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Korg TR Rack

Expanded Access Synth Module By Simon Trask
Published February 1998

Korg TR Rack

Korg's new module makes the synthesis technology of their flagship Trinity workstation range more affordable — but at what cost?

Korg have traditionally augmented their synth workstation ranges with a rackmount model, allowing musicians to buy the workstation's synthesis technology without having to buy into the workstation concept or pay workstation prices. However, since its introduction two years ago, Korg's flagship Trinity range has been without a rackmount alternative, leaving musicians with the stark choice of going without or coughing up the readies for a workstation model. With the base model costing almost two and a half grand on release (now down to £1799) this has hardly been a cheap way to get the Trinity's underlying ACCESS (Advanced Control Combined Synthesis System) synthesis and multi‑effects technology.

However, at last the company have come up with a rackmount model, the TR‑Rack. Not only does it make the Trinity's ACCESS technology available at the more, er, accessible price of £999, it also has 32Mb of sound ROM — that's 8Mb more than the Trinity — and provides twice as many built‑in Programs, Combis and Drumkits as the workstation. Presumably this is why Korg describe it as Expanded, because the only expansion option retained from the several workstation models is the DR‑TRI digital audio output board. But despite its extra sonic capabilities, is the new module a case of too little, too late?


The TR‑Rack is an all‑rounder, sample‑based subtractive synthesis module in traditional vein, neither making GM/GS/XG compatibility its mission in life (unlike Roland's SC and Yamaha's MU modules) nor focusing on a particular musical niche (unlike Emu's Orbit and Planet Phatt modules). In this respect, it's more closely aligned to Alesis' QSR and Roland's JV2080 synth modules, which it sits between price‑wise. However, like the Trinity it offers only 32‑voice polyphony — half that of the Alesis and Roland modules.

Korg's new module imports the Trinity's synthesis and multi‑effects capabilities wholesale, while providing an additional 40 Multisamples and 200 drum samples, together with additional patch memories to take advantage of them. Program and Combi banks A and B, which are the same as those on the Trinity, are augmented by new Banks C and D, while the Trinity's 11 Drumkits have been augmented by a further 11 new pre‑programmed kits and a user kit memory.

Seasoned Korg users will feel at home with the TR‑Rack's Program and Combi architectures. Like the Trinity and earlier Korg synths, the TR‑Rack has three performance modes:

  • Program (single part/channel)
  • Combination (up to eight Timbres/channels)
  • Multi (16 Tracks/channels, for use with MIDI sequencing)

For those new to the Korg architecture, a Combination (usually referred to simply as a Combi) allows up to eight Programs to be used together in a composite key and velocity split/layer texture. With their budget NS5R GM/GS/XG module, introduced since the Trinity's release, Korg enabled Combis to be assigned to Multi‑mode Tracks for the first time, providing a convenient way to integrate pre‑defined split/layer textures into a MIDI multitimbral context. However, disappointingly, they haven't taken the opportunity to add this capability to the TR‑Rack (though you can, as always, use Combis MIDI‑multitimbrally by assigning some or all of the Timbres to different MIDI channels).


The TR‑Rack employs a versatile multi‑effects architecture, first introduced on the Trinity, which is built around a mixing desk‑style arrangement of Master (ie. send/return) and Insert effects, with 14 Master and 100 Insert effects to choose from. The Master effects section consists of reverb/delay and modulation effect processors, which are common to individual Programs and to all eight Combi Timbres and all 16 Multi Tracks. Each Program/Timbre/Track has two effect sends per oscillator routed to the Master effects. Returns from these effects are then mixed in with the output from the Insert‑effected signal and routed through master low and high EQ before being sent to the stereo outs. An individual Program, Timbre or Track can have up to three or four Insert effects, depending on whether the selected Program is in single/double or drum mode. These effects are configured in series, with the output from effect 3 routed direct to the main stereo outs and also sendable to the Master effects via two effect sends.

The quality of the effects is everything we've come to expect from Korg, while the sheer number and variety of Insert effects is nothing short of amazing.

