The iZotope Möbius Filter is an infinitely ascending or descending filter sweep based on the Shepard Tone effect that creates the allusion of a tone that continually ascends or descends in pitch, yet ultimately seems to go no higher or lower. I’ve heard this effect in scary/sci-fi movie soundtracks.
The Möbius Filter comes as a native plug-in that works on either mono or stereo sources. It has an X/Y pad with a virtual joystick you can click and drag around to set the center frequency at 175Hz to 10.8kHz on the X-axis and the resonance of the filter expressed as 0 to 100 on the Y-axis. Higher resonance values cause the filter to nearly whistle. There are two filter types: “phaker” and peak, and you can pick in which direction the Shepard tone filter goes, up or down. I liked the host sync feature to lock the sweeps to song tempo—it makes this crazy effect sink more into the mix.
I liked using the iZotope Möbius Filter to randomize reverb returns and delays, and I used it as a much more interesting phaser or flanger psychedelic effect. Möbius Filter is $49 MSRP and available for download.
BARRY RUDOLPH is a recording engineer/mixer who has worked on over 30 gold and platinum records. He has recorded and/or mixed Lynyrd Skynyrd, Hall & Oates, Pat Benatar, Rod Stewart, the Corrs and more. Barry has his own futuristic music mixing facility and loves teaching audio engineering at Musician’s Institute, Hollywood, CA. He is a lifetime Grammy-voting member of NARAS and a contribut- ing editor for Mix Magazine. barryrudolph.com