This second article about New England Digital's Synclavier II is intended to be less of a review and more of a discussion of the innovative features that make up the real-time performance system.

The basic set-up of the Synclavier II for performance consists of a keyboard unit; a squarish 19" rack size 'black box' (known as the digital synthesiser) containing the 16-bit 'Able' micro and up to 4 synthesiser cards, each with 8 complete synthesiser voices, and in/out peripheral connections; one or two disk drives, a couple of Morley pedals for real-time changes, and (for the UK) an AC/AC converter to match power supplies correctly.

There are other options that can be added to this hardware - a Winchester disk will greatly increase memory storage and access time, a computer terminal (VDU + alphanumeric keyboard) gives visual programming and comprehensive sound sampling, and a printer lets you print out a complete musical score. All this is discussed in the February 1983 issue of E&MM.

Since the cost of the 32-voice synthesiser performance 'package' as outlined is the princely sum of £21,900, the decision to invest in the Synclavier must be a purely personal one that is precisely based on your musical requirements at this time and for a good few years to come. At the moment, the outpouring of computer-based instruments makes a 'compu-age' machine an attractive proposition. Nevertheless, the price range is as wide as the options available to us. Is it really necessary to spend all that money just for the privilege of owning one of the most expensive systems around?

Well, fortunately the speculation doesn't end there because the Synclavier does enable sophisticated sound synthesis to be achieved in its own unique way - through the use of Partial Timbres. But is the quality up to studio use? Is it easy and quick to use in performance? Do the performance controls give plenty of on-stage effects? Is the system reliable as a portable package? These and many other questions are the more 'personal' attributes that will obviously help you make your decision.

There's no doubt the Synclavier is up to studio recording standard - the sound sampling is particularly clear - although there are two filter cut-off's that remove the high frequency clocking/glitching (heard as a sort of metallic ringing, especially on low notes) and always need to be considered. In practice, many studios direct inject the instrument's mono output without filtering and then use a steep low pass filter or parametric EQ to present the optimum signal.

This signal 'clean-up' may seem a somewhat detrimental step, especially for musicians who steer away from noise reduction, limiters and the like, but it's likely to be standard practice for computer music systems in the immediate future - for instance, with sound sampling there's a need on occasion to redefine the HF cut-off for a new timbre or 'edge' - and systems like the Fairlight use software to specify individual filter levels (aside from normal filter shaping). The final result is in most users' opinion perfectly usable.

Another factor in this additive/FM synthesis system is the possibility of an extremely strong unrelated overtone that does wonders to the edges of your speaker cone! The range of volume is certainly wide and simply means that the potential is there to be used sensibly. Tremendously bright sounds with the utmost clarity are a feature of this instrument - a specific example (provided by Bernard Xolotl) is Don Robertson's 'Star Music' on E&MM Cassette 9. Put the FM Ratio Control into operation and you'll get the most realistic bell sounds you've ever heard, but how do you get anything else you want? Well, the main panel controls on the keyboard unit allow you to set the precise 'timbre' for any notes played as with any other synthesiser. But the way it's done is completely different.

As for general portability, the system can be packed into 3 flight cases, one for the synth boards and computer which is supplied, and two optional cases for keyboard unit and disk drive, leads etc. - all of which fits into the back of a Ford Capri. The keyboard unit only weighs 25 lbs - less than a Minimoog!

So the performance set-up can be done surprisingly quickly, and with a set of 64 sounds loaded from disks (and a polysequencer as well, if you want), each of the 128 red buttons on the front control panel above the 61-note C-C keyboard are illuminated (on or blinking) when selected to give you direct feedback of the current status.

Control Layout

The front panel is divided into 5 main sections from left to right, starting with a large spring-loaded knob that changes settings of the variable function buttons in the remaining 4 sections.

