -12 dB LPF (-12 dB/octave Low Pass Filter) has a more gentle slope than the -24 dB LPF, producing a more natural-sounding effect.

(➝ "-24 dB LPF")(➝ Figure 6-1)

Figure 6-1

CUTOFF[0...127]

Sets the cutoff frequency. Increasing this value will raise the cutoff frequency.

"CUTOFF" can be varied by time-variant change produced by Filter EG, by keyboard play- ing dynamics (velocity), and by note location (keyboard track- ing).

If the "CUTOFF" value is set too low, the volume may be ex- tremely low, or you may hear no sound at all.

Figure 6-4

The effect of resonance

LPF

RESONANCE [0...127]

Sets the resonance of the filter. This will emphasize the overtones near the cutoff frequency specified by "CUTOFF," adding a distinctive character to the sound. Increasing this value will increase the effect. (➝ Figure 6-4)

Since movement of the "CUTOFF" knob will affect the overtones that are boosted by resonance, it is best to adjust "CUTOFF" and "RESO- NANCE" in conjunction with each other.

FILTER EG INT

[-63...63]

This specifies how time-variant modulation from the Filter EG will be applied to the cutoff frequency (➝ Figure 6-5). The cutoff frequency will change over time according to the Filter EG settings, modifying the tone. For example, you can use this to create a sound that gradu- ally begins to brighten when you press the key, and then gradually becomes darker.

This INT (Intensity) parameter specifies the depth (sensitivity) to which the Filter EG will affect the cutoff frequency.

With a setting of 0, the Filter EG will not affect the cutoff frequency. In- creasingly positive (+) settings will allow the Filter EG to have a corre- spondingly greater effect on the cutoff frequency. (➝ Figure 6-6)

FILTER KEY TRACK

[-63...63]

This specifies how keyboard track- ing (the keyboard location that you play) will affect the cutoff fre- quency.

For example if the sound played by the C4 key has the desired tone but higher notes no longer have reso- nance or are too mellow-sounding, you can adjust keyboard tracking to make compensations so that the cutoff frequency will rise for higher notes.

With positive (+) settings, the cut- off frequency will rise as you play upward from the C4 note, and fall as you play downward. With nega- tive (-) settings, the cutoff frequency will fall as you play upward from the C4 note, and rise as you play downward.

LPF (Low Pass Filter)

HPF

-12dB/oct

-24dB/oct

BPF

Frequency

Cutoff

Low resonance value High resonance value

Increasingly negative (-) settings will allow a correspondingly greater effect in the opposite direc- tion. (➝ Figure 6-7)

With a setting of +48, the change in cutoff frequency will be pro- portionate to the change in pitch. With a setting of 0, key- board tracking will not affect the cutoff frequency.