Arthelion Releases MOLOSS II FREE hybrid synth plugin for Windows.


Arthelion releases MOLOSS II, a free synth plugin for Windows.

MOLOSS II is a reworking of the original MOLOSS I hybrid synth.

Some of you might remember we covered MOLOSS I back in 2019, and many of you felt it had potential but wasn’t quite there yet.

As a free and open-source plugin, we expected that work would continue and improvements would come down the line.

Here we are, a few years later, and MOLOSS II is ready to go.

Anyone who tried the original version will be glad to know that the core intention of the synth stays the same and hasn’t lost any ambition.

MOLOSS 2 retains the original architecture that delivers a vast range of sounds while leaving a relatively small footprint on your CPU.

Arthelion combined several synthesis types and techniques that were hugely popular in the 1980s and are retro-cool today, including subtractive and additive synthesis, frequency modulation, and cross-modulation.

MOLOSS 2 has four voices that can modulate each other in frequency or amplitude. Each voice starts with a VCO module, followed by a resonant filter, VCA, three ADSR envelopes (with Key Follow), and four LFOs, each with Delay and velocity controls.

MOLOSS 2 also retains the vast modulation matrix seen in version one and boasts improved embedded effects (Chorus, Stereo Delay, and Reverb).

While the reworked version keeps most of the features found in the original, work has been done under the hood to stabilize the engine and improve the sound.

The area that received the most criticism last time around was the interface, which was far from user-friendly. We’ve all experienced plugins of various types that have the potential to be incredibly powerful if they weren’t so painfully tedious to use.

Thankfully, MOLOSS 2 has dragged itself out of that category, thanks to a new design signed by Lozzec.

The new interface looks immediately more modern, and most importantly, parameters are clearly identified, and everything appears to be in its right place.

With an interface that should allow more time for actual sound design and less time spent wondering where you are, MOLOSS 2 could be a monstrous freebie.

I know the SoundCloud demo track came from the old version, but the kid in me can’t help being reminded of that extremely ambiguous old-school video game music. It is the kind of track that waits for you to either kill the level boss or be killed before a few subtle changes see it transition to a more definitive victory or game-over theme.

Nearing the end of the month, here’s another reminder to grab Plugin Boutique’s August gift while you can (the FM8 deal is a nice opportunity to claim the free gift).

MOLOSS 2 is available in VST format for Windows.

Audio plugin and standalone application.

Download: MOLOSS 2


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James is a musician and writer from Scotland. An avid synth fan, sound designer, and coffee drinker. Sometimes found wandering around Europe with an MPC in hand.


  1. There’s a lot of weird quirks (filter envelope seems to start from 0 and end at the cutoff position, resonance seems to not increase above 50%, LFO waveshape isn’t selectable, osc mixer reduces the level of the current waveshape when you add another), but the core sound is quite nice, and the UI is easy to use. this is a good free synth.

  2. THANK YOU for adding “for Windows” to the headline! For us Mac users, getting excited to download a plugin and then hitting the last line, “only available in VST format for Windows”, is a real letdown. Well done!

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