Yamaha DX7 II FD Reference Manual page 13

Rl-R4
The time it takes to reach an EG level parameter during the course of a note is determined
by the corresponding rate parameter.
0 Slowest rate (longest time) from one EG level to the next.
99 Fastest rate (shortest time) from one EG level to the next.
Rate 1 (R1) determines the rate at which the operator's level rises from IA of the previous
note (almost always 0) toLl. R2 specifies the rate at which the level move from L1 to L2,
R3 specifies the rate at which the level moves from L2 to L3, and R4 specifies the rate at
which the level moves from L3 to IA after the key has been released.
Used in conjunction with EG levels, rates provide a completely flexible means of creating
various volume and timbre envelopes. These can be used to simulate acoustic instrument
envelopes or
to
invent new envelopes never before heard.
Rs The first parameter in the EG display is the Rs (rate scaling) parameter. This parameter
determines the extent to which EG rates will speed up as higher notes are played on the
keyboard.
0 EG rates will not be affected by playing higher keys.
7
EG rates will be strongly affected by playing higher keys.
Rate scaling is used
to
simulate the change in the envelope of higher pitched notes evident
in many acoustic instruments. For example, if you play the lowest and highest notes on a
piano with equal force and hold the keys down, you will notice that the highest note dies
away long before the lowest note. As higher notes are played, the EG rates become faster.
Rate scaling allows you to duplicate this effect in your own DX7 II voices.
- 10-