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KORG OASYS 1.01 (MAC/WIN)

October 1, 2000
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Lost in a desert of me-too music technology? OASYS is no mirage.iFonzo

Rumors of a Korg product called OASYS have been circulating in the audio industry for years. Depending on whom you talked to, OASYS was a keyboard instrument, a sound card, a software synthesizer, a dessert topping, or a floor wax. In the mid-'90s, an OASYS keyboard instrument was actually announced; then it quietly disappeared. At last, the "legendary OASYS project" (to QUOTE Korg's own publicity) has delivered a product: the OASYS PCI system. As it turns out, reality has proven to be more intriguing than the rumors.

The OASYS system combines a high-quality, 12-channel, 24-bit DSP PCI card with software hosted on the Mac and, by the time you read this, the PC. (I tested the Mac version.) The system benefits from several lines of research and development undertaken by Korg. The OASYS synthesis algorithms are largely based on the physical-modeling technologies used to create such Korg products as the Prophecy, Trinity, Z1, WaveDrum, and MS2000. The OASYS effects catalog expands on the Trinity effects set. The system hardware resembles the 1212 I/O card, but OASYS has superior audio specifications and much more DSP power.

VIEW FROM THE TOPOASYS stands for Open Architecture Synthesis System. "Open architecture" means the system is software configured and therefore versatile and easily upgraded. Depending on how you set it up, OASYS can be a MIDI synthesizer, a MIDI-controlled mixer, an effects processor, a 24-bit sound card, or any combination of the four. Whenever Korg devises a new synthesis algorithm, it will be available to OASYS users as an Internet download.

OASYS divides its processing tasks between hardware and software. The hardware component is a PCI board with five Motorola DSPs, which handle all the audio processing by running code downloaded from the host computer. The board supports 12 audio channels, configured as stereo analog, stereo S/PDIF, and 8-channel ADAT Optical. All channels are available concurrently.

OASYS PCI Editor is the centerpiece of the host software. Editor presents a polished user interface for the OASYS mixer functions and also acts as a synthesizer and effects editor/librarian. In Editor, you construct system configurations called Multis. A Multi encapsulates synthesis and effects algorithms, signal routing and mixing, MIDI channel and modulation assignments, and all other settings. Editor and the OASYS PCI Engine driver translate a Multi into DSP code and download it to the OASYS board. As the code runs, you control it in real time via MIDI or with onscreen faders, knobs, and other gadgets.

The host software also includes audio and MIDI drivers. Korg provides drivers for ASIO, Sound Manager, and Windows MME. DirectX is not supported. These drivers ensure compatibility with all major audio programs, including digital audio sequencers.

FreeMIDI, OMS, and serial-port drivers let you control OASYS from Mac MIDI sequencers and external hardware, and the system offers full MIDI support in Windows as well. Under FreeMIDI or OMS, OASYS appears as two 16-channel devices, labeled "OASYS PCI A" and "OASYS PCI B." The Mac serial-port driver supports only 16 channels, but digital audio sequencers such as Mark of the Unicorn's Digital Performer and Steinberg's Cubase VST can use OASYS as a MIDI device and simultaneously process and mix audio tracks via ASIO.

OASYS integrates smoothly with host-based effects, such as MAS, DirectX, and VST plug-ins running in your host audio software. Because the OASYS board handles the system's audio computations, the OASYS software makes few demands on your computer. Therefore, you can run host-based plug-ins with OASYS effects and synthesizers without swamping your CPU.

THE HARDWAREThe OASYS hardware consists of a full-length PCI card with four connectors (see Fig. 1). The analog I/O connector accommodates a breakout cable that provides four 11/44-inch jacks (two in, two out). The analog inputs and outputs are unbalanced, and they are referenced to a +4 dBu signal level. OASYS employs 24-bit, 1285 oversampling sigma-delta converters for analog I/O.