Things start to get more complicated when it comes to assigning Insert effects — especially in Combi and Multi modes. Depending, essentially, on their mono/stereo configuration, individual Insert effects are classified as either size 1, size 2 or size 4. Insert effects for each Program, Combi or Multi can't exceed a total combined size of eight, which leaves you trading off number of effects per Timbre/Part against number of Timbres/Parts effected. At one extreme, you could have eight Timbres/Tracks, each with a single size 1 effect, while at the other a single Timbre/Track could use two size 2 effects and one size 4 effect.

First Sight

Korg's TR‑Rack is a standard 1U‑high, 19‑inch rackmount module in a not‑so‑standard silver casing, giving it an appearance that is both stylish and functional. Gone, inevitably, is the large graphical touch‑sensitive screen of the Trinity workstation models. However, in its place a sizable 2x 20‑character backlit LCD provides unusually, yet satisfyingly, large lettering, making it easy to read even from several feet away; not only is this an obvious advantage for a rackmountable module, it also makes the TR‑Rack more readily accessible to partially sighted musicians. The Rack's front‑panel buttons, on the other hand, are of the fiddly fingertip‑sized variety, as favoured more usually by Yamaha — not the most comfortable in use. The volume knob, power on/off switch and stereo headphones socket are all conveniently located on the front panel, leaving a minimalist collection of buttons to the right of the LCD for mode selection, LCD page and parameter selection and editing, and compare, write, reset and note‑play functions. The A4 button simply plays the currently‑selected sound at pitch A4 when pressed — a handy function to have for trying out sounds when you don't have a connected keyboard to hand. A red pinpoint LED above the button acts as a MIDI indicator, flashing on and off when MIDI data is received.

Each Program and Combi on the TR‑Rack is assigned to one of 16 sound categories, indicated in the lower line of the LCD in Play mode. The Rack's front‑panel Cursor left/right buttons double as category‑select buttons in Play mode, while its Page +/‑ buttons let you scroll through Programs or Combis in the current category — making it easy to try out, say, all the keyboard or all the bass sounds. The Yes/No buttons, meanwhile, allow you to step sequentially through all the available patches.To edit Programs or Combis you just press the Edit button and use the Page +/‑ button to scroll through the LCD edit pages. There's no shortage of these — Combi Edit mode has 47 of them! Bizarrely, holding down the page, cursor or yes/no buttons doesn't have a repeater effect, so you have to press the relevant button once for each page or value change. Fortunately, combination button‑presses allow you to 'jump' values in steps of 10 or 128, but overall there's still an unnecessary amount of button‑pressing involved.

Despite the large, clear display, then, front‑panel editing on the TR‑Rack is a bit fiddly, so it's good news that the module comes supplied with two floppy disks containing Emagic's SoundDiver Trinity editor/librarian software and Korg MIDI driver software, both available for Mac and PC. It turns out that the SoundDiver software is essential if you're serious about Program editing, as the module itself doesn't provide full synthesis or effect parameter editing from its front panel; instead, this is left to the editing software and MIDI SysEx. Quite why this is the case isn't clear, as full editing would have entailed only some additional LCD pages. As it is, you're limited to adjusting the overall sound of existing patches (you can't, for instance, assign different Multisamples or drum samples to the oscillators).

Incidentally, while we're on the subject of computer linkups it's worth mentioning that the TR‑Rack's rear panel augments the standard MIDI sockets with a To Host serial port for MIDI communication. Using this port and a standard computer serial cable, you can connect the module to a PC or Mac without the need for an intervening MIDI interface.

The TR‑Rack's rear panel.The TR‑Rack's rear panel.

Synthesis And Sounds

With the TR‑Rack, Korg have eschewed the multi‑synthesis approach of their Prophecy monosynth and Z1 polysynth, in favour of more traditional sample‑based subtractive synthesis. It's worth remembering that the company helped pioneer the sample‑based approach a decade ago with the M1. Over the years they've steadily improved and fine‑tuned it, and the ACCESS synthesis technology of the Trinity, and now the TR‑Rack, represents the most highly developed version. The Trinity has acquired a reputation for superior sonic quality, clarity and presence, thanks not least to its use of 48kHz samples; the desire to maximise signal quality was apparently also the reason why Korg stuck with 32‑voice polyphony.

