Korg Digital Voice Processor DVP-1
Is it a vocoder? Is it a harmoniser? It's both — and a bit more, besides, as Jim Betteridge finds out.
When you hear the term 'Vocoder', what do you think of? Freddie Mercury bathed in a million watts of carefully diffused light? The 'talking orchestra' effect is so distinctive that it's no wonder it enjoyed only a relatively brief popularity before becoming passe?
Vocoding is only one of the facets of the new DVP-1 Digital Voice Processor from Korg, and as a vocoder it has both more and less than past machines have offered. With a standard Vocoder the idea is generally to take a basic sound, which for simplicity we'll call the 'carrier', eg a string synth, and impress on it the tonal characteristics of your voice. The vocoder achieves this by doing a real time spectral analysis of your voice (ie: a look at its tonal characteristic) and then superimposes that via a system of filters on to the carrier. Thus you control pitch and chordal structure from the keyboard of the synth whilst adding the human touch via a microphone as you play it. The theory is great, but in practice there can be a few difficulties. To ensure a satisfactory result, it is necessary to choose a basic sound with the right harmonic content. Such a sound isn't always what the artiste desires and my memories of the client/engineer/vocoder interface are not altogether happy ones.
As a vocoder the DVP-1 is concerned exclusively with the generation of choral sounds and so it doesn't offer the facility of choosing your own carrier, but instead provides a single prerecorded human voice-type sound stored in ROM — the same basic idea used with the DW6000 and DW8000 synths. The fact that it has the general harmonic content of a range of human voices definitely gives you a head start when it comes to trying to make the thing talk. The other important difference as compared to vocoders of old is that the process is entirely digital, and thus it's fast and accurate. And what a joy it is to use: drum up a few mega-dramatic chords (max five-note polyphony), summon your most operatic singing voice, add an Albert Hall or two of reverb and, zappo!
"To the full-voiced choir below.
In service high, and anthems clear,
As may, with sweetness, through mine ear,
Dissolve me into ecstacies.
And bring all Heaven before mine eyes."
No, but be fair, it is a laugh. We are definitely talking 'The Power and The Glory' and Awe-inspired Neighbours. The strength and flexibility of the effect is not easy to describe, but the phonetic and overall tonal tracking is very good so that as you change the timbre of your voice from pure, high and open to deep, rich and bassy, so the timbre of the Vocoder output changes, even though the pitch is controlled by the keyboard. As a musical reference the tendency is to sing the top note of the chord you're playing, but by singing up and down the arpeggio of the chord you can get some very dramatic effects. Similarly, modulation can be achieved by changing your embouchure and creating different resonances within your mouth and head (it helps if you've done some Tibetan overtone chanting, obviously).
That's the good news about the Vocoder, but it has to be said that there are limitations. A simple noise gate with fixed attack and adjustable decay helps to keep the noise to a subjective minimum, but even so the effect is accompanied by a fairly audible sizzling sound which becomes increasingly noticeable as you go for a more gradual fade in or out on notes. Apart from the decay time adjustment on the gate, such fades are courtesy of a simple amplitude envelope generator (attack and release), careful adjustment of which can produce a softer more natural sound, depending on what voicing you're after. Here again, the gentler your entry and exit, the more noticeable the noise. Another unwanted effect is that of 'cockling' or a soft warbling sound heard as the Vocoder tracks constant sweeping changes in timbre. If you sing aaaayyyyeeeoooowwweerrr, for instance, the thing purrs like a digital cat. This is unfortunate but, as the saying goes, 'It'll sound alright in the mix', and indeed people have been putting up with the most diabolical side effects of nice sounding primary effects for years, and I'm sure a little gentle warbling won't put them off this one.
A separate pitch envelope determines by how much, and at what speed, the pitch of the note wavers before coming to rest at its final value. Though it's unconscious, humans do tend to affect a little dip or peak such as this and it can give a greater realism to the sound if used very subtly. There are also other controls with which to ensure optimum tracking accuracy and phonetic definition with different types of human voice, but in fact I found them to make little difference — it tracked well however it was set. It is necessary to play around with the EGs and practise the syncing of hands and voice to get the best results with minimum click and noise. The tracking isn't really quick enough to follow very wide, fast pitch/note changes, although I suspect that half the trouble could have been my unpractised technique, and a consequentially imperfect hand/voice sync.