All digital audio connections are also 24-bit. The ADAT Optical connectors each carry eight channels of audio to or from ADAT-compatible devices. The digital-breakout connector fans out to a cable with three pairs of jacks: a pair of RCA S/PDIF connectors, a pair of BNC word-clock connectors, and a pair of 9-pin ADAT-sync (time-code) connectors. OASYS has no MIDI ports; the system can use any outboard interface to send and receive MIDI via OMS or FreeMIDI.

The board's audio engine includes four 100 MHz Motorola 56303 DSP chips. An additional 80 MHz Motorola 56301 chip communicates with the host and performs other nonaudio chores. The processors execute DSP code at 480 million instructions per second. The system uses 24-bit buses throughout; it computes internal arithmetic with 56-bit precision. In some cases, OASYS uses 96-bit precision in its calculations!

The board's internal clock supports 44.1 and 48 kHz sampling rates. You can clock the board from an external device via the word-clock input, or you can provide a master clock to other devices from the word-clock output.

OASYS has no breakout box, but you can obtain up to ten additional analog I/O channels by connecting external converters to the ADAT Optical and S/PDIF ins and outs. The board is very quiet, but consider external converters if you're ultrafussy about noise picked up from the host computer.

PCI cards share the ground and power with the rest of the computer and are susceptible to a certain amount of system noise. Fortunately, I could hear system noise at the OASYS analog outputs only when I cranked my mixer and amplifier way beyond their normal operating ranges and listened on headphones.

GETTING STARTEDI installed OASYS on a 333 MHz Power Mac G3 running Mac OS 8.6. I followed the installation guide and experienced no problems installing, connecting, or running the hardware and software.

To install the hardware, just open your computer, snap in the card, and connect the required cables. Installing the software is also easy. The OASYS installer program loads OASYS PCI Editor, ASIO 2.0 and Sound Manager drivers, MIDI drivers, and other low-level components into your system. Note that some audio programs, such as BIAS Peak, support only ASIO 1.0. The OASYS Web site has an ASIO 1.0 driver for use with such programs.

Next, set the sample rate, audio-buffer size, and other audio parameters. The final step is to configure OASYS PCI Editor to communicate with either FreeMIDI, OMS, or the serial-port driver. If you choose FreeMIDI or OMS, you use their respective setup programs to install OASYS as a pair of 16-channel devices.

I tried a variety of software with OASYS. My main applications were MOTU Digital Performer 2.61 and BIAS Peak 2.10. I also took OASYS for brief spins with TC Works' Spark 1.5 and Tom Erbe's SoundHack (using Sound Manager). In addition, I used OASYS as a stand-alone, keyboard-driven, FreeMIDI and OMS device and as an OMS device driven by Opcode's Studio Vision Pro 3.5.4. In all cases, OASYS performed its audio and MIDI functions flawlessly.

MEET A MULTII set up a simple Multi to introduce you to the main elements of the OASYS user interface and to demonstrate some of the aspects of the system's versatility. This Multi is designed to work with FreeMIDI and Digital Performer, which aren't shown.

Fig. 2 displays six channels of the 12-channel Mixer window. At the bottom of each channel strip is a slot indicating the input source. Signal paths throughout the Mixer are stereo, but input sources can be either mono or stereo. In this example, inputs 1 through 4 are synthesis programs that model various instruments: Jazz Flute, Jazz Organ, E Bass Bright, and MiniBass 1.

The input to channel 5 is a stream of audio data. Streams are audio "pipelines" through which ASIO-compatible programs can send signals in real time. A stream can be mono or stereo. The input stream to channel 5 in this example, which is stereo, comes from two Digital Performer tracks. The input to channel 6 comes from the OASYS analog inputs.

In terms of MIDI, Mixer channels are normally assigned to a FreeMIDI or OMS device (A or B) and a MIDI channel number. The MIDI assignment routes MIDI messages to any synthesizer or effects on the channel, as well as to all the channel's faders, panpots, switches, and other controls.

