ADSR Sounds offer the OPL ($49 value) FM synthesizer by discoDSP as a FREE add-on with any paid purchase throughout September 2022.
OPL is based on the Yamaha OPL (FM Operator Type L), a budget sound chip that delivered FM synthesis for computer applications in the mid-1980s.
I feel like I should stop writing right here; if sounding like a computer from the mid-1980s doesn’t do it for you, I don’t know what will.
Joking aside, when it comes to FM synthesis, Yamaha is always one of the first names that come to mind, especially with the DX7, so it’s not a bad idea to look at them as inspiration for this kind of plugin.
There are, of course, many DX7 software emulations like Arturia’s DX7 V and the free Dexed synthesizer. There are also smaller and much lighter hardware alternatives, like the Korg Volca FM or Reface DX7.
If you’re wondering why I’ve said DX7 so many times in a few short sentences, it’s probably a hangover from my recent failed bid to buy one very cheaply.
The plugin emulates the OPL chip and provides all features of the OPL2 and some from the OPL3.
At the top of the interface, you’ll see Channels, and each channel has two oscillators capable of producing eight different waveforms. The waveforms include Sine, Half Sine, Absolute Sine, Quarter Sine, Camel Sine, Square, and Logarithmic Sawtooth.
Most of the GUI is taken up by the Modulator and Carrier sections, each of which has identical controls. Beneath the selectable waveforms is an ADSR envelope, and further down, you’ll find controls for Vibrato, Tremolo, Sustain, and Keyscale Envelope Rate. You can also adjust the velocity sensitivity to suit how you are playing.
At the bottom of the GUI, you can adjust the depth of the Tremolo/Vibrato effects, switch the algorithm (FM/Additive), engage a handy Percussion Mode, and load SBI files (the Creative Labs instrument file format).
In my opinion, FM synthesis like this, whether hardware or software, tends to offer some terrible sounds and some great sounds, with the bonus of some so awful that you have to love them, which makes them pretty amazing.
OPL is available in AU and VST formats for macOS (10.11 upwards) and Windows (all versions). Not compatible with ProTools.
Download: OPL (FREE with any purchase @ ADSR Sounds)