unlike most four-operator FM synthesizers, however, ESFM does not have an algorithm selection. instead, it uses a fixed operator arrangement, but allows you to independently control the output and modulation input levels of each operator. this allows it to reproduce a few common four-operator algorithms, as well as unique combinations where operators act as modulators and carriers at the same time.
- these are normally used for the drum channels in ESFM's OPL3 compatibility mode.
- however, in ESFM, operator 4 can be modulated by operator 3, whereas in OPL3 drum mode the rhythm channels cannot be modulated.
- __note__: usage of noise mode "Top" is discouraged for now as it is not properly emulated yet, and results may change when the emulation gets fixed in the future.
- **operator routing preview**: shows how operators are connected with each other and with the audio output (at the bottom).
- left-click pops up a small "operators changes with volume?" dialog where each operator can be toggled to scale with volume level.
- right-click switches to a preview display of the waveform generated on a new note:
- **AM Depth (DAM/AMD)**: when enabled, LFO tremolo is deeper (1dB off; 4.8dB on).
- **Sustain flag (SUS)**: when enabled, the envelope pauses ("sustains") once it reaches the Sustain Level and does not proceed to the release phase until note off.
- **Envelope Delay (DL)**: determines the delay time before the envelope is triggered. the bigger the value, the longer the delay (0 to 7).
- a change of one unit doubles or halves the delay time.
- **Attack Rate (AR)**: determines the rising time for the sound. the bigger the value, the faster the attack (0 to 15).
- **Decay Rate (DR)**: determines the diminishing time for the sound. the higher the value, the shorter the decay. it's the initial amplitude decay rate (0 to 15).
- **Sustain Level (SL)**: determines the point at which the sound ceases to decay and changes to a sound having a constant level. the sustain level is expressed as a fraction of the maximum level (0 to 15).
- **Release Rate (RR)**: determines the rate at which the sound disappears after note off. the higher the value, the shorter the release (0 to 15).
- **Total Level (TL)**: represents the envelope’s highest amplitude, with 0 being the largest and 63 (decimal) the smallest. a change of one unit is about 0.75 dB.
- **Key Scale Level (KSL)**: also known as "Level Scale". determines the degree to which the amplitude decreases according to the pitch.
- **Key Scale Rate (KSR)**: also known as "Rate Scale". determines the degree to which the envelope execution speed increases according to the pitch.
- **Frequency Multiplier (MULT)**: sets the coarse pitch offset in relation to the note (0 to 15). the values follow the harmonic scale. for example, 0 is -1 octave, 1 is 0 octaves, 2 is 1 octave, 3 is 1 octave 7 semitones, and so on.
when fixed frequency mode is enabled, the Tune and Fine Detune sliders will be replaced by **Block (Blk)** and **FreqNum (F)**, which allow you to input a raw frequency value into the operator.
the actual frequency is determined by the formula: `FreqNum*(2^Block)`.
in other words, FreqNum defines the base frequency, while Block determines the scaling factor in octaves.
due to a quirk in how the envelope delay feature works, the **Envelope Delay** macro can control the operator's key-on status for a limited amount of time after a note is played. a value of 0 represents key-on, while a value of 7 represents key-off.
note that the macro cannot exceed 659.1 ms in length - anything beyond that will be treated as a value of 0.
### operator arpeggio and pitch macros
among the available macros are **Op. Arpeggio** and **Op. Pitch**. these work like the **Arpeggio** and **Pitch** macros featured below, but are applied to the individual operator, overriding the **Arpeggio**/**Pitch** macros respectively.
the **Tune** and **Fine Detune** FM parameters are still respected when using these macros.
### fixed frequency macros
when fixed frequency is enabled for an operator, the **Op. Arpeggio** and **Op. Pitch** macros will be replaced by the **Block** and **FreqNum** macros. these can be used to change the operator's fixed frequency over time.