In the example Multi in Fig. 2, all the Mixer channels are assigned to device A. The flute and organ are assigned to MIDI channels A1 and A2, respectively, and the two bass programs are layered on channel A3. (Unlike a hardware synth, OASYS can have more than one patch on a single channel.) In effect, Mixer channels 1 through 4 constitute a 3-channel, multitimbral synthesizer. Channels 5 and 6 are assigned to MIDI channels A5 and A6, respectively.

Each channel strip has a panel with four slots for insert effects, as shown in the FX Auto-load section in Fig. 2. These slots let you add a chain of effects to each channel. Effects are inserted in series, prefader. The example Multi uses only a few insert effects: a rotary-speaker emulation for the organ on channel 2 and an equalizer on the bass on channel 3.

The Out selector in the center of each channel strip routes each Mixer channel to an output bus. In the example, all signals go to the Master output (more about the Master outputs shortly).

Each Mixer channel can also be routed to any two of the system's four send buses, usually for effects processing. Two send-bus selectors (marked "A" and "B") are located at the top of each channel strip. Each has a level control, a mute, and a pre/postfader send selector. In this example, channels 5 and 6 go to send bus 1. The green "P" indicator at the top of channel 6 shows that its signal is sent prefader.

RIDING THE BUSOASYS has four send buses; to save space, I've only shown send buses 1 and 2 (see Fig. 3). Like Mixer channels, send buses support up to four effects. In Fig. 3, a hall reverb is plugged into bus 1 and a ring modulator is on bus 2. The sends are routed to the Master output. All send controls, such as the return fader and panpot, can be MIDI-automated.

In Fig. 3, send bus 1 receives signals from Mixer channels 5 and 6, while send bus 2's signal comes from a mono ASIO stream from Digital Performer. The Stream In menu at the bottom of each send bus selects a mono stream, which is summed with any signals bussed in from the Mixer.

Finally, notice that each output bus connects to a stereo pair of physical outputs (see Fig. 3, right). Each output bus strip has four slots for a final chain of effects, and controls can again be automated via MIDI.

You can route any Mixer channel or send bus output directly to one of the six output buses. Alternatively, you can route signals to a logical output called the Master Bus, as in Fig. 2. One of the six physical buses is always designated as the Master Bus, and all signals directed to the Master Bus go there. By simply designating a different output as the Master Bus, you can instantly reroute all signals to a different physical output. The example Multi uses the S/PDIF output, as indicated by the red Master Bus LED on the S/PDIF strip.

In this example, OASYS serves as MIDI synthesizer, mixer, and effects device, as well as a "plug-in" for processing Digital Performer tracks. This might seem complicated, but it took only a few minutes to set up.

PATCHES AND PROGRAMSBefore considering OASYS as a synthesizer, two basic OASYS terms must be explained: Patch and Program. An OASYS Patch implements a basic synthesis algorithm, such as a physical model of a trumpet. A Patch is a fundamental construct - you can tweak a Patch's parameters, but you can't create a new Patch in the OASYS PCI Editor. To do that, you must use SynthKit, an unsupported algorithm-development tool available free from the OASYS Web site (see sidebar, "Roll Your Own").

Programs are constructed from Patches and/or effects. A synthesis Program combines one or two Patches with insert effects. An effects-only Program contains effects but no Patches. This section discusses only synthesis Programs; I'll cover OASYS as an effects processor later.

Korg provides 28 Patches and hundreds of Programs based on these Patches. You select Patches and Programs from the Catalog window, where you'll find them organized into folders by type.

Patches function within Programs, and Programs function within Multis. To edit Patch parameters or just hear what a Patch sounds like, you must first create a Program containing the Patch. Then, you load the Program into one of the channels of a Multi.

In order to create or edit a Program, you open a Program Editor window (see Fig. 4). Here, you can specify the Patches that make up the Program. For each Patch, you set the number of voices, voice-allocation method, overall tuning, and other parameters. You can also set up microtonal scaling and key or Velocity splits.

