Resonator effects are useful for adding pitch to unpitched sounds and for bringing out the harmonic content of pitched sounds. I'll use Ableton Live 4's Resonator plug-in to illustrate both processes. Although true resonators are more complex, if you don't have Live 4 or another resonator plug-in, you can experiment with several very short feedback-delay lines in parallel. The delay time in milliseconds for a resonant frequency F in Hertz is 1,000/F. (To calculate it in samples use SR/F, where SR is the sampling rate.)
Applied to broad-spectrum sounds (noise and percussion, for example), resonators “ring” at each of the resonator frequencies. Applied to pitched sounds, resonators reinforce harmonics at the resonator frequencies; if those frequencies are not present in the sound, the resonator will dampen and discolor the sound.
In Perfect Harmony
To get a feel for using resonators, create a MIDI track and insert Live's Impulse plug-in followed by the Resonator plug-in. Fill the eight Impulse pads with some pitched and unpitched sounds. Turn off the Resonator's input filter, and use mode A with high Decay, Color, and Dry/Wet settings. Set the pitches for resonators II through V to -12, 7, 16, and 19 semitones, and set the fine-tuning of resonators III through V to 2, -14, and 2 cents, respectively. (The cents settings compensate for equal-tempered tuning.) Set resonator I's Note an octave above the desired pitch.
FIG. 1: A clip envelope for resonator IV's Pitch is used to track the third voice of a chord sequence. The vertical zoom and pitch range of the MIDI sequence are critical to accurate tracking.
To hear just the odd harmonics, turn off resonators I and IV. To set all resonators to odd harmonics, set the pitches of resonators II through V to -19, 9, 15, and 21, and set the fine-tuning of resonators I through V to 2, -2, -16, -33, -4. Finally, set resonator I's Note an octave and a fifth above the desired pitch. The Live project called TryEm.als on the EM Web site has both setups, and the table TryEm.rtf shows the semitone and cent offsets for the first 16 harmonics.
You can use clip automation to make the Resonator follow the chords in a MIDI clip. Setting up the automation is easiest if you ensure that the pitch span of the MIDI clip is C2 to C6 by temporarily editing the clip. Enable Clip Envelopes, select resonator II's Pitch for editing, and set the Clip Window's vertical zoom so that you see just the -24 and +24 scale markers (see Fig. 1). Then, in Automation Draw mode, set the value to the lowest note in each chord. Repeat for the resonator III through V Pitch envelopes, matching successively higher chord notes. Do not automate resonator I's Note setting, and manually set it to the C that produces the best results (usually C3 or C4). Other settings will transpose all the chords, which can be useful as long as you aren't playing the original MIDI clip at the same time.
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Alternatively, you can automate resonator I's Note to follow a bass line or lead and use one of the harmonic settings previously described to enhance the material's harmonic content (see Web Clip 1). Turn different resonators off or adjust their gains to alter the effect. Try mode B, which works especially well with bass. Finally, turn on the input filter, set it to bandpass or notch mode, and apply some clip automation to its frequency.
Vocode Me Not
Resonators can be used to impart a quasi-singing character to speech that is different from the effect of vocoding; the speech is more clearly articulated, but the timbral range is more limited. Resonating vocals works better with chords than harmonics. For an interesting contrast, vocode the speech with noise to turn it into a whisper before resonating. That trick works well with bass and lead tracks also (see Web Clip 2).
Post — Resonator processing is especially useful when applied separately to the two sides of the stereo output because resonators II and IV are sent to the left channel, while resonators III and V go to the right channel. (Resonator I goes to both channels.) Ensure that Resonator's Width is set to the maximum, and then try equalizing the channels separately as well as adding a small delay to one of them (see Web Clip 3).
Len Sasso is an associate editor of EM. He can be contacted through his Web site atwww.swiftkick.com.