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Korg Trident Polyphonic


Korg Trident Polyphonic Synthesiser.


It really must be quite difficult for musicians to assess the more expensive large scale polyphonic synthesisers. Not too many shops can afford to have demonstration instruments for customers to try out, and since these instruments often have multiple outputs (and no built-in echo or reverb) it certainly makes hearing realistically the true potential of sound sources and treatments unlikely. Of course, many dealers are aware that the 'non-musically educated' salesman is just not on - no 'genius at the keys' is called for, simply people who know the instruments' functions well enough to demonstrate them. The larger instrument manufacturers (and shops) often hold regional seminars which are always worth attending and usually free as well. Reading our reviews should help, and listening to the E&MM cassette should give a lot of people a chance to hear the instruments not at their local shops. You may hear an instrument being played at a concert. Rick Wakeman played a stack of Korg instruments recently at Hammersmith, London (see the December 1981 E&MM feature) and out of the melee of instrumental music suddenly came this big orchestral sound - all issuing forth from one instrument, the Trident!

So I'll take a closer look at this impressive synthesiser and perhaps the review will set a few musical minds tingling. Actually, it's been quite a while since I've had that 'shivers down the spine' feeling one usually gets with classical music from a synthesiser - but here it is! So many musicians are still experimenting with multi-tracking, drum machines and effects, that it's easy to overlook the importance of dynamics and subtle layering to enhance the emotional levels that music has always been capable of. There's no criticism implied here - there is so much to learn about the applications of electro-music that it can be a lifetime study, as I'm finding out!

The Trident is really 3 main instruments in one, with 8-voice programmable polyphonic synthesiser, brass and strings. The synthesiser section can be programmed with sounds that are stored in 16 preset memories and it also contains 3 presets for piano tones. Both brass and strings have their own independent sound shaping sections and strings have a unique bowing effect treatment. In addition, a flanger is built into the instrument for on-board treatment for one or more sections. Although the keyboard is not touch-sensitive, there is an 'octave split' facility that lets you place the 3 sections in upper, lower or both keyboard ranges. Further performance effects can be obtained with the joystick controller and delay vibrato.

The instrument is well constructed in the shallow angled style adopted for most of the Korg range except the large 'studio' synthesisers, with rosewood end pieces and plastic/metal panels, measuring 1012(W)x 52(H) x 520(D)mm. It is easily portable at 21 kg and consumes some 40 watts. Nice Korg touches are the main cable tie-up brackets at the rear and also the top panel legending which is useful in the confines of a small studio for locating sockets.

The Trident's sound generation is by eight VCOs, which are controlled by the keyboard via microprocessor-based key assigner. The VCOs are actually linear types, which have superior stability and tracking; there is only one antilog converter which is multiplexed between the VCOs so that they all have exactly the same characteristics.

The VCOs feed eight separate VCFs (based on the SSM 2044 IC) and eight VCAs for the synthesiser section; the string section also has eight VCAs and VCFs, but the filters are simple single-pole types in this case. The brass section also uses eight VCAs, but only one common filter (an SSM 2044), and the bowing effect is also achieved with a single VCA and VCF common to all the voices.

Widespread use is made of 'bucket brigade' analogue delay (BBD) devices; three are used in a 3-phase ensemble generator, with a fourth to provide vibrato. A compressor/expander system is used in this section to reduce noise. A SAD 1024, which has a longer delay time, is used in the flanger section to produce an intense flanging effect.

All the control sections are located in one main block above the keyboard (from left to right): Key Assign, Flanger, Synthesiser, Brass, Strings and Output; the joystick is in the usual position to the left of the keys. On the rear panel is a memory protect switch which ensures 'permanent' storage of your 16 preset synthesiser sounds, along with 13 jack sockets for signal outputs and various control options. It's worth noting these initially as they offer several useful functions. First, volume pedals (such as Korg MS-01, 04) can control a mixed volume output or any one or more of the 3 main sections with low/high level output jacks sockets provided. The Brass and Synthesiser sections' VCFs can have their cut-off frequency modulated via a pedal - making a possible five pedals usable in a working situation! There is a damper jack for footswitch control of piano presets (Piano 1, 2, Clav) sustain and extension of synth release time. A Brass external trigger IN gives that extra control from a sequencer, drum machine, foot-switch or trigger controller (e.g. Synclock).

