Duck Call: Manual

Sidechain, gate and choke. Step right up.

Duck Call is an effect for the OP-1 on hundekraft. Something hits, and your sound dips out of the way (duck), or opens up only on the hit (gate). The hits come from the beat grid, a tape track, the input, or the sound itself. It is modeled on Befaco's PercAll, a Eurorack module of decay envelopes, VCAs and choke switches.

The screen is an early 20th-century carnival duck shoot. Every hit knocks rubber ducks down, the rifle fires on the beat, and the curtains, waves and sight show your settings. You can read the whole effect at a glance.

Install

Duck Call is one file, duckcall.knl. It needs hundekraft 3.2 or later on the OP-1.

1. Download duckcall.knl.
2. Open the hundekraft workshop in Chrome.
3. Go to the Your plugins tab and choose Add your plugin files. Pick duckcall.knl.
4. Choose Connect my OP-1, then Review changes, then Send.
5. When the OP-1 asks, press T1 to install.

Load: open the FX screen of a synth, the drums or the master, and pick duckcall from the effects.

To update, add the new duckcall.knl the same way. A file with the same name replaces the old one, and your sounds keep their settings.

The screen

Every part of the scene is tied to a knob, in that knob's color. The scene moves while sound comes through or the tape runs. In silence it holds still.

Fig. 1: just after a hit on beat 2 at 1/4. A front duck is going down with green ricochet dashes, the rifle's muzzle flash is still lit, and the sight's tick for that beat is white.

On white's page 2 (flip), the white arc grows from the top of the knob: left toward gate, right toward duck.

Fig. 2: the curtains for each shape, left to right: pump, linear, hold, choke. The inner edge is the curve your sound follows after a hit.

Fig. 3: the waves with the shortest attack (sharp, choppy peaks) and the longest (rounded swells).

Controls

Push blue, green or white for page 2. Push red to switch choke on. Page 2 settings are saved with the sound. The choke switch is not, so it starts off each time you load the sound.

The values shown on screen are the real ones, so green's label reads the actual depth, not the knob position.

Fig. 4: page 2 on every knob. Each knob gets a ring inside it and its value on a colored chip: attack, accent, flip (at flat, so the rifle aims straight ahead) and choke.

Sources

Red picks what makes the hits. The first eight are the beat grid. The rest listen to audio.

Fig. 5: the sights. Beat sources show a ring with a tick per pulse (the white tick is the pulse that just fired). Tracks show corner ticks for their number, tape has spokes, the input is a peak and SELF is a small mic.

The beat grid follows the tape while it plays and restarts with it. With the tape stopped it keeps running at the OP-1 tempo, so playing keys pumps on the grid too. Accent (green, page 2) shapes the bar: the 1 always hits at full strength, the beats come next, and the in-betweens are softest.

Audio sources listen for a jump in level after a quieter moment. Each hit's strength is its loudness in the first 10 ms, so a soft hit gives a shallow, short dip and a hard hit a deep, long one. After a hit, the detector waits 30 ms before it can fire again. A hit quieter than the sensitivity is a miss: nothing happens to the sound, and the ducks dodge. A hit that lands on the 1 of the bar knocks the back pair down, like a beat source.

Duck, gate and the four shapes

Flip (white, page 2) sets what a hit does. Shape (white) sets the curve the level follows after it.

• Duck: the level drops on each hit, then comes back. The classic sidechain pump.
• Gate: the sound is silent until a hit opens it, then it closes again. Chops pads into rhythm.
• Flat: in the middle, hits do nothing. Turn slowly from duck through flat to gate to fade one into the other.

Attack (blue, page 2) rounds every corner of the curve, both into the dip and back out.

Fig. 6: duck at full strength on 1/16 with the choke shape and a long length. Hits come faster than the dips can recover, so most ducks stay down and the ricochets keep flying.

Choke

Push red to switch choke on, the way PercAll's choke switches work. With choke on, a hit on the partner track ends the current dip or gate on the spot.

Red's chip shows the pair, for example T2 CUT T1. When a choke lands, the sight is crossed out with a red X and the ducks react right away.

• In gate: the hi-hat trick. T2 opens the sound, a T1 hit slams it shut.
• In duck: a T1 hit lets the sound pop right back up.

The partner has to be a tape track that is playing back. The switch is not saved with the sound.

Fig. 7: gate on T2 with choke on. A T1 hit just landed: the sight is crossed out, the ducks drop, and red's chip reads T2 CUT T1. The rifle aims left for gate.

Recipes

Starting points. Put Duck Call on the sound named in each row, then set the knobs.

Self swell makes every new note dip and swell back in, like a reverse attack. Bounce back pumps on the grid, and a T1 hit lets the pad back in early.

Tips and tricks

• Duck shines on long sounds. Pads, chords and bass show the pump best. On drums, the dip lands right on the hit, so you mostly hear the drums get quieter.
• Duck too subtle? Go to Hold or Choke, and push strength past 70%. Pump is the gentlest shape.
• Gate is all-or-nothing. Between hits the sound is silent, so a long length keeps more of it.
• Short length and fast divisions stop the dip from finishing. At 1/16 with a long length, each hit restarts the dip before the last one recovers, and the sound stays low. Shorten the length or slow the division.
• Long attacks need room. A 100 ms attack can't reach full depth on a 60 ms length.
• Accent turns a grid into a groove. On 1/8 or 1/16, push accent up until only the beats, then only the 1, come through.
• Sensitivity is your filter. On a busy track, raise it until only the loud hits duck. Ghost notes become misses, and the ducks dodge them.
• The ducks tell you what's working. If the ducks aren't going down, the hits are too soft or too short to make a real dip.
• Flip is playable. Sweep white's page 2 from duck through flat to gate during a take.
• Keys pump with the tape stopped. The beat grid keeps the OP-1 tempo, so you can jam without pressing play.
• Use T1 for your kick. Choke and the kick pump both expect the drums there.
• SELF is a ducker for the sound itself. Every new note dips it, a quick way to get swells and "backwards" attacks.

What's saved with the sound: all four knobs and the three page-2 settings. Not saved: the choke switch.

Specs and credits

Designed by Steph Simorka. Built on the hundekraft plugin SDK. Inspired by Befaco PercAll. Released under GPL-3.0-or-later with the OP-1 firmware permission.