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Elka Synthex

The Synthex was first introduced to the music public in prototype form at the Frankfurt Musik Messe in 1981. It represented a radical departure for the well established Elka-Orla company in Italy, who are well known for their large range of home and portable organs, rotary speakers, amplifiers, string and preset instruments and drum machines.

The design of the Synthex was initiated as a complex synthesiser rather than a development of an Elka organ and was done by a local engineer who now works full time with the Elka research team at their Italian factory. At its launch it generated a lot of excitement, utilising the best of the TTL/CMOS circuit designs available. Nevertheless, its venture was such an important one for Elka that they were anxious to get their first polyphonic synth full of the features that would benefit musicians. More research and development resulted in the substantially improved instrument appearing at Frankfurt in 1982, with additions that included the sequencer.

There is no doubt that the features and quality of the Synthex as a true polyphonic synthesiser put this Elka product well in the running alongside current, higher-priced instruments.

The Synthex is an 8-voice digital polyphonic synthesiser - that means it has 8 complete synth 'voice' circuits available, each with 2 oscillators, noise generator selection, multimode filter, filter EG and amplifier EG for individual triggering from each note played in one of 3 different modes. Extensive LFO, joystick, ring modulation, glide/portamento, detuning and transposition effects are available as well as different chorus options. The whole instrument is entirely programmable and will store 40 of your own programmed sounds as well as 40 factory-made presets. At any time a program can be updated and reprogrammed. The instrument has a 2-channel output with footswitch options and standard mono cassette interfacing for storage of your programs.

In addition it features a versatile 4-track sequencer capable of recording four monophonic lines that can be looped, edited, transposed, synchronised with external instruments such as drum machines, and allocated to a portion of the keyboard so you can play along with the sequence in realtime. The sequence can then be dumped on to cassette tape through the interface.

Synthex opened up.


The instrument is supplied with a strong chrome stand that allows you to set your playing angle, as well as a flight case for transportation. The control panel areas are built on a black metal chassis that fits into a dark wooden case measuring 20 x 43 x 6 (W,L,H) inches, and weighing approx. 90lbs.

The whole layout of the controls is logically presented, with left to right placement of synthesis sections across the upper main panels as you'd expect: LFO, Tuning, Oscillator 1 & 2, Glide/Portamento, Noise, Filter, EGs and Envelope Control, and chorus effects.

Directly above the 61 note C to C keyboard are the joystick, program selection buttons and volume controls. To the left of the keyboard is the sequencer section and although it's more usual to find performance controllers here, it does make you want to 'play' it in performance.

Access to the internal circuitry is made by removing 4 screws and lifting the hinged front panel. Actual construction and wiring is extremely creditable as the photographs show.

The analogue style digital controls have their individual circuit boards mounted directly behind the panel, whilst the main processor, EPROM (2516) storage of factory presets, and logic control boards are mounted in the instrument base to the left of the 4 voice cards containing dual synth voices. Incidentally, these each consist of no less than 109 TTL/CMOS ICs! With this high chip count, the designers have wisely incorporated a fan in the base right hand corner next to the power supply.

The whole system runs extremely quietly (including the fan), with presumably straight interchanging of most boards for quick servicing being essential since the ICs are mainly direct-soldered onto PCBs.

Playing Modes

Since the synthesiser is a programmable preset polyphonic, it is provided with a control panel that always gives visually an indication of what's going on. Then at any time you can instantly modify any control by simply adjusting it. All the white selection buttons have built-in red LEDs to show their selection for a particular sound - whether factory preset, your program memory preset or panel. The 26 black rotary controls are also programmable and Tuning, Volume, Balance and Sequencer rotary pots are white to indicate non-program types.

Once the instrument is connected (to a stereo system for best effect) via 'Upper' and 'Lower' jack sockets and switched on at the rear, playing can immediately commence by selecting Preset, Bank and Program buttons to give one of the 40 factory preset sounds.

Three playing modes are available: Normal, Split and Double. The default mode is always Normal, which puts the last chosen sound over the entire keyboard. Playing in stereo is enhanced by notes being allocated to left and right (i.e. upper and lower outputs) in apparent random fashion as you play.

Pressing the Split button along with your chosen split-point note on the keyboard puts different sounds at lower and upper ends. The upper sound selected is shown by the display LEDs (including an Upper button) and can be further modified via the panel or completely reprogrammed by choosing a new user memory or preset sound. Similarly, depressing the Lower button shows the setting for the lower part of the keyboard which can then be further edited also.

The third mode is Double and puts lower/upper presets on each note played (but of course, reduces the number of notes available to four). That offers the possibility of big sounds using four oscillators per note and complex synthesising from two presets combining together.

In the volume section there's Balance (between upper and lower presets), Output Volume and a Stereo/Mono switch to complete the basic setting up.

Part of the main panel.

