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Differential Audio

FS-256 Additive Synthesizer

FS-256 Additive Synthesizer

Regular price $2,300.00 USD
Regular price Sale price $2,300.00 USD
Sale Sold out


The product is not yet available for purchase and is still under development, it is not 'Sold Out'.

Rendered and prototype images are not representative of the final product and will be updated soon.

Product price is not final and subject to change.

Thank you for your understanding as we work to bring this product to market in early 2024.


Engineered and manufactured in Canada, the FS-256 includes wood side panels.

Shipping & Returns

Shipping is included free of charge. Please see our return policy for details.


Length: 350mm (13.7")

Width: 220mm (8.6")

Height: 100mm (3.9")

Dimensions subject to change

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FS-256 Features

The FS-256 is a powerful polyphonic and multitimbral desktop synthesizer that generates sound using additive synthesis, which sums multiple sine waves together into a final output.

  • 256 additive oscillators of 32 partials each - up to 8192 sine waves generated from the device.
  • Each partial is independently controlled with user defined envelopes, over a range of variables.
  • 8 4-partial additive LFOs per additive oscillator with user programable envelopes.
  • 2 sine wave LFOs -per- partial for user defined AM and FM modulation per partial.
  • Up to128 polyphony, 16 multitimbrality.
  • Real time FFT display of channels
  • Dual 5" 800x480 touchscreen for GUI and to define partial variable envelopes
  • 24 smooth rotary encoders to control additive oscillator macro controls
  • Fully balanced stereo 1/4" Line Out, Line Out Aux (TRS, +4dBu).
  •  Fully balanced stereo 1/4" Line In (TRS, +4dBu),
  • Dual mono 2.5mm 5VP-P analog in and out, Headphones 1/4" (TRS)
  • MIDI In and Thru, Micro SD card on the back panel.  USB device as part of future firmware update.

Welcome to the world of Additive Synthesis

Create beautiful, textured and unique sounds only possible through sound design from the ground up.

Sound Design

Each of the 256 additive oscillators in the FS-256 generate 32 indepentantly controlled sine wave partials which are summed together to produce the output of a single additive oscillator. Each sine wave partial can be independently controlled by generating envelopes via the touch screen displays for the following parameters:

  • Partial Amplitude
  • Partial Frequency
  • Partial AM Frequency
  • Partial AM Gain
  • Partial FM Frequency
  • Partial FM Gain

The user generates the envelopes to define these parameters by drawing curves on the touch screen display to set time and values from MIDI Note On and Off. This solution reduces the complexity of inputting such a large amount of data required by additive synthesis. Envelopes are not limited to a traditional ADSR pattern. This gives you full control over the sonic evolution of a sound - from rise and fall times of each partial amplitude, frequency deviation, AM and FM modulation per partial. Each partial has its own sine wave AM and FM sine wave LFO.

There are an additional 8 4-partial LFO's dedicated to each additive oscillator, that control global AM, FM, amplitude and frequency controls for the oscillator as a whole.

The front panel encoders allow the user to control a sound for a range of parameters, such as: detune, LFO freq and gain, oscillator partial spacing, rolloff and partial enables.

Voices, MIDI, Polyphony, Multitimbrality

Each of the 256 additive oscillators in the FS-256 are identical, and are treated as resources to be assigned to voices. When a patch is loaded from memory or created from scratch, the oscillators required for the voice are allocated from the pool of available oscillators with mixing handled automatically. This allows the 256 additive oscillators be allocated in a wide range of configurations.

Additive oscillators can be assigned into groups that prioritize polyphony, meaning that the oscillators are grouped to generate a common sound, but can be activated together for a larger polyphony. Conversely, the oscillators can be grouped together to form more sounds (multimbrality). This allows multiple sounds (instruments) to play concurrently.

There is a tradeoff between polyphony and multimbrality to share the oscillator resources in the device. Do you want a diverse orchestra with many solo instruments, or one big polyphonic snare drum band? Any range between the extremes is possible.

Performance, Song and Voice Modes

Voices can be created, saved and loaded to work on sound design for a particular voice.

Saved voices can then be moved into 'Songs', where different voices respond to assigned MIDI channels for a song composition or performance.

Songs can be arranged into 'Performances', arranged from 'Songs', for quick select to move from one song to another with the voices loaded automatically.


The FS-256 come built in with multiple sound effects, powered by its own dedicated ARM processor.

Future Features

Future featues may include, via firmware updates:

  • Polyphonic aftertouch
  • MIDI Sysex
  • USB device
  • Share your voice patches with the community with author and patch name recorded.

Feature Disclaimer

Not all features will be available at release time. The following incomplete list shows some features that are not done and does not include all uncompleted features described above. They are on our roadmap. When available, these features will be available via firmware updates.

  • USB Device mode. Used for SD card updates from host computer. MIDI over USB from host is also a possible future feature. Note: until this feature is ready, the user mounts the SD card to host computer using the included SD card reader.
  • Improvements to Phase and Amplitude PA controls algorithms.
  • All Future Features listed above
  • Free Shipping

    Note: shipping policy is subject to change, but the plan is:

    Shipping is included in the purchase of the FS-256. Purchaser is responsible for any import duties and taxes of their home country.

  • Warranty

    Note: warranty policy is subject to change, but the plan is:

    A one year limited warranty is included with the purchase, registration required. Warranty is subject to terms and conditions (don't spill a beer on the unit).