effects can be applied to the selected operators. A setting of 7 produces maximum sensitivity and therefore maximum effect depth.

12: KEY VELOCITY

While the DX27 has no key velocity sensitivity of its own, its voice generators will accept key velocity data from an external MIDI controller keyboard which does have this feature. This function determines the sensitivity of each operator to keyboard velocity sensitivity data from an external keyboard connected to the DX27 MIDI IN terminal (key velocity sensitivity = the harder you play a key, the louder the note. Timbre variations are produced when keyboard sensitivity is applied to a modulator).

The data range is from 0 to 7. At 0, key velocity sensitivity for the selected operator is OFF. A setting of 7 produces the highest sensitivity, and therefore the greatest effect. If KEY VELOCITY is set to other than 0, the volume produced when DX27 keys are pressed will decrease.

13: FREQUENCY RATIO

These parameters determine the actual frequency of each operator. For operators which function as carriers, this determines the actual pitch of the sound produced. For operators functioning as modulators, this determines the harmonic spectrum of the sound produced.

Each operator can be set to any of 64 different frequency ratios, as follows:

DX27 OPERATOR FREQUENCY RATIOS

0.50

0.71

0.78

0.87

1.00

1.41

1.57

1.73

2.00

2.82

3.00

3.14

3.46

4.00

4.24

4.71

5.00

5.19

5.65

6.00

6.28

6.92

7.00

7.07

7.85

8.00

8.48

8.65

9.00

9.42

9.89

10.00

10.38

10.99

11.00

11.30

12.00

12.11

12.56

12.72

13.00

13.84

14.00

14.10

14.13

15.00

15.55

15.57

15.70

16.96

17.27

17.30

18.37

18.84

19.03

19.78

20.41

20.76

21.20

21.98

22.49

23.55

24.22

25.95

 

 

These frequency ratios have been carefully chosen as the most useful for voice programming. A ratio of 1.00 sets the selected operator to standard pitch—a pitch of 440 Hz will be produced when the A3 (A above middle C) key is pressed. A ratio of 0.50 produces a pitch one octave lower, and a ratio of 2.00 produces a pitch one octave higher than standard pitch, and so on. The fractional ratios-1.73, for example—produce extremely complex waveforms when combined with operators set to other ratios, permitting the creation of an unlimited variety of sound effects including extremely realistic bells, explosions, etc. Even ratios are useful for creating musical instrument sounds. It is possible to combine a modulator set to a fractional

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