FOREWORD

Five voices of analogue synthesis, controlled and modulated polytimbrally. We’ve taken ideas from our decade of modular exploration, and reimagined how we reach into polyphony.

Each voice is shaped by its harmonic energy while three core timbre modes push into richer territory. From simple suboctave and noise waves, through frequency modulation, and landing in formant synthesis. All squeezed through a lowpass/gate combination, providing balance and occasionally emphasis.

No digital multi-effects here, just spectres in the machine. A novel configuration of three filters, two delays, and feedback. front and almost centre — this resonant body is meant to be played. sequenceable, modulatable, while feeding back not just sound, but shape for unfolding cybernetics.

And to modulate! Everything mappable to everything else, tactile input extended on the fly, mapping as a performance in itself. Sources are dynamically phased across voices, and stretched in relative duration. Gestures are captured into five recorders, extending play rather than overriding it, all twisted in time at your whim.

Atrium is deeply learnable, and for those moments of quick change, instantly recallable. Extensible with USB and MIDI and CV input.

A Players Manual

We wanted to make a manual that isn't just technicalities, but rolls in jumping-off points for your discovery. Atrium is quite a deep instrument and one shouldn't expect everything to be perfectly clear the first time around. Coming back to this document from time to time should be rewarding as certain elements require a degree of familiarity.

At the same time, you don't need to read through sequentially (though we do think it reads well in the presented order). Playing with Atrium will always be the best teacher, so if you have the instrument with you, make sure to work through the descriptions and examples on-device! Some things are hard to describe with words or even pictures.

Finally, this is a living document. As the project develops further, we'll be extending & updating this manual. Presently this refers to version 1.0.0 firmware (that which ships on the initial Atrium devices), and in the future we'll mention where things have changed.

A Note On Style

Throughout this manual, we'll use a few formatting tricks to help break up the text:

• Features: whenever you see text in this color, it means we're talking about a core concept or feature of Atrium.
• Hardware interactions with a feature: whenever you see text with this formatting, it intends to instruct you toward a physical interaction with Atrium.
• These callouts provide broader context and technical information for what's being discussing.
• These callouts provide instructions for additional play.
• These callouts provide waypoints for additional reading within the Player's Manual.

BEGIN

Introductory Videos

If you haven't seen these videos and want a top-level overview of the workflow of Atrium, this is a great place to start. While they are not exhaustive walkthroughs, they should give some context for the kinds of interactions described in this document.

On Gestures

Demonstrating some of the gestures that will serve as trusted tools on your first adventures with Atrium. Everything from making notes and navigating pitches to mapping modulation and recording your unique gestural dialogues. Building blocks for developing a personal technique.

On Systems

Articulating the core systems for composition and environment building in Atrium. Methods for structuring play, while allowing and encouraging the artist to embed personal creative ideas. These systems set the rules of play, subtly redefining the specifics of familiar gestures.

Topics

• First Steps: Let's not fuss around, but get you making sound!
• Connectivity: All the ins + outs.

First Steps

Let's not fuss around, but get you making sound!

First you'll need to provide Atrium with power. If you ordered a PSU with your instrument, you're good to go. Otherwise you'll need a USB-C power supply that can deliver 3A of 5V power. Most modern computers or battery power banks will work in a pinch!

• Connect your PSU to Atrium's power port located behind the tempo knob, at the far left of your instrument.

Lights, wonderful lights! Take in the scenery for a moment, ahhh. A deep breath in, and now we need sound!

• Connect Atrium's audio output to your speakers or headphones. Headphones, or a stereo 3.5mm cable should attach to the left jack (labeled phones on the front panel). See connectivity for other options.

The control most boring, yet most powerful:

• Turn up volume, right by the audio output jacks.

At this point, the best thing to do is MOVE EVERY SLIDER AND KNOB AS QUICKLY AND DRAMATICALLY AS POSSIBLE.

Is this a joke? Certainly not a good one! But it teaches a valuable lesson — your best teacher on this journey will be your ears. Throughout this manual, you'll build a connection between gesture and resultant sound.

Interactions

If you're ready to start learning, there are a few pieces of context to keep in mind:

• Firstly, notice the five frosted regions through which white & grey stripes are visible. These are touch sensitive, and a core interface into Atrium's polyphony.
• Next, imagine splitting the interface in two — one half near (with the sliders), and the other far (with the power & audio cables). The controls nearest you are about the sound, while those further away are about the system. In the beginning, focus your attention on the nearer sound controls — they are more immediately satisfying, and easier to understand intuitively.
• Sneak a peek at polyphony by holding the chord button and moving the notes slider. And remember, if things get strange you can reset everything by holding the load button, and pressing clear — loading nothingness.

That's it, you're ready to go.

Try and remember there's no rush, and take time with the sidequests that arise!

Connectivity

Note: this image's orientation makes a lot more sense looking down from the top of the unit, but we wanted to capture the visual of the back panel accurately.

Outputs

Mono or stereo output on 3.5mm cables, split between three modes, depending on how you're connected:

• Mono mix ( right ): if only one cable is connected to the right output, then the stereo signal is mixed down to mono and sent across that one cable. This is marked as mono on the top panel.
• Dual mono ( left & right ): if two cables are connected to the left and right outputs, then the stereo signal is split across the cables.
• Headphones / stereo TRS ( left ): if only one cable is connected to the left output, then the stereo signal is sent across that one cable. This is marked as phones on the top panel.

CV Inputs

Three control voltage inputs on 3.5mm cables. Designed with Eurorack systems in mind, but will work with any traditional CV source.

• Each input ( a b c ) responds to a +/-5V range.
• Voltages up to +/-12V are safe to connect, but there will be no further response beyond +/-5V.
• Signals received over these inputs can be mapped to any parameter, just like the internal modulators.

The ports are indicated by arrows on the top panel with the letters a, b, c within.

When CV cables are connected, you'll see the corresponding light shine above the cv key.

MIDI

Two MIDI connections on 3.5mm cables:

• MIDI out, type A
• MIDI in, automatically accepts both type A and B

The ports are indicated on the top panel by arrows pointing down (in) and up (out). To connect to classic DIN MIDI jacks, you'll need an adaptor.

Remote

Two USB connections for different layers of inter-connectivity:

• computer: This USB-C port is used for MIDI and serial communication back to a host device, eg. a DAW running on your computer. Atrium will enumerate as a standard MIDI device when connected to a host through this port. Indicated by a laptop icon on the top panel.

If you're powering Atrium from a computer's USB port via power, these computer signals will also be sent on that cable. In this case, leave the computer port unconnected, as attaching it steals priority from the power port.

• controller: This USB-A port is used to host MIDI or serial devices, eg. traditional MIDI keyboards, MIDI CC knob boxes, and (soon) monome grids. It provides up to 900mA power. Indicated by a one octave keyboard icon on the top panel.

The light above this port will shine when a USB device is connected & powered up.

Power

One USB-C port for power & data (MIDI and serial).

• We recommend a supply capable of delivering 5V @ 3A. The optional power supplies provided by Whimsical Raps meet these specs.
• When connected to a host computer, this port can carry both power and data, meaning that you can power Atrium while its connected to your DAW & other software. In this case, do not connect anything to the computer port.

When powered on, the light window above the port will shine. The left light indicates power, while the right light indicates that this cable sees a USB connection to a host computer.

ON GESTURES

On Gestures

"Demonstrating some of the gestures that will serve as trusted tools on your first adventures with Atrium. Everything from making notes and navigating pitches to mapping modulation and recording your unique gestural dialogues. Building blocks for developing a personal technique."

Topics:

• Notes & Articulation: How to choose pitches & then articulate them
• Timbral Control: Navigating Atrium's three timbral modes (wave, fm, and form)
• Spectre: Resonant tone shaper for filtering & feedback delays
• Lowcut & Volume: Essential tools!
• Gestures: Five ephemeral sketch pads for movement

Notes & Articulation

One of the ideas at the heart of Atrium is that pitch is at the same level of importance as any timbral control. By escaping the strict coupling between pitch selection and envelope articulation of traditional keyboard synths, Atrium offers free interplay between amplitude and harmonicity. Let's explore the different facets of playing Atrium: how to choose pitches, how to voice them, and how Atrium's polyphony interacts with the broad concept of 'notes'.

notes & sustain

First sound! To articulate notes, move the sustain slider up; this slider animates all the active voices at once. As the sustain slider moves up, you'll see the lights to the right come alive and you'll hear the oscillators drone.

Atrium sings with five voices of polyphony. When first powered up, the same pitch is sent to all five voices. Change the position of the notes slider to change the pitch of every voice.

We'll cover how to shape note events in the contour section, and we'll cover how to select which voices are active in the drone section.

chord

While these oscillators sound nice altogether, it's far more fun if the notes are different!

To provide each voice with its own pitch, press and hold chord while moving the notes slider up or down. You'll hear the voices spread away from the root note, either positively (up) or negatively (down). The root note is always the position shown nearest to the notes slider.

The display to the right of notes functions as a small notation device. It represents the active pitches with a piano-style layout turned on its side like a melodica. When chord pushes notes out of range, you'll see them shadowed at half brightness in the nearest octave possible.

chord spreads out all five voices with equal spacing between them — up to a two octave range in either direction. These notes will typically be quantized by scale, meaning if you spread chord a small amount, you'll have multiple voices playing the same pitch.