To edit Patch parameters, you open a Control Panel window (see Fig. 5). Each type of Patch has different parameters, so each has a different Control Panel layout; Fig. 5 displays the Control Panel for the Mini Synth Patch. The Control Panel layouts are clear, the parameters and controls are grouped logically, and the controls (knobs, switches, for example.) are appropriate for each parameter. These serve as terrific patch-editor windows, and they make editing even the most arcane physical models intuitive and enjoyable.

The Control Panels provide extensive MIDI-modulation and automation possibilities. Double-click any parameter name, and the Modulation Palette pops up, which lets you assign two controllers to any parameter. OASYS supports many interesting combined or modified controllers, such as Mod Wheel + Aftertouch and Exponential Velocity. You can also record and play back the movement of knobs, switches, and other controls in the Control Panel via System Exclusive messages.

OASYS provides a great editing environment, but it's not perfect. There is only one level of Undo and no edit/compare function. In addition, you can't select multiple parameters for copying and pasting.

I liked the spacious layouts, but some might feel that the OASYS windows are too large. It would be nice to have an option to display windows at a reduced size.

OASYS AS A SYNTHESIZEROASYS stands out from the common run of synthesizers because of its synthesis algorithms. The system employs several traditional synthesis methods and also offers a number of physical models. Many OASYS models are highly realistic and responsive to expression controls, and they show unusual attention to the details of sound production. I can only touch on a few favorites here. For detailed information on the OASYS models, download the Patches and Effects Guide from the OASYS Web site.

Among the electroacoustic instrument models, the Tonewheel Organ Patch takes top honors. This Patch models the tonewheels (61 of them!), drawbars, and key-click and percussion mechanisms of a B3-style organ. The Tonewheel Organ Patch achieves phase coherency between the tonewheels by modeling their individual behavior. (Sampling individual B3 notes can't do this, because the phase of any sample is unrelated to the phase of any other sample.)

The key-click and percussion emulations constitute a mini synthesizer in themselves. OASYS also includes an equally detailed rotary-speaker effect based on the Korg Toneworks G4. Korg has programmed many variants of the Tonewheel Organ, ranging from a funky Jimmy Smith sound to a distorted, churchy timbre recalling The Band's Chest Fever.

Another outstanding electro-acoustic keyboard Patch is the Reed Piano. This model sounds exactly like my first electric piano, a late-1960s Wurlitzer. Happily, the reeds don't break, corrode, or detune.

I've spent countless hours programming analog synthesizers, so I can attest that Korg did a lot of homework in designing its analog-synth models. Because they run at full audio rate, the OASYS envelope generators really sound analog. As a result, they are extremely smooth and free of "zippering." OASYS uses audio-rate envelopes in all Patches, not just in analog emulations.

OASYS gets hosts of other analog details right, too. For example, you can modulate the cutoff frequency of the Mini Synth (Minimoog) model's filter at audio rates. The Mini Synth also emulates "soft" VCA distortion, generates correct pink noise, and even has oscilator-range switches labeled like organ stops (2', 4', 8', for example)! The Pro Synth (Prophet 5) model is equally accurate, including great-sounding hard oscillator sync and full 0 to 100 percent pulse-width modulation. How about an ARP 2600 model, Korg?

The Percussion Synth and Beat Box Patches emulate analog electronic percussion; the Beat Box has a 16-step sequencer. These models sound as cheesy as the machines they emulate; I don't care for them, but no doubt they'd be useful in your next dance production. I wish Korg had provided physical models of drums or orchestral percussion instead. Surely the company that gave us the WaveDrum can do better?

While I enjoyed the simulations of great keyboards from the past, I found the acoustic-instrument models more interesting. These include winds (flute, sax), brass (trumpet, trombone), plucked strings, slap bass, and vocals. My particular favorite is the Tenor Sax. Like the other wind/brass models, this Patch emulates several subsystems of the instrument (reed, bell, bore) and player (embouchure, breath pressure), as well as the interaction and feedback between them. The sax model becomes extremely expressive and flexible once you've learned to manipulate its parameters. It can give you everything from a dry, breathy Gerry Mulligan tone to a raspy, honkin' R&B sound.

