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Digitech VHM5

Intelligent Harmoniser

With four independent harmonies and its 'intelligent harmonising', Digitech's VHM5 pitch shifter promises much. Rowland Jones puts it to the test.

The first thing that I have to say about the Digitech Vocalist, the company's new 'intelligent harmoniser', is that it is a serious piece of musical technology; not just a serious piece of technology, but a serious piece of musical technology. The reason I say this is that in the brief time I spent in the company of this machine, it became clear that it has massive potential for anyone who has (or is prepared to learn) some musical theory. In short, it's a beast, one which needs some understanding and taming, but the effort is most certainly worthwhile!


With that in mind, let's take a look at the Vocalist. It's smaller than a copy of Sound On Sound, but nevertheless it has a substantial feel to it. Its matt casing is quite attractive, with a large display and big rubber buttons which are easy to use, even on the cruciform shaped parameter selector. The Vocalist offers 5-part harmony (the original signal plus four harmonies), employing 16-bit sampling with 24-bit internal processing, and it's the latest in a line of pitch shifting devices from Digitech, who have really jumped in at the deep end by calling this the Vocalist since the human voice must be one of the hardest instruments to harmonise, with its fluctuating pitch and other nuances. The 'intelligent' tag refers to the fact that the harmonies that the unit can generate do not have to be simple fixed interval shifts; the Vocalist can listen to the input signal, and generate useful musical harmonies according to rules determined by internal parameters (which are, of course, under your control).

Connecting the Vocalist up is easy enough. The input can either be directly from a microphone or from a line input, allowing the unit to be fed from an effects send. The input level is set by a fader on the front panel, and there is a -10/+4db switch at the back of the unit. The output is also controlled by two front-panel faders marked Vocal and Effect — Vocal is the original signal, and Effect the harmonies. The use of the unit's stereo outputs is unfortunately a little restrictive; the left output used on its own gives the original signal plus up to four harmonies, or using both outputs you get original plus harmonies 1 and 2 from the left channel and harmonies 3 and 4 from the right. If you were driving the VHM5 from an effects send, you would obviously take the original signal out of this (by simply setting the Vocal fader to zero) but it would still be more flexible to have four separate outputs so that you can spread your harmonies right across the stereo image; a few brownie points lost there.

Having wired up the Vocalist, the next stage is to get some harmonies out of it. The manual is reasonably good and enables you to get up and running easily, but after that it's not quite so helpful in explaining the way in which the unit's parameters operate. "First Impressions" gives a few examples of how to use the Vocalist, and I have to admit that after trying out one of these ('Amazing Grace'; not one for the hip-hop fans out there, nor a particular favourite of mine, I have to say) I was stunned by the result.


The danger with any harmoniser is that the harmonies will sound, how shall I put it, electronic? Too perfect? In order to create a more natural sound, Digitech have designed this unit specifically for vocal applications, and new DSP software ensures that vocal notes are shifted without vocal cavity overtones or resonance, which give a human voice its distinctive sound, being affected. Digitech have also built in several facilities which can 'humanise the harmoniser'. The pitch of each harmony can be randomised to a different degree (Off, Low, Medium, or High) which adds a degree of 'random out of tuneness' (sic) to the harmonies. Besides this, you can set a different portamento for each harmony. The combined effect of these does humanise the overall sound considerably, and bearing in mind that the harmonies are there to add weight to the main vocals, the overall effect is superb. So how does this Vocalist know what to sing?


The VHM5 operates in two basic ways; both of which can be determined by either the settings on the unit or via a MIDI controller; keyboard, sequencer or whatever. These two modes of operation are Chordal Harmony and Scalic Harmony.


In this mode, the unit generates harmonies based on a range of chords; maj, maj7, min, min7, dom7, min7b5, aug7, and dim; and any four of these can be used within each program (there are four variation buttons to switch between the four chords you've assigned). By selecting a chord type and a note you define a chord on which the harmonies will be based; A maj, C dom7 etc. You can also specify what notes are generated: one above, two above, one above and one below, one above and one unison etc., up to a maximum of four notes.


This mode generates harmonies based on a key and a scale, and you have a choice of six scales: Maj; Min; Chromatic; Blues; Wholetone; Diminished. Again, you can select any four of these within a given program. Rather than specifying notes as 'above' or 'below' the root, you can select an interval (3rd) or select the notes in the scale: eg. 1-3-5; 1-2-6; or even 5-6-1-2-3. In each case '1' is the original note, and the other numbers refer to the notes on the scale; if numbers come before the '1' they indicate the octave below, and after the '1' they indicate notes in the octave beginning with the root note.

To illustrate how these approaches differ in practice, imagine two configurations, one chordal, one scalic, both set for C maj. Using the Chordal harmony set to produce two notes above the input, if you sang a C then E and G would be generated as harmonies; the same happens in the Scalic mode if you specify 1-3-5 for harmonies. But what if you then sing a D? The Scalic mode will give you F and A, but the Chordal mode will still give you E and G since D is not in the Chord of C maj. This is achieved by the 'no change' function, where the Vocalist keeps the harmonies generated by the last input note, until the pitch of the input reaches a note which generates a new set of harmonies, say, an E in this case, which would generate a G and the C above that, whereas Scalic would give G and B.

