FireBird 2 is now being offered for free by Tone2 the German company based in Munich.

FireBird is not just a subtractive synthesizer but also uses Harmonic Content Morphing synthesis (HCM) which lets you load waveforms from a library and transpose it to bring out different harmonics. The release also contains 70 additional sounds.

Features

• Very easy to program and easy to use 

• A unique sounding synthesis: Harmonic content morphing (HCM) 

• High sound quality: Warm, transparent 

• 437 hand picked presets included, over 1000 sounds available 

• 84 oscillator types containing 18,000 morphable waveforms 

• 38 different filter types 

• True stereo mode, 4x unison mode, and up to 8 oscillators per voice 

• Can sound like other synthesis methods - additive, subtractive, AM, FM, phase distortion, supersaw, vocoder, sync 

• Can sound like natural instruments like piano, brass, organs... 

• 23 spectral manipulations or “modifiers” can be applied to the oscillators 

• 21 arpeggiator types 

• 13 effect typesSkinable user interface 

You can download from Tone2 here:
https://tone2.com/html/firebird%20vsti%20vst%20synthesizer%20plugin.html