PPG Wave 2 Synthesiser
8-Voice Polyphonic Digital Synthesiser with 8-Track Digital Sequencer
Each month we review the latest Electro-Music Equipment — from synthesisers to sound reproduction and effects! E&MM's special in-depth reviews look at what's new in the world of commercial music — a vital updating for both electronics designers and musicians.
PPG have been designing and building synthesisers in Germany for several years but, to date, have not made them available elsewhere. Their range of instruments covers monophonic models through to the complex 360 Wave Computer and the company in particular specialises in digital synthesiser technology.
The Wave 2 combines new digital microprocessor circuits with accepted analogue control synthesis and thus aims to overcome the complexity often inherent in computer based systems through its analogue settings and realtime keyboard. The result is an instrument that sounds quite unlike other performance synthesisers, producing complex digital waveforms that can be filtered to produce a vast range of sounds.
Rather than produce an instrument following the conventional sine, triangle, sawtooth and squarewave basic sound sources, PPG designed the Wave 2 with banks of waveforms that are digitally produced. They are contained in 30 'Wavetables' which are accessible through a numerical keypad linked to an LCD 80-character display.
This innovative idea solves the problem of many programmable synthesisers — their inability to show the control settings of memorised sounds. Hence, information on all controls can be displayed and through the keypad can be used to update and change the preset sounds.
There are 5 separate displays available for indicating the main panel functions, digital routing and control, oscillator tuning, analogue control settings (on a scale from 0 to maximum 63) for both channels A & B, and Sequencer/Arpeggio functions.
Each of the Wavetables contains 64 different waveforms. These are programmed at the factory and stored in part of the 24K EPROM memory making a total of 1920 in all available. The rest of the EPROM space holds the control information for sending data to and from the main 6809 microprocessor. Some Wavetables have a reasonably smooth transition through their 64 waveforms whilst others have very dramatic changes that contain strongly accentuated and very different harmonic structures — it is with these latter Wavetables that the Wave 2 makes some unique sounds.
Eight oscillators all receive the waveform control information that sets the basic waveform structure, filter and VCA action, which therefore shapes the required harmonic structure. The keyboard then takes any eight notes played and sets each oscillator's basic pitch. As soon as you change waveforms all eight voice synthesisers are reshaped identically to sound the same. Selection of the waveforms is made from the Analogue section on the left half of the front panel either manually, using the 'Partial Wave Numbers' (PWN) control or automatically, with an ADSR envelope.
All the digital information is entered with the numerical keypad and 'display select' buttons on the right half of the panel.
There are two other important design concepts on the Wave 2. First, the relatively low number of analogue controls is achieved through a triple-sharing system that lets you select the panel mode to allocate a specific routing for each set of functions. Second, the notes played on the keyboard can be stored in the 12K RAM memory of an 8-track digital recorder in numerous ways for simultaneous or individual playback.
On powering the instrument you immediately have access to a total of 100 programmable stereo sounds. Thirty of these (and possibly more in production models) are supplied factory preset although the user can reprogram all of them if he wishes.
The Wave 2 might be considered at this stage just like another programmable polyphonic instrument with program numbers punched in on the numerical keypad. But it is also like an analogue synthesiser and if you want to change any of the settings you simple move the desired control in the analogue section. This gives great potential for continually updating sounds during performance, with memory storage at any time.
In the 'Multiple Function Analog Control Panel' from left to right, we start with a Master Tune for adjusting the pitch of all oscillators simultaneously ± semitone to other instruments and a Master Volume output.
Next there are two ADSR generators: Envelope 1 and 2. In the first of the 3 panel modes, indicated by LEDs in the Panel Function section and selected from a 'Display Select' button, Envelope 1 can be used independently for the Low Pass Filter and the PWN. Envelope 2 controls the VCA shape (or loudness). The maximum Attack time is 14 seconds with Decay and Release lasting up to 30 seconds.
Switching to second panel mode, the top controls now determine LFO parameters for setting a delay before the LFO operates, Waveform (continuously variable through triangle, sawtooth, reverse sawtooth and square wave), intensity of modulation and LFO speed.
The LFO can be selected by viewing the LCD display and inserting a '1' instead of an '0' after two code letters representing modulation of pitch, partial wave numbers, filter frequency and VCA, with LFO triggering able to give sequential running of the oscillators. What was Envelope 2 now becomes Envelope 3 and has Attack, Decay and Depth controls for EG pitch changes. Although the adjustments made in each panel mode are held whilst you set your sound up, in order to retain the complete synthesiser 'preset' you must then put it in a program from 0 to 99, using Data Transfer, otherwise the sound will be lost on selection of another program. Data Transfers can be done in 9 different ways allowing update of certain sections of information.
Analogue panel 3 mode now assigns the original 8 controls of Envelope 1 and 2 as volume level outputs for the eight tracks of the sequencer/arpeggio digital recorder in the instrument. The LFO speed control now adjusts the sequencer master clock rate.
At first, this jumping around from one mode to another appears slightly confusing, but of course, all the information can be seen as numerical values for each setting on the LCD display. In performance, switching from one panel mode to the next is simply a touch of a button. I like this method, because you can focus on the LCD display rather than peer back and forward over numerous controls.
The output of the standard Wave 2 instrument is stereo and for each program there are outputs A and B. It can also be supplied with 8 individual outputs from its sequencer. The 'Group' button (in Display Select) chooses either or both channels and is indicated on the main display and on the two Panel Function LEDs. So you can produce two completely different sounds (based on the same Wavetable) from the same program.
Exciting possibilities come from this truly stereo programming. Selection of VCA envelopes will simulate panning from one channel to another and echo, with individual change of one channel only giving de-tune, chorus and complex tonal effects.
