Amsynth is an easy-to-use software synth with a classic subtractive synthesizer topology.

• Dual oscillators (sine / saw / square / noise) with hard sync
• 12/24 dB/oct resonant filter (low-pass / high-pass / band-pass / notch)
• Mono / poly / legato keyboard modes
• Dual ADSR envelope generators (filter & amplitude)
• LFO which can modulate the oscillators, filter, and amplitude
• Distortion and reverb

amsynth.github.io
github.com/amsynth
en.wikipedia.org/wiki/Amsynth