De La Mancha has re-released unstable – a VST for Windows that they say ‘likes to mess around with your audio pitch’ – as a free download.

It features 3 subtle pitch modulation modes to simulate the unpredictable pitch instability of an old tape machine or an analogue synth.

They note, “It doesn’t only do subtle though, you can also put it in ‘insane’ mode if you’d rather just FSU.”

Features:

• 3 modes of continuously random pitch modulation
  • buzz – rapid, fuzzy modulation
  • wobble – medium, jerky modulation
  • drift – slow, gentle modulation
• adjustable frequency and level for each modulation mode
• master level mode to adjust overall subtlety of effect
• wet / dry mix level control
• insane mode – removes all subtlety and smacks your pitch up
• all controls mapped to midi CC values

Unstable used to be a payware plugin, but is now free as a free download via the DLM site.