Memorising a Sound

The programming section contains four groups of switch buttons: Banks 1-4, Programs, 0-9, Memory/Preset/Panel/Write buttons and Split/Double/Upper/Lower buttons.

A combination of Bank and Program buttons allows you to select either 40 factory presets or 40 of your own 'Memory' presets. A sound can be put into a memory allocation by simply choosing Preset or Panel, and then pressing down Memory and Write buttons, whose LEDs flash 4 times to indicate it's entered.

You can't swap directly, say Preset 4 Bank 1 with Preset 3 Bank 2, but you can take Preset 1 Bank 1 and put it into Memory 1 Bank 1. If you do need to use a sound in a different location, you can take a preset program and copy it on the panel (by following LED settings and trimming pots) and enter that instead.

Writing in the sounds is therefore straightforward and a 'Write Enable' switch at the rear protects your memories during performances. A useful footswitch function is 'Program Advance' which steps round the 0-9 program buttons, making quick changes of performance easy (once you've selected the right Bank).

Synth controls

In the tuning section, a Master Tune control gives ± 1 tone adjustment to other instruments. Programmed controls are Detune ± 1 semitone and Oscillator 2 Sync button, which locks the pitch of Osc. 2 to Osc. 1.

Two comprehensive oscillators are provided with virtually the same controls. Five octave switches select 16, 8, 4, 2, 1 pitch footages and there's a Transpose switch for each that gives rotary switching 0-12 semitones (up to 1 octave).

Sequencer section.

The six waveforms available are triangle, sawtooth, square, pulse, Osc. 2 (or 1) pulse width modulation and ring modulation. A pulse width control sets pulse shape between 0 and 100% (in other words you'll lose it at both ends). The Oscillator Modulation button simply utilises the other oscillator as its modulation source (the only difference between the oscillators). The effect is more related to the buzzing you get from fast LFO modulation of pitch. The digital Ring Modulator also relies on the use of both oscillators as inputs to produce sum and difference frequencies. The advantage overall of both these settings is that they enable complex ringing sounds of the bells, cymbals, gongs variety - especially coupled with the use of the two Transpose switches for creating musically precise timbres. In fact, the Transpose switches make good performance controls in themselves for instant 5⅓, 2⅔ and other mixture settings.

Volume control for each oscillator is also provided so that your sound programs can all be set at the right level. A Glide/Portamento section offers these pitch effects for either or both Osc. 1 and 2. Portamento gives fastest slide effect at '0' (but not off) and 5 seconds slide at maximum speed setting. The effect always occurs at the rate set independent of position. An interesting Glide effect can be made some 32 semitones up or down to the notes(s) played, although the bottom note of the keyboard is its lowest note available. White and Pink noise can also be chosen in the noise generator section plus volume adjustment.

Multimode Filter. This particular section offers more filter control than you'll find on most synths, with 24dB/0ct Low Pass (standard filter for sharp, dramatic synth tone changes), 6 dB/Oct Band Pass (for gentle selective filtering), 12 dB/Oct Band Pass (for fat brassy sounds), and 12 dB/Oct High Pass (for thin, stringy, ethereal effects).

The normal Frequency Cutoff, Resonance, Keyboard Filter Follow (0-100%) and filter Envelope Depth controls are given, with Resonance going smoothly into oscillation at its halfway point. This produces good definition of harmonics (as you'll hear on Demo Cassette No. 8). There's also inversion of the envelope which is always interesting to use when you can add a positive envelope with it (as in Double mode).

Separate Filter and Amplifier envelopes have Attack, Decay, Sustain and Release controls with maximum times of Attack at 8 seconds and Decay/Release at 30 seconds. Two extra Envelope Controls put the VCA into Hold (continuously on) and select Release, the latter making quick changes to 'organ' style keying possible.

In keeping with other polysynths, chorus circuitry can be added at the end of the signal chain, with 3 types of effect available. These give varying degrees of chorus by inserting one to three free-phase BBDs in parallel - ideal for rich orchestral ensembles or more bizarre effects. One unusual occurrence was that during switching of the Chorus buttons, the sounds playing during release of a note switched off abruptly.

LFO and Tuning sections.


The LFO section is another special for the Synthex, quite separate from Joystick modulation which employs its own separate LFO. There are four waveforms to choose: Triangle, Sawtooth, Inverted Sawtooth and Square. Besides a Frequency Control (from a fast 30 cycles or so to slow 1 cycle every 12 secs), there's routing paths with individual depth adjustment for Osc. 1/Osc. 2, Pulse Width 1 & 2 and Filter/Amp modulations (this with delayed switch-on up to 10 secs).

Joystick. It's quite a luxury even today to have an extra LFO, so this performance controller offers 4-way modulation effects of Bend up and down, Oscillator and Filter. Both Oscillator and Filter have modulation controls for Bend and LFO on Upper, Lower or both sound programs in use. The frequency of this LFO 2 is set by two sliders that together give a wide range of Initial and Delta modulation effects. Pitchbend is ± 5th interval and slight glitching was noticeable on upward bend towards its maximum position.

