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Monday, October 28, 2013

Korg Oasys

Open Architecture Synthesis (Preview)


Reviews : Keyboard

Amidst the parched sands of the NAMM show, PAUL WHITE found welcome relief at Korg's Oasys of advanced musical technology, where the latest efforts of the company's US R&D team were unveiled.

Up to now, we've had analogue synths, sample-based digital synths, FM digital synths, wavetable digital synths and, more recently, physical modelling synths. Korg's new Oasys synth is based upon 'open-architecture' digital signal processing, which means it can be whatever its software tells it to be. DSP, being digital, can't produce true analogue synthesis, but Oasys can accurately emulate it, so what Korg are telling us is that their new baby can be anything you want it to be -- and it can be several different things at the same time. Apparently, the machine has up to 32-part multitimbrality and can combine different methods of synthesis, allowing you to use, for example, analogue-sounding bass parts, FM piano parts and physically-modelled sounds in one composition. 20-bit D-to-A conversion at a 48kHz sampling rate also ensures a high degree of audio fidelity.




Judging by the extensive demo, Korg have taken great strides in the area of physical modelling. Unlike Yamaha's VL1, which emulates wind instruments (monophonically or duophonically), Oasys is capable of modelling many kinds of instruments, including wind, reed, strings, plucked strings and electric piano, all polyphonically.

For those unfamiliar with modelling, it involves creating a mathematic model of an instrument and the means of playing it in software, the aim being to make the model respond in the same way as the real thing. In the case of a flute, it will squeal if you 'blow' too hard; in the case of a guitar, the harmonic structure will change depending on how hard you 'pick'.

The open architecture system doesn't place a precise limit on polyphony, though in practice, polyphony varies depending on the complexity of the synthesis algorithms being run. We were told that the theoretical maximum polyphony is 112 voices, but in real-world situations, I would imagine this to be significantly less, especially if physical modelling synthesis algorithms are being run.

Physical modelling algorithms seem to be too complex for the average user to create from scratch, so Korg's sound designers are creating algorithms for specific instrument types. Key parameters which the user can control in real time are then brought out to physical controls or controller inputs, and in the case of more conventional synthesis methods, the user can build sounds using standard building blocks. Waveform RAM is included for sample-based synthesis, and demonstrations of even simple FM and analogue synthesis algorithms showed just how good this machine could sound. Because the synthesis algorithm comes as part of the patch information, there's no need to update the system when a new algorithm is developed -- new sounds are simply supplied on disk.

To simplify the user interface, Korg have implemented a touch screen (TouchView) which has features familiar to those of the Macintosh I'm currently writing on. Parameters are adjusted with graphic sliders on the touch screen, and selecting any of them (simply by touching the one you want) magnifies the selected fader for more precise control. On an analogue synth model, the faders would be used to access the usual waveform, envelope and filter controls, whereas in the very accurate Hammond organ simulation we were treated to, the faders became drawbars. Icons represent block diagrams of the various synthesis models, and the result is a simple, intuitive interface that does away with conventional up/down buttons. With a processing capability of over 220 million instructions per second, Oasys is considerably faster than the fastest desktop computers currently available, and though no announcement was made as to other applications for Oasys, the open DSP architecture suggests that it may also be capable of hard disk recording applications, with a suitable hard drive.




So how are the various parameters controlled in real time? In addition to the 76-key, aftertouch sensitive keyboard, Oasys is equipped with familiar controls including a joystick, a pressure sensitive ribbon controller and a breath controller input. There are also assignable buttons, faders and expression control pedal inputs. At the demo I attended, the breath controller wasn't in use and the ribbon controller hadn't been fitted, yet the instrument was still capable of providing very lifelike 'overblown' flute and sax sounds, plus a very organic acoustic guitar simulation.

Other significant features include: eight polyphonic analogue outputs with balanced stereo master outputs, 8-channel ADAT optical interface, built-in 1.44Mbyte floppy drive and SCSI interface.

Korg anticipate putting Oasys on sale later this year. No exact price was suggested, but a figure of between £3000 and £5000 seems likely. Before you write this off as being well out of reach, Korg also revealed that several other products using aspects of this technology are being developed in parallel, so the wait for lower cost spin-offs might be much shorter than you think.

Published in SOS March 1995

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