See below for more details on panning!

As the voices are panned in the stereo field, you'll hear the notes of the chord in opposite channels — for linear scales, these are the highest notes when chord is up and the lowest notes when chord is down. Meanwhile the root note is always in the centre of the stereo field.

If you want to get back to unison, hold clear and press chord.

chord has a larger black key. In Atrium this means the key is a shift or meta key.

octave & glide

In addition to the three-octave range of the notes slider, there are two octave keys. Press either of the octave keys to transpose the current notes by +/- 2 octaves.

Press the glide key to add three depths of glissando between the last note and the next note: just a smidge / acid-style bends / swooping arcs.

Note that glide performs exponential glissandos, moving very rapidly at first, then slowly settling at the target. This is also known as constant time interpolation, ensuring that no matter the distance between notes, they always travel over the same duration.

strum touchplate

There is a touchplate to the right of the sustain slider, which lets us conjure each voice individually. Voices are ordered vertically from bottom-to-top, demarcated by each light trio.

Touch the strum touchplate to articulate the contour (envelope) for each voice.

strum works in conjunction with the sustain slider’s position:

• With the sustain slider down, only the touched voices are sounded.
• With the sustain slider between min and max, touched voices will be raised to full sustain levels, which is a fun way to add ‘accents’ to a drone.
• With the sustain slider at max, touch has no audible effect on already-sustained voices.

All of these are valid interactions: strumming, tapping, holding, or performing little exploratory swipes. Touch the strum touchplate with multiple fingers to articulate many different voices simultaneously.

Moving a touch vertically in either direction picks through the different voices. Meanwhile, where and how you touch on the plate's horizontal axis also influences the results:

Atrium's touchplates use capacitive sensing which allows us to track how strongly any press is held down. In addition, the touchplate itself is designed to have maximum sensitivity in the middle of the horizontal axis, while the edges allow more subtle gesture.

Touch and hold the middle of the voice's zone: This strong and sustaining gesture will open the contour while you hold it. The contour will begin its ramp, with the voice sustaining for as long as its held, then removing touch will release the contour.

Touch and hold the right edge of a voice, then slide it to the centre: Through this gesture you're able to directly control the articulation of the voice from quiet to loud and back again. Using this gesture, you can dynamically play bowed-swells without adjusting the contour settings.

Try different finger positions to adjust the response. A pointed fingertip will be more gentle, while a flat finger will evoke the strongest response. Dragging a flat finger down strum will smoothly fade between different voices.

voicing touchplate

The voicing touchplate, located underneath the piano-overlay, provides additional modifications to the current spread of notes with a note-folding technique. This is best explored with a modest chord spread, to really hear what's going on.

voicing is highly interactive with the active scale selection. Depending on the number of notes in your scale, you'll see drastically different results.

Drag a finger upward on voicing and notice the lighting display indicates the amount of folding. This takes the chord as it's currently voiced and redistributes the notes by selecting a sub-set of possible tones from the scale.

Drag voicing downward, and into the negative region to introduce more bassy tones. This segment of voicing performs "drop-n" voicing tricks, taking one of the voices from a chord and transposing it down an octave. The negative section of voicing steps through five distinct regions, where each voice is dropped one at a time. This technique creates what are often called "sugar chords".

To clear any active voicing modification, hold clear and press anywhere on the voicing touchplate.

Global Tuning

If you're playing with a group, or recording with acoustic instruments that aren't tuned to A440, you can fine-tune Atrium's global tuning:

Hold alt while dragging a finger along the voicing touchplate to set a fine-tune adjustment. Flatten or sharpen by up to 1.2 semitones. More-dramatic tuning changes (and transpositions) are available in the scale editor.

To reset to default tuning, hold alt, then hold clear, then touch voicing.

Panning & strum Voice Allocation

Atrium pans the five voices evenly through the stereo field. Put simply, the root note is always in the centre, and any chord spread is alternatively panned left/right. The result is a pleasing width to the sound without an overt bias of pitch between sides.

If we use the strum touchplate as a form of notation, voices are spread in the stereo field:

R: voice 5 (hard right)
r: voice 4 (centre-right)
c: voice 3 (centre)
l: voice 2 (centre-left)
L: voice 1 (hard left)

In terms of pitch and chord spread, link the strum touches to given notes of a chord:

R: voice 5 (root+4)
r: voice 4 (root+2)
c: voice 3 (root)
l: voice 2 (root+1)
L: voice 1 (root+3)

The above is only precisely true for a specific setting of chord (moved upward by a small amount), but it illustrates the motion of tones. If chord is moved downward, the + above would become -.

In other words, the outer edges will always be the furthest away from the root, whereas the inner edges will be only a degree or two away.

Timbral Control

Let's be honest, you probably messed with the controls covered in this section as soon as you figured out that the sustain slider makes sound happen. No matter. Welcome, impulse-informed adventurer — much information & inspiration awaits.

Atrium has a wide range of sonic potential through its three timbral modes — cycle through synthesis techniques by pressing the timbre-mode key (labeled wave fm form).

While each modality has a distinct character, the effects of the sliders are generally consistent in their impact:

• energy : Adds harmonics when moving away from the centre.
• timbre : A secondary oscillator which further shapes the output. Typically, this controls the intensity of the effect.
• tone : Controls the secondary oscillator, revealing more of the identity of the given mode.

Between the energy and timbre sliders is a light bar that displays the harmonic content of the current timbre selection. The fundamental pitch is at the centre, demarcated by the horizontal line. The lights above the fundamental are added overtones (harmonics), while the lights below are undertones (sub-harmonics).

wave

Fresh inspiration drawn from poly-mythologies of the 80's. wave adds a secondary oscillator in parallel to the primary oscillator. This mode offers a cross-fading mix of sub-octaves (either one or two down) and white noise, with simultaneity in-between. Its interface suggests new & dynamic gestures apart from traditional dedicated levels.

energy

Under the hood this is a three-way crossfade between square, sine, and sawtooth waves.

Controls the harmonic energy of the primary oscillator:

• add odd harmonics: move energy up
• add all harmonics: move energy down
• soften to a sine: set energy midway

timbre

Controls the mix level of the secondary oscillator.

As timbre is increased the lowpass/gate will become increasingly overdriven, leading to softly-saturated sounds. Depending on the energy control, this can surprisingly have the effect of softening the sound. Keep this in mind as you explore the sustain modes as it will interact with resonance in the filter!

tone

Fades the secondary oscillator between three different forms:

• -1 sub octave: set timbre to max
• white noise: set timbre midway
• -2 sub octave: set timbre to minimum

The transition between these forms is continuous and provides great opportunity to add just a little noise or sub-octave. This can be great for sprinkling some grit onto a sound.

fm

Two-operator frequency modulation. Capturing many great modular-style sounds, with an interface that makes things much easier to keep in tune. The "modulator" oscillator will accurately track across the full frequency range, so you can dial in precisely the amount of instability you want (or don't want).

Technically Atrium performs phase modulation in order to accurately track pitch. Sonically there is no difference, but this explains the quick pitch-bend when fm is selected if timbre is high. We kept the name "fm" as it's a more widely recognized label.

energy

Controls the harmonic energy of the carrier oscillator:

• add odd harmonics, move energy up
• add all harmonics, move energy down
• soften to a sine, set energy midway

As timbre is increased to the maximum, energy is subtly pulled back toward sine. You probably won't notice, but it pleasantly avoids some strangeness at the extremes.

timbre

Controls the depth of the frequency modulation. At the minimum there is no modulation, while the effect is very dramatic at the maximum.

tone

Fades the ratio of the modulator frequency to the carrier frequency:

• 2:1 : set timbre to max
• 1:1 : set timbre midway
• 1:2 : set timbre to minimum

With the settings between these three positions you'll hear and see sidebands appear. These can be leveraged to create great bass tones below the fundamental.

form

Building on our Mangrove formant oscillator, this is a new shape for a local classic. The primary oscillator is used to create the impulses that you hear. Meanwhile the secondary oscillator defines the frequency of these impulses.

Before exploring form, make sure to set tone to its minimum to avoid immediate confusion!

energy

Controls the harmonic energy of the impulse oscillator:

• add odd harmonics, move energy up
• add all harmonics, move energy down
• soften to a sine wave, set energy midway

energy is highly interactive with both timbre and tone and you might notice that even the midway point can get very gritty! When exploring form it's best to start with energy midway, then use it to add two different kinds of harmonic grit.

timbre

Controls the size of your instrument:

• for "smallness": move timbre up
• for subharmonic pitch divisions: move timbre down

Subharmonic pitch divisions are these glorious shifts in pitch that occur at the bottom of the range. They follow the pattern of:

• down one octave
• down one octave + a fourth
• down two octaves

They are the inverse of the harmonic series and are a fantastic tool for adding breadth and dynamism to a patch. This is especially effective when polyphonically modulating timbre to have the different voices sweep through the subharmonics at different moments.

For the curious: these divisions happen when the primary oscillator's impulses are longer than those of the driving secondary oscillator. This causes the primary oscillator to skip some triggers, effectively dividing the pitch. There is a small ambiguous region between each division allowing for multiphonics, where multiple divisions can be heard simultaneously.

tone

An alternative title is "secondary oscillator frequency multiplication" but that's a mouthful! What's important is that tone is incredibly interactive with timbre.

