Harmonic Tremolo

This was inspired by the idea of providing a tremolo that effected high and low frequencies differently. Splitting the signal with a SV Filter delivered some really interesting results (as well as a strong phase tone that I like a lot).

The bypass of the effect is done with the depth control (top right, blue value button), but it is also tied to CC7 or the expression pedal input. If you don’t have a midi controller or expression pedal connected, you will want to choose another way of controlling the Audio Balance between the wet and dry signal on Page 3: “mod ctrl”.

My rig is set to a midi expression pedal on CC7. The Depth value on the front page sets the max depth of the effect. At 100%, the expression will sweep from 100% wet to a bypassed, dry signal.

The default engage will be just a hard chop tremolo, but a long press of the right footswitch will phase-flip the low frequency, so the chop will be frequency based, and there will always be some signal present (either low or high).

The visual feedback in the center of the pedal flashes the low-high frequencies, so it is very easy to tell if the two rates are together or opposite one another.

Short presses of the right footswitch cycle through the frequency engagements of the trem.

1. The initial step is both highs and lows, providing the most normal tremolo and the phase-flipped alternating harmonic tremolo achieved with the long press.

2. The second step modulates the low end and leaves the high frequencies uneffected.

3. The third step modulates the high end and leaves the low frequencies uneffected.

4. The fourth step leaves both low and high frequencies uneffected. This provides a notch where the two frequencies cross.

The center frequency can be swept with the Center Freq control (bottom left, purple value button). Moving the center frequency can drastically shift the tone when splitting or inverting the frequencies.

The tremolo defaults to a square wave, but can be shaped with the Slope value (right center, aqua value button). Increasing the slope will ramp the waveform until it becomes a triangle wave for a smoother tremolo effect.

The center footswitch engages the phaser, sync’d to the tremolo by default. For a standalone phase tone, select the 4th tremolo mode where both the high and low frequencies are uneffected. The other modes combine the sweeping phase with the tremolo modulation. The phaser is always a triangle wave, and its sweep is visualized by the blue chase at the top of the UI page.

The phaser rate can be uncoupled from the tremolo with the Phaser Drag knob (bottom right, white value button). This gets most interesting with a medium-fast tremolo and a much slower phaser tone. The higher the value, the more drag… so higher numbers mean a slower phase.

Long pressing the center switch ramps between fast and slow modulation rates. This is designed to speed up and slow down like a rotary speaker cabinet— the ramp speed between the two rates is controlled by the Ramp Speed (bottom left, 2nd column, blue value button).

The fast and slow rates are set with the two Rate controls (top left, both columns, aqua value buttons).

The rates of the high and low frequencies can be further differentiated by the Horn Speed (center left, 1st column, blue button), which allows the high frequencies to be set at a different speed from the low, de-synchronizing them.

The phase of the low frequencies can be further adjusted with the Woofer Align (center left, 2nd column, blue button), which provides a sweepabe 90 degrees of phase offset in conjunction with the 180 degree phase flip offered by the long press of the right stomp switch.

Because the effect is based on dual LFOs in sync, the frequencies may become desynchronized during edits, adjustment, and time playing. If the high and low frequencies are misaligned for reasons other than changing the Horn Speed or Woofer align, the left footswitch will re-sync the modulators.

4 comments on “Harmonic Tremolo
  • Rob Flax on said:

    Just tried this out today. Sounds awesome!

  • UncleGroOVe on said:

    Congratulations. Thank you for the very interesting walkthrough, too…! Can’t wait to give it a try :-)

  • EakEak on said:

    I just registered to let you know that I use this patch every day. It is very thoughtfully laid out, inspiring and useful. I recommend this effect to anyone with a zoia, and i do hope you make more. Thank you for the upload,

  • thunderpuppy on said:

    @EakEak – thank you! Very kind of you to say

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    • Platform:
    • Category: Effect
    • Revision: 1.0
    • License: Creative Commons Attribution Share Alike 4.0
    • Modified: 4 years ago
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      Likes: 9
      Downloads: 1294