A member of the metamusic series, the Husserl metasequencer is a polyphonic step sequencer with 16 intermodulating sequencer channels. This section introduces Husserl 1.0's architecture, environment, and presets.

Sequencer Types

Each of the 16 sequencers can play interactively in four main modes (clock, step, layer, and fugue), as described below.

Clocked Sequencers

In clock mode, all sequencers divide down the main clock by their individual tempos, so they can advance to the next step in their patterns at different times. All sequencers can also modulate each other. In the following example, two sequencer channels are in loop mode. The two loops are clocked and synchronous on the left. On the right, the loops have different tempos, and the second also has shuffle. When channel 2 modulates channel 1's pitch, then channel 2's pitch is sampled on each of channel 1's clock edges and added to channel 1's pitch at its output. The diagram shows the resulting pitch waveforms.

Husserl: Channel 2 Modulates Channel 1 Pitch
Husserl: Channel 2 Modulates Channel 1 Pitch

When sequencer patterns advance to their next step at exactly the same time, then all sequencers can pick up modulations from all others in exactly the same cycle. If the patterns advance at different times, then a channel that is being modulated samples the value from the modulation source each time it advances. So in the right-hand diagram above, the second sequencer changes pitch a couple of times without affecting the pitch from the first sequencer. Nonetheless, when the two sequencers advance on the clock cycle, the first sequencer still receives pitch modulation from the second.

Stepped Sequencers

When in step mode, MIDI or other sequencers act as trigger sources , advancing the stepped sequencer's pattern by one step at each trigger.

In the following example, two clocked channels at different rates trigger notes on a third stepped channel (without any pitch, velocity or duration modulation). The trigger sources have different durations, but the stepped channel has its own note duration. The diagram illustrates the note output. For simplicity, the notes are shown with equal durations that do not overlap, but any pattern step, in any mode, can have a different note duration that may overlap with subsequent notes.

Husserl: Two Channels Trigger a Stepped Channel
Husserl: Two Channels Trigger a Stepped Channel

In the above example, the triggers from sequencers 1 and 2 coincide exactly with each other on several clock cycles. The third, stepped channel can either trigger just once on the coinciding triggers, or advance twice, playing two pattern steps in the same clock cycle (indicated by a shaded area in the above example). Of course, the stepped sequencer may also change its own velocity on each pattern step, but the above example shows equal velocities at each step, for simplicity.

Layered Sequencers

In layer mode, MIDI or other sequencers gate a clocked sequence pattern.

In the following example, two channels are offset by an octave from each other and gate a third. The diagram shows the gate for the first two sequencers, and the pitch for the third channel. The gated channel, running at a different tempo, plays a clocked loop, also receiving pitch modulation from the two trigger sources. When the trigger sources overlap, it layers two notes on its output, exactly an octave apart, in each of its clock cycles.

Husserl: Two Channels Gate a Layered Channel
Husserl: Two Channels Gate a Layered Channel

The layered channel could also apply its own pitch, duration, and velocity to each note it generates, but the example shows it with equal values for simplicity.

Fugued Sequencers

In fugue mode, MIDI or other sequencers trigger a pattern which then plays by itself to its end, at its own clocked rate. Additional triggers play another

In the following example, two channels trigger a fugued channel. The diagram shows the gate of the trigger sources and the pitch of the fugue channel. On each rising edge of the gate, the fugue creates a new set of notes, and the last two fugues overlap with each other.

Husserl: Two Channels Trigger a Fugue
Husserl: Two Channels Trigger a Fugue

All sequencer channels have an additional option to reset to the pattern beginning on any trigger. In fugue mode, such resets cause the current pattern to stop playing and restart from its beginning.

Recursive Modulation

A note which is triggered on one channel by one sequencer, then modulated by other sequencers, can recursively modulate the trigger and modulation channels, then synchronously output triggered and trigger notes in the same clock cycle.

Typically, with all the modulation available, even two or three channels alone can produce a complex, evolving melody. It takes less than a minute to draw up a complete new pattern that can play without repeating itself for minutes, or even hours. Melodies can be recorded onto an empty channel and played at the same time, so the instrument is capable of making its own evolving musical patterns.

