Sound Design Workshop: A Subtle Shift

Aug 1, 2009 12:00 PM, By Len Sasso

           
 

A SMOOTH ALTERNATIVE TO FLANGE, PHASE AND CHORUS EFFECTS

The Uhbik-S frequency shifter’s unusual options include offsetting the shift frequency and phase between stereo channels, and tempo-synched shift amounts.

Frequency shifting and its first cousins, ring and amplitude modulation, are usually associated with clangorous sci-fi sound effects. But with the right settings, you can use frequency shifting to modify drum and percussion sounds, create a subtle alternative to flanging and phase shifting, and mimic the fattening effect of multiple detuned oscillators without the inherent speedup in beat frequency with rising pitch.

One of my favorites of the recent batch of frequency shifters is Uhbik-S in the Uhbik collection of effects plug-ins from U-he software (u-he.com, see Fig. 1). I'll use that in my examples, but you can accomplish the same thing with any frequency shifter, and many DAWs, such as Ableton Live 8 and Apple Logic Pro 8, include them.

Drum Shift

Frequency shifting (aka, single-sideband modulation — a combination of ring modulation and filtering) leaves only one of the sidebands produced in ring modulation (you choose which). It produces clangorous sounds because all harmonic relationships are offset by the same amount. For example, when you frequency shift the sine wave components of a 100Hz sawtooth (100, 200, 300, etc.) by 50 Hz, the resulting components (150, 250, 350, etc.) are no longer multiples of the lowest; frequency shift a flute and you no longer have a flute. But because drums do not have harmonically related frequency spectra, frequency shifting a drum simply produces a drum of a different color.

You can create an unusual percussion part from a simple kick drum loop with a few feedback-delay effects followed by frequency shifters (see Web Clip 1). Use a couple of effects buses, each with a multitap delay followed by a frequency shifter. Set the frequency shifters to a full-wet mix and experiment with shifts in the 200Hz range. Starting with a kick drum sound, an up-shift will give you a bongo-like sound, whereas a down-shift sounds like a brush slap on a high tom. Use the delay taps to create bongo and brush patterns between the kick drum hits. Variations in the kick drum pattern will, of course, alter the other parts. With Uhbik-S, try feedback settings between 50 and -50 to adjust the bongo's timbre.

Frequency shifting is a handy tool for modifying one or more pieces in a drum kit. If you're using loops, you'll need separate loops for each kit piece you want to modify. If you're using a multi-output drum machine, send the target kit pieces to their own outputs.

A shift of a few Hertz with a 75-percent-wet setting and slight modulation of some kind (use the Offset knob in Uhbik-S) will add variation to a kick drum part. Shift a snare drum 500 to 700 Hz with a 50-percent-wet mix to add a rim-like sound. Shifts between 500 and -500 Hz with small Offset settings work well with hi-hats; adjust the wet/dry mix to taste. With Uhbik-S, you can add a tempo-consistent swish to a ride cymbal by using the 1/16 frequency range with a Shift setting around 25 and a mostly dry mix. Use the Phase knob to set the phase of the swish relative to the stick hit (see Web Clip 2).

A Different Flange

Flanging, chorusing and phase shifting all produce the familiar sweeping sound of a moving comb filter. Frequency shifting produces a similar sound, which to my ear is smoother and more subtle (see Web Clip 3). The dry/wet mix and amount of feedback determine how pronounced the effect is. Unlike flanging or phasing, the sweep is always in one direction. That's determined by the parity of the shift: Negative shifts sweep down and positive shifts sweep up. Uhbik-S' Offset and Feedback knobs accentuate the sweeping, making it sound more like standard phasing and flanging.

Slightly detuning the oscillators is an old trick for fattening a multi-oscillator synth patch. You can accomplish the same thing without the pitch-related speedup in beat frequency by passing a single-oscillator patch through a couple of frequency shifters in parallel. Use up- and down-shifts of a few Hertz (see Web Clip 4). Use similar settings to emulate the ubiquitous Rhodes tremolo. Uhbik-S' Offset and Shift both affect the rate, while Offset also produces different right-side and left-side rates.

Len Sasso is an associate editor of EM. For an earful, visit his Website, swiftkick.com.