Using the keyboard select modes you can specify (counting from the left) from which note the split point should be to put channel A and B on each half.
Besides the full keyboard in 8-note polyphonic mode, there are 8 other modes that give choice of oscillators on each channel, choice of the number of oscillators on each note and keyboard split. This makes utmost use of the 8-note system — you can achieve rich string effects from 4 oscillators on two monophonic notes using key split or play top solos to left hand chords just as easily.
Other uses for the keyboard (highest note played) voltage are: 'Keyboard Follow' opening the filter up the keyboard over 7 increasing amounts, loudness balance at low and high ends and particularly interesting, its control of PWN, being able to select individual waves on each note or produce whole sweeps of partials from note jumps.
Locating and modifying all information on the display is done by moving a cursor to the data e.g. SPLIT 10, and then typing a new number. There's a clear perspex spring-loaded wheel for pitch-bends (up or down 4 semitones) on the left of the keyboard that's usefully angled towards the player. I would have preferred at least an octave jump here.
Each oscillator can be adjusted in 4 'micro' steps from -1 to +2 for rich 'chorus' and de-tuning effects. A further instruction (shown on the display along with micro tuning) enables the pitch of individual oscillators to be stated as a number which is the semitone count from the bottom note e.g. '12' is 1 octave up, '31' is 2 octaves and a fifth up. All eight oscillators are therefore capable of wide parallel interval playing from one or more notes (Ravel 'Bolero' style!).
Two types of control from finger touch operate. First, there is the 'electric piano' kind of touch sensitivity that generates a control voltage dependent on the velocity of a pressed key. This will open the filter or increase the volume on faster touch playing.
The second type is pressure sensitivity, the control voltage being derived from the action of a firmly pressed key. A little disappointing, in terms of mechanics, as the whole keyboard droops with the key(s) depressed (memories of the EMS Polysynthi here!) yet it does its job of altering (individually or collectively) the filter, partial wave numbers, loudness and LFO modulation intensity.
If you play big chords on a particularly dramatic wavetable, the sound can be very dense and somewhat overpowering. This is where the ability to select one or more waveforms of a Wavetable is very useful. It's done by adjusting the 'Env. 1 Wave' control which really sets the number of waveforms heard in sequence from 1 to 64 at attack, decay, sustain (holding one waveform) and release times. Aurally, a sweep at varying speeds from one waveform to the next is heard, starting from the point set by the PWN control (e.g. '½-way is waveform 32). If a start is selected from say, waveform 50, then provided the ADSR carries on after 64, the table skips back to 1.
Here's another plus — the effect will convince you that echo and reverberation are present on long releases!
Every wavetable has triangle, sawtooth and pulse waveforms available as the basis of standard analogue synthesis. These occur usually at the end of the PWN sweep where waveforms are more widely separated on the control's movement. The Low Pass filter present can further modify a partial wave using its Cut-Off and Emphasis (resonance) controls.
'Test and Cancel' is an unusual facility that checks oscillators, so that if a problem should arise, the particular board can be located and 'cancelled' — ideally a safety feature to get you out of trouble on stage.
The rear panel has a data in/out socket for micro connection, control voltage in, gate in and out, headphones, sustain switch, and cassette 5-pin Din interface socket. All the program information can be dumped onto a standard mono cassette (it takes about one minute). Instruction 1 dumps the program data, 2 dumps the sequencer tracks, 3 loads from cassette and 4 will verify a dump.
The addition of an 8-track digital recorder in the Wave 2 must make it a really attractive proposition and it can be used to record up to 10 sequences and/or arpeggio effects. A sequence can only be recorded by entering each of the eight possible layers one at a time in monophonic fashion. The big advantage here is the possibility of recording 8 melodies using completely different synthesiser sounds. Alternatively, arpeggios that rise, fall or do both on a chosen chord, have random selection or continuously moving groups of notes, and have a specified number of notes in a loop taken from your chord are easily done using a keypad instruction.
A sequence can run from 0 to 99 times (the latter makes it a continuous repeat). Further layers would be played whilst hearing previous tracks. Provided memory is available (no running indication of this on the present model), up to 10 'labelled' sequences on up to eight tracks can be recorded. Routing can be changed while the sequence is running as well as in single step mode.
Needless to say, numerous editing features and modes of operation are available, with updating of pitch, filter, waves and EG filter control at the mixdown stage possible (Panel mode 3). A total of 2000 events can be recorded and an optional expansion card will bring this up to 6000 events in all.
Because the Wave 2 is micro-based and software controlled it can easily be updated. Here lies its main strength although the purchaser will want the instrument to be versatile and fully operational when he buys it.
There were one or two 'bugs' in the system that I am informed will definitely not be in the production model and, like any other powerful control processor, has to be used with some thought to achieve its full potential. Jittering can occur if you stop PWN between two waves although in practice your ear would make you move on to a complete wave. Two nice features are auto-cursor movement from one data point to the next and the LCD display has a useful control that adjusts the 'output angle' to suit your position during performance. Wave 2's sequencer would be very versatile indeed if it could record realtime polyphonic music as well as single melodies and the initial click track needs to be a 'click' and not its present 'note' which clashes with your key notes. Another interesting extra that could be implemented is to have mixer settings remembered as you adjust them during your sequence realtime playback — but of course you have to stop somewhere! As the instrument stands it presents a new concept of sound synthesis in the studio or on stage. If you don't believe me, listen to its special sounds on E&MM's Demo Cassette 3!
The Wave 2 has been competitively priced at £3232.16 including VAT and comes in a black metal cabinet with electric blue front panel (Length 92cm, Depth 55cm, Height 17cm). It is obtainable in the UK from Desert Distributors, (Contact Details).
Review by Mike Beecher
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