More Possibilities

Husserl 1.0 provides a number of additional functions for each sequencer channel:

  • Each sequencer can filter, clip, mirror, transform, and scale pitch and/or velocity (optionally on particular pattern steps) on input triggers and modulations, or on output notes.
  • Each pattern sequencer has a dedicated bar sequencer which can change the pattern sequence each bar cycle, providing up to 2,048 pattern steps.
  • Each sequencer can trigger automatic snapshot change after a settable number of pattern cycles.
  • Each sequencer can record notes from MIDI and any number of other sequencers, simultaneously playing back the resulting pattern in a different tempo.
  • Each sequencer can output pitch bend, aftertouch, and MIDI controller values with adjustable smoothing rates. Each sequencer supports preset and custom pitch remapping to 38 different scales on output and modulation values.

See the A panelset reference for more information.

I/O Options

Any sequencer channel can send its notes to any MIDI output. Internally, 33 separate voice allocators support up to 512 voices and 512 modulations in parallel. The number of voices and sustain mode is settable for each MIDI output separately. Four MIDI outputs may also be set to send different notes and controller modulations to up to four other instruments inside Reaktor.

See the B panelset reference for more information.

Demo Synths

The Husserl ensemble contains some demonstration synths to show what the instrument can do. All the applicable instrument controls are set up as automation parameters and receive terminals for sequencer modulations.


This design is a feature-enhanced version of the Soundforum Synthesizer from Native Instruments. The instrument contains some additional modulation controls and a CPU-optimized version of the 6REV reverb unit. The panel is also optimized to reduce its consumption of screen real estate, while providing complete access to all its controls.

analog synths
analog synths


The same as Analog, with some output-stage additions: a monophonic input with EQ, limiting, and ducking (the volume of the synthesizer reduces when there is an audible signal on Reaktor's audio inputs).


There is also a demo drums unit in Husserl. In the single-output version of Husserl, the drums synth is on the demo synth's B panel. In the multi-output of Husserl, there are two analog instruments and an additional, separate drums instrument. Each of the demo instruments are connected up to a separate send channel from the Husserl instrument. The drums instrument contains CPU-optimized versions of the basic drums units that were originally included with Reaktor 3.

drum synths
drum synths

The drums instrument also includes its own separate reverb unit. Separate reverb from notes and drums provides a clearer sound (ideally there would be a separate reverb for each drum, but this is just a simple demo unit). The drums instrument additionally provides for waveform samples that can replace the synthesized sounds for a number of the drum sounds.

In the drum machine, each of the drum units may be triggered by a single note in a 1-octave range. The octave in which notes are triggered is user selectable, via the octave dial in the instrument's top left corner.

The notes are mapped to standard General MIDI drum note assignments for the instrument types, as follows:

Drum Notes

Note Drum Sound


Bass drum


Sub Kick


Rim Shot




Snare (Gated)


Tom 1 (Low)


Hat 1 (Closed)


Tom 1 (High)


Hat 1 (Open)


Tom 2 (Low)


Hat 2 (Gated)


Tom 2 (Low)

Demo Snaps

The ensemble also includes 150 demo and tutorial snapshots and 8 user banks, with 2 analog-emulation synthesizers and a multimode synth/sampler drum machine.

Architecture Details

Internally, the channels actually process data for each clock cycle in a series of phases. The following diagram illustrates the Husserl structure at a high level.

Sequencer Channel Architecture:

Husserl: Sequencer Channel Architecture
Husserl: Sequencer Channel Architecture

The easiest way to understand this is to consider an example.

Dataflow Example

Here is how Husserl handles a snapshot configuration where the clock triggers channel 1, and notes from channel 1 trigger channel 2.

  1. Upon receiving a clock pulse, channel 1 divides it down and if it's time, advances the beat filter. If the beat filter step is on, the pattern advances. At the end of the pattern, the bar sequence may also advance. The trigger then passes through the matrix to channel 2.
  2. The second channel performs the same activities to generate modulations, which are then passed to all other channels, including the one that triggered it. So for example, pitch values from channel 2 can change channel 1 in the same step, even though channel 1 actually triggered channel 2.
  3. When all triggers have completed processing, each channel adds up the modulations it has received from other channels. Then, and only after that, the notes from all triggers in the clock phase are output, all at the same time.
  4. The notes then pass into separate voice allocators: one for the on-screen display, 16 for the 16 MIDI output channels, and 4 for other instruments in the Reaktor ensemble. Each voice allocator maintains its own polyphony, with solo and mute applied across all 20 instrument outputs.

