Yamaha DX7 Product Manual - Page 31
Envelopes and Envelope Generators - low volume control
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26 Envelopes and Envelope Generators When the operator reaches LEVEL 1, it doesn't stay Consider what happens when you play a note. The there. Instead it immediately begins moving toward the volume goes up to some value, then eventually falls to next level in the envelope, LEVEL 2, and it moves to nothing, with some sort of reasonably well defined pat- LEVEL 2 at RATE 2 (R2). tern that is characteristic of the particular instrument. The change from LEVEL 1 to LEVEL 2 can be an For example, a low note on a pipe organ starts slowly increase in level, or a decrease in level, depending on when you press a key due to the time the column of air the values you have chosen for these points in the enve- takes to build up in the long pipe, and the note takes a lope. If, for example, you set LEVEL 1 at the mid point, while to die away as the column of air collapses in the and LEVEL 2 at maximum, when you play a note, the pipe. In contrast, a note played on a wood block starts level of the operator will increase to LEVEL 1 and con- quickly as the mallet strikes the block, and dies quickly tinue increasing to LEVEL 2. If RATE 1 and RATE 2 are as the block stops resonating. The overall pattern of the similar, you won't hear two distinct envelope segments. volume when you play a note - how loud the note Instead there will be one smoothly increasing sound. becomes at any instant, and how long it takes to change Suppose, however, that RATE 1 and RATE 2 are quite in level - is known as the "volume envelope." Organs different - say RATE 1 is slow and RATE 2 is fast. In and wood blocks have very different envelopes. With that case, you'll hear a distinct "knee" as the sound some unusual "synthesizer" voices, a note may not end slowly reaches LEVEL 1 and then jumps to LEVEL 2 at at zero volume, so the next note won't start at zero the faster rate. volume. In some cases, notes can start at maximum, If LEVEL 2 is lower than LEVEL 1, then the sound then go to zero when you press a key then come back will begin decreasing in level as soon as it reaches to maximum level when you release the key; These are LEVEL 1. falling to LEVEL 2 at RATE 2. If LEVEL 1 and exceptions to the rule, and such notes still have enve- LEVEL 2 are both set to the same level (other than lopes, even if they are inverted. zero), RATE 2 has no meaning since the sound is Similarly, changes in timbre occur from the onset of a already at LEVEL 2 the instant it reaches LEVEL 1; note to the time it dies away; these changes can also be therefore set it to 99. In any case, the sound continues defined by an envelope. to move on to LEVEL 3. In the DX7, each of the 6 operators can be pro- The sound moves from LEVEL 2 to LEVEL 3 (which grammed with its own envelope. Generally speaking, if may be higher, lower or the same as LEVEL 2); the an operator acts as a carrier in a given algorithm, its transition occurs at RATE 3. You may see the similarity envelope controls the volume of the note. If an algo- between the second and third segments of the DX7 rithm acts as a modulator, its envelope controls the envelope illustrated (LEVEL 1 to LEVEL 2 and LEVEL 2 timbre. (This is a useful conceptual model, although to LEVEL 3) and the decay portion of a standard ADSR. somewhat of an over simplification.) If LEVEL 1 is the highest level in the envelope, LEVEL 2 Illustrated here is a copy of the envelope diagram near over a half a minute to reach LEVEL 1, depending on is lower, and LEVEL 3 is still lower, you have a 2-stage the upper right corner of the synthesizer front panel. We the setting of RATE 1 (R1). decay to LEVEL 3. If, on the other hand, LEVEL 3 is set have a few additional notes of explanation. The illustra- NOTE If you are familiar with analog synthesizers that higher than LEVEL 2, then only the LEVEL 1 to LEVEL tion is an aid to visualizing the DX7 envelope settings as have Attack-Decay-Sustain-Release envelope genera- 2 segment is a decay, and the LEVEL 2 to LEVEL 3 you program or edit a voice. There are actually trillions tors (ADSR EGs), you may recognize the line defined segment becomes a secondary attack (at RATE 3) to the of possible envelopes you can define with these EGs. by R1 and L1 as the "attack" portion of the envelope. higher level. Each envelope generator in the DX7 permits you to There are parallels between a conventional ADSR EGs LEVEL 3 is different than the first two because when set 4 different LEVELs and to set 4 specific RATEs at and the DX7's EGs. However the DX7 envelopes are it is reached, the sound does not automatically move which the envelope moves from each level to the next. much more flexible than ADSR types because the DX7 toward the next level. Instead, the sound remains at We use the term "level" rather than "volume" or "tonal offers 8 precisely programmable parameters (R1, L1, LEVEL 3 for as long as you hold down the key.. or if a value" because the envelope of the operator you're R2,L2. R3,L3, R4, L4) instead of 4 (A-D-S-R). I t ' s not sustain pedal is used, for as long as you step on the adjusting could affect the volume or timbre depending really important for you to understand ADSR enve- pedal. LEVEL 3 thus corresponds to the sustain level in on the operator's location within the algorithm. lopes when you're programming the DX7, but if you a conventional ADSR envelope. LEVEL 1 (L1) is the level to which the operator begins already do and are curious about the comparison, see When you stop pressing on a key (or lift your foot moving as soon as you press down the key The opera- the envelope discussion in the Advanced Program- from the sustain pedal), the sound immediately begins tor may reach L1 almost instantaneously, or it may take ming Notes section of this manual. moving toward LEVEL 4 at RATE 4. It makes no differ-