Key Assign



The Trident uses micro circuitry to process information from the keyboard and controls 8 separate synthesiser units for polyphonic 8-note playing. A total tune control sets the keyboard pitch + one semitone for matching to other instruments.

An Assign mode switch gives two options of playing action for the synth section: either employing a different VCO Circuit Module for each key, so that long release settings will continue for each note; or where the same module operates for each key (unless additional notes are played), so that only the last notes have the release. The first mode is ideal for harp, guitar and piano style playing, whilst the second effectively emulates an ensemble. One little irritation however is that no change of mode must be made whilst notes sound or you'll have a temporary drop in pitch to the lowest note!

The Trident opened up.


Synthesiser



This section consists of 2 VCOs, VCF and VCA programmable controls which are coloured orange. VCO1 contains 16',8',4' pitch selection of sawtooth, square wave, pulse width (PW) and pulse width modulated (PWM) waveforms. So anything resembling a sine or triangle is obtained by filtering one of these. In fact, the waveforms on an oscilloscope showed slight impurity in the stated waves (with a reversed sawtooth used), although it was not really noticeable when listening. There's also PW/PWM basic pulse 'shape' and PWM 'speed' controls. The speed varies from 2 cycles per second to a fast buzz. Some slight jitter of the waveform was noticed when pulse width was manually changed.

VCO2 can be added to VCO1 at 16', 8' and 4' pitches and it's nice to see a programmable 'detune' pitch control (± one semitone). Often, this has to be done manually on other synthesisers. Korg takes this a step further by providing a 'detune' switch that lets you readjust VCO2 detune, yet still holds programmed settings.

No noise generator is provided, which is a surprise on an instrument of this calibre.

The VCF is a low pass type with cut-off frequency, resonance and EG depth controls. The latter is interesting because at positions right of centre '0' it gives increasing positive intensity for the EG shape, and to the left it gives increasing negative intensity. A three-position switch selects the amount of change in cut-off frequency according to keyboard notes played - either off, half or full. Since the filter will go into self-oscillation above setting 8 on resonance, this keyboard track switch is useful for using the filter oscillation musically.

The VCA can be switched to operate from the EG controls (the usual ADSR) or with on/off organ style keying. Maximum times are: attack 25, decay 18, and release 18 seconds.

Besides the detune option, there is a cutoff frequency 'fine' adjustment control (with centre indent) and a solo release on/off switch which are not programmable. The latter puts release on the last note only during mono solos.

Programming is extremely easy. Once a synthesiser sound is created in the 'manual' mode, one of the sixteen 'program' positions is selected using Bank A, B and program 1-8 buttons. Having selected Bank A or B with memory protection switch off, a press of the 'programmer write' button at the same time as a program number button will store your settings.

Three piano tone presets are also provided: Piano 1 - acoustic, Piano 2 - electric, and Clav - a bright 'clavinet', harpsichord type of sound. They are really programmes that are internally preset settings of the synthesiser section. Some improvements to these sounds could have been made by the provision of a separate EG for the VCF. Nevertheless, the cut-off frequency 'fine' control allows plenty of tonal adjustment.

A volume control and on/off output switch completes the synthesiser section. Similar controls are given for brass and strings so that together they really act as mixer levels with a total volume mix for the three sections provided in the final output stage. Here also is a phones output socket and level control.

Brass



Some fine brass sounds, solo and ensemble, can be achieved with this section, and the provision of VCF and EG controls gives the player what is in effect use of another poly synthesiser (but with only one common filter). Both 16' and 8' pitches can be combined and sent to a VCF (similar to the synthesiser). Thus, the possibility of using two oscillating filters at once gives scope for new effects. The EG intensity for the brass only sets positive levels for the ADSR shaping controls provided. Maximum times for the EG are: Attack 4, Decay 6 and Release 14 seconds.

