Expert Sleepers has released the Windows VST version of Warbler and updated The Mac OS X VST versions of Meringue to v2.0.1 and Warbler to v1.0.1 . These patch releases fix compatibility problems with certain hosts on Intel Macs, notably FXpansion's VST-to-RTAS wrapper.

Warbler is at heart a vibrato effect, with additional controls that allow chorus/flange/delay type effects, as well as quite unusual hybrid sounds that aren't easily categorised.

• The vibrato depth ranges from subtle modulations to extreme pitch effects. The vibrato LFO (low frequency oscillator) can be set from 0Hz to 5kHz and is controlled by 3 knobs to allow accurate control over the whole range.
• The vibrato LFO shape can be selected from a variety of options and smoothly changed between them.
• The LFO speed and the vibrato depth can themselves be modulated by two extra LFOs.
• A 'bias' control is provided to change the effect from simple vibrato to something more like a traditional chorus or flange. Feedback can also be applied to give deeper, more resonant flanges or to produce echo effects.

The plug-in works as a generic n-to-n processor i.e. it will do mono-to-mono, stereo-to-stereo, 5-to-5 etc. Good hosts will also allow its use as a mono-to-stereo effect (e.g. Logic does this). A 'spread' control is provided to offset the LFO phase per channel - giving a result much like a classic 'stereo chorus' effect.

Warbler costs $19. A demo version and various audio demos are available.