There are many other possibilities. MIDI can also trigger channels, as well as the clock. Triggered channels can themselves trigger other channels too. For example, low MIDI notes could step channel 2, which trigger channels 3, 4 and 5. High MIDI notes could trigger channel 6, which itself triggers channels 7, 8 and 9. Thus the combined channels can provide complex rhythmic and melodic responses for real-time performance.

Intermodulation Details

Perhaps the most unique facet of Husserl is its built-in intermodulation. The design is intuitive and flexible; generally, when you set a modulation, it occurs where you expect. Conversely, if you don't want a modulation, you can stop it from happening. For example, Husserl separates triggers and gates from pitch, velocity, and duration information. If you want one sequencer to trigger another, but not change the note pitch, you can leave the pitch modulation off. If you want a sequence to modulate another's pitch, but not trigger it, you can set the pitch modulation without a trigger. And if you want a note to modulate the note which triggered it, you can do that too.

In Husserl, pattern steps can do more than simply trigger or gate another pattern step. Multiple patterns can also gate a clocked sequence polyphonically, or trigger entire fugues of chords running concurrently. Simultaneously, patterns can modulate each other without triggering them. To do so, Husserl internally handles notes from modulation and trigger sources differently, while providing a consistent and simple interface for both.

For example, if a trigger starts a fugue, and it also modulates the fugue's pitch, then all the notes in the fugue are transposed by the trigger note's pitch, but not by other notes from the same sequencer. Other notes from the same trigger source start other fugues, which are transposed separately. So, if the trigger sequence is C3, C4, C5, then triggers start consecutive fugues that differ in pitch from the previous one by an octave, and the single-octave transposition remains for all notes in the entire length of each fugue separately, even if the fugues overlap.

At the same time, other sequencers can modulate the fugue pitch but not trigger the fugue itself. In that case, the fugue sequencer samples the pitch from the modulation source each time a note plays, in every single sequence. It then applies that transposition to all fugue notes, no matter when or who triggered them, until it receives a different pitch from the modulation source. Now in writing, that is quite difficult to explain, and probably difficult to understand. But when the result is heard, it sounds intuitively correct.

In terms of musical control, a matrix of over 1,000 pins interconnects 16 sequencers. But each sequencer's panel contains just its own trigger and modulation sources, keeping the interface simple; and in the global panels, all the interconnections are accessible on one unified view, with lights to indicate trigger firings. So the complexity is contained, but totally accessible.

Intermodulation can occur not only in fugues, but also in polyphonic layered and stepped sequences, in exactly the same way. If pitch modulation is not turned on, then the trigger source advances the step or gates the layer, but the trigger's pitch does not affect the step or layer pitch. If pitch modulation is turned on for the trigger source, then the trigger source's pitch applies to that step, or to that layer, but not to other steps or layers from the same sequencer. However, if a third sequencer is modulating pitch, but not triggering the step or layer, then the third sequencer's pitch affects all notes on the triggered step or layer until the third sequencer changes pitch, or the modulation is deactivated.

And just so, as for pitch modulation, so also for velocity and duration modulation. Husserl contains complex logic to distinguish multiple modulations from different sequencer sources, and depending on whether they are triggers or not, handles the modulations differently. But the end result is an intuitive sound, exactly as one expects, within a single, simple, unified, and prebuilt interface.

Reflective Modulation

Modular designers are well familiar with timing and synchronization problems. In Husserl, the modularity is built in, so the most complex timing and synchronization is already pre-assembled for you. With the embedded modulation matrix architecture, all notes can modulate all others--even notes which triggered them--which is a very difficult level of synchronization to achieve, even with dedicated hardware.

In the above example for instance, a fugue can modulate the pitch of the sequence which triggered it, while simultaneously being modulated by other sequences. By varying the tempo and timing of the fugue and other sequences, and muting a few modulation sources, this creates rich melodies which sound deep, yet not random. Our ears pick out the hidden ordered relationships between the notes, but obscured by unknown layers of patterns, we are uncertain exactly what the relationship actually is. The effect is independent of music genre--the melody can be in a rock beat, or in a slow ambience, or in a jazz piece, or in the slow movement of classical strings, or in a fast paced electronica trancescape, and the same fascination results. With just three or four sequences, Husserl mysteriously makes its own melodies to enchant composers, musicians, and audience alike. And there are 16 sequencers, and many other ways to massage the sound.

