Friday, April 17, 2009

Technos Acxel Resynthesiser - 1988

Technos Acxel Resynthesiser - 1988

What exactly is resynthesis? Resynthesis is the process of analysing a sound and arranging a number of sound components, like oscillators and amplifiers, to reproduce that sound.

In other words, a sound is digitally sampled and then analysed and recreated with a series of sine wave oscillators (as in additive synthesis) whose pitch and frequency change over time.

If you have a sophisticated additive synthesiser, you could create the sounds manually, but the beauty of resynthesis is that this process is automated. It selects the basic frequency and amplitude of the various harmonics (the number of which varies according to how many you have available, though the default amount is 32 per voice on the Acxel) and creates envelopes which vary these levels over time.

The advantage of resynthesis over sampling is that while samplers treat sounds as a whole, resynthesis involves breaking a sound down into each of its component parts, or harmonics.

The components are all independent and can be adjusted individually, so you have more control over the sound.

Ideally, a resynthesiser will sound as good as a sampler, but it will provide additional control over the sound.

Ever tried to copy the violin scrapes and breathy attacks of the D50?

If so you'll have found you can't do it using simple sampling - you still hear the fundamental pitch underneath the effect.

With resynthesis you can remove the pitched component of the sound (ie. the fundamental and perhaps a few of the other first harmonics).

Another problem overcome by resynthesis has to do with the link between pitch and duration of samples.

Transposing a sampled sound upwards by one octave cuts the length of the sample in half and transposing it downwards by that amount doubles it.

With resynthesis pitch is independent of duration, consequently sound duration may remain constant over the entire range of a keyboard, and time expansion and compression without pitch change become possible.

And this is what the Acxel is all about. The name Acxel, by the way, stands for Acoustic Element.

In the company's terminology, each harmonic of a sound (represented by an individual sine wave) is referred to as an Acxel.

The individual Acxels are then "added" together to form a complete, resynthesised whole.

The Acxel is also an additive synthesiser and if you don't buy the optional Acxelizer, which performs the resynthesis process, then you're left with a very extensive additive synthesiser.

Back to nuts and bolts. The Acxel consists of two basic parts: the Solitary, a large rack-mounted black box which holds the system's plug-in cards, a 31/2" floppy drive, 2Meg of RAM and the various audio, SMPTE, MIDI, CRT terminal, printer and hard disk connectors; and the Grapher, the company's revolutionary interface.

Future plans also include an optional high-quality dedicated keyboard controller.

The Grapher is an impressive, touch-sensitive terminal that features an 80-character LCD as well as a 32X64 matrix of red LEDs which can display waveforms, envelopes, relative harmonic levels and a host of other functions.

All of the "switches" on the Grapher which surround the rectangular matrix and all of the points on the matrix itself, turn on or off with the touch of a finger, making the system very fast - drawing an envelope or a waveform is simple and extremely intuitive.

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