Harmonic relationship:

• add overtones: set timbre north of centre and move tone
• add chaotic multiphonics: set timbre south of centre and move tone

When timbre is high, increasing tone has an "oscillator sync" sound, sliding upward through the first 5 harmonics. It can sound like a resonant filter, and works especially well if you drop octave to its lowest setting.

When timbre is in the pitch-division region, tone's effect is quite chaotic, but still reproducible. There is a deep matrix of possibilities here! Due to the combination of pitch division & frequency multiplication, there are many pitches available outside of the harmonic / sub-harmonic series.

Spectre

spectre is a resonant tone shaper, which adds both filtering and feedback delays to the five oscillators. It features three analog bandpass filters which are sent through two BBD delays in a dynamic feedback loop. The filter settings are captured in a sequence, allowing them to be stored and recalled rhythmically with the lens sequencer, with three levels of morphing.

spectre knob

spectre is both the name of the processor and one of its parameters.

The spectre knob is a macro control, controlling the balance of dry, filtered, and delayed sounds, all while driving the feedback intensity. Think of it as a dynamic scan through the discrete facets of the circuit. This control can feel very different depending on both the source material (the five voices) and the other settings within this region. This macro traverses three zones, cleanly moving unique parameter scalings through an expressive range. Starting fully counter-clockwise and moving clockwise:

1. Moving spectre from counter-clockwise to 10:00 crossfades from the dry signal to the filters' output without any delay. Reminiscent of the sculpting found in Three Sisters.
2. As you increase spectre clockwise to around 2:00, the output of the filters is progressively fed into the stereo delay, adding feedback as you go. The delayed signal is heard only through this feedback path, leading to ever-growing resonant echoes.
3. Continuing to increase spectre to full clockwise crossfades the filtered signal into the dry signal with direct delay output, while reducing feedback. Maximum feedback at the start reduces to ~50% at full clockwise.

Each section of spectre has its own quality and is useful as a static tone shaper for the whole instrument. Both edges of the range will prioritize the dry signal, leading to the brightest full-spectrum tones. Meanwhile the centre of the range is decidedly coloured and allows the spectre processor to shift your sound more dramatically. It can be really fun to modulate this control, but feel confident to leave it in a static position & define a resonant shape for your patch!

time

The time knob controls the delay time for spectre's feedback path.

The delayed signal is only heard when the spectre knob is above 10:00.

As is common in Atrium, higher settings (clockwise) are faster:

• Turn time counter-clockwise to set the delay time to 800 milliseconds.
• Turn time fully clockwise to speed the delay up to around 1.5 milliseconds.

While this might sound straightforward, there are a lot of interesting things that happen across this range, interacting strongly with the filter settings. At the shortest times you'll approach some clangorous tones, applying a comb-filter effect — this can be fantastic for imparting a strong resonant quality to your patch.

Conversely the slowest speeds are notably lo-fi, owing to the nature of bucket-brigade delay technology. At these long times, the sampling rate is greatly reduced and high-frequencies will be lost. When using long delay times, focus on filter frequency settings in the lower half of the range.

When modulating time, if the mapping source is polyphonic, voices 1 & 5 will be used to control the left & right channels independently. Try mapping (just a little) lfo to time, then spread out the phase to hear the echoes bounce against each other. Perhaps even modulate phase for a through-zero chorus effect.

spectrum touchplate

The arch around spectre is a touchplate that controls the spectrum of frequencies to be filtered. Think of it as an equalizer that passes only three selectable bands. The range from left to right is around 100Hz to 12kHz allowing for dramatic shaping of your voices.

Swipe with one finger to adjust the cutoff of all three filters, adjusting each frequency band by an equal amount. If you continue to push to either extreme, the filters will coalesce at a single frequency — they will retain this alignment even if you then move in the opposite direction. To bring all three filters' frequencies to the centre of the arch, hold clear and touch the spectrum touchplate.

To spread the filters, changing their relationship to one another, employ a two-finger touch instead. You can either:

1. Hold one finger down to 'pin' one side and move another finger on the opposite side to manipulate that filter's cutoff value without moving the other two.
2. Spread both fingers away from the arch's centre to pull the left- and right-panned filters further away from one another, which keeps the centre steady.
3. Push the bands together with two fingers to bring them both closer to centre.

While the factory patches typically place the left filter to the left of centre (and vice versa), this can lead to an imbalanced stereo field where the left channel has more bass. You can however use the third two-finger gesture to cross over the centre channel, flipping the spectral panning. When using two-fingers, the left-most touch on spectrum will always correlate to the left output channel — use this to determine the organization of frequency bands.

lens & morph

As you explore spectre, you'll find that the placement of the filters strongly affects the final shape of the signal. Atrium offers a sequencer to spectre, named lens, which stores up to 11 snapshots of different cutoff frequency landscapes.

• Press lens to step forward through the sequence.
• Cutoff adjustments (with spectrum touch) directly modify the current sequencer step.
• To change the sequence bounds, see sequences.

The abrupt changes of lens steps can be softened with three levels of slew. Press the morph key to cycle through slew times. When morph is active, touches on spectrum will also be smoothed out. This can be lots of fun with the longest morph setting and a spectre setting with lots of feedback — listen as the feedback latches onto different harmonics in the sound while it slides about.

morph moves the frequencies linearly, at a fixed pace. As such, morphing frequencies that are far apart will take much longer than those that are close together.

Stereo Field

Put simply, spectre is a stereo effect, but part of its magic comes from entangling the left and right channels. While these are implementation details, perhaps they will give a curious few of you new ideas on how to use spectre.

How the signals flow:

1. Atrium's five voices are mixed down to a stereo pair. Each voice is spread evenly across the stereo field, with voices 1 & 5 at hard-left and hard-right respectively.
2. This stereo mix of the voices is sent to each filter: Left->Left, Right->Right, and Left+Right->Centre. The central filter thus operates on a "mono" mix of the signal.
3. Filter outputs are also mixed (again) to stereo: Left->Left, Right->Right, Centre->Left+Right. This is the signal you hear as the "filtered" sound, but is also used for feedback...
4. Stereo feedback is sent into the delays, up-mixed the same way as in step 2, and recirculated into the three filters.

The result is feedback that cross-pollinates across the stereo field via the centre frequency band. You'll find that spectre can often have a narrowing effect on the sound which is often useful to make Atrium sit better in a mix; taking up less space. By the same token, you can exaggerate the stereo effect with dramatic frequency settings, lens sequences that alternate left/right panning, and polyphonic modulation of time which pulls the stereo width out considerably.

Lowcut & Volume

At the top-right of Atrium's rising edge, we find two finishing touches before the dish is served.

lowcut

A gentle, variable, highpass filter (6dB) is applied to the output of the five voices. spectre takes input after this filter, so its output is left unaffected.

Press the lowcut key to increase the cutoff frequency, removing more and more of the low-end signal from the voices.

This might sound boring on digital paper, but this intermediary filter opens up new sound design options which would've been difficult to provide otherwise.

Use the lowcut at full-strength to create spatialized hi-hats from wave's noise generator! Or spice up a low-frequency spectre feedback loop by using lowcut at mid-strength to add a bit of form's sizzle.

Of course, don't forget that lowcut is classically useful for polyphonic pads, like string sounds. If you're in the studio and find Atrium is just too big in the mix, try bumping up this setting.

volume

While volume is pretty self-explanatory, we had to call it out as an essential. Turning clockwise makes Atrium's output louder without changing its timbre. Still there are a few tricks with this control.

Firstly, the static position of this control is not saved in patches. You'll always be controlling the main output level of the instrument directly, so different patches don't jump dramatically in volume.

Meanwhile volume is a valid mapping destination! Be careful here as the effect of the same mapping intensity behaves differently depending on the position of the knob. That said, it's a fun way to add some shaping after spectre has been applied.

Map lfo to volume for classic tremolo, or even apply contour over an oscillating spectre patch to re-apply some articulation and break up the feedback.

Gestures

Reflecting on all the ways we've interacted with Atrium so far, there are so many compelling sidequests inside a simple slider flick or a knob twist. Worlds are revealed, obscured, remade. To cap off the gestural section of the Player's Manual (and before we get into creating persistent Systems), we invite you to eschew absolute truth in favor of ephemeral gonzo recording.

The final boss of On Gestures: gestures themselves. Five temporary sketch pads for movement.

Basics

Conceptually it's easiest to think of gestures as tiny loopers of your manual articulations. When you find a motion you like the sound of, you can capture it as you play, and have it repeated ad infinitum. With a single press, playback can be stopped, then pressed to restart again. All gestures can play at once, but it's fun to use them as alternating motifs with different groups. Of course there's more to it, but this is a good mental model to start your exploration.

Keep in mind that the timing of gestures is directly linked to the clock (and thus the tempo knob). Before continuing, be sure that tempo is not at the minimum, and you're seeing the metronome happily tick away.

Recording

• To begin recording, press one of the five white gesture keys. Recording begins immediately!
• Interact with Atrium's parameters.
• To stop recording, press the same gesture key. Playback begins the moment you stop recording.
• To stop, press the same gesture key.
• To restart playback, press it again!

Presently only knobs & sliders are captured by gestures. This will change in future.

