Stereo Morphing Z-Plane Filter

With our MORPHEUS digital filter module, we’re finally able to unleash the full power of the 14-pole Z­-Plane Filters that Dave invented for the E-mu Morpheus synthesizer.

The MORPHEUS Eurorack module includes over 280 filter configurations, what we call Cubes. Each Cube is composed of up to 8 complex filters that you can picture as being at the corners of a three dimensional cube (hence the name). Morpheus gives you the ability to smoothly interpolate between those 8 filters within the cube’s three dimensional space.

Due to processor limitations back in the day, the original Morpheus was capable of real-time morphing in one dimension, but interpolation in the frequency and transform dimensions were set at note-on and remained static for the remainder of the note. But even with that limitation, Morpheus offered sonic capabilities that are unmatched to this day.

With the MORPHEUS filter module, you now have simultaneous real-time CV control of all three dimensions, for dynamic timbral effects unlike anything you’ve ever heard before. In stereo.



MORPHEUS features include:

• Over 280 14-pole filter configurations

• Real-time manual and CV control of Frequency, Morphing and Transformation

• The ability to save hundreds of customized filter configurations

• A sequencer for stepping through filter configurations under trigger or clock control

• A large OLED display for programming and realtime display of morphing

Like all Rossum Electro-Music digital modules, all parameters are available for adjustment with a single button press. No menu diving.

MORPHEUS is available now from Rossum Electro-Music Dealers worldwide.


A Closer Look at What Makes Up a Morpheus Filter

A Morpheus Filter (i.e., what you select and load into Morpheus to process your audio) is actually the top level of a three level hierarchy. The three levels are:

A Frequency Response

This is the most basic construct of a Morpheus filter. It is essentially a single static configuration of Morpheus’s 14 poles and zeros. For example, a frequency response might be configured as six independent bands of parametric EQ and a low pass section.


Even this basic building block is capable of creating filtering and resonant spaces of enormous complexity. But the real power comes from the ability to interpolate between multiple Frequency Responses.

A Cube

Cube provides the structure we need to control the interpolation between multiple Frequency Responses.

To start with a simple example (actually simpler than any of the actual Cubes),  imagine 2 different Frequency Responses and a single morph parameter to interpolate between them.


By varying that single CV-controllable parameter, you’re actually interpolating between 20 different frequency, bandwidth, resonance, and gain parameters simultaneously. We can visualize the result as looking something like this:


The next step would be to add another pair of Frequency Responses and control them with two parameters. That would look something like this:


In this case, the two parameters (Frequency and Morph) define a point on a virtual plane that specifies the interpolation between the four Frequency Responses. Cubes like this are referred to as ”.4” cubes.

Finally, by adding four more Frequency Responses, we have a full 3D Morpheus Cube, now controlled by three parameters, FrequencyMorph, and Transform.

In this case, you will be interpolating between all 8 component Frequency Responses, displaycontrolled by the position of the single interpolation point within the virtual 3D space. For ease of visualization, this is displayed (along with the resulting output frequency response) on Morpheus’s graphic display.


A Morpheus Filter

Finally, at the top level of our hierarchy is the fully-configured Morpheus Filter. This consists of one of the 289 Cubes and the various parameters set in Morpheus’s Edit Filter Menu.


In addition to three dimensional filtering, Morpheus is capable of producing a wide variety of unusual and distinctive types of distortion (depending on the character of individual cubes and the nature of the signals being processed). This is separate from the usually unwanted distortion produced by overdriving the input or by too high a gain through the filter.

All of the Morpheus Filters that are based on “.4” Cubes have the Transform control knob and CV input set to control distortion (since with only 4 Frequency Responses, there is no Transform axis to control anyway). However, even for the full 3D Cubes, you have the option of programming the Transform control and CV to control distortion, in which the the actual Transform value is set as a static value in the Edit Filter Menu.

Suffice it to say, Morpheus distortion adds an additional (and highly dramatic) option to its sound design capabilities.