At extreme settings, Tenor Sax can also produce strange sounds bearing little resemblance to a saxophone. Working with three simple parameters - Breath Pressure, Breath Noise, and Growl - I was able to morph from an almost unpitched "blowing into a bottle" sound to a snarling, nearly inharmonic timbre. This startling effect was enhanced by using a Yamaha BC3 coupled with a MIDI Solutions Breath Controller (which converts breath-pressure signals from the BC3 into MIDI Breath Controller messages) to control these parameters. In fact, all the wind/brass models are more expressive under breath control, even with my crude technique.

I like the plucked-string models almost as much as the winds and brass. My only complaint about the acoustic models is that Korg didn't provide more of them. In addition to percussion, OASYS models of bowed strings, clarinets, double-reed woodwinds, and world-music exotica will hopefully surface in the future.

Some OASYS Patches don't use modeling technology. The Z1 Organ Patch is based on additive synthesis, which is an effective way to "model" a pipe organ. The Virtual Phase Modulation (VPM) Patches are equivalent to 2- and 4-operator FM algorithms. Phase and frequency modulation are similar techniques, generating spectra that sound almost identical. (For more information on these techniques, see Curtis Roads's book The Computer Music Tutorial [MIT Press, 1996].) The VPM Patches and Programs sound quite a bit like early Yamaha 4-operator FM synthesizers, but with better envelopes and 24-bit dynamics.

AS AN EFFECTS PROCESSORI've long been a fan of Korg effects (I still use my Wavestation A/D), so I wasn't surprised by the high quality of the OASYS effects library. The catalog contains over 130 effects, including the complete Korg Trinity effects set. Effects types include reverb, delay, phasing and flanging, pitch shift and chorus, EQ and filtering, distortion and lo-fi, dynamics processing, amp/speaker and Leslie emulations, panning, ring modulation, tremolo, vibrato and other modulation effects.

Like Patches, effects are fully MIDI-controllable, and they are edited from Control Panels. In my book, this is a big bonus. If you were programming a reverb, would you rather use the tiny LED on an effects box or the OASYS O-Verb Control Panel (see Fig. 6)?

Effects-only Programs store effects configurations that are independent of any particular input source. Korg provides a large number of effects-only Programs. Some are ready-made effects chains, designed for processing particular types of signals. For example, Programs in the Electric Guitar group exploit various combinations of overdrive, EQ, amp simulation, and other effects suitable for making your Strat cry the blues.

Other effects-only Programs capture particular settings of one effect. For instance, the O-Verb group contains 36 assorted hall, plate, and other reverb and ambience programs. This group of Programs derives from Korg's new O-Verb algorithm, which makes its debut in OASYS. The O-Verb reverbs are, to use a technical term, gorgeous. They are spacious and transparent, with smooth, natural-sounding tails. You want them.

If you use many host-based plug-in effects, your CPU undoubtedly runs out of processing power sometimes. An overloaded processor might refuse to run the effects you want, or it might simply crash. OASYS effects can really help with this problem. You can run the less-demanding effects (such as small Pluggo effects) in your digital audio program while streaming other tracks to OASYS for more computation-intensive processing (such as reverb). The OASYS effect may very well sound better than the plug-in it replaces, so you can win on two fronts with this strategy.

PERFORMANCE ISSUESSpeaking of processor performance, OASYS faces limits that apply to any real-time system with a fixed amount of computing power. For example, consider polyphony. The number of voices you can squeeze out of a given Patch type depends on the complexity of the algorithm, the sample rate, and most of all, the number of other patches and effects running on the DSPs. Korg documents the maximum polyphony available from each Patch type; at 44.1 kHz, this ranges from a low of eight voices (Pro Synth) to a high of 61 (Tonewheel Organ). Korg gives similar statistics for the number of copies of various effects you can theoretically use.

