The Sound of the Voice
Korg DVP1 Vocoder
Korg's Digital Voice Processor is the first digital vocoder, but offers a number of other facilities as well. Tim Goodyer finds out what it has to say for itself.
At last, Korg have applied digital technology to one of the music industry's most underused and underrated electronic instruments - the vocoder. Does the new DVP1 deliver the goods?
As a species, the vocoder has been on the endangered list for some while now. Manufacturers have killed off the few survivors one by one, without making any effort to replenish the dwindling stock. Old stalwarts such as the Sennheiser vocoder have made occasional forays into the open, but are jealously guarded by over-protective owners. Sometimes the odd, ageing specimen - usually a Roland VP330 or its rack-mounted stablemate, the SVC350 - finds its way into E&MM's classified columns, but is snapped up before the print run is complete.
The vocoder is a 'love it or hate it' instrument. Those who love it recognise it as one of the last truly unexplored areas of modern music technology; those who hate it assume 'Mr Blue Sky' impressions represent the extent of its usefulness. I'd put myself in the former camp: people may have given the instrument up as a bad job, but that, it seems to me, is where innovation should begin.
Right, let's get a couple of things straight. First of all, what is a vocoder?
Briefly, it's a device that allows you to articulate a sound using your voice. This involves superimposing your vocal characteristics (as picked up by a microphone) onto another sound source. More often than not, this source is taken from something like an electronic keyboard, in which case the sound retains the pitch it had when it was fed into the vocoder. Alternatively, the source may be generated within the vocoder itself, in which case the vocoder requires either a keyboard of its own to determine the pitch of the sound, or an external input to do the same job. The Roland VP330 belonged to the former category; the new Korg DVP1 belongs to the latter.
But the DVP1, being an entirely new machine, bristles with modern innovations like programmable patch memories and MIDI control. It holds 64 patches onboard, and is five-voice polyphonic over five octaves in most modes.
It also has the facility to operate in the absence of any voice input, using internally-generated vocal characteristics instead. This is termed Internal Wave mode, and is one of four styles of operation, selectable from the front panel but, sadly, not usable in combination. The three others are Vocoder (just described), Harmonize and Pitch Shift, the last two lying outside the scope of 'vocoding' in the conventional sense.
Beginning with Vocoder mode, this has four factory programs, christened Normal, Clear, Soft and Ensemble. The Normal and Soft settings are rather indistinct, and the chorus on the Ensemble is a little excessive, leaving the Clear setting as the most usable.
The control parameters that go up to make these sounds (and indeed all the DVP1's effects) vary from the recognisable to the obscure. Amongst the former are such familiar items as waveform selection, portamento, and modulation generation (Korg parlance for an LFO), while the latter include something called 'Formant' and something else called 'Breath Bypass'. Formant is said to emulate the resonant frequency of the human vocal passage, and to give an impression of the age and sex of the voice. It sounds more like a resonant filter to me, but it's effective in shaping the sound all the same. You can even route MIDI pitchbend data to the Formant circuitry, with resultant timbral modifications every time you move the wheel/lever/joystick.
If all this fails to give the vowel sound you're after, a Freeze facility allows you to hold a short section of the input vowel to shape your sound.
Like all other vocoders, the DVP1's circuitry is capable of handling only vowel sounds, which leaves us with something of a problem: without consonants, most sounds appear indistinct and artificial. To overcome this, the Korg's Breath Bypass feature is designed to put the missing consonants back into the output signal. Three control parameters are tied up with this: Level, which determines the balance between consonant and vowel components of the output, and Level and Pitch Threshold, which determine the sensitivity of the bypass circuitry.
There are one or two other refinements worthy of mention. First of these is a straightforward attack-decay envelope giving control over volume rise time and release time. Simple but effective.
Then there's a pitch envelope generator. Not a great innovation, I'm sure you'll agree, but one that's capable of adding subtler, less obvious facets to the vocoded sound.
Internal Wave is essentially the same as the Vocoder mode, except that the microphone input is replaced by one of eight synthetically-generated voice waveforms. These come in a variety of styles, covering male and female sources and a variety of vowel shapes: a, la, lu and wo. Some 24 of the 32 factory programs are devoted to effects generated in this way, and the Formant parameters crop up again here to lend a helping hand.
To my mind, though, the internal settings are the least useful aspect of the DVP1. Some of the waveforms represent a valiant effort at replicating vocal sounds, but I'm left thinking that the technology at this level is well below that needed to synthesise a sound is complex as the human voice.
Many of the sounds are thin and, worse, dynamically repetitive. Part of the beauty of a vocoder is the freedom of articulation it affords, whereby no two sounds need ever be exactly alike. Use an internal waveform, and you kiss that unpredictability goodbye.
That said, the Internal Wave memories can easily be turned into Vocoder memories by muting the internal waveform, after which they provide useful starting points for experimentation, and yield far better results than the vocoder presets themselves - I found muted Internal Wave patch 27 offered the best vocoder sound on the machine.