Clearing

To clear a gesture, hold clear and press the corresponding gesture. The gesture can be playing while this occurs; Atrium will simply reset the parameter to its current panel value.

Modifiers

By default, each gesture runs asynchronously and for a free, unquantized duration. There are five modifiers available which change different facets of each gesture beyond its default behavior. This is where the black gesture key comes into play - again the black key acting as a shift key for controlling others.

The currently selected gesture recording is indicated below the black key. Anytime you interact with a gesture's white key, it will be selected for editing. If you want to select a different gesture, tap the black gesture key.

With the desired channel selected, hold the black key, and press the white key corresponding to the desired modifier.

step

step quantizes playback of the events in the loop; the recording buffer is sampled once per clock pulse, then held until the next pulse. When enabled, step adds the feeling of “sample and hold” to continuous parameter adjustments, adding a rhythmic effect to the motions.

Beware though! These updates won't magically be linked to the clock's phase. Instead the sampling happens in terms of the gesture's duration. A recording that is 3.5 beats long will have an irregular pulse to the steps. This can be used to creative rhythmic effect, or see the len and beat modifiers for a more rigid effect.

len

len quantizes the duration of the loop to a multiple of clock pulses. This is not a pre-fixed number; rather, len reflects the duration of each loop but snapped to the beat. For example, two len-quantized loops can be fourteen and fifteen pulses long, respectively. This creates a feeling of cohesion between multiple running loops.

• When recording with len enabled, you’ll see that your ‘stop recording’ press is quantized to the next beat. This means that the loop’s length is baked into the recording, and will always be an integer multiple of clock pulses.
• When playing a freeform recording back with len enabled, the timing is compressed downward, playing slightly faster so all the events are executed within the allotted time.

beat

beat quantizes the gesture key’s presses to the next clock pulse.

• When recording with beat enabled, you’ll see that your ‘start recording’ press is quantized to the next clock pulse. When combined with len, this allows for classic beat-based looping, where the start and end of the loop are perfectly in-sync with the clock’s pulse.
• When playing back with only beat enabled, your ‘start playing’ press is quantized to the next clock pulse. Your ‘end playing’ press is still immediate.

beat and len are two sides of the quantization coin. If you're looking to create loops with tight synchronization, it's best to turn them both on.

scan

scan compresses event playback to the duration of a single clock pulse. This is useful for creating your own uniquely-shaped modulators and is a fun way to remix and recycle your recorded gestures. If beat isn't enabled and you launch playback with scan, you’ll see that the playhead ‘picks up’ wherever it is in the phase between clock pulses; enabling beat will ensure that scan's playback waits for the next clock pulse to start playing.

link

link is useful to synchronize multiple gestures together, driving the playback of the target gesture from the playhead of a source gesture. The same gesture can be used to drive the playback of multiple others, allowing for different depths and dimensions of interdependency.

To link a gesture to another:

• Select the target gesture whose playback you want to affect by pressing the black gesture key until the target's number is listed.
• Then hold the black key and press link (you can now release the black key if you wish)
• The link light will flash, and a light bar will appear above the currently selected link source. By default, this will be the target's own channel.
• Press the gesture key of the source; the one you’d like to drive this playhead. The interface will automatically exit upon selection.
• If you hold the black key again, you’ll see a pulsing light bar above the linked playhead source.
• To clear the link, and return to normal playback control, hold the black key and press link. The pulsing light bar will disappear.

Some notes about link:

• When a gesture uses the playhead from another to drive its playback, all of its events are compressed or expanded to the timing of the source playhead. This also means that the target gesture's key no longer controls its playback, since that is taken from its source playhead.
• If a linked playhead has any timing modifiers enabled (len, beat, scan), those will affect the playback of the target gesture. For example, if you link gesture[2] to take its playhead from gesture[1], and gesture[1] has beat and scan enabled, then gesture[2] will also wait for the next clock pulse to begin playback and its events will be compressed to the duration of a single clock pulse.
• We can also complect our linking! For example, we can link gesture[2] to take its playhead from gesture[1], but we can also link gesture[3] to take its playhead from gesture[2]. What’s fun is that this doesn’t mean that gesture[1] is now driving both gesture[2] and gesture[3] — rather, gesture[2]’s original playhead is now driving gesture[3]! It's a great way to manipulate the timing of gestures beyond simply scaling them all up or down with tempo.

The gesture section's interface is utilized in numerous other ways through the instrument, which will all be covered in the following section (On Systems):

• Saving & Loading Patches
• Editing Scales
• Clusters

ON SYSTEMS

On Systems

"Articulating the core systems for composition and environment building in Atrium. Methods for structuring play, while allowing and encouraging the artist to embed personal creative ideas. These systems set the rules of play, subtly redefining the specifics of familiar gestures."

Topics:

• Saving & Loading Patches: How to capture and restore configurations of Atrium's landscape
• Contours & Drone: Envelopes, timing, voicing configurations
• Mapping: Extend your articulations with extra hands
• LFO: The "scroll wheel" at the heart of Atrium
• Clock: Atrium's heart beat
• Sequences: Decoding the light-glyphs which hold stateful memory
• Scales: Modify pitches, arpeggiate to the clock, and turning off quantization
• Clusters: Store voice configurations for rapid alternation

Saving & Loading Patches

With so many hallways inside a single Atrium session, a patch is not merely a 'preset sound' you like, but a complete configuration of the landscape. At its best, a patch invites further interaction, where loading it again will lead to many more sounds than found in your last foray.

To fully encourage this type of exploration, Atrium supports a total of five onboard patches. Each factory patch is a tiny world to explore, and each patch is editable and can be overwritten freely.

A patch is a snapshot of the entire state of Atrium. Control positions, scales, sequences, mappings — anything except gestures and volume. Accordingly, you can encode so much musical information into a single patch.

Template: Resetting State

While many synthesizers have an "init" patch (a blank slate to craft a new preset), Atrium has a patch template. This special patch is a collection of defaults that provide a straightforward musical layout without any of the complexities of mapping. This template is an ideal tool for initial explorations as it enables you to jump back to known state without any hidden modulations affecting your play.

When Atrium is powered on, it always loads the template patch. You can recall it at any time: hold load and press clear.

Loading the template patch will ensure:

• Maps are all cleared.
• Gestures are all cleared.
• All continuous controls are set to the current slider and knob positions.
• Touch plates are reset to their default values.

In contrast to Atrium's other patches, the template will always set Atrium to follow the current position of the knobs & sliders. This cancels any "pickup" state that arises when setting mappings or recording gestures. The important part is that after loading the template, every knob does what it says on the tin.

Loading

To load one of Atrium's five patches:

• Hold load. You'll see a steady L indicator in the extension window letting you know you're about to load a patch.
• The currently-loaded patch's light will be illuminated on the gesture keys.
• Press a gesture key to load the associated patch (1-5, from left to right).

If you've previously loaded a patch, Atrium will light the associated gesture-key, and display the number of the patch in the gesture window. If you see t in the window, the last patch loaded was the template.

Loading a patch is instantaneous, so you can quickly jump around your saved patches in a live context.

Loading a patch restores everything. Think of it as a snapshot in time while working on a patch. As such, anything you're working on will be overwritten including mappings, gestures, MIDI settings — the works!

Factory Patches

You've probably already jumped through these, so here's some context for what the factory patches are! There's lots of talk of mapping here, so feel free to jump back after you've read further and hopefully it will make some more sense!

1. Dialogue

(from dani derks)

"Designed to be a hand-played dialogue with the machine.

• sustain / strum opens contours (which are mapped to adjust timbre)
• Five clusters are stored for tonal exploration
• Two custom scales, similar voicings but usefully different — I like choosing a chord and tapping between the two options
• LFO is upward-modulating the voicing touchplate and downward-modulating the contour, a smidge in each case
• notes are inverse-mapped to spectre's cutoff frequencies, which makes for a compelling "woah" when changing notes, scales, chords, octaves and having low tones bring the spectrum frequencies high

Still a bunch of hands-on available — flip the notes slider up and down, make a few rapid timbral changes, spread the spectrum, etc."

2. Place

An exploration of parallel major 7th chords. spectre's frequencies control the notes spread, while the wrapping of lens advances through the sequence. The LFO drives the timing, including some subtle chorusing of time. Meanwhile that LFO is randomly stepping around, searching for it's right place.

3. Cyan

A delicate recreation of Bill Evan's opening chords on Blue in Green. While it's just beautiful on first glance, there's so much fun to be had just playing tempo and speed. This uses drone to pluck through the chord tones, while contour is used to animate each event. voicing is pulled all the way down, leading to a deep bassline (with upward contour stretch) and closely voiced chords atop.

4. Lovely

Music box from an ancient pipe organ that never was. Old world, churchy vibes. There's a lot of modulation happening that I'm grateful isn't a modular spaghetti patch. Highlighting the use of phase to spread the notes into 3 distinct groups, along with lens clamped to a cycle of six values. This started as an attempt to build a waltz preset, but it strayed pretty far!

5. Barry

Built on the "diminished sixth" scale. The rhythm has this fascinating gallop to it (and is in 11). The trick here is dialing chord to articulate every second note in the scale, mapping change to advance drone, which is configured to sound only every second pulse. The result is an alternation of major 6th chords, and diminished 7ths, whenever drone repeats. There's a couple other 8 note scales on-board to hear the same effect with different harmony. Play with length to find some other groovy zones.