User Interface

To provide rapid access to any panel control with just a few clicks, Husserl has two panelsets, arranged as A and B panels.

The panels provide different views in different slices. The A view integrates all the controls for each sequencer channel in one simple panel. The B view contains cross-sections of specific functions across all sequencers: snap data, modulation matrices, I/O configuration, and pitch maps.

Later sections describe the panelsets in detail.

The Environment

Reaktor can operate in standalone mode, or embedded within another application as a VST or AU instrument. Here are some notes on configuring Reaktor: For more information, see the Reaktor documentation and the Native Instruments Website at http://www.native-instruments.com .

Standalone Operation

When you launch Reaktor as a standalone application, you can connect it to hardware and software synthesizers with MIDI. Often electronic music setups have dedicated ports for each hardware device. If this is the case, you can use a MIDI patchbay to restrict channels to particular ports. For Windows, the most common is Midi Ox from http://www.midiox.com . For Macintosh, see the patchbay at http://notahat.com .

If you are connecting another synth that expects input on a MIDI port, you may also need a MIDI virtual cable on Windows. The traditional Hubi's loopback device is now superseded by Midiyoke, also available from http://www.midiox.com .

VST Operation

In VST Mode, Reaktor is dependent on support from the VST host as to handling MIDI Multichannel MIDI I/O has been found to function correctly on Cubase, EnergyXT, and Bidule.

Ableton Live

VST is functional on Ableton Live, but Live only supports capture of one MIDI channel. To do so, configure a MIDI track over the track containing the Reaktor VST. The following diagram illustrates the connection.

An alternative in the Live environment is to install Bidule as a VST client inside Live, then open Reaktor as a VST client inside Bidule. Bidule supports multichannel MIDI I/O, so instruments can be put inside Bidule for VST automation there.

Ableton Live MIDI Settings

Ableton Live MIDI Settings
Ableton Live MIDI Settings

AU Operation

The AU standard does not permit AU clients to transmit MIDI to their host. It is theoretically possible to send MIDI data to a knob in a Reaktor client, then record its automation in Logic, but the configuration to convert the automation data to MIDI notes is more complex than warrants this approach.

If your host sequencer only supports AU mode (such as Logic) then MIDI connection is directly possible only through Reaktor in standalone mode. Typically it is best to make Logic a slave to the Reaktor clock and run from the instrument clock, in this configuration.

Connecting Reaktor Instruments

By default, Husserl is connected to its own demo instruments as follows:

  • ANALOG is on AUX1.
  • ANALOG2 is on AUX2.
  • DRUMS is on AUX3.
  • AUX4 is spare.

You may prefer to play your own instruments on MIDI or as other instruments inside the Reaktor ensemble.

Deleting the Demo Instruments

It does not impact CPU load if you turn the demo instruments off, and you won't be able to play the demo snapshots if you delete them. But you can help your ensemble load more quickly by deleting the demo instruments. To do so:

  1. Open the ensemble structure. If you are not using the audio in, you can save a little CPU by muting the audio-in block (right click and select mute). The audio-in block cannot be deleted in the Reaktor structure.
  2. Open the Husserl instrument. In order that the demo ensembles inherit snap changes from the parent Husserl instrument, the demo instruments are inside the Husserl instrument. Select the instruments at the right of the structure, ANALOG, ANALOG2, and DRUMS. Now you can delete them.
  3. If you put your own instruments inside Husserl, you can configure them to receive snapshot changes from Husserl by opening their instrument properties, then selecting the snapshot 'store by parent' and 'recall by parent' options.
  4. You must configure your instruments to receive note information from Husserl. In your instrument toolbar, open the IN menu and move across to the INT MIDI submenu. From the list, make sure there is a dot by an AUX instrument.

For the single channel version of Husserl, there is just one instrument to choose (Husserl itself). For the multichannel version, there are more instruments called AUX1, AUX2, AUX3, and AUX4. In versions with the AUX outputs, the Husserl instrument itself should not be connected to other instruments.