Vesta Kozo have an uncanny knack for turning out the right product at the right price and the DIG-420 looks set to continue in that tradition.

Sampling delay lines are no longer front page news, but it is certainly true that very few of the cheaper ones offer keyboard control over pitch, and those that do tend to be very expensive and favour MIDI as a control system. As most samplers of this type are monophonic, it does seem more logical to use the old CV and gate system as you can then use any one of a dozen or more popular mono analogue synths to control it without tying up your latest MIDI-equipped polysynth.

As you might have guessed, this is the approach that Vesta have taken. Moreover, the DIG-420 can play back samples over three octaves as well as behaving as a conventional digital delay. Unusually, the sound stored in memory is retained when the power is off which can be a real boon, but there's no way to dump samples to tape other than as straight audio sounds which would then have to be resampled before use.

In both the delay and sampling modes, the bandwidth is 7.5kHz for all delay settings which is less than you get with a good dedicated DDL such as the Vesta Kozo DIG-411, but it is just about adequate for most purposes. The maximum sample or delay time is one second and the signal to noise ratio is a commendable 95dB. One other compromise that has had to be made in the delay department is the absence of a modulation section, but then I think that most people are going to be interested in this machine more for its sampling capabilities than its potential as a delay line. The input and output levels are both -20dBm, which is great for plugging in high Z mics or instruments, but not such good news if you want to use it in the insert points of a desk that operates at +4dBm. In this event, a level matcher such as the one described in this issue would take care of the problem. Otherwise, you may be better off plugging it into the mixer's mic rather than the line input to compensate for the low output level.

Construction

This is of course, a 1U rack mounting unit and it can only be a matter of time before someone puts a 48-track recorder into the same sized package. All the controls are located along the front panel and all the sockets are on the back panel which is all as it should be. The front panel is the one that sports the gaily coloured knobs (if you're not au fait with this kind of thing) and there are detachable feet for desk top use if you don't want to house the unit in a rack. All in all, the construction is well executed, both inside and out and should give no cause for concern.

Before getting down to the nitty gritty we'll have a quick tour of the...

Controls

From left to right, the first control is the Input Gain control, with its trusty LED ladder meter by its side, and I'm sure that none of our regular readers will have any problems with that section. In the sampling mode, however, this control kindly agrees to act as a level control for the stored sound - a nice touch. Less logical is the fact that whilst in the sample replay mode, this control works the opposite way round giving maximum level in its anticlockwise position.

Next in line is the Mix control which again is fairly straightforward in that it balances the level of the delayed and dry signals. In the sampling mode it performs the same task, which allows any signal present at the input to be balanced with the sampled sound. One practical example of this could be sampling a sound from your synth and then setting up a new sound so that the new and sampled sounds play together. The machine actually allows you to layer two or more samples, but more of that in a moment.

Feedback or Overdub acts normally in the DDL mode in that it feeds some of the output back into the input. This enables multiple repeat echoes to be set up. In the sampling mode, this control determines the overdubbing level when you're layering sounds.

The Sample/Delay switch is a simple push-button with two status LEDSs: green for Delay and red for Sample. Every time it's pressed, the mode changes.

The delay time or the sample time, (depending on which mode is selected) is set up using the Range and Multi controls. Range is an 8-way rotary switch and Multi is a fine adjustment control. When you're sampling, new sounds are only written into as much memory as is selected by the Range switch, and any previous bits of sound in the remaining memory stay intact. This can be used to advantage as a crude form of editing and up to eight different sounds can be spliced together in this way. A viable editing procedure would be to fill up all the memory, and then overwrite seven out of the eight sections with a new sound. A further new sound could then be recorded over the first six sections and so on until all eight sections contained different sounds which might, for example, be in the form of an arpeggio or a simple sequence.

"As most samplers of this type are monophonic, it would seem more logical to use the old CV and gate system."

Moving along we come to another button for Hold/Record and this again has a red status LED. When you're using the DIG-420 as a DDL, this functions as a conventional hold switch that causes any sound in memory to loop indefinitely but in the sampling mode, it's the button that initiates the recording of a new sample.

A two position slider switch comes next and this offers the options of Trig or Gate and is only pertinent when the machine is being used as a sampler. In Trig mode, a sound will play to the end once a key has been depressed unless a key is again pressed before the note finishes, in which case it will start to play the new note. Conversely, in Gate mode the sound stops as soon as the key is released. Both modes suit certain playing styles and so it's very useful to be given the choice.

The Play switch is used to replay a sound stored in memory and the red LED above the switch flashes when the switch is pressed.

Bypass mutes the sound coming from the memory in either Delay or Sampling mode and there's a red status LED to let you know what is going on. This function is also duplicated by a rear panel socket.

The power switch is a tiny rocker switch and although it has no status LED, the rest of the front panel comes alive with twinkling LEDs so you'll knew it's on.

Back Panel

Back panels are usually pretty boring affairs but this one has a fair selection of jack sockets to hold our interest. In the signal department there is of course an Input socket and we have both Direct and Mix outputs for those who want to experiment with stereo.