An interesting item from the top-of-the-range Korg studio PS3300 is the Trigger Select. This will restrict operation of the Brass EG until 2,4,6 or 8 notes are played together, according to the switch position. Multiple or single triggering is also selectable and an external foot switch will also trigger this section. These internal interfacing extras give the brass much greater independence when playing with synth and strings in the same part of the keyboard - brass sounds fade away or punctuate, whilst strings hold on and synth has a contrasting character of its own. So here's how the Trident makes such a powerful orchestral blend in live performance.

Strings



The full blend of double bass, cello, viola and violin is captured using the 16', 8' and 4' pitches in combination or separately. Volume shaping is done with attack and release controls, with full sustain level held whilst one or more notes are played. Maximum times are: attack 12 and release 16 seconds. Instead of a VCF, the strings go through an adjustable equaliser with high and low settings. When using these with a filter 'keyboard balance' control, a wide range of string timbres that mellow or brighten over the keyboard can be obtained. For example, it's usually essential to soften the bass and brighten the top octaves to get a string quartet sound.

Three effects can be switched in or out independently: Vibrato, Ensemble and Bowing. Vibrato is generated with a BBD chip and can be delayed up to 1 second. Vibrato intensity and speed can also be set. Ensemble is the familiar 3-stage BBD phase effect for string orchestra sound. 'Bowing' is an effect so far unique in name to this Korg instrument, but it actually is simply a preset AR envelope that operates on new keys played (after all notes are released) to simulate the accent heard at the start of bowing across the string. When creating solo instrumental sounds it adds that extra touch of realism. Tone and volume level controls adjust the depth of filter and amplifier change. It obviously only works when the string attack time is kept short.

Rear connections.


Vibrato and Joystick



Besides the strings having vibrato, a general vibrato is provided operating on all three sections at once. A fixed delay of ½-second can be switched in and intensity can be adjusted. Hence, the quality of orchestral strings, for example, is due to five BBDs operating at different speeds to give that minute variation of pitch common to unison strings.

The performance control on the Trident is the traditional Korg 4-way joystick. I enjoy using this, although you obviously have to take your left hand off the keys to move it, and that's really not the answer for a polyphonic - maybe we'll be going back to the knee levers and foot pedal rocker switches next! If you play in a band, it's no problem of course - it's the solo player that is restricted somewhat. Left and right movement of the joystick gives pitchbend down and up a fifth. Move the stick up and you get vibrato, move it down and trills appear - both set by intensity and speed controls. Trills can be done up to a minor 3rd interval.

Finally, the Trident in many ways achieves a characteristic sound all of its own simply because it incorporates a very good flanger. This creates not only flanging, but rich phasing effects that can be switched in or out of each section. Using speed (with up to 15 seconds per cycle), intensity, feedback and centre delay time (called manual) controls, some remarkably clear metallic sounds, moving phase and flange, feedback swoops etc. are easily produced. The flanged signal returns onto the separate section lines prior to mixing and therefore gives an unusual mix with 2 or 3 sections in flange mode - each Output carrying a general flange mix. Some signal cancellation might be expected, but in fact the aural result is a pseudo stereo effect that spreads the sound nicely.

Conclusions



Flanger adds the finishing touch to an instrument that has the potential to produce a tremendous variety of musical sounds. Since flanging and phasing have become vital sound treatments for the musician, it is e a sensible addition for the Trident.

I would have liked a separate EG for the synthesiser VCF and the inclusion of a noise generator - both important items for good synthesis. I also have to admit a preference for left volume controls in one place for all sections, although the optional pedals more than make up for this. It is surprising that no touch-sensitivity is incorporated - Korg's Sigma has it and it would have given that extra playability in performance.

The control parameters are more than adequate and the layering and synthesising possible on the Trident, combined with programming makes this an instrument that gets better the more you play it.

The Trident costs £2,310, including VAT and is distributed in the U.K. by Rose Morris & Co., Ltd., (Contact Details).



Previous Article in this issue

Advanced Music Synthesis

Next article in this issue

AKG D330BT and D202


Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.

 

Electronics & Music Maker - Feb 1982

Scanned by: Stewart Lawler

Gear in this article:

Keyboard > Korg > Trident

Previous article in this issue:

> Advanced Music Synthesis

Next article in this issue:

> AKG D330BT and D202


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