A frequency shifting Audio Units plugin, Shift is modelled on Harald Bode's 1960s Frequency Shifter. Like many other Sinevibes plugins, it adds motion to its underlying sound-manipulating concept with a step sequencer. Here, that means up to 32 steps of envelope-modulated frequency shifting, with each step's envelope shape selectable from a choice of eight single- and double-cycle ramp and pulse waves.
The step sequencer syncs to the host DAW (at rates from 1 bar to 1/64 per step) and features a swing control for syncing playback up to shuffled material. You also get global controls for the envelope decay (Envelope Time) and attack/release smoothing (Envelope Lag).
The range of frequency shifting for each step is +/- 10kHz, and the scale is logarithmic, so the resolution is higher towards the centre of the slider range. The slider handles are context-sensitive, indicating centre, plus or minus but relaying no actual +/- frequency value, which is confusing.
Rounding things off are eight memory locations (with copy and paste), randomise (Chaos) and three 'multiply' options for repeating the first four, eight or 16 steps across the full sequence. Finally, the Effect Balance control plays an important role in generating barber pole phaser effects - see Bodes well.
In contrast to a pitchshifter, which creates harmonically predictable pitch shifts by multiplying frequencies by a ratio, Shift applies a user-selectable shift in Hertz to the whole signal. This can result in anything from slightly dissonant pitch adjustments at gentle settings to metallic, ringing, bleepy effects at extreme settings.
It's also worth noting that by applying a fixed negative shift, it's mathematically possible for frequencies to be shifted below 0Hz. In practice, this results in an inverted phase signal with a frequency equal to the overshoot.
Naturally, the audible effect of this depends on the frequency content of the source signal, but large negative shifts can easily produce many high harmonics, and the further down you shift, the more you get.
The real winner here is Shift's sequencer. Using this, you can create anything from subtle bar-long shifts to cool repeating 16th-note patterns and beyond - apply the latter to loops for some wicked R2D2-style moments. Deployed more subtly, it can add pleasant movement to musical parts, while blending in the original signal can introduce some phasing to enhance the sound further.
Shift is yet another excellent little plugin from Sinevibes, and a useful 'turn to' when you're looking to spice up lacklustre sounds or are just seeking inspiration, with the sequencer adding the rhythmic element so essential in much of today's sound design.
Useful additions would be some longer sync options (2 bars, 4 bars and longer) and the aforementioned frequency shift amount readout for the sliders, but at $29, this is a bargain for Mac musicians, with huge creative potential and a great sound.