The keyboard pitch control is via MIDI, and there are also other internal facilities of the DVP that can be controlled from a MIDI keyboard's pitch bend and modulation controls. The pitch wheel effects a straight all-notes polyphonic bend of whatever you're playing with the limits of the bend being adjustable on the DVP — it would be nice to have a 'top or bottom note only' bend. The pitch EG can be used to effect a slight natural slur into a note, but if you are used to playing synth, the pitch wheel is far more effective in this regard, and you could even get quite ethereal, if so desired.
The mod wheel can be applied to the DVP's internal LFO to effect amplitude and/or the frequency and/or the timbre of the output with adjustable delay and depth. There is also a portamento effect which can be kicked in and out via a footswitch.
If you want to leave your own voice out of proceedings entirely there is an 'Internal Wave' mode which basically consists of eight pre-recorded vocal sounds that can be replayed with five-note polyphony from a MIDI keyboard simply by depressing the keys:
1. Female 'a' 1
2. Female 'a'2
3. Male 'a' 1
4. Male 'a'2
5. Male 'a'3
6. Female 'la'
7. Female 'lu'
8. Male 'wo'
As a general wash these aren't at all bad although the consonants are effectively indiscernable and it lacks the punch of the human modulated sound.
Apart from being a vocoder the DVP1 is also a polyphonic (up to five notes) pitch changer/harmoniser. The 'Harmonize' mode allows you to sing a note and add a five-part harmony to it by fingering the desired chord on your MIDI keyboard. You can either select a reference key (zero pitch change) from which all pitch changes are referenced, or you can use the 'Key Change' mode in which the first key you depress (after all keys have been released from the previous chord) becomes the reference key, thus allowing you, within limits, to actually play the controlling keyboard as a musical instrument as well. Alternatively, in the 'Pitch Change' mode, the DVP acts as a fixed interval harmoniser, whereby you set between one and five pitch intervals in semitone steps, and then whatever note you sing or play into it, you get those fixed harmonies added. If you don't want copious harmonies but would settle for a thickening effect, the Unison/Detune mode allows only a single harmony to be set with the other notes of the chord put slightly out of tune by an adjustable amount, giving the effect of sophisticated double tracking. It's the same idea as the unison and detune facilities found on synths.
In all four modes — Vocoder, Internal Wave, Harmonize and Pitch Change — it is possible to punch in a Chorus effect. The parameters of this effect are fixed, and as a chorus device on its own, it's a little too fierce. As an effect for big choral sounds, though, it works well, although you are limited to four-note polyphony when its switched in.
The vocoder became largely extinct because of the peculiarity of its effect. The DVP-1 is wonderful for putting big choral arrangements together quickly, and it's possible that with a little experimentation and experience, almost-normal sounding backing vocals might be possible — is the session singer to go the same way as the string player and drummer? I doubt it, actually.
Asa harmoniser it's very glitch-free and offers an extraordinary five pitch change channels for a relatively low price. The drawback for many serious studio applications is its 6.5kHz bandwidth (+/-3dB), which is what you might expect from a cheap cassette player.
Although it has 64 effects preset memories in which can be stored the vast majority of the variable parameter settings, no-one at Korg has bothered to put together some suggested factory presets. When you turn the machine on, you basically have to start from scratch, and until you've read a good deal of the manual and played around for a while, it's all a bit baffling. This isn't helped by the lack of any English speaking display. All you get are three sets of two digit numbers to show programme number, parameter number and value. What number equals which parameter is printed on top of the unit's case (little use if in a rack) and in the manual, but having to constantly refer to a chart for editing is definitely yesterday's problem — most devices costing this much will have a programmable alphanumeric display to let you know where you are. As a hire item, then, the hire company would have to create and store some good workable effects if the client is to get some immediate, one-day use out of it.
This slight lack of ergonomic up-to-dateness is also seen in the provision of only a front panel input socket, even though they have generously included both XLR and jack. For rack mounted use, most studios would want access via their patchbay, and thus a rear panel socket is a necessity.
An interesting product and the best and most flexible source of instant choral glory I can think of for under £1000. It possibly has more applications for live work where bandwidth and a little noise isn't so important, and where instant real-time harmonising is necessary. For studio work I can see it being hired in for specific applications more than being bought as a permanent fixture. One thing's for sure, though, someone's gonna have a hit single with that 1000-piece choir effect sooner or later. Thinks...
Review by Jim Betteridge
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