Onsen Audio OS-251 is a new free Synthesizer plugin (macOS, Windows, & Linux) combining a Juno-style design with a Lo-Fi sound character.
Synthesizer plugins don’t have to be expensive. There are even very good plugins that cost nothing, see Vital, Surge, or those from Full Bucket Music. And now it’s time for another free plugin.
The new company Onsen Audio has today published OS-251, a free Lo-Fi Synthesizer plugin for macOS, Windows, and even Linux.
Onsen Audio OS-251
For the development of their OS-251 Synthesizer plugin, Onsen Audio was inspired by the legendary Roland Juno-106 design. This is known to be very simple and effective. OS-251 is not analog emulation but a new synth with its own engine and character. It’s a 10-voice subtractive synth that uses digital algorithms to give a warm, lo-fi character to the sound.
The core uses a single oscillator with sine, square, saw waveforms including a shape parameter. Plus, you get a square sub- & noise oscillator, and flexible pitch controls. The oscillator has alias noise (specific to digital signal processing) famous on classic samplers like E-mu SP-12 which adds a lo-fi feeling to the sound. Then, it has a bi-quad lowpass filter (LPF) and high-pass filter (HPF), each with frequency parameters. LPF has additional resonance.
Further, there is also modulation, which is as simple as in Juno. An envelope generator for the LPF & amplitude and a single LFO with sync. The latter controls LPF, amplitude, and shape parameter. At the end of the signal chain, you have a chorus effect. At the end of the signal chain, you have a chorus effect just like the original.
At first glance a nice, solid free Synthesizer plugin. There are not many features, but it is an instrument with which you can get results quickly.
Onsen Audio OS-251 is available now for free for macOS, Windows, and Linux. It runs as VST3 and AU plugin.
More information here: OA