Unlike the Moog Source control knob that relies on mechanical momentum from the musician's left hand to reach its target setting, this knob is a 'return-to-centre-off' spring action that allows increasing count up or down dependent on how far to the left or right you turn it. The result is shown as 4 digits on the display 'window'. It also indicates the number of voices in the system on power-up, as well as each time a new sound timbre is selected. During recording, it shows the tempo readout based on the built-in metronome, and the number of notes left in the recorder. Errors in recording are also shown as they occur and the particular 'unit' in use is seen from one of 4 red LEDs for milliseconds, Hertz, Decibels or Arbitrary.

The selection buttons are in four groups from left to right for the envelope generators and pitch/harmonic control, 16-track digital memory recorder, keyboard instrument control and real-time effects, and timbre store/recall to and from disk.

Digital Synthesis

The Synclavier II has voice synthesiser channels (normally from 8 to 32) that use digital techniques to generate audio timbres. Waveforms are generated from a series of numbers through digital-to-analogue conversion. The external computer receives information for a note played - its harmonic content, volume envelope, duration, pitch and other parameters - from the keyboard unit, and transfers it to the synthesisers as a complete set of data. In this way, the digital synthesisers can carry out the repetitive job of producing waveforms while the computer 'organises' the situation.

Disk Drives

One or two of these can be used in either 5¼" or 8" format (the former is more readily available), and these provide the system program software as well as storage for your timbres and sequences. Here then, is one of the biggest selling features of the Synclavier II - the possibility at any time to update your operating system software or indeed change it to perform a completely different task. For example, by loading NED's SCRIPT program you've created a whole new computer VDU orientated editor/composer system. Of course, the hardware must be versatile enough and of sufficient quality to communicate with this software, which is presumably why NED have kept the keyboard unit as the 'musicians interface', with easily updated voice cards in the main computer/synth box.

It takes just over 10 seconds to use the disk to load 64 new timbres (i.e. program sounds) into the keyboard unit. 10 disks are supplied for the performance system. Five are back-up copies and consist of a system software disk, plus 4 others with 64 different examples of timbres on each as well as space for 8 x 10,000 note and 2 x 6,400 note sequences made with the 16-track recorder (on 5¼" disk - 8" gives more).

In the timbre store/recall section, two rows of 8 buttons let you recall a particular timbre on the loaded disk (taking only one second to do so). The current keyboard timbre will remain - a nice detail - until you use the recall buttons.

A wide range of sound timbres are given as examples, many of which are reproduced on E&MM Cassette 9, along with some live sound samples. They include traditional instruments, sound effects like church bells, percussion, and more synth-type sounds. No noticeable instrument omission is apparent - percussion sounds are particularly interesting including cymbals as well, with plenty of strings, woodwind, brass, piano and plucked instruments.

Up to 8 voices will be used to make a particular timbre for each note played, so the 32-voice system may reduce your polyphony to 4 notes at a time occasionally. The Synclavier only does this when the 'chorus' function is used, in reality giving a duplication of a voice with slight detuning. Nevertheless, the computer is always making maximum use of the 32 voices so that mixed timbres may well be alternating on the same voice with the memory recorder for full track operation, and you are able to specify several different mono/poly algorithms.

The Partial Timbre Method

Each synthesiser voice is termed a partial timbre and from one to four of these go together to produce a complete TIMBRE. The partial timbre has its own tuning, harmonic structure, frequency modulation, volume envelope, vibrato and portamento.

In a similar way to analogue machines, a sound is built up in steps, but not with VCO, VCF, VCA and LFO elements. Instead, the first step is to make a periodic waveform from a simple sine wave to a complex wave with up to 24 harmonic components.

Next, this waveform may be frequency modulated (FM). Immediately the character will be greatly changed with sparkling overtones to give very bright, brassy, percussive or resonant sounds that may be unrelated to the fundamental - here's where the metallic clangs, bells and exciting tonal nuances come from.

After these 'steady states', two temporal shapes can be set for Volume Envelope (VE) and for depth of FM modulation, called the Harmonic Envelope (HE).

All this is set up using the button on the left of the panel with the control knob and forms the basis for making a partial timbre. Further musical embellishments can be added, such as vibrato and portamento. A further three partial timbres can be made to combine with the first one to make your final timbre. Already, the complexity of the sound, or rather the 'synthesising potential' is increased greatly over most synth systems currently available. Even further modifications can be made, such as individual tuning for each timbre and different start times, as well as changes to the 'whole' timbre - up to an amazingly rich note containing 8 synthesisers for 4 partials with chorus!

