Mutating Spectral Resynthesizer

Rossum Electro-Music Software Architect Bob Bliss (who also, as it happens, fathered E-mu’s famed “EOS” Emulator Operating System) has created Panharmonium, a unique music and sound design tool that lets you analyze the spectral content of any audio signal and use that analysis to drive a bank of from 1 to 33 oscillators. Depending on various control settings, Panharmonium can accurately reproduce the input spectrum in real time or modify it in a multitude of wildly creative ways. All with an interface whose immediacy encourages performance and interaction.

Panharmonium input can be anything from a single oscillator to an entire mix (including vocals). From dense, swirling pads and drones that evolve with the input’s changing spectrum, to clock-syncable spectral arpeggiation, to as-yet unnamed harmonic effects, Panharmonium opens up an entirely new world of sonic possibilities.

Additionally, Panharmonium can take a snapshot of an instantaneous spectrum and use that as a complex harmonic oscillator, which can then be modified and modulated by all of Panharmonium’s other controls.  

Panharmonium accomplishes its magic though a combination of functional submodules:

Spectral Analyzer

The Spectral Analyzer provides tools for defining the analysis process. 

– The Slice parameter sets the rate at which the incoming audio is transformed to spectral data. It can be set by the Slice and Multiplier controls, the Tap button, or by an external clock signal. Very short slice times result in real-time spectral data, while longer times can create rhythmic spectral patterns. 

– The Center Freq and Bandwidth controls (and associated CV inputs and attenuverters) control the range of frequencies to be analyzed. The Bandwidth control allows the selection of narrow to wide pass bands on the left side of the pot and narrow to wide notches on the right side of the pot. The ability to sweep the frequency and modify the bandwidth under CV control opens up a wide range of sonic effects.

– The Freeze button lets you freeze the spectral integrator, sustaining the currently analyzed spectrum.

Spectral Modifiers

These controls allow you to creatively modify the analyzed spectra.

– The Voice parameter lets you select from 1 to 33 oscillators to resynthesize the spectrum.

– The Blur parameter (and associated CV input) is a spectral lag processor that controls how quickly the spectrum can change.  

– The Feedback control lets you route the resynthesized audio back into the entire processing chain for subtle or dramatic feedback effects. At its max, the output becomes self-sustaining, even if the input is removed.

Oscillator Bank

The Oscillator Bank resynthesizes the analyzed spectra.

– The Waveform parameter selects the oscillators’ waveform. In addition to the usual sine, triangle, sawtooth and pulse waveforms, two special crossfading sine and sawtooth waveforms are included.

– The Freq control lets you tune the oscillators over a +/-7 semitone range. The frequency is further controlled by the 1V/Oct input and the FM input and attenuverter.

– The Octave control, not surprisingly, shifts the pitch of the output by octaves.

– The Glide parameter sets the amount of polyphonic glide (i.e., each oscillator has its own glide circuit).

– The Mix control (and associated CV input) sets the balance between the original input audio and the resynthesized audio.

Optional Functions

A number of optional functions can be selected by using the Output Mode and Tap buttons.

– Holding the Output Mode button and adjusting the Slice control enables Drums Mode, which optimizes the spectral analysis for drums and other percussive inputs.

– Holding the Output Mode button and adjusting the Freq control enables Spectral Warping. In contrast to conventional frequency adjustment, where the harmonic relationships between the spectral elements are preserved, Spectral Warping shifts the harmonic elements individually, producing a variety of clangorous, swarming textures.

– Holding the Tap button and adjusting the Freq control quantizes the resulting frequency adjustments to semitones.

Spectra Memories and Presets

Panharmonium provides 12 user Spectra memories and 12 user Presets.

– The Spectra memories let you store up to 12 frozen slices. When selected, a spectrum (up to 33 oscillators wide!) replaces any live input and can have its pitch controlled by the 1V/Oct input and FM controls. 

– A Preset is a snapshot of all of the module settings, along with the value of any CVs present at the moment the preset is saved.

Panharmonium  is 26HP wide and 25mm deep.

Power requirements (max):  140mA +12V, 30mA -12V. Reverse polarity protected.

Panharmonium is available now from Rossum Electro-Music dealers worldwide.

Control NYC’s Panharmonium Demonstration Series.

Learning Modular’s Panharmonium Tutorial.

Rossum Electro-Music’s Software Architect Bob Bliss presents a Panharmonium intro demo at Synthplex 2019.

View or download Panharmonium documentation.

Panharmonium Quick Start Guide (PDF)

Panharmonium Manual (PDF)

Download the latest Panharmonium firmware.

The latest version of Panharmonium firmware is 1.50l_220430

NOTE: This version fixes some bugs associated with rare manufacturing variations in the hardware. If your Panharmonium is functioning correctly, there is no need to update.


To check the version that’s in your Panharmonium, simultaneously press and hold the Tap/Opt + Freeze + Output Mode/Option buttons and then press the Preset 1 button. The Spectra and Presets LEDs will display the firmware version. The Spectra LED number is the number before the decimal point and the Presets LED number is the first number after the decimal point.

NOTE: This is the version included with the initial shipments of Panharmonium.

If you’ve saved over the factory Spectra and Presets and would like to restore them, download the file below and follow the procedure in the Utilities chapter of the manual.

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.

Updating your Panharmonium Firmware

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 sometimes 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 in your Panharmonium:

  • Connect a patch cable from the output of whatever you are using to play the .wav file to the 1V/Oct Input on your Panharmonium (we’ve found that a regular Eurorack patch cord works fine).
  • Turn on your system while holding Spectra 5 & 6. The Multiplier 2, 8, & 32 LEDs will light.
  • Press Tap/Opt. The Multiplier 2, 8, & 32 LEDs will go out, and Spectra 1 will light to indicate that Panharmonium is waiting for audio.
  • Play the software WAV file into the 1V/ OCT input. (See the hints below for successful WAV playback.) Spectra 2 will light to indicate that audio has been detected. Spectra 3 will light to indicate that it has recognized the audio as software data. As the file header loads, the Multiplier LEDs will act as a VU meter for the incoming audio.
  • Once past the header, the Multiplier LEDs will act as a progress indicator. The six LEDs will light in sequence as the data is loaded.
  • At the end of the transfer, Spectra 4 will light briefly to indicate that all is well. Your module will then reboot automatically.
  • If instead, all of the Multiplier and Preset LEDs light, the update was not successful.

    This is very rare and almost always because of a playback level that was either too low (most often) or too hot. In that case, click the Tap/Opt button, adjust the playback level, and try again.

    If it still doesn’t work, get in touch via our Support Request Form and we’ll help you get it handled.



Click here to download panharmonium_1.50l_220430 as a zip archive.

Factory Spectra and Presets 


Click here to download panharmonium_content_1.00lc_190618 as a zip archive.

Boot Software


Click here to download panharmonium_boot2_190618 as a zip archive.