In its Harmonizer role, the DVP1 offers two factory preset effects, and is capable of shifting the pitch of the input signal by as much as an octave either sharp or flat. This interval is determined from the keyboard with reference to a Key Note, which is freely variable in semitone steps over the working range of the machine.
The Harmonizer story isn't over, though, since the DVP1, clever little beast that it is, still has four more voices at its disposal (three if you use the chorus). Thus, you can create a chord by setting these voices to various intervals.
Pitch Shift mode (also two presets) has a couple of strings to its bow. The first of these is a straightforward modification to the pitch of the input signal, controllable in 100th-semitone steps over a range of an octave either side of the input signal pitch. In small doses, this can be used to fatten sounds or, as the manual observes, to provide a solution to feedback problems. But seeing as the DVP1 is capable of producing up to five voices, and four of these are idle in normal Pitch Shift operation, you can call the other four into play with pitch discrepancies specified by a Detune function, to fatten the sound further.
Speaking of sound-fattening, the Korg also has a built-in chorus, though it's used at the cost of one of the unit's five voices. If that limitation sounds as though it might be unbearable, you can always buy a separate chorus machine, safe in the knowledge that you could part-exchange an old noise gate to help pay for it, as the DVP1 has a gate built in. This particular gate offers control over both Threshold and Decay parameters, operates in all but Internal Wave mode, but is not a programmable function.
If you really want to, you can set the Pitch Shift mode to zero, which leaves the unit clear to be used purely for its chorus and/or gate.
Quite a bit has been done, ergonomically, to make the Korg good to use. All connections are on the rear panel with the exception of the input, which takes both canon and standard jack forms on the front panel. The front panel layout is clean and logical, and features a choice of canon and jack inputs (all other connections are at the rear); an input level trimpot and attenuator (switchable between -50dB, -10dB and +4dB, which is a good range); a choice of three output levels (Direct, Effect and Total); mode selection switches (including Chorus and Unison controls); and a Tune pot covering a range of a quarter-semitone sharp and flat.
Like most modern musical machinery, the DVP1 employs digital parameter access in the programming department. Not an ideal state of affairs, this, though your endless button-pressing is eased by three numeric LED indicators on the front panel, which give simultaneous readouts of program number, parameter number, and parameter value.
The Korg's 64 internal patch memories are arranged in the familiar eight-banks-of-eight format (program numbers 11 to 88), and each memory can store the operation Mode (including Chorus and Unison on/off), and all control parameters with the exception of gate and MIDI setup. The unit comes with 32 factory programs, loaded in memory locations 11 to 48 and, curiously, repeated in locations 51 to 88. The manual includes a useful chart that shows all the parameter settings used to produce these presets.
Of course, the DVP1 would be nothing (well, not much) without MIDI, so is equipped with MIDI In, Out and Thru sockets on its rear panel. The application of MIDI In and Thru should be obvious by now, but what of the MIDI Out? Well, this provides a means of communication between the DVP1 and a suitably interfaced computer, and is the only route by which you can dump your own programs. Computer-assisted parameter editing may also be carried out over the MIDI bus, but unless you fancy yourself as a budding programmer, you're at the mercy of the software houses as to whether any of this will ever be possible.
One nice touch is the inclusion of a MIDI Indicator, a front-panel LED that lights to indicate the presence of incoming MIDI data - a great time-saver when setting up isn't going smoothly.
Even better, the Write and Write Enable/Disable switches serve a dual purpose. When the Write function is disabled, the Write button acts as a MIDI reset for clearing the sort of corrupt MIDI data that so often results in droning notes.
The only blight on the DVP1's MIDI map is the fact that it isn't sensitive to either initial velocity or aftertouch - which goes against current trends somewhat. Maybe they'll rectify things on the MkII model.
But back to the good news and Korg's novel-sounding Key Window feature, which is in fact the equivalent of establishing keyboard zones, and employs two user-definable parameters to determine its top and bottom extent. The result of this is that you can define any area of the unit's operating range within which you wish it to respond, so you can split the controlling keyboard or restrict response to any specific area within its range. However, by setting the top of the window below the bottom, you can create a specific area within the keyboard range where it will not respond - in other words, a window.
As it stands, there's no way you can use a voice to articulate your favourite synth patch. Initially, I was worried that this would undermine the potential of the DVP1, but although I did find myself wishing I could use a rich string or vicious Moog lead patch as a starting point from time to time, the system does cover most eventualities.
And the DVP1 excels in a couple of other areas, like the creation of off-the-wall effects that simply aren't possible with 'ordinary' synths and samplers. If you fancy it, you can program a superb imitation of moaning monks - a little reverb and a few well-chosen notes around middle C soon have you believing you've moved your studio/rehearsal/bed room to a small uncharted island off the Scottish coast, never to be heard from again.
Unlike so much recent gear, and despite the lack of touch response, the DVP1 is an exceptionally expressive instrument. It represents a very real innovation, and time spent exploring its possibilities is both exciting and rewarding.
Review by Tim Goodyer
Previous article in this issue:
Next article in this issue:
mu:zines is the result of thousands of hours of effort, and will require many thousands more going forward to reach our goals of getting all this content online.
If you value this resource, you can support this project - it really helps!