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Contours & Drone

From the outside, the way a synthesizer plays seems like it has most to do with the oscillators at its core — but this is only half the story! How the voices are articulated is just as important as the synthesis modes available, and Atrium offers a robust system for affecting both the shape and timing of note events.

sustain modes

As you may have noticed, the sustain slider doesn’t statically control volume — its movement corresponds to the opening of a lowpass/gate for each voice, which combines filtering and amplification to create an organic-sounding contour.

To change the modality of this architecture, press the sustain-mode key (labeled: gate filter reso) at the top of the strum touchplate:

  • gate : Controls loudness with subtle filtering.
  • filter: Prioritizes the lowpass filter aspect, for a more characterful sound.
  • reso: Adds resonance to the filter, emphasizing & overdriving frequencies as it opens.

These settings will interact with Timbral Control. reso mode in particular will behave quite differently for voices that have few (vs. many) harmonics. When using the wave setting for timbre-mode, the lowpass/gate will be overdriven when timbre is set high. This creates a juicy softening effect especially present in filter and reso mode.

contour

The shape of a note contains a wellspring of emotional information. Soft swells, long tails reverberating after an initial strike, clippy little boops; these each evoke different temperaments. There's much to explore in the lifecycle of a note, far past whether it's 'on' or 'off'. Atrium's contour holds the envelopes that help shape our perception; each voice articulates using length & ramp, repeats itself in loop, and is stretched into creative overlaps.

length & ramp

All the knobs on Atrium follow the same concept: as we increase the parameter, we add intensity to it.

length describes the overall cadence of the envelope cycle. The "intensity" of this parameter is measured by rapidity; in a musical context, speedy events typically communicate urgency whereas slower onsets or recessions give a sense of spaciousness. As such:

  • to slow things down: turn length counter-clockwise
  • to speed things up: turn length clockwise

At slowest, contours will reach a full 20 seconds per cycle, while the fastest settings are measured in milliseconds.

ramp controls the balance of 'attack' and 'release' in the contour's shape, taking time from one edge and passing it to the other. Turn ramp fully counter-clockwise and the 'attack' portion will be instant, jumping immediately to the sustain value. Turning ramp clockwise steals more of the envelope time for the 'attack' portion, leading to gentle swells at midway, and reverse-reverb sounds at maximum.

Moving sustain or playing with strum will articulate the voices according to length and ramp. Experimenting with different settings here will greatly impact the feel of strum in particular, leading to many different playing styles.

As you explore, the lights under the strum surface will help illustrate the contours' unfolding. Each voice has three lights in a row, showing 'attack' at left, 'sustain' in the centre, and 'release' on the right. All lights turn off when the voice is silent.

Example: sustain slider

  • set length to 9:00 and set ramp to noon
  • quickly push the sustain slider up to full to articulate the note’s onset with a swell
  • wait until the light on the left of strum has completed its transfer to the centre
  • quickly pull the sustain slider down to articulate the note’s decay with a slow recession

If you set the sustain slider halfway, then the onset and decay will each take half the time they do when sustain is at its extremes. This is because length defines a speed of motion in terms of the full range of contour. Atrium is a dynamic system of interrelated gestures and responsive control, and this subtle detail creates many possibilities soon to be discussed.

Example: strum touchplate

  • set length to 10:00 and set ramp fully counter-clockwise
  • touch the strum touchplate down the middle to 'pluck' all the voices like a stringed instrument, with an immediate onset and a gentle decay

loop

Pressing the loop key will cause Atrium to endlessly cycle the contour of each voice. The maximum intensity of the looping contour is set by sustain and/or strum, so even while looping you still maintain control over dynamics. Setting sustain to the minimum will silence the output as normal.

Example: sustain slider

  • turn ramp fully counter-clockwise
  • set length to 1:00
  • slowly raise the sustain slider

Hear how the cycles slow as sustain reaches its apex, then accelerate as you pull back down to silence.

To mirror this example with touch, set sustain to zero, then press your finger to the right edge of strum, slowly pulling it into, and away from, the centre of the touchplate.

stretch

Cycling the voice’s envelopes is really fun and powerful, especially with the responsiveness of varying sustain levels. So far though, all these voices are aligned together; each articulation taking the same amount of time. If we look to Just Friends, using envelopes which cycle in “tempic relationships” can open up much new terrain…

stretch allows us to break apart this alignment, altering the relationships between voices in terms of their length.

Two vertical touchplates (on either side of the loop indicator and drone display) bend these timings for the left & right channels. stretch uses the centre channel as a fulcrum, always pinned to length setting, while bending the outer channels faster or slower.

  • Spread a chord so each voice has a different pitch.
  • enable loop and set length to noon so we hear a slow and steady pulse.
  • To slow the timing for a voice pair: slide your finger down the corresponding stretch panel.
  • To hasten the timing for a voice pair: slider your finger up the corresponding stretch panel.
  • Note the bar-graph that is displayed when touching stretch, pushing up from the bottom for positive values, and pulling down from the top for negative values.

The left side of stretch affects voices panned to the left (voices 1 & 2). Voice 1 is affected the most, while Voice 2's length is affected by half. For the right channel, Voice 5 is affected the most, and Voice 4 at half strength. At the extremes of stretch the length of the outermost channels is multiplied or divided by a factor of 6.

If you've been exploring stretch with loop engaged, the voices will be compressed & expanded into a polyrhythmic relationship. By dialing in specific stretches you can find all kinds of inter-related musical phrasing.

When playing strum to directly articulate voices, stretch allows the response of the voices to be tailored to a compositional landscape. Increasing both sides of stretch with a positively spread chord will allow drone-like articulation of the central bass note, while the higher tones will be short and snappy blips.

To return all voices to their central timing, hold clear and touch both sides of stretch, seeing how the associated lights turn off when doing so.

drone

By default, all five voices are controlled by the sustain slider. At some point you may wish to focus in on only two or three — there are a lot of compelling musical gestures which can be achieved with dyads! Of course, you can use the strum touchplate to ‘solo’ voices, but maybe you’d like to capture ‘snapshots’ of particularly interesting voice groups?

If the drone glyph is approximating the ~ character, then all five voices will respond to the sustain slider.

Press the drone key to enable the sequence and start moving through snapshots of different voice configurations. The first five slots are mapped to voices 1 through 5.

At first glance the drone key simply steps through the voices. Tapping it rapidly, or mapping the clock to advance it, is a fun way to play through the voices dynamically. You can still play all the voices with strum, but sustain will set the drone level for only the selected voice.

However! The drone key is not just a voice selector, but it is in fact a sequencer! sequences are a type of memory that Atrium uses to store different configurations of a parameter, and their corresponding key acts like a sequencer, cycling through those configurations. In this case, our parameter is a list of "which voices are active". These 'snapshots' are a powerful compositional tool of Atrium’s sequences.

The sequential voice selection is interesting, but we can alter & extend this arrangement. Multiple voices can be active at each step!

  • set sustain to maximum to hear the voices droning.
  • hold drone and press strum to toggle voices on and off for the current sequence step.
  • release drone to stop editing the sequence stage.

A quick tap of drone will select the subsequent step of the sequence, after which you can again hold drone to edit the newly selected step. As you edit the steps, you'll hear the voices react immediately. The drone display will show the selected step with a bright light, and any active voices with dimly lit stages.

To disable drone's sequencer and return to "all voices active", hold clear and press drone.