Saving

Atrium's patches can be overwritten at any time. Use this to incrementally develop an existing patch by overwriting the same slot, or replace them with something totally different!

To save a patch:

• Hold alt, then press & hold load.
• With these keys held, you'll see a pulsating S indicator in the extension window letting you know you're about to save a patch.
• The currently-loaded patch's LED will also be lit, guiding you if you want to overwrite (or avoid) the current patch.
• Press a gesture slot to save into the pressed patch slot.

Saving a patch stores:

• the state of all controls (knobs, sliders, touchplates, modal keys)
• scales
• mappings
• sequence values and bounds
• clusters
• MIDI settings
• tempo

Note that gestures and volume are not saved.

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.

Mapping

As you play through the many nooks and crannies of Atrium, you may wish for extra hands. Atrium can easily integrate many sources of modulation, both internal and external, to extend your articulations and deepen your explorations.

Mapping is the connection of sources to destinations (aka paramaters). In other synthesizers this is often called a "modulation matrix", or in a modular synth, these are the cables that string together a patch. Atrium allows every modulator to control any number of parameters, and any parameter can be modulated by any number of sources. Each of these mappings has an intensity, allowing remote-control to be dramatic, or extremely subtle.

The gateway to mapping is the big peachy-coloured map key (illustrated above), and you'll see corresponding italicized text around the interface to match. These markings indicate Atrium's mapping sources which you'll be needing shortly...

Mechanics

The general process of creating a mapping is:

• Press & hold map to display all of the available sources. Lights will be near each associated key with a peach backdrop.
• Select the source by pressing the source's key.
• Once a source is selected, you can release map.

You're now viewing all the mappings associated to the selected source.

• Move the destination parameter to define the depth of modulation you’d like to apply. You can map any source to multiple destinations at the same time. We encourage you to start small, as its so lovely to have a little modulation animating many controls versus applying ‘an LFO effect’.
• Lights on the interface will indicate the depth of modulation applied. If a control is already at the limit, but you want to go further, move the control the opposite direction, then back again.
• Once your mappings are dialed-in, press map to exit.

After mapping is applied, affected parameters can still be manually manipulated. Manual changes alter the baseline from which your modulations are articulated.

To adjust the depth of an existing mapping, simply follow the same process above. Once you re-select the mapping source, you’ll see the current depths of modulation indicated with varying light intensity at each destination.

Clearing a Single Mapping

To clear just one mapping:

• Select the source for mapping (as above).
• Hold clear and interact with any mapped parameter to release only that parameter from the source’s control.

Clearing all Mappings of a Source

If you want to clear all mappings for a given source (eg: stop the lfo from dominating a patch):

• Hold map and press clear (you can now release both keys).
• Any source with active mappings will be lit.
• Press the source’s key to release all of its mappings.
• Press map to exit.

Muting

Sometimes, we may want to simply mute a modulator’s effect without clearing it:

• Hold map and press mute (you can now release both keys).
• The mute light will turn on. All sources will dimly light.
• Press the source’s key to mute it. The source's light will become bright.
• Press map to exit.

You'll see the mute light stay on, indicating that at least one mapping is muted.

Note how the process for clearing and muting are very similar. It's a good moment to commit the process to memory: Holding map then pressing a modifier (like clear or mute) will affect the source as a whole.

Polytimbrality

In Atrium, polyphony is not just about setting five different pitches and articulations, but also in the application of mappings. Many parameters are themselves capable of polyphony, leading to the "polytimbrality" demonym. All five of Atrium's sliders are a good case for this point. Take energy for example, which can be set uniquely for all five voices. With only a single slider though, access to this voice-wise control is found in the mapping system.

So now we must understand that some modulators are polyphonic, while others only monophonic. Atrium will always try to maximize polyphony when mapping, but if either source or destination are only monophonic it will fall back to unified control. This is described further below, but for now let's get into the sources.

Continuous Modulators

lfo

An internally-generated low-frequency oscillator (LFO). See lfo for much more detailed information!

speed adjusts the rate of oscillation, from around 10 seconds at its minimum into (low) audio rate at its highest intensity (around 100Hz).

phase staggers each of its five voices in time, revealing the polyphony of the LFO.

shape cycles through different waveforms to change the character of oscillation.

Atrium holds 11 default shapes! Learn how to access them in the sequences section.

notes

A signal that represents the frequencies selected by notes. This signal is polyphonic, just like the notes it represents.

• The octave keys shift this modulation signal up and down.
• glide is not factored into this modulation signal.

freqs

Captures the frequencies of spectre's three bands.

• morph is factored into the expression of freqs modulation.

When mapped to a polyphonic destination, this modulation is polyphonic — the left channel is voice 1, centre is voice 3, and right is voice 5. Voices 2 & 4 take the midpoint of their nearest channel.

When spectre is at it's minimum and its effect is not heard, the frequency touchplate (and lens) become a great tool for directly manipulating polyphonic parameters in a manual fashion.

step

This signal turns the lens sequencer into a stepped, rising ramp. The range is dynamically controlled such that the first lens step provides no modulation and the last step provides maximum modulation.

contour

The envelopes created by contour are exposed for further note-event mapping.

• Since contour is built upon the interactions between sustain, ramp, and length, there’s much to be explored here!
• Try mapping contour to notes, and then stretch the contour for each pair. Now, sustain modulates notes polyphonically.

loudness

Captures the overall amplitude of the instrument.

• Note that if your volume is low, you will not likely hear the effects of this mapping.

loudness is highly useful when coupled with spectre, allowing self-limiting delay feedback that can stop you flying off into saturated echoes.

Event Modulators

An event-type modulator is sort of like a square pulse with an extremely slim width. They’re basically the ‘onset’ of an event, rather than a continuous stream unfolding.

These modulators are useful for stepping through sequences or triggering contours, but they’re also useful for adding percussive movement to continuous parameters like spectre’s frequencies and the energy, tone, timbre trio.

change

Creates an event whenever a voice’s pitch changes.

1. Turn ramp all the way counter clockwise.
2. map change to sustain to trigger the contour only when that voice has a note change.
3. This is particularly fun when a chord is spread, as notes movement might not change all voices at once.

change is polyphonic, but when mapping to a monophonic destination only changes of the root note will trigger an event. This means that changing chord will not trigger events, but moving notes will.

When scale is disabled (unquantized mode), the change modulator is replaced with a set of differentiators. We use this big word to say: the more rapidly you move notes, the larger the modulation signal created.

clock

A steady pulse emitted according to tempo. Every clock pulse creates an event.

See the clock page for much more detailed information!

Limit Modulators

When any knob or slider reaches the extremes of its range (minimum or maximum), a modulation signal is generated. These limit-type modulators are binary in nature — simply on or off. Through most of the range the signal is zero, presenting nothing of import. When the control reaches the selected limit, a full-scale modulation is activated.

These sources are a powerful tool for extending the playability of Atrium. Canonically these signals are used for advancing sequencers, or automatically pressing keys. This doesn't stop them from mapping to continuous controls though, just be mindful of how deeply parameters can be affected by the full-scale signal!

To map a limit-modulator:

• Hold map and move a slider or knob to its minimum or maximum value. The corresponding light will illuminate and the source is selected for mapping.
• You may now release map.
• Select any keys to 'press', and/or adjust destination controls.
• Press map to exit.

Now, bring the newly mapped slider or knob to its extreme to articulate the new mapping.

Limit modulators unlock powerful compositional actions! For example, they can transform sustain slider flicks into a lens -stepping meta-gesture.

Both minimum and maximum limits are independent sources. They can be applied to orthogonal actions, but it's also useful to apply them in tandem. Try mapping energy's limits: 'up' to increase the octave, and 'down' to decrease. Now a single motion controls sonic timbre as well as harmonic range.

Monophonic vs. Polyphonic Parameters

Atrium has two parameter archetypes: monophonic and polyphonic. Monophonic parameters are single-focus, either unifying all voices under their purview or representing a singular function. Polyphonic parameters, on the other hand, hold a value for each voice.

To illustrate the difference: what should happen when we map contour to volume? While each of the five voices have their own contour which reflects their unique enveloped articulations, volume is a final-stage control, operating on a mixed-down stereo signal. As a result, volume can only meaningfully parse one channel of control, and is considered a monophonic destination.

When a polyphonic modulator is mapped to a monophonic destination, the value of the third voice becomes the single channel of control.

So what happens when volume receives a polyphonic signal from contour? Rather than merge all five envelopes into a gurgling mess, Atrium only sends the contour of the central, or third, voice.

Other examples of monophonic parameters:

• tempo, which controls the rate of the clock
• lens, which controls the spectral placement of spectre's filters
• scale, which sets the field of possible note values for all voices

Alternatively, what happens when contour is mapped to a destination like notes? Since these are both polyphonic parameters, we'll hear (and see!) each voice selecting its own new note from the scale along its contour — try hand-playing from the strum touchplate to hear each voice individually arpeggiate as its envelope opens and closes.

Even though the energy meter in the timbral-control section only reflects the third voice, energy / timbre / tone are all polyphonic parameters. Polyphonic modulations to these destinations will be applied to each voice individually.

Pickup Behavior

Since you've been exploring mapping, you may have noticed that after moving knobs and sliders to set modulation depths, some lights have turned on around the interface after exiting mapping. These lights indicate that the physical position of the control has diverged from it's symbolic level.

