Attack delay — an auto-swell envelope and delay

Combined, they can make pseudo-reversed delays, or plucky rhythmic delays, or ring-modulated delays. Or you can leave the delay out of it, and get all of those effects without the delay.

Based on the EHX Attack Decay, the patch uses an envelope to swell in notes or decay them away quickly. There’s also an added sustain stage, which can allow your notes to hold after they swell in, or fade out when combined with the decay stage.

The envelope can be looped, allowing for everything from ring-modulated/downsampled sounds (when each stage is at its lowest) to vibey tremolos.

Each stage of the envelope can also be controlled by tap tempo (or CV), as can the delay, and the envelope and delay have separate clock dividers (on page 1) to allow for lots of interesting rhythmic juxtapositions.

The attack and decay stages can also be shaped, allowing for blends from exponential to linear to logarithmic curves. I owe Willem Zenhorst a debt for figuring out the logarithmic curves, and the process has been added to the Tips and Tricks page with attribution.

The delay is a standard clean delay w mod. I played around with a few types, and I found this the most pleasing for the clean rhythms it generated, but there is enough CPU overhead to change the type if you would like another.

The signal path is stereo (which may be a mistake, honestly, but you can always use it in mono) throughout. The onset detector responsible for the envelopes relies on audio from the left input.

Sorry about the rambly video. I’ve been sick the past couple of weeks (you can get some nasty upper respiratory illnesses that aren’t COVID, it turns out).

Controls:

Stompswitches:

Left: Tap tempo — this tap tempo is used for the envelope stages and for the delay; there is a clock divider for each on page 1

Middle: Loop envelope — you can also achieve this using the button on the front page. By looping the envelope you can create some interesting, viby tremolo sounds (if you want a “depth” control, try adjusting the “Mix” parameter); when the envelope stages are set very short, you can get some cool ring-mod/downsampled sounds — try adjusting the curves of the envelope stages or minutely adjusting their length to create different timbres.

Right: Mutes the delay — this actually sets the delay mix to 0, rather than bypassing it, so when this is engaged, you may hear audio already being processed through the delay.

Front panel:

The front panel is broken up into two sides. On the left are the controls for the envelope. On the right are the controls for the delay.

Envelope controls:

Each stage of the envelope has a CV control, e.g. “Attack,” that lets you set the length up to 8 seconds. Below these are buttons labeled “Tap Tempo.” You can set them to set that stage to tap tempo, which will override the CV.

The attack and decay stages have controls called “Exp – Lin – Log”: These control their curves, from exponential curves which will swell in slowly, to logarithmic curves that will rise quickly. They can be blended with the linear amount to makes them less dramatic as needed.

Exponential curves are good for volume swell effecs, or plucky decays. Logarithmic curves remind me a little of the sound of a pedal steel guitar.

There are pixels below these controls which show the state of the envelope when it is active, with each segment of the envelope receiving its own pixel.

Beneath the pixels are two buttons:

“Loop env” reproduces the function of the middle stompswitch.

“Retrigger” should probably be left on. It allows the envelope to be retriggered before it completes its cycle. It can be useful to turn it off if the envelope is looped, as each new trigger will cause the tremolo to reset (which itself can be cool). It can also be used as a sort of “manual tremolo” where you can play beneath a decaying envelope until it reaches silence, at which point the next note will cause the envelope to open again.

Delay controls:

These are standard controls. The only real difference here is that the delay time can either be set by the “Delay time” parameter or by tap tempo.

Global controls:

“Mix” controls the wet/dry mix for the patch. Because of the volume attenuation inherent in volume swells, I’ve tried my best to get the mix so that wet and dry are equal in volume, but it’s a juggling act. I’ve starred the output gain control, if you need to adjust that to compensate for some unwieldy mix amounts.

“Sensitivity” controls the sensitivity of the onset detector. These are finicky beasts. If you want each note to be recognized, say, in a plucky decay, go for higher values. If you’re looking for smoother swells, I’d suggest lower ones. It can take a minute to dial in the appropriate sensitivity to what you want to achieve.

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