However, these are best-case figures, based on dedicating the entire system to one Patch or effect. In practice, you typically have multiple Patches and effects trying to share the OASYS resources. The available number of voices or effects is often far less than these figures indicate.

For example, the Multi in Fig. 2 employs three monophonic synthesizers, a 61-voice organ, and four effects. This Multi gobbles up almost all the resources of the DSPs, leaving little room for anything else.

When a Multi exceeds the available resources, OASYS gives an error message. In this event, you must reduce the polyphony of a Patch, remove an effect, or otherwise reduce the DSP load. Until you do, OASYS won't play any audio. This is desirable behavior; the system is smart enough to know it's about to be swamped before it blows up. All the same, it's often difficult to predict whether a given combination of Patches and effects will work. Balancing the load of voices and effects is the trickiest and most frustrating aspect of working with OASYS.

THE WRITTEN WORDOASYS includes three manuals totaling about 700 pages: the Installation Guide, the Users Guide, and the Patches and Effects Guide. In addition, there is an OASYS FAQ that addresses all sorts of performance and compatibility issues; it is essential reading.

The OASYS documentation is pretty thorough and clearly written, but it needs more tutorials and graphics. The tutorials in the MOTU Performer Getting Started manual would serve as a good model (pun intended) for Korg's writers. Also, the factory synthesis and effects Programs should be documented, at least in summary form. As of now, you have to actually edit a Program to find out about its Patches, effects, controller assignments, and so on.

You can download all the OASYS documents from the OASYS Web site, free of charge. The site has lots of good info, and many sound demos in MP3 format. You can also download the full OASYS PCI Editor as a soundless demo.

CLOSING ARGUMENTSA fully professional product, OASYS boasts excellent audio quality and elegant and reliable software that interfaces neatly with other MIDI and audio programs. Most of the factory Patches and effects sound great, and there's a lot of potential for programming and sonic experimentation. On musical and sonic grounds, OASYS more than stands up to the competition.

Given the steep list price of $2,200, however, you need to ask whether OASYS is cost-effective compared to alternative setups. But don't make the mistake of simply comparing OASYS to other sound cards; OASYS is much more than a sound card. Could you buy an equivalent sound card, a few dozen VST Instruments, and an equivalent collection of VST or MAS effects plug-ins for the same price? Not likely; a high-quality reverb plug-in alone can cost more than $400. Another contender might be CreamWare's Pulsar II, which, like OASYS, is an evolving system. Pulsar II uses a very different user interface, however, and doesn't feature the physical models that OASYS offers.

Only you can decide if OASYS fits your needs. As for me, I see an OASYS in my future, and I'm heading for it right now.

If you want to develop your own OASYS Patches from scratch, you need to get SynthKit from the OASYS Web site. SynthKit is a Mac-only environment for developing synthesis and effects algorithms that Korg engineers have used for several years as an in-house development tool. Now it's available as a free, unsupported adjunct to the OASYS PCI system.

SynthKit presents a graphical environment that superficially resembles many modular software synthesizers (see Fig. A). You grab icons representing algorithm elements, or "blocks," and connect them using virtual "wires." Many blocks are familiar elements of synthesis: oscillators, filters, ADSRs, mixers, noise generators, delays, and more. But SynthKit also gives you access to low-level physical-modeling components, such as Hammer, Bow, Cylinder, Glottal, and Reed.

Once you have connected your blocks, the algorithm is compiled into DSP code and downloaded to the OASYS hardware. You can then listen to it and control it via MIDI. When you're satisfied with the design, you can save it as a Patch and use it in the OASYS PCI Editor environment.

Remember that SynthKit is an engineer's tool, not a sugar-coated collection of audio toys. Despite an extensive manual, you're on your own; forget about calling a tech-support line to help develop your physical model of a sarangi. Regardless, SynthKit promises sound hackers endless hours of fun.

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