The TR‑Rack's Program architecture provides two oscillators, each of which is routed through its own filter and amplifier sections with associated five‑stage pitch, filter and amplitude envelopes and pitch and filter LFOs. For each Program you can choose between single/double and drum oscillator modes; the latter allows you to assign any of the Rack's Drumkits to a Program. Korg introduced a number of new developments with their ACCESS technology, to enhance the Trinity's sonic flexibility (all now found also on the TR‑Rack). For instance, you can assign two Multisamples to each oscillator and velocity‑switch between them, with user‑definable switch points. Drumkit programming has been similarly enhanced, with user‑definable velocity switching between two drum sounds on each key; other parameters you can set per individual key include filter on/off (but not individual settings), pan position, master effects send levels, and Insert effect routing (off, 1‑4). A Start Offset parameter allows playback of Multisamples and drum samples to begin from within the sample. This is typically used to soften the attack characteristic of a sample, and can be particularly useful on drum and percussion sounds.

Korg's ACCESS technology brought up to date the filtering on their sample‑based synths, with a multi‑mode resonant filter that the company first introduced on the Prophecy. Two filters per oscillator, a choice of low‑pass, high‑pass, band‑pass and band‑reject filter types, filter resonance, and the ability to modulate resonance from velocity are all features of the Trinity (and now the TR‑Rack) filter section. Also introduced by the ACCESS technology was a sophisticated matrix modulation system which Korg called AMS — Alternate Modulation Source. This provides 26 control sources, routable to 27 destinations, with the ability to assign the same source to more than one destination.

The TR‑Rack will delight anyone who has been waiting for Korg to make the Trinity's impressive sounds and effects available in a more affordable rackmount form.

I've already described the TR‑Rack's sophisticated Master/Insert multi‑effects architecture. The quality of the effects is everything we've come to expect from Korg, while the sheer number and variety of Insert effects is nothing short of amazing. Probably just about every effect you can think of has been included — and remember that you can mix and match effects in series, within the limits imposed by the effect size system. If you love working with effects and exploring effect combinations, the TR‑Rack will keep you happy. Dynamic modulation of effect parameters is also provided, with a choice of 26 modulation sources, so you can do clever tricks like controlling Doppler effect pan depth from aftertouch. Insert effects typically have two or three parameters that can be modulated dynamically, though some have four or even five, so there's plenty of scope for live (and also MIDI sequenceable) effects control. Also controllable live via MIDI are Program, Timbre and Track effect‑send levels for the Master reverb/delay and modulation effects, as well as selected Master effect parameters.

The 40 new Multisamples in the TR‑Rack provide a mixture of keyboard, bass, brass, guitar, hit and and noise sounds, and include a stereo‑sampled acoustic piano which improves on the existing offerings. However, the bulk of the new samples contained in the extra 8Mb of sample ROM are drum samples, and around half of these are new bass and snare drums. Korg have always been both generous and adventurous with their drum and percussion samples, and the TR‑Rack continues satisfyingly in this tradition.

The new samples are put to good use in the new Drumkits, which extend the Trinity's range impressively. The new Programs and Combis, meanwhile, maintain the high standards of programming we've come to expect from Korg, and provide plenty more of the sorts of sounds that Korg fans have come to know and love — not the least of which are rich strings, shimmering pads, punchy basses, crisp keyboards and evocative atmospheres. Check out Program D03: Bells in Motion, and the charmingly titled D83: Chasing Comets, for some classic smooth, shimmering, tinkling pads. Program C23: Old/Dark EP is a lovely swirling old mellow Rhodes sound which makes good use of the Phaser + Tremolo Insert effect (and remember that this effect can be retained in Combi and Multi modes), while C16: Vintage Grand is a '70s‑style electric grand with a very appealing warmth to it. Program D13: Double Strings and D06: Dance Piano provide classic Korg smooth strings and bright, percussive piano respectively, while D01: SinisterDrug@3AM and D21: Drub Square are good examples of the sort of deeply atmospheric sounds that Korg synths do so well.