For interfacing to a synth or sequencer there are CV and Gate inputs and the gate needs a 5v positive going pulse to operate. The other sockets duplicate front panel functions for foot switch control and these are Play, Hold and Bypass. To complete our tour of the back panel we find a captive mains lead and a fuseholder - stirring stuff eh?

Sampling the Wares

The sampler is surprisingly easy to use, no thanks to the leaflet supplied in lieu of an operator's handbook, but there are a couple of things to watch. I tried out the delay mode first and found that this would not work if the CV and Gate leads from the synth were plugged in so out they came. From then on the delay section presented no problems and it's easy to set up repeat echo, slapback and ADT effects.

"Because of the limited sampling time, it's a good idea to sample short sounds, because anything that's still going on when the sampling process ends is going to sound unnaturally cut off."

Back in with the CV and Gate leads and it was time to try the out the sampling facilities, but again nothing worked; the unit won't perform unless you unplug the CV and Gate leads and indeed, it produces some pretty grim noises to indicate its displeasure. Once these leads were duly unplugged yet again, the sounds went in a treat and a quick push of the Play button enables you to check exactly what you have got.

Plugging in the CV and Gate leads one more time and connecting a reluctant ARP Axxe onto the other end, I finally got the machine to speak but it appears that if you sample the full one second with the Multi control in its calibrated position, the sound may be played back at or below its sampled pitch, but not above it. Also the maximum pitch occured at about half an octave above the centre of the keyboard, so you need to check what output voltage your synth gives. Most are one volt per octave but they don't all inform you which octave they start at. The DIG-420 only accepts voltages in the range zero to three volts; above this, all the keys will play the same pitch.

Once these limitations had been discovered and understood, things made a lot more sense and you can get some really expensive sounds out of this system with only a little practice, though most samples require a little echo or reverb to add a bit of life.

It's possible to tune the pitch of the stored sound by using the Multi control and in this way you can sharpen the pitch above that of the sampled sound but the notes do become correspondingly shorter (as you might expect). This is a physical restriction imposed on all samplers that work in this way as pitch change is accomplished simply by altering the replay speed of the sample. Also don't forget that even if you don't have a keyboard, you can still use the DIG-420 to sample percussive sounds and retrigger them from your drum machine.

Editing using the 8-position range switch is rather crude and you effectively end up butt jointing chunks of sound, so you may well end up with clicks where the samples join up. This control does have another more practical use however, and that is to trim off the front of a sample if you've left a gap between pushing the Record button and initiating the sound. Remember though that you can only switch in or out an eighth of the memory at a time so this is not a very precise way to edit.

A few notes on the types of synth that will work with the DIG-420 are in order at this point. As the one volt per octave system is employed, most analogue monosynths such as Roland, Moog, ARP etc. will drive it but early Korg and Yamaha models employed a Volt per Hz system which is not compatible. ARP synths have both Gate and Trigger outputs and you should use only the Gate output. Also the sampler requires a trigger input of +5v or more to function, so again, the majority of synths will drive it. However, synths using an S-trigger system such as the old Korgs and Moogs may give problems. The older Korgs will probably be totally incompatible due to their linear oscillators but if you are handy with a soldering iron, you can build an S to V converter which will let you use your Moog Prodigy, Rogue or whatever. If you have this problem, the circuit for a simple converter is shown in Figure 1. This will not, though, function the other way round as a V to S converter.

Conclusions

It would seem that I have spent rather a long time pointing out things that this machine can't do rather than telling you what I thought of the things it could, but then the user should surely know about these aspects as well.

Once you have found out how to drive the thing properly and can get the sample into it at the right time and the right level, it can sound very good indeed. Because of the limited sampling time, it's a good idea to sample short sounds, because anything that's still going on when the sampling process ends is going to sound unnaturally cut off and may well end with a click or a thump. In this respect, voice samples work well as do things being hit or plucked, and it won't take you long to find the types of sound that best lend themselves to sampling. Using the layering facility, you can build up complex choral sounds which sound most impressive with a touch of reverb.

Three octaves may not sound like a lot of range but it is in fact more than most samplers give you and generally speaking, sampled sounds are most effective when played back within one octave or so due to the Micky Mouse effect that excessive pitch increase causes. Tracking accuracy is good over the whole three octave range causing no noticeable tuning problems and the limited bandwidth is less of a problem in the sampling mode than it is when the unit is used as a DDL.

At the price, this is a very useful piece of gear that can be put to real creative use and my only real quibbles are the bandwidth restrictions and the fact that you have to keep unplugging the Gate and CV leads before you record a new sample or use the device as a straight DDL. A sound operated trigger would have been nice, but then you can't have everything perfect and still expect it to be cheap.

If you are serious about sampling but like most of us have to budget carefully, this one is worthy of very serious consideration, despite its little idiosyncracies.

The Vesta Kozo DIG-420 costs £330. Further details are available from: MTR Ltd, (Contact Details).