"So what?" you might say. Which system is best? Now this is the whole point of what I said at the very beginning; this is musical technology. This machine needs understanding in a musical sense, and it needs experimentation; that will take time, but it's time well spent because the scope of the machine is enormous. The VHM5 comes with 128 presets (programmed into locations 129-256) and the same 128 are duplicated in editable locations 1-128. The presets are made up of: First Impressions (1-16); Chordal Harmonies (17-47); Vocoder (48-49); Pitch Correction (50); Special Effects (51-53); Scalic Harmonies (54-128).

Within any preset you can combine scalic and chordal harmonies (ie. set the four harmonies independently to operate in scalic or chordal modes), so as you can see, there's a lot to go at.


Besides generating harmonies based on a program's user-programmed or preset parameters, the VHM5 can also use a MIDI input (from, say, a keyboard) to change those parameters in real time, and thereby offer realtime control over harmonies; in the chordal mode it will select a chord (if you played C-E-G, the VHM5 would select C maj) and in the scalic mode it will select a key (you play C-E-Ab, the VHM5 selects a wholetone scale in C; C-G-Bb gives Blues in C, and so on). Using the unit whilst accompanying yourself on the keyboard is pure magic, but once you've got over the shock you should note that if you try to play an actual accompaniment, rather than block chords for the VHM5 to follow, you're likely to produce some rather strange harmonies; the inadvertent 7th, for example!

There's lots more you can do with MIDI besides this. You can of course select a program via MIDI program changes, or select the various options within a program (scalic or chordal harmony modes, for example) by using program changes or MIDI notes. Continuous controllers can be used to control certain parameters, such as vibrato depth and harmony volume. This would be really useful in a live situation, where you could use the modulation wheel on your keyboard to control the volume of the harmonies and fade them in gently at certain points in a song.


On the subject of live use, Song Mode offers the facility to record all the harmony changes within a song, and then step through them change by change, within a single program. This needs a fair amount of planning however, but since you can also use a footswitch to change programs, as well as step through the changes in the song, you have a lot of freedom to create varied and natural sounding harmonies.


There are other ways to use the Vocalist besides a simple (?) harmony generator; some where realism is not the desired effect. One of these is Vocoder mode, where the harmony notes do not begin until they are played either on the built in keyboard or via MIDI. The built in keyboard can also be used to generate cue-in tones, and to facilitate harmony programming. Another option is pitch correction, a monophonic mode which generates a 'replacement' for the input voice, doing for out-of-tune vocals what quantisation does for sloppy playing — you sing a note, and the Vocalist will correct it to the nearest correctly-tuned semitone. I have to admit to not liking this function particularly, as the replacement voice sounded rather unreal. The Special Effects are precisely that; interesting but, I think, of limited use.


I have only a few minor criticisms of the Digitech Vocalist; the manual could be better (but then what manual couldn't do with a bit of a rewrite?); the menus are not instinctively easy to use, which is almost inevitable with so many options available; and the outputs could have been better used. Apart from those niggles, the VHM5 is a wonderful piece of kit, not just because of its facilities, but because it's refreshingly different — it's not another synth, another sampler etc. For that reason, I've talked about operational features rather than specifications, because there's nothing with which to compare the Vocalist; the Eventide Harmonizer is in a quite different price bracket, though I understand with fewer features (but wonderful sound quality — Ed). However, there is one question mark in my mind: at whom is the Vocalist aimed? At £899 it's probably too expensive for the average Portastudio user; so that means it must be aimed at the lower end of the semi-pro/professional market — 16-track and budget 24-track. The only problem is that this market probably would not benefit from the Vocalist as much as the home studio user, who has the time to understand it and use its facilities to the full. So there's a slight contradiction there. There's also the live music market where, again, there's a bit of conflict.

The cabaret soloist would love one at the right price, but a band? Could this be the first time a singer gets a piece of equipment from the recording advance? Me? I'd kill for one.


Digitech VHM5 Vocalist £899 inc VAT.

John Hornby Skewes & Co.. (Contact Details).


Signal-to-noise: >88dB (A-weighted).
THD: <0.03%.
Sampling: 16-bit linear at 31.25kHz.
Bandwidth: 30Hz to 30kHz (dry).
Bandwidth: 30Hz to 12kHz
(vocal range only; eliminates sibilants).
Max input: +12dBm or -8dBm (selectable).
Max output: +8dBm (5-part harmony)
+3dBm (pitch correction)
Mic input: XLR 2.2kOhm impedance, balanced
Line input: 1/4" jack, 24kOhm input impedance, unbalanced.

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Shape Of Things To Come

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Sound On Sound - Copyright: SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.


Sound On Sound - Oct 1991

Donated by: Bert Jansch / Adam Jansch

Gear in this article:

Studio FX > Digitech > VHM5 Vocalist

Gear Tags:

Digital FX
Pitch Shifter

Review by Rowland Jones

Previous article in this issue:

> Shape Of Things To Come

Next article in this issue:

> Electronic

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