Unlike the MOSS multi‑synthesis technology of the Prophecy and Z1, the TR‑Rack's ACCESS technology makes no attempt to move beyond the familiar territory of sample‑based subtractive synthesis. At the same time, while the Trinity range can be expanded with an attractively‑priced Prophecy Solo board to complement the sample‑based sounds, the TR‑Rack has no such provision — a fact which will no doubt disappoint some prospective Rack purchasers. According to Korg UK, accommodating a Solo board option in the TR‑Rack would have meant turning the module into a more expensive 2U unit, and they decided instead to keep the price as attractive and the size as compact as possible. Still, the TR‑Rack's generous 32Mb of PCM sample ROM, 512 Programs, 512 Combis and 24 Drumkits — 8Mb more ROM than the Trinity, and double the number of patches and drumkits — mean that you're hardly being short‑changed in the sounds department.

Not being able to assign Combis to Tracks in Multi mode is disappointing, while some users might wish for more than the Rack's two separate outs for external effects processing. The absence of full front‑panel editing is also a little disconcerting, though the included PC/Mac editing software does at least provide computer users with the means to get at every parameter. On a more positive note, the module does retain the Trinity's DI‑TRI board option, allowing its four audio output signals to be transmitted in the digital domain using Alesis' multitrack digital audio format.

The TR‑Rack will delight anyone who has been waiting for Korg to make the Trinity's impressive sounds and effects available in a more affordable rackmount form, and will also, no doubt, re‑establish the company as a major presence in the professional synth module market.


Polyphony: 32 oscillators (single‑oscillator Program: 32‑voice polyphony; double‑oscillator Program: 16‑voice polyphony)
Multitimbrality: 16 parts (in Multi mode); 8 parts (in Combi mode)
Sound ROM: 32Mb
Synthesis method: ACCESS sample‑based subtractive synthesis
Programs: 512 (128 x 4 banks)
Combis: 512 (128 x 4 banks)
Effects: 100 insert effects, 14 master effects
Display: 2 x 20‑character backlit LCD
Connections: L/Mono and Right stereo audio jack outs; two separate audio jack outs; stereo headphones jack; MIDI (In, Out, Thru); To Host PC/Mac serial interface; digital audio out and 48kHz wordclock in (require optional board); AC power input socket
Option: DI‑TRI digital audio interface board
Weight: 2.8kg

Sound Categories


  • Keyboard
  • Organ
  • Mallet
  • Bell
  • Strings
  • Vocal/Airy
  • Brass
  • Woodwind/Reeds
  • Guitar
  • Bass
  • Plucked Synth
  • Synth Lead
  • Motion Synth
  • Sound Effect
  • Drums/Percussion


  • Pad & Lead
  • Bass
  • Splits
  • Breathy/Airy
  • Bell & Mallet
  • Motion Synth
  • Keyboard Synth
  • Strings
  • Orchestral
  • Horn Section
  • Guitar
  • Bass
  • Ethnic/Trad
  • Organ
  • Complex
  • Drums/Special FX


  • Standard
  • Processed
  • Jazz/Brush
  • Analog/Club (Mega‑Mix)!
  • Psycho
  • BassDrum&Snares
  • Toms&Cymbals
  • Percussion
  • Orchestra&Ethnic
  • 01/W Total
  • 01/W Producer's
  • Vintage Kit
  • Ezer Goodie
  • WellArrrd
  • Hip‑Hop/Rap
  • Pop/R&B
  • Jazz/Funk/Reggae
  • House/Techno
  • Industry/Analog
  • Funk Drummin'
  • Aggressiv Vox


  • Characteristic rich, full, dynamic Korg sound.
  • Large PCM ROM.
  • Generous number of Programs and Combis.
  • Large lettering used in the LCD.
  • Trinity editor/librarian software included as standard (for PC/Mac).
  • ADAT digital interfacing option (DI‑TRI board).


  • Full parameter editing only available via MIDI.
  • Can't use Combis in Multi mode.
  • Holding down front‑panel buttons doesn't scroll through values or pages.


An impressive module which will bring the top‑quality, professional sounds of the Trinity workstation to a wider range of synthesists.