# 5.10 OpulenZ

OpulenZ is an emulation of the Yamaha YM3812, a.k.a. OPL2, FM synth chip which was used i sound cards around 1990 - the Adlib and Sound Blasters. It generates sound through frequency modulation or adding 2 oscillators.

![OpulenZ](/files/-LuiQDfV_WQVgzeqeNYY)

## 5.10.1 Operators

The two oscillators are called operators. In FM mode (bottom left), operator 1 modulates operator 2. Otherwise both operators are routed to the output.

## 5.10.2 Controls

For each operator, the controls are:

* **ATT, DEC, SUS, REL:** an ADSR envelope
* **KSR:** keyboard scaling rate. When KSR is on, envelopes get faster when the pitch rises.
* **PERC:** percussive envelope. Makes the envelope go straight to release ignoring held keys.
* **TREM:** applies tremolo (slight amplitude modulation) to the operator
* **VIB:** applies vibrato (slight pitch modulation) to the operator
* **FEEDBACK:** only for operator 1 - feeds a portion of the operator's output back into ir
* **LVL:** the output level of the operator
* **SCALE:** determines the scaling applied to the output level when the pitch rises
* **MUL:** the frequency multiplier for the operator. 1 stands for the standard pitch played on the keyboard, 0 is one octave below.
* **WAVEFORM:** selection from 4 waveforms: sine, half sine, absolute sine and quarter sine. NB: a DC removal plugin might be a good idea when routing waveforms other than sine to the output.

### 5.10.2.1 Global Controls

* **FM:** when this is on, frequency modulation is used. Otherwise the operators are mixed together.
* **DEPTH, TREM and VIBR:** these select deeper tremolo and vibrato. Applies to both operators.

## 5.10.3 Useful Resources

Getting started with FM: <http://www.gorenfeld.net/lou/fmguide.html>

Programming the AdLib/Sound Blaster FM Music Chips: <http://www.shipbrook.net/jeff/sb.html> (some of the controls are presented inverted in LMMS, to fit better with other symbols)


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