The VRC7 chip contains a customized OPLL (YM2413) unit that has 6 channels for frequency modulation synthesis (FM sound). This chip was used in Lagrange Point by Konami.
It has 15 predefined patches and one user defined patch, the predefined patches are customized for VRC7 and not the default OPLL ones. The chip is also limited to one user defined patch, so it's not possible to use different user defined patches in different channels at the same time! Please see documents about YM2413 or documents about FM in general if you need more information.
Note release can be used on these channels to enable the sustain flag.
The instrument editor allows use of one of the predefined patches or the custom patch. The predefined patches are defined in hardware and cannot be changed.
The custom patch settings are enabled when patch 0 is selected and are used to customize the modulator and carrier oscillators.
Attack, Decay, Sustain, Release | ADSR envelope for the volume level. (0 - 15) |
Amplitude modulation | Applies a fixed tremolo effect at 3.7 Hz (on/off) |
Vibrato | Applies a fixed vibrato effect at 6.4 Hz (on/off) |
Sustained | Switch between sustained and percussive tone (on/off) |
RATE key scale | Increases the ADSR rate for higher pitches (on/off) |
Key Scale Level | The attenuation level for RATE, according to table 1 (0 - 3) |
Wave rectification | Half wave rectification of the sine wave (on/off) |
Multiplication factor | Multiplies the frequency with a factor, according to table 2 (0 - 15) |
Feedback | Modulator feedback (0 - 7) |
Modulator Level | The mixing level of the modulator wave into the carrier wave (0 - 31) |
Key Scale Level table
0 | 0 dB/oct |
1 | 1.5 dB/oct |
2 | 3 dB/oct |
3 | 6 dB/oct |
Multiplication factor table
0 | ½ |
1 | 1 |
2 | 2 |
3 | 3 |
4 | 4 |
5 | 5 |
6 | 6 |
7 | 7 |
8 | 8 |
9 | 9 |
10 | 10 |
11 | 10 |
12 | 12 |
13 | 12 |
14 | 15 |
15 | 15 |