The Technos Acxel may look similar in operation to a sampler, although its workings were very different and the sound structure is accessible. Where samplers used an A/D converter to convert a continuously-variable analogue signal into digital data, the Axcel worked on the premise that any sound, no matter how harmonically complex, could be broken down into a finite number of sine waves, and that these sine waves could be individually altered to fundamentally change the sound, producing what Technos founder Nil Parent termed re-synthèse. The Acxel was invented by Pierre Guilmette, the operational design was Nil Parent realization, the system was developed at Technos, company own and directed by Pierre Guilmette, Nil Parent and other partners.
Utilising a FFT (Fast Fourier Transform) analysis, sounds inputted into the Acxel were broken down into a number of variable-amplitude and variable-frequency sine waves, up to a maximum of 1024. Once sounds had been processed by the Acxel, all the constituent waves could be pitched up or down by the same factor, which had the effect of increasing the pitch of the sound without affecting length, or introducing any of the digital artefacts that traditional samplers did (for example, pitching all waves up by a factor of 2 would raise the overall pitch of the sound by 1 octave, without affecting length. Using a traditional sampler, pitching a sound up by 1 octave would result in it being halved in length).
The Acxel also had the capability to synthesise sounds from scratch. The same 1024 sine oscillators, that in fact can be of various waveforms including of draw-able shape, which were used to resynthesize sounds could also be used for additive synthesis. You can either take Analyzed sounds and modify them. A large palette of parameters and controls is accessible, on the same manner if you start from scratch or from analysis, and in Real Time:
o Draw waveforms directly onto its LED matrix display with finger-tip (a feature once offered by the Fairlight CMI almost 10 years previously, albeit using a video monitor and light-pen).
o Draw dual Spectrum type shapes for Amplitudes, Frequencies (with separate: Integer / Decimal parts, and Envelope Variation), Phases – Corresponding to each parameter the base spectrum and the MIDI control spectrum.
o Draw dual Envelopes to each Oscillator Parameter: Amplitude, Frequency – Corresponding to base envelopes and MIDI control envelopes, independent on each oscillator.
o Draw dual Envelopes to each voice parameter: Volume, FM, Color, LFO1, LFO2 – Corresponding to base envelopes and MIDI control envelopes. Draw waveforms for LFOs.
o You can also apply a digital type of filtering named COLOR filter. With center frequency envelope. The frequency is expressed as harmonic number, then you apply the filtering on the same manner at 100 Hz or 2000 Hz or 5000 Hz. With possible selection of harmonic numbers to be filtered or not (example to keep fundamental). With drawn envelope and filter shape (Low pass, High pass, Band, User-drawn response curve – for example Comb type shape)
o FM (Frequency Modulation) envelopes is also accessible and applied on the created sound structure (or analyzed).
o Other controls and editing: Timbre interpolation, Time stretch / expansion, extended MIDI controls (programmable control curves), muting elements, chorus.
In this video:
Technos Acxel gets sequenced by the Elektron Octatrack, lfos controls different arpeggiator settings. the sound from the Acxel gets routed back into the Octatrack for some effects mangling.