Morpheus Specifications








20,000 Dynamically Allocated


Audio L/R

2x 3.5mm mono socket

100kΩ Input Impedance

Full Level Frequency CV 

1x 3.5mm mono socket

100kΩ Input Impedance

Attenuverted Frequency CV

1x 3.5mm mono socket

100kΩ Input Impedance

Attenuverted Morph CV

1x 3.5mm mono socket

100kΩ Input Impedance

Attenuverted Transform/Distortion CV

1x 3.5mm mono socket

100kΩ Input Impedance

Filter Sequencer Dec

1x 3.5mm mono socket

100kΩ Input Impedance

1.6V threshold

Filter Sequencer Inc

1x 3.5mm mono socket

100kΩ Input Impedance

1.6V threshold

Filter Sequencer Reset

1x 3.5mm mono socket

100kΩ Input Impedance

1.6V threshold


Audio L/R

2x 3.5mm mono socket

1kΩ Impedance


+/-12V via 16-pin, Doepfer-style connector


135mA +12V, 25mA -12V (maximum)


18HP (W); Panel to power connector (with connector plugged in) 25mm (D)


1x 16-pin, Doepfer-style cable
4x M3 screws
4x M2.5 screws
4x Nylon washers

1x Quickstart Guide

Morpheus Overview

A comprehensive overview of Morpheus from Ben “DivKid” Wilson, featuring extensive filter examples with a variety of audio sources, as well as an introduction to Morpheus’s Filter Sequencer.

Morpheus Introduction and Overview

A concise introduction to Morpheus from our friends at Control. The first of their three Morpheus videos.

Exploring the Morpheus Cube

The second video from Control looks at the key structure of the Morpheus cube.

The Filter Sequencer

The third and final Control video looks at Morpheus’s flexible Filter Sequencer.

Morpheus Noise Shaping 

Another from DivKid.  Here, he walks through a variety of Morpheus filters using noise as a broadband input.  The noise was run through a low pass gate which was struck rhythmically to show how the filter responds to changing amplitudes.

View or download Morpheus documentation.

Morpheus QuickStart Guide (PDF)

Morpheus Manual (PDF)

Download the latest Morpheus firmware.

  • The latest version of Morpheus firmware is 1.00v_170111

To check the version that’s in your Morpheus, press and hold the Edit Filter button until the Utilities screen appears. You will see the current version at the bottom of the screen.

  • The latest version of Morpheus Cubes file is 1.01vc_170120

NOTE: The cubes file has been updated since the initial shipments of Morpheus. 

This revision fixes an error in the Null Cube in which the gain at the cube corners where Frequency and Transform CVs are -5V and Morph is either -5V or +5V was +12dB rather than the intended 0dB.  In the new revision, the Null Cube has 0dB under all CV conditions as intended.  No other cubes are affected.  We recommend all users update to this new cube data.

To check the version that’s in your Morpheus, press and hold the Edit Filter button until the Utilities screen appears. Scroll down to Load Cubes and click the encoder the see the current version. Press Edit Filter to return to the Utilities menu.

  •  The latest version of Morpheus Boot Software is vulcan_boot2_161121

It’s very unlikely you will ever need to update this. If it ever becomes necessary, we’ll put appropriate instructions here at that time (you can also refer to the manual).

To update your firmware and/or filter cubes and/or boot software, you will need to play the .wav file(s) linked below into the Full Level Frequency CV Input of your Morpheus.

We’ve had good luck playing the file directly from a computer (but see the warnings below) and from mobile devices. In theory, any device that will play a .wav file without distorting the data should work. However, here are some caveats:

  • If you are steaming the file directly from the web, be sure that your data rate is sufficient to keep up. If necessary, wait until the file has been completely buffered before starting playback.
  • If you are playing through an audio interface, it should output line level.
  • If you are playing the file from a computer or phone, quit Facebook, your email client, and any other software that produces audio. Any other audio injected into the stream will cause the update to fail. If you’re using an iPhone, temporarily placing it in Airplane Mode will prevent any incoming call or message notifications from interfering with playback.
  • We have found that Safari on the Mac plays the file in a way that keeps it from being successfully recognized and decoded. If you are using Safari, we recommend downloading the zip archive below and playing the file from the local copy using Quicktime Player.
  • In fact, if you are having any problem streaming the file, downloading the zip archive is a good alternative.

To update the firmware and/or filter cubes in your Morpheus:

  • Connect a patch cable from the output of whatever you are using to play the .wav file to the Full Level Frequency CV Input on your Morpheus (we’ve found that a regular Eurorack patch cord works fine)
  • Make sure there is no input into the attenuverted Freq CV Input (not even a patch cord).
  • Set the Frequency Knob to its center position (0V).
  • Go to the Utilities Menu by long-pressing the Edit Filter button.
  • Select Load Software or Load Cubes or Load Boot Software from the menu.
  • Press the Encoder switch twice as instructed.
  • Start playback of the .wav file. If you’re loading firmware, you should see a green progress message in the display (for Cubes or Boot software, you’ll see an orange progress bar):


  • When the file transfer is complete, press the Encoder again to reboot into your new firmware.



Filter Cubes


Boot Software