Harmonic Coefficients

On the Synclavier II, the periodic waveform is constructed by adding 24 harmonically related sine waves of different amplitudes through a process of Fourier additive synthesis. In the Pitch/Harmonic control section, the buttons are used to select the particular harmonic and the control knob then sets its amplitude. Any changes you make can be heard by pressing a key at any time. Square, sawtooth and triangle can be dialled in to save time and a group of harmonics can be set simultaneously for equal amplitude.

Frequency Modulation

This is created by phase-modulating the periodic waveform by another sine wave. What is interesting, is that the additional overtones that result from FM may be harmonically or inharmonically related to the original tone, depending on the 'ratio' of their frequency. A 'spectral plot' paragraph can be made of overtones versus frequency to show that these overtones may well appear below the original (or carrier) frequency as well as above. This is the case with non-integer FM ratios, e.g. 0.1, unlike integer FM ratios, where the spectrum is harmonic and above the carrier.

In more practical music terms, you get less of your basic sound (periodic waveform) as you increase FM modulation depth and more increase in the new overtones - so here's another feature of the Synclavier that makes tone changes with a difference. In practice, it takes some time to get something musical going with FM that doesn't turn into gongs and the like. Very subtle tuning is required for the harmonic envelope's peak, sustain and FM ratio settings.

Temporal Envelopes

The heading sounds different, but it's really good old EG for changing filter (harmonics) and volume. Both HE and VE have a similar function button to define these parameters through time: delay, attack, initial decay, final decay can be set from 0 to 99mS with peak and sustain for VE from 0.0 - 100.0dB and HE from 0 to 1000arb. The unusual feature here is the variable peak level - most analogue synths have a maximum for this, and it enables much more variation between the partials. The variable delay time is also something that should be on every synth with multi-EGs.

Modulation

The keyboard instrument control section offers the sophisticated sort of modulation synthesists expect. Vibrato can be given to each partial using one of 10 wave shapes - five each for sine, triangle, sawtooth, inverted sawtooth and square, which either brings in the effect by setting rate, depth, and attack (a gradual increase in modulation over maximum 10 seconds), or by setting peak or sustain for the HE above zero.

Portamento can be a gradual slide between notes (polyphonically) over a long period of one minute or less. The slide can be linear, changing at the same rate from start to finish, or logarithmic, which accelerates the pitch change.

Tuning can be adjusted conveniently in octaves (cycling through with the button) or with a control knob from 0.0 to 1760.0 in .1Hz increments. Tremolo (AM) can be obtained by using small tuning offsets between partials to produce 'beating' of waveforms, and tuning is important to create the widest use of different harmonics in each partial.

Another interesting feature is Final Decay adjustment that will double the length of the final decays every octave lower. Piano-type sounds obviously become more realistic for a start.

A Bounce button saves a lot of time as it will copy one partial timbre onto another - useful when 4 partials are basically the same for a particular timbre, like an organ note with just pitch differences. Partial timbres can also be selected for a sound in the memory bank to form a new timbre. Erasing partials is also easy to do.

The Chorus function duplicates a partial at a preset interval apart, from rich unison doubling (by slight detuning) to several octaves up or down.

Repeat gives continuous triggering of keys held and Arpeggiate causes notes to sound one after another (in the order of playing). Incidentally, the memory recorder will store these effects.

Performance Controls

Overall tuning of the keyboard is quickly done with the Tuning Base function - normally A = 440 Hertz (with other notes computed for the mathematical ratio 1.059462 to give the equal-tempered scale we all use these days). An Octave Ratio function allows different note span tuning such as microtones, quarter tones and whole tones.