If the difference between theory (parameter level) and practice (physical level) is small, these lights will be dim, and you can carry-on as normal. The difference between the two states will be reconciled as you next move the knob, and you probably won't notice.

If however this difference is large, you'll see these 'pickup' lights lit brightly. The control will no longer respond to your immediate touch, and you'll need to move the physical control toward the light until the link to the parameter is regained. Often a small nudge will be enough, but you may have to move up to halfway in the extreme case.

When the physical state is fully caught up, the lights will be extinguished.

Pickup behaviour is most notable when loading patches. You can simply ignore these indicators until you need to move that specific parameter.

External Modulation

External modulation is described in full in the On Connections sections for MIDI and Control Voltage.

For now we'll just mention that both control voltage and continuous MIDI sources are distributed through this same mapping system. Everything you've learned above will be equally useful in that extended context.

LFO

A staple in synthesis, the Low Frequency Oscillator (lfo) is a sprite which re-invigorates the player's imagination with new energy. It is both a collaborator waiting in the wings to dutifully carry out a repetitive task and an impish source of instability & uncertainty.

speed

The classic control of any lfo! speed affects the frequency of oscillation from around 10 seconds (0.1Hz) at its minimum, up to low audio rate at its highest intensity (around 100Hz). Grabbing hold of speed as you play a patch will bring pure, simple joy!

If you're unfamiliar with modular synths, the concept of audio rate modulation might be a new addition to your toolkit. Essentially, if our lfo is running fast enough to be heard (the range of human hearing starts at approximately 20Hz), then it can introduce tonal & timbral textures to the modulated parameter that are imperceptible at slower rates / lower frequencies.

This is the point where rhythm becomes pitch!

Example:

• Start with a sine: wave mode, mid-energy, zero timbre
• Set the lfo's speed to its minimum and set its shape to triangle (the third in the sequence)
• Map the lfo to increase energy
• Start increasing speed
• As speed approaches 2:00, you'll hear the changes start to distort into a new waveshape and a new, lower tone is introduced
• Different (en)harmonicities await beyond!

shape

At first-touch, Atrium presents four basic shapes, cycled through by its shape key:

1) Ramp: rises smoothly, before sharply resetting to zero.
2) Sine: a smooth up-and-down path with a natural feel.
3) Triangle: a rigid up-and-down motion.
4) Square: alternates between the high and low state.

These shapes each animate the window at the centre of the phase circle, illustrating the progression of the modulator. You'll also see the light nearest the shape key pulsing in time with the modulation.

Each shape presents a different character and will be useful for many different things. An in-house favourite is using ramp to articulate energy, acting out a dramatic plucking of harmonics.

Beyond these first four shapes, Atrium includes 7 more default shapes:

Learn how to access these in the sequences section.

5) Stepped Random: jumps to a new random value every cycle.
6) Smooth Random: slides to a new random value over the course of each cycle.
7) Crease: similar to Ramp, but resets half-way through the cycle and moves with bipolar motion.
8) Sinc: A trigonometric function that smoothly rises once to full level, then a second time to a lower level.
9) Pulse: Similar to Square, but is "high" for only 1/5th of the cycle.
A) Scanner: Similar to Triangle, but compresses the motion to 2/5ths of the cycle.
B) Bubbles: A jagged series of five rising ramps, each reaching higher than the last.

Many of these, and especially shapes 8 through B, will become very useful when exploring phase below.

phase touchplate

Atrium's psychotopography borrows from many somatic experiences, both within music-making and beyond. The lfo's circular phase touchplate evokes memories of the "scroll wheel" navigator from early-aughts digital devices. Run a finger along it in a clockwise circular motion to separate the cyclical modulators for each voice.

phase pushes out four voices, while it's centre channel remains static. This phasing moves from a gentle sequential strumming, to equidistant five-note arpeggios, and far beyond. As you continue to scroll the voices will overlap and pass through one another. All kinds of irregular rhythms, as well as interference cancellations will occur along the way. At the maximum the voices will realign, but with the voice order reversed.

• Scroll phase to its minimum (counter clockwise) to unify modulation across all voices.
• Increase phase clockwise to offset the modulation among the voices.
• Hold clear and tap phase to set to halfway, creating two distinct groups: voices 1/3/5 and voices 2/4.

When lfo is mapped to a monophonic destination, only the centre channel is used. This is the static voice that remains unaffected by phase, furthering the idea that phase is our interface into polyphony for the lfo.

Clock

Alongside all of its lilting gestures and invitations for direct in-the-moment touch, Atrium holds a simple, reliable sense of metronomic time.

Usage

Control the clock rate, and its cute little metronome, with the tempo knob. The range swings from 40bpm up to 640bpm. There's a small region at the counter-clockwise end where the clock is stopped entirely.

Note the line on the panel, to the left of tempo. If you can see the inner line, you're in the "deadzone", which freezes the clock.

Without any existing mappings, Atrium's clock has two purposes:

1. Control recording & playback speed of gestures.
2. Drive the arpeggiator embedded in the Scale Editor.

Beyond this, there are no pre-determined routings — it's up to the player to decide! To help kickstart your imagination, some favourite maps include:

• Plucking sustain while cycling through drone snapshots
• Advancing sequences like lens, or toggling loop
• Adding bursts of binary modulation jumps to the timbral controls

And, of course, the clock can be mapped to another modulation source. Control loops (eg. mapping clock to lens while freqs increases tempo in return) can yield predictably unpredictable results. However, since the clock is a core component of gesture's playback, changes to tempo are not currently able to be recorded as part of a gesture.

The clock can be overriden, or exported, via MIDI which is described in the dedicated MIDI section.

tap-tempo

To set the tempo by feel, you can tap the tap key next to the tempo knob. Four consecutive taps with a roughly consistent tempo will set a new BPM.

Once tap-tempo has taken over, the tempo knob will shift to control divisions and multiplications of the tapped tempo. You'll see both lights at the tempo edges illuminate to indicate you've arrived. The ratios, counter-clockwise (slower) to clockwise (faster), are:

• 1/4
• 1/3
• 1/2
• 2/3
• 1 (at noon)
• 3/2
• 2
• 3
• 4

The lights at tempo's limits will shift their balance left-to-right as you select different ratios. While hard to read in the absolute, they will give you a sense of the range, and each step is visible as you rotate.

To clear tap-tempo, hold clear and press the tap key. This will return you to the normal tempo state which may have changed dramatically if you altered the clock ratio!

Sequences

Across Atrium’s interface, you’ll find displays with light-glyphs consisting of 11 individual segments:

These indicate sequences, which can hold up to 11 steps of state information for their associated parameter. They are found near scale, shape, lens and drone. Tapping the key near these parameters selects a new set of data, which is why we refer to these keys as sequencers. sequences will wrap after the sequencer reaches its last stage.

In Atrium sequences all operate on complex data. Each stage contains a list of values too complex to perform in a live manner. These tiny systems enable us to expand the capabilities of the instrument, while asking the player to manage only a simple "next" gesture.

By default, each sequence is clamped by a small range, so as not to overwhelm with possibility. As you orient to Atrium’s system, you may desire more states to bounce between. Perhaps you want only a subset of those possibilities — there is significant joy to be uncovered in simply toggling between two meaningful states.

Refining & Extending sequences

To change the length of any of the sequences:

All sequences contain one to eleven steps.

• Hold alt and press the sequencer key corresponding to any of the above-mentioned sequences. Each of the available options will be illuminated with a cross.
• The extension display will now show an E, indicating that we are editing the selected sequence's bounds.
• The selected sequencer will display the length of the sequence.
• Press the octave keys to adjust the length of the sequence up or down.
• Press alt to exit.

This is only half the story, though it is the most common usage. You can change the length of the sequence, as well as the start point. Thus we can begin counting from 2 or 3, not always 1. Furthermore, the value we edited above is not in fact the length, but rather it is the last stage of the sequence. Increasing the start will shorten the length!

• Hold alt and press the sequencer you wish to edit.
• Press the sequencer key again to toggle between start and last stage.
• Note the lights beside the octave keys flip as you press the sequencer, indicating start (down) or last (up).
• Press alt to exit.

The start and last stages may be set to the same value, and these values will not be allowed to cross.

When editing sequences, you can edit multiple different elements by pressing another sequencer key.

Hexadecimal

The keen eye might notice that we can only display the numbers 0-9 on these small displays. As such we lean on the hexadecimal system to count the numbers 10 (A) and 11 (B). There's no greater meaning here, just a solution to a problem!

Scales

Scales are very fluid on Atrium, supporting different tuning systems such as twelve-tone equal temperament (12-TET), Just Intonation, and microtonal adjustments between values. While a scale can be defined traditionally as a list of ascending pitches, Atrium is equally comfortable with electronic / computer music traditions by using scales to hold sequences of pitch.

Template Scales

Atrium's template patch contains a collection of scales for your initial explorations.

• Press scale to advance forward through the list of scales.

The template will cycle through just four chords. Explore each one with notes and chord before advancing. A harmonic sequence will unfold leaving space for you to stitch together each tonality.

