Frequency Shifting is for processing inharmonic or atonal sounds: snare, tom-toms, cymbals and percussion instruments. PSP HertzRider's interface allows for some crazy sounding effects akin to ring modulation but I find it useful for rescuing weak-sounding drum kit parts during a mix.

PSP Audioware HertzRider has two shifting engines that can be used for stereo source tracks with an input source switch for applying separate frequency shifting to the two tracks at a time in stereo. You may also link the two shifters together or not--plus you can one shifter shift up in frequency while the other shifts down by the same amount. I liked the "LED" read outs for the (+/-) shift amount for both shifters and there is a range switch for selecting a range of +/- shift values: 1kHz, 3kHz, and 10kHz.

For most applications such as shifting percussion, the 1kHz range is more than enough but the other ranges offer strange ring modulation-like effects especially when used with the LFO section at the bottom of the GUI.

The LFO section has controls to select various modulation waveforms and then the Rate and Depth of the modulation. There is also the Spread knob and Spread LEDs to setup and monitor LFO phase spread between the two shifters. This section finishes with: Bypass, Output level, a Wet/Dry mix control, and Dry Defeat control that automatically makes Wet/Dry 100%--great if you use PSP HertzRider as a send/return effect or parallel processor. I would caution its use by always listening summing the left and right channels in mono to check if there are moments of phase cancellation.

I had a great time and a lot of fun using PSP HertzRider in my latest Pop music mixes. I am mostly interested in re-pitching percussion instruments to fit better into my mixes. There are some good presets in its preset manager for making crazy drum breaks by unlinking the left and right channels and shifting in opposite directions. Tom-tom drums can be easily shifted downward to turn them into cannon fire; drum breaks are easily automated into wacky, EDM-style processed chaos!

PSP HertzRider uses double precision floating-point computations and supports sample rates up to 384kHz. It has minimal latency and runs in VST, VST 3, RTAS, AAX, and AU in Macs and PC DAW hosts.

PSP Audioware HertzRider Frequency Shifter Plug-In sells for $49 download only.