It's also possible to change the relative pitch of any note in the scale with the buttons in the Pitch/Harmonic control section: C could be slightly sharp, D could be slightly flat and so on. New scaling will be saved on disc when a timbre bank is stored for later recall in performance. Of course, it may be purely academic to play with Just Intonation, Pythagorean or Mean Tone scaling, unless you're intending to perform pre-Baroque or Baroque music with a synthesiser - who's going to accept that, I wonder?

The Synclavier II keyboard can be split into lower and upper sections, with a different timbre on each. Split is at middle C by default, or wherever you want by pressing the split-point note. Real-time pitch bend is, I am told, not likely to be available from the long ribbon controller shown in the pics as it was rather too much like the Yamaha CS range controller. Nevertheless, you can use the control knob instead, over a maximum bend of 2 octaves up or down. Unlike the Chroma, pitch bend or volume changes cannot be recorded.

Foot Pedals

Two American Morley pedals can be used for overall volume control and real-time changes. A whole section of 16 buttons is devoted to the latter for switching effects on or off, so due consideration to performance control has played an important part in the instruments design.

A 'patch' of different effects to be controlled by the pedals can be saved on disk and changes can be made to Attack, Decay, Peak/Sustain level of the HE and/or VE for 1 to 4 partials in use, Portamento rate, and optional Key Velocity. All these changes can be recorded with the music as they occur.

Rear Panel

Footswitches can be inserted in the rear sockets for hold, repeat, Portamento, Sustain and Arpeggiate. A variable level headphone output is provided plus punch in/out footswitch for the recorder, CV outs for Keyboard Gate, Trigger, CV (1V/Oct on last key played) and possibly ribbon. There's also additional analogue machine CV outputs linked to controls in the output filter section that enable Low Pass, High Pass and Band Pass parameters in external filters to receive either fixed or variable CV outputs from the last key played - maximum volts to about 10V.

Finally, a Pitch Bend input enables an external sequencer CV to control timbre pitch.

16 Track Digital Memory Recorder

There's space only for a brief mention of this obviously important feature. It's almost like using a 16 track tape recorder as the controls are similarly named, but the final output will either be a mono mix or a stereo mix. The latter is an option that will allow defining of each track output from 0-200 points across the stereo field.

Undoubtedly, the pro-user will consider this factor carefully - there are easy ways to overcome the limited output facility, but they do involve using a studio multitrack recorder to lay similar tracks in groups at a time, so that further processing can be made in the usual selective way. Don Robertson has had individual output sockets built into the system, and others like Patrick Gleeson have sync'd two machines together for full stereo imaging.

Basically, the recorder offers 16 tracks recorded individually with 16 different timbres that can be played back with any combination of tracks from internal sync or an external sync source of 50 Hz (prerecorded from the Synclavier as a click track on your multitrack machine). Tracks can be merged to give up to 32 voices on just one. External footswitch punch in/out is provided and fast forward and reverse controls accelerate like a normal recorder. Both speed and pitch can each be varied for any of the 16 tracks independently. Transposition of any sequence track is possible and a very special facility is looping that can be done as many times as you like for a given number of notes on any one track. This is a great programming time and memory saver, with breaking-out of the loop at any time done manually, as well as track 'soloing' for monitoring purposes. Other extras include overdubbing of the same sound on one track, or bouncing down the same instrument to one track, while SMT (Select Memory Timbre) lets you swop instrument timbres around after recording, and SKT (Select Keyboard Timbre) will change any part of the timbre make-up on a particular track without the need to re-record it.

Ultimate Synthesis?

This short discussion can only serve to highlight the features of the Synclavier II which are presented fully in two very large manuals (with regular updates). Certainly, every musician should be aware of its unique method of synthesis and provided you accept its inputting methods, it is likely to enable the most exacting construction of sounds (or timbres, as they say). For your money, then, the quality is there and the computer software such as SCRIPT, with sound sampling, as well as a complete programming language (MAX) for you to develop your own system software must be regarded as a highly sophisticated open-ended workhorse for the professional composer, particularly if he or she likes to perform his or her music as well. Gerry Rafferty, Tony Banks (Genesis) and Phil Oakey (Human League) have just purchased Synclavier II's, so we should be hearing a lot of new sounds in the near future.