When you're ready to explore further afield, extend the sequence! The pre-defined scales are:

1. C major
2. A dorian
3. D diminished lydian (roughly)
4. G dorian (with C in the bass)
5. C diminished 6th
6. C major pentatonic (over a C bass pedal)
7. C major scale in 5-limit just intonation
8. Sama Gana in C
9. C lydian arpeggio (over two octaves)
10. Bb major 7th arpeggio (with detune)
11. C major 7th arpeggio (with detune)

Quite an assortment! Don't fear the academic names though (I had to look them up in many cases), just sweep around notes and hear the different tonalities and effects embedded within.

While we're here, pay special mind to scale 6 which bounces back to the root note between every ascending scale tone. If this scale is selected & chord is spread out, you'll still hear the tonality of the scale, but the sound will be deeply rooted to the fundamental C pedal tone.

Scales 7 and 8 are a demonstration of Atrium's microtonal tuning, where scale tones are adjusted in pitch to create more deliberate consonances and dissonances.

Scale 9 shows how scale tones can go outside of the one-octave range. As you move notes you'll hear the arpeggio reset at each octave.

Scales 10 and 11 have many copies of each scale tone, each subtly detuned from the rest. As such, a simple 4-note arpeggio becomes far more interesting. Try adding just a little chord spread to hear the detune flow across the voices.

The Scale Editor

While the above scales are fun, they're also somewhat esoteric! A good time now then, to define your own:

• Double-tap the alt key at the top-right of the instrument. Notice the message of encouragement on the panel: tap! tap!
• A broken S will appear in the extension window.

With a "tap! tap!", the notes & gestures sections of the interface will change, indicating that you are in the scale editor. In this mode, the hardware and interface work a bit differently, providing a different perspective on pitches:

• The gesture controls navigate the scale
• notes and the controls adjacent are used to define a single tone in your scale.
• scale allows global control of all notes in a scale

While the Scale Editor is active, the remainder of Atrium continues to function as normal! Continue to play with the timbral controls, and shape your contours while editing. This helps keep editing fun, and opens up performative options.

Press alt at any time to exit the Scale Editor.

Navigating

The linear gesture display (above the keys) will show a preview of your scale - One light per scale tone. The currently focused note will be brightly lit.

• press beat to move focus right by one.
• press step to move focus left by one.
• Focus will wrap to the other end if we move past the maximum or minimum.

As you move focus, the newly selected note will be heard on all five voices.

Train your muscle memory here a little. Resting your middle-finger on len is the intended technique (you'll need that key shortly), which should make the 'left' and 'right' movement feel more natural.

Editing Notes

After you've found a note you want to change (perhaps a major 3rd should become minor), leave it focused and try out these options:

• Move notes up and down to adjust the current value in semitones from its current position.
• Press octave up and down to add and subtract semitones manually.
• Hold glide and move notes to set the value to the absolute position of notes.
• Touch voicing to add microtonal offset to the value.

To remove any microtonal adjustment, hold clear and press voicing.

The notes display will give you context for what exactly you're editing. The brightly lit note is being modified presently, while the dimmer notes illustrate all selected tones in the scale.

Adding Notes

To extend your scale, by adding a note:

• hold len and press beat.

You'll see the gesture light-meter extend one light to the right. New notes are always added to the end of your scale, and will default to the note C.

Conversely, shorten your scale by removing a note:

• hold len and press step.

The note to be removed is always the last note in the scale.

Each scale supports from 1 to 25 notes.

Transpose a Scale

So far we've just edited single notes, but you can easily adjust the entire scale at once.

Press scale and notice the pulsing lights that appear on either side of the selected scale number. When you see these lights, you are editing all steps simultaneously. Try transposing the scale by pressing octave up a few times.

Toggle this whole-scale editing off by pressing scale again.

Arpeggiator

While editing a scale, you may find yourself wanting to hear the focused note in context of the full scale. Sometimes it's hard to know exactly which pitch you're after without also stepping through the rest of the scale.

To automate this movement, press the black gesture key and a clock-synced arpeggiator will be activated. Try turning the tempo knob as it plays!

While the arpeggiator is running, you'll see the playhead advance in the gesture display (indicated by a solid light). Meanwhile the focused note (the one you're editing) will stay in place and its light will pulse gently.

Toggle the arpeggiator on and off by pressing the black gesture key, or simply exit the scale editor by pressing the alt key.

scan modifier

Stepping back from the precise editing of the above, we can opt for a more dynamic and playful style of editing using the scan modifier.

• Press scan to toggle on the coupled mode.

Now the focus will also follow the playhead of the arpeggiator.

Experiment with adjusting notes as they cycle through the arpeggiator, or add some dynamic wiggles by moving notes. For the adventurous, try holding glide to "draw" in a scale shape as it plays. Many fortuitous accidents await — luck is the residue of design!

If you find something that's almost right, it's often helpful to disable scan and perform your finishing touches with a more methodical approach.

Performing

This bit's important!

In the Scale Editor, the remainder of Atrium's parameters remain accessible as normal. Additionally, chord remains active, while being extended somewhat:

• Hold chord and move notes to spread the chord.
• Hold chord and press glide to enable portamento.
• Hold chord and press the octave keys to transpose the sound (but not the scale).
• Hold chord and press scale to select the next scale for editing.

In particular, notice how adding some chord spread is an another tool to hear your scale tones in context, while editing.

All combined, the Scale Editor provides much more than simple data management — it’s a fully-featured performance interface! Keep in mind that any existing mappings will continue to be applied while editing. This can be confusing, but also rewarding.

When you're done:

• Press alt to exit the Scale Editor.

The arpeggiator is turned off, the chord spread is disabled, and notes returns to wherever it was set before entry.

If you've found a great sound that you want to carry with you outside the Scale Editor, you can exit by:

• Holding chord, press alt to exit, and latch current settings.

Get Unquantized

To disable scale quantization altogether, hold clear and press scale. Now notes will freely articulate pitch through all the microtonal in-betweens. Pressing the octave keys still jumps down or up from the current value.

Try holding chord and spreading a microtonal chord. Applied subtly, each of the five voices receives a slight shift in pitch, creating a classic detuned sound that increases the perceived ‘massiveness’ of the instrument.

The notes slider provides about 13 cents of granularity. For more precise microtonal settings, it's best to configure custom scales.

Clusters

As you explore notes, voicings, chord shapes, and octave manipulations, you may find a few you’d like to confidently land on in a performance. clusters will help here; they store snapshots of the current state of pitch information.

Up to five configurations of these pitch-centric parameters can be captured, and instantly recalled.

The interface again uses the gesture region, and is thus unavailable from within the Scale Editor.

Navigating clusters

• To store a cluster, hold chord and press an unlit gesture key.

Storing a cluster captures the current state of:

• notes
• chord
• octave
• voicing

Recalling a stored cluster uses the same physical gesture:

• Hold chord and press a lit gesture key.

• To erase a stored cluster, hold chord, then also hold clear and press a lit gesture key.

Further details

clusters are saved & loaded with patches.

clusters are a powerful tool for setting tonal waypoints within Atrium's landscape. Notice that your current scale selection is not part of their scope! This is by design. Decoupling clusters from scales creates opportunities to describe the general shape of a chord. This shape can be recontextualized by cycling through the scale it voices. Think of them as directions of travel, rather than a strict 'score'.

ON CONNECTIONS

On Connections

Atrium is a fantastic canvas for solo exploration, but also plays well with a wide range of other devices. It features a full toolkit of hardware connections on the rear panel, unlocking many modes of external control and communication. See Connectivity for more-robust details on these connections.

Topics:

• MIDI: Sending and receiving MIDI messages to devices and computers.
• Control Voltage: Receiving control voltage (CV) signals into Atrium's mapping network.

MIDI

External MIDI devices can be integrated into Atrium’s mapping system, providing remote control over its parameters or tagalong buddies in clocked step.

Getting connected

Atrium has three hardware options for sending & receiving MIDI messages:

• USB-A port: Connect an external controller via the USB-A port on the rear panel. Use your favorite knob box, MIDI keyboard, or sequencer! Up to 900mA of power is provided -- enough for most controllers.

• USB-C port: Atrium will appear as a MIDI device (named "Atrium") on a connected computer. Exchange messages with your favourite DAW or other MIDI-enabled environment.

• TRS-MIDI: Hardware MIDI devices can connect over TRS-MIDI via the midi in and midi out 3.5mm jacks (on the rear panel). midi in automatically accepts either type A or type B connections. midi out uses the more common type A pinout. If your device uses 5-pin DIN cables, you'll need adaptors.

When powering Atrium from a computer's USB port, the MIDI connection is available over this same cable. Otherwise, attach a cable to the computer port to communicate.

MIDI Input

Available are a few different classes of MIDI messages, as well as different workflows. Each set has it's own implications for use: note takeover dramatically changes the impact of Atrium's controls, while clock and CC input are a more natural fit into the map-centric workflow.

Notes

To treat Atrium as a more traditional "desktop synthesizer", you'll want to enable note control. This modal setting will take over note allocation, and sustain articulation.

Enter the MIDI input settings:

• Press midi.

You'll see the interface go blank, apart from an X in the scale window & a dimly lit metronome.

Make sure to experiment with glide with MIDI, it's super fun.

• Press scale to cycle through the voice allocation options:
• X means no "takeover" is performed (this is the normal state).
• P stands for "polyphonic", accepting MIDI messages to dynamically allocate pitches & articulate them with sustain.
• U switches to "unison" mode, where all five voices are addressed by the most recent MIDI note.