Rear connections.


The advantages of the sequencer should be obvious to most synth players and inbuilt systems are equally attractive provided they're easy to use in performance. This sequencer is able to record and playback at variable speed (set by the Frequency control or an external clock 'Sync In') up to four monophonic tracks. Recording of each track can be either in realtime with automatic error correction (i.e. tidying up of extra sequences to the first sequence), or step by step up to 128 notes per track.

Since no manual is available in English to date, here's how the sequencer functions. Two groups of buttons, some with multifunctions, operate the Sequencer. The first has Write, Beats/Rests/Split, Delete, Loop, Stop/Ready/Reset, with the second selecting the four tracks. There's also a Gate control that adjusts the size of the pulse in step mode to enable staccato/legato playback.

Writing a Sequence. For Realtime mode: Press Write, Sequence 1, 2, 3 or 4, then press Ready. Set Frequency to centre position or higher (otherwise it won't catch fast notes). Press Play and the sequence starts from the first key played. The sequence LED flashes at the frequency selected, and goes out when you press Stop, or it's run out of memory, or you've added Loop to keep it repeating.

For Step Mode: Press Write, Sequence number, then play note required followed by Beats button until you've finished - then press Stop. The Beats LED flashes to show it's taken the note and if you want a rest you simply press the button without playing a note in between. You can specify a 'sustain on' by making sure you hold down the note during Beats press.

To playback in either mode: Press Ready, any of the sequence tracks you require, then press any key to start - the actual key pressed will set the pitch of the replayed sequence. Choosing new keys during playback will immediately change the pitch of the whole sequence on the next pulse (or note in real time). To finish press Stop or use Loop for continuous repeats.

There's also a Sync Out socket at the rear for sending the clock pulse to control other sequencers or drum machines, although it's more likely in practice that you'll use Sync In from a tape code track or drum machine.

If you add another sequence - I tried one in Step mode starting on an off-beat, this plays back as it should until you put it with Sequence 1 when it pulls itself onto the beat to synchronise itself - quite inventive for a micro!

Whilst you're adding further sequences, the previously recorded ones can be played to get correct multitracking. It's done by pressing Write, the sequence track numbers to be recorded, then Ready. Now the playback sequences are selected and the recording starts as soon as a note is played. If your first note is a rest, you simply play any note first and then start the sequence from its number button.

Starts always take place from the beginning and can be initiated if you prefer by pressing a key, then the Seq. button, but each time you add another track you always have to bring it in right at the start to make musical sense of multitracked lines.

Close-up of processor and voice boards.

Playback with normal mode gives centre mono on chosen memory/preset/panel sound. Then you can use Split for using sequencer on lower, with you playing on upper keyboard along with it. In Double mode, the top 2 octaves are available to play while the sequencer uses the lower notes for pitch access - but 4 sequences will take all 8 voices leaving you with none!

Editing is reasonably easy and facilitates deletion of notes in several ways. For example, when the sequence is running, pressing the Write button enables stepping through the sequence by tapping the Sequence button until the wrong note is reached. The note is then deleted by pressing the Delete button and one or more notes can be inserted as before using the Beats button. To set the split position for the sequencer (i.e. how many lower notes are used for pitch change) you press Write once, hold Split and then play the split-point keynote at the same time as tapping the Write button again.

In realtime the sequencer length is quite short and each sequence memory cannot be shared to make one longer sequence. However, it does allow 12-bar riffs to be composed and then transposed - a lot depends on the clock speed set during record to catch the fastest notes played. Step mode is ideal for the familiar Tangerine Dream, Klaus Schulze type of sequencing and with 80 sound programs available at the touch of a button at any time during playback, makes an exciting instrument feature to use - especially as it can be saved on cassette.

Finally, as well as Sequencer Sync In/Out switchable rear sockets, there are footswitch make/break sockets for Program Advance, Glide, Portamento, Hold and Release; external pedal control of either or both upper/lower sound filters, output sockets, and cassette interface sockets enabling storage of your 40 programs and sequences.

Joystick section.


The quality of the pre-programmed sounds is good although it's quite likely that the production instruments will have a greater range of more representative sounds, including plenty of brass, wind, string, piano and percussion. The Synthex has all the clarity and feel of a top line digital instrument. It's challenging to use as every parameter offers immediate exploratory synthesis from your chosen sound program. You won't find any touch or pressure sensitivity but you will find that you can go on creating original sounds and effects. At a price of £2,500 including VAT, it's very competitive, considering the memory, extra features, full programming and built-in sequencer.

The Elka Synthex is distributed in the UK by Elka-Orla (UK) Ltd, (Contact Details).

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Synthesiser Update

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


Electronics & Music Maker - Dec 1982

Gear in this article:

Synthesizer > Elka > Synthex

Gear Tags:

Analog Synth


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> Synthesiser Update

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