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OPQ Programmer's Guide V 1.1
Pins not mentioned above are not connected anywhere in PSR-70, so it is impossible to
say anything about their purpose.
3
OPQ synthesizer basics
Main specifications of the OPQ FM synthesizer:
•
8 voice channels, i.e. 8 voice polyphony
•
4 operators per channel, so there are 32 operators altogether
•
8 algorithms
•
separate ADSR envelope generator for each operator
•
one LFO, can be used for AM (tremolo) and FM (vibrato)
•
monophonic (non-stereo) output
There is no percussion mode nor "sacrifice channel count and get more operators per
channel"-modes as in OPL3. This makes OPQ more straightforward from programmer's
point of view.
The "stereo or not stereo" question is quite clear: it is not stereo. The digital signals going
to the DAC are named LSH and RSH, which gives a clue of Left and Right, but it is better
to think that there are two separate output channels, and each voice channel can be sent
to either of them or both. This can be useful for routing purposes but it is not stereo. The
arrangement is similar to OPL3 synthesizer. Even PSR-70 does not use the output
channels as left and right, it uses them for controlling the effects routing.
3.1 Operators and channels
Against Yamaha tradition, I will be numbering everything starting from 0, also the
operators.
This table summarizes which operators form each channel's channel-specific operators:
Ch0
Op0
0
Op1
8
Op2
16
Op3
24
Table 1. Operators
All four operators of one channel are not equal:
•
In all algorithms, Op3 is always a carrier, never a modulator. It is also kind of
"master operator" regarding to triggering, see chapter 3.3.
Ch1
Ch2
1
2
9
10
17
18
25
26
Ch3
Ch4
3
4
11
12
19
20
27
28
Ch5
Ch6
5
6
13
14
21
22
29
30
5
Ch7
7
15
23
31
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