Once you've selected your note allocation style, press midi to return to normal usage.

You'll notice a few things have changed:

• notes and chord are disabled.
• Playing notes on the keyboard will update the notes display.
• sustain will be opened according to the velocity of your played notes.
• scale will be blank, indicating "unquantized" mode.

But many things have not changed, and that's great! You can move around octaves, add glide to your notes, and even adjust voicing (in the downward direction) for some surprising voice spreading. Existing mappings to note and chord will still apply which can be quite confusing if you're not sure what's going on.

Map the tiniest amount of lfo to notes and spread out the voices with phase (sine is a great shape to start with). With polyphonic play you'll get that vintage warble, while unison becomes a massive drifting swarm. Add some glide and you'll be in bassline heaven.

While scale is disabled when entering a MIDI note mode, you can re-enable quantization by tapping scale. This can be helpful to stay in key, or provide a new interface into a "sequence" style scale.

Mapping Sources

Above the midi key you'll see three icons. From left-to-right these represent:

• Mod Wheel
• Pitch Bend
• Aftertouch

When an attached MIDI device sends these messages, they are automatically exposed here, ready for mapping.

• Hold map and press midi to select these MIDI sources.
• Tap midi to cycle through the three options.
• Each source can be applied as a mapping, just like a normal map source.
• Press map to exit.

Map a little Pitch Bend to notes for traditional effects. The depth of the mapping affects the range of bend. The bend will be heard while mapping, so you can play the keyboard and notes slider simultaneously to find the right depth.

Try assigning your pitch wheel elsewhere!

CCs

Beyond these dedicated mapping sources, MIDI CC messages are also freely assignable. To achieve this, Atrium uses "MIDI learn" to create these assignments.

While this occurs outside the formal mapping system, the process is nearly identical, only differing in the method of source selection (ie. selecting a CC number):

• Press learn to listen for MIDI CC messages. The cc light will pulse.
• On your controller, move the knob/slider you will use to control Atrium. The cc light will illuminate solidly & this CC is selected as the source.
• Move Atrium's controls to define the depth of modulation for this CC. The learned icon will light (three arrows pointing outward).
• To assign a different CC, simply move the next knob/slider to be mapped.
• As you send different CCs, the learned icon will indicate whether this CC has any existing mappings.
• Press learn again to exit.

As you're learning CCs, any changes you make to the hardware controller will be immediately applied. This allows you to audition the full range of the mapping while configuring it. Use this feature to interactively find the right depth for your learnings.

Through MIDI learn, we're able to create types of macro controls that are otherwise not possible on Atrium itself. Consider learning a single CC to increase speed while decreasing tempo. Now your MIDI controller will increase the speed of some modulations, while decreasing others!

Clock

Atrium can receive MIDI clock via any input that's sending a clock signal. When enabled, the MIDI clock will override Atrium's internal clock:

• Press midi to enter the MIDI input settings.
• Press tap to toggle receiving MIDI clock. You'll see the metronome LED animation engage when enabled.
• Press midi to exit.

Now Atrium's tempo knob acts as a clock multiplier/divider, with these divisions:

• 1/4
• 1/3
• 1/2
• 2/3
• 1 (at noon)
• 1.5
• 2
• 3
• 4

MIDI clock input expects standard 24ppqn timing signals. Other timings will further multiply the range, though should remain musically relevant.

MIDI Clock Output

Atrium's MIDI output specification is still in its infancy. Presently only clock is supported, though this will change in future.

Clock

Share Atrium's clock via MIDI, through any (or all) of the ports:

• Hold alt & press midi to select the MIDI output settings.
• The extension window roughly displays an M for MIDI.
• Press tap to enable clock output. The metronome will pulse.
• Press alt to exit.

By default, Atrium will send its clock signal to all of the outgoing ports. To choose only a specific output destination:

• Hold alt & press midi to select the MIDI output settings.
• Press midi to cycle through the destination options.
• Press alt to exit.

Each destination has an associated light, and by default they will all be on:

• USB-A port: lights controller (piano keyboard icon).
• USB-C port: lights computer (laptop icon).
• TRS port: lights the midi key's window.

Control Voltage

While the Whimsical Raps catalogue is historically rooted in our Mannequins offerings, we're sometimes self-conscious about noting the conceptual overlaps between Atrium and modular synths. And yet! As Atrium ventures into uncharted territory, proving the strengths of its own perspective & versatility, we know first-hand the joys of integrating tools one is already familiar with into a new environment.

So, with excitement for the conversations Atrium can have with a larger ecosystem of voltage-controlled sources, we've added three 3.5mm inputs for integrating control voltage (CV) into Atrium's lexicon. These inputs are located on the rear of the instrument, next to the audio outputs; demarcated on the panel with three grey triangles pointing inward. Through these ports, any CV source can be brought into the landscape of Atrium's modulation network.

The CV inputs respond to a +/-5V range. Signals up to +/-12V are safe to use.

Integration into Atrium is straightforward! Each input is simply a new source of mapping.

Map a CV input:

• Hold map and press cv to the left. Input a will be focused.
• Change focus among the three inputs (a, b, and c) by pressing the cv key.
• The focused signal will be indicated above cv, the light brightening according to the received voltage.
• Move the panel controls to dial-in mappings from the focused input.
• Press map to exit.

While it is safe to send signals outside of Atrium's expected range (+/- 5V), any signal outside this range will simply be clamped.

The CV inputs are bipolar, meaning they accept both negative and positive voltages. If you’ve performed a cv mapping and you invert the polarity of the incoming signal, its affect on the mapped parameters will also be inverted. eg: If you’ve mapped a cv source to increase timbre, sending a negative voltage will actually decrease the parameter.

AFTERWARD

Farewell

Phew.

Many words, and somehow not enough? We will continue to update this document as we go, as things change, and as we learn from you how Atrium thrives in your hands & home.

If ever you need us, please reach out: service@whimsicalraps.com

We'd love to see what you make with Atrium. Truly. Over the past few years Atrium has been like an imaginary friend; it has been real, but only inside of whatever room we were also in. We'd love to be surprised — made aghast, even — at how you navigate its surface and systems. Please share your findings with us (and a few close friends) on the Whimsical Maps Discord server.

Of course, our further discoveries will be shared too, at atrium.whimsicalraps.com

Much gratitude is due to Jeffy Branion for his sharp editing eye & keen sense of language.

Thank you, endlessly.

<3,
Whimsical Raps

Credits & Thanks

Trent here. Firstly, huge thanks to Dani Derks who co-wrote this manual, and was a fantastic sounding board throughout Atrium's development from the small to the large. To all the Whimsical Rats: Manami, Eric, Souha - a million thank yous for helping to keep the business running while I was lost in Atrium land (and your help on the project too).

So many wonderful people have helped this project along, but a few special shoutouts. Brian Crabtree for inspiration and reflection throughout the years. Meng Qi for helping me learn to celebrate the unusual, and your undying enthusiasm. Václav Peloušek for always asking the probing questions, searching for the limit of how far we can push an idea. Didi Michel for the friendship, teaching me how great it feels to work with others, and the "Whimsical Raps" name.

And to my loving partner Taylor who always listens to my harebrained ideas, and understands whenever I would vanish into a development spiral.

Trent.

Technical Specifications

• Voices
  • 5x analog oscillators with waveshaping
  • 3 timbre modes: suboctaves + noise, frequency modulation, formant synthesis
  • 5x lowpass/gates: 3 modes (amp+filter, filter, resonant filter)
• Spectre — resonant tone shaper
  • 3x analog bandpass filters
  • 2x BBD delays in feedback loop
  • embedded sequencer
• Variable highpass filter (6dB)
• Gesture Recording
  • 5x recorders
  • multiple parameters per recording
  • record any interaction
  • optionally quantize length and playback start/stop
  • step-wise or continuous playback
  • open ended recording duration
  • timing can be linked between recorders
  • variable playback rate (via Clock speed)
• Modulation
  • map any modulation source to any parameter
  • mappings have continuous depth & polarity
  • no limit on number of mappings
    • Clock: continuous time or tap-tempo (with musical division/multiplication)
    • LFO: polyphonic, 11 default shapes, phase-offset between voices
    • Contour: polyphonic envelope, loopable, timing of individual voices can be stretched
    • 6x additional sources, generated from synthesizer state
    • external sources from MIDI and CV input
• Patch storage
  • 5x onboard patch slots
  • instant recallability
  • patch management with software companion
• Hardware
  • MIDI in (3.5mm), accepts type A and B
  • MIDI out (3.5mm), type A
  • 3x CV inputs (3.5mm, +/-5V range, protected to +/-12V)
  • stereo output (3.5mm)
    • dual mono (left/right)
    • headphones / stereo TRS (left)
    • mono mix (right)
  • USB-C power: 5V, 3A
  • USB-A host: connect MIDI or serial devices (keyboards, controllers). provides up to 900mA power
  • USB-C device: MIDI & serial (DAWs & other software)
• Physical
  • polycarbonate & aluminium enclosure
  • mechanical keyswitches
  • capactive multi-touch plates
  • 11.25” x 8.75” x 1 7/8”, 2lb 5oz
  • 286 x 222 x 48 mm, 1.06kg
• 3 year warranty