Digital reverberation is probably the fastest developing field in music technology at the moment. Mark Jenkins brings you a round-up of what's currently available.

The power, richness and clarity of today's music is partly due to low-noise recording techniques but mainly due to the widespread use of artificial ambience. So it's no surprise that most studios have (or would like to have) anything up to eight or ten digital reverb units.

Ironically, it's only four years ago that digital reverb became truly affordable with Yamaha's introduction of the R-1000. Relatively noisy and with only four main settings, the R-1000 nevertheless converted many studios from the dubious delights of spring lines to the undoubted pleasures of digital. Oddly enough, many companies were slow to follow up on the lead set by Yamaha, and the second generation of affordable reverbs appeared only eighteen months ago with the launch of the MIDIVERB from Alesis.

Meanwhile, those with the cash still had a wide choice of top-quality professional reverb units to select from. Lexicon's 224X, the AMS RMX-16, and models from Quantec, Yamaha and Publison did tremendous business considering their multi-thousand pound price tags, and many of them are still the first choice of top studios today.

However, with the increased quality of cheaper reverbs - such as the astonishing 16-bit Alesis Microverb - and the tendency for even relatively inexpensive units such as the Ibanez SDR-1000 to offer dual channel operation and multi-effects capability, the days of the reverb giants may be numbered.

In this round-up we're taking a look at the field of digital reverb as it stands today. The listing here is by no means comprehensive, since it does not include units no longer in production. As with synthesizers, sequencers and other hi-tech gear, you'd be surprised to see how many popular units fall into this category: the Alesis MIDIVERB and XT:c, the MXR 01a, the Yamaha R-1000, the Lexicon PCM-60 and many other models still freely available on the secondhand market, for instance.

Whether it's best to go for a secondhand digital reverb or the very latest model is a matter of personal preference. There are certain trends in reverb design which have appeared over the last year or so which you won't find on older models, however high their quality. On the other hand, many digital reverbs (such as the Lexicon PCM-60 and MXR 01a) were being constantly updated with new software, so it's important to find out what software revision is being offered if you're going for a secondhand model.

Take, for instance, reverse reverb. This effect is common on the current Alesis, Roland, Yamaha, Korg and many other models, but you won't find it on the old R-1000 and won't be able to add it with a software update. How useful is the reverse effect? It certainly can't be used every day of the week, but it does have certain applications for exotic drum and vocal sounds and for producing a 1980's version of the reversed tape effect.

It's also a fact that most digital reverbs aren't just digital reverbs any more - the Ibanez SDR-1000, most of the Alesis, Korg and Roland models, the ART DR-1 and many other units offer delay, autopan, flanging, chorus and several other effects, so buying a unit 'on the cheap' which only does reverb or only does delay may seem uneconomical. Of course, these versatile units still only produce one effect at a time, but that's changing gradually as other manufacturers follow the lead of Roland, whose DEP5 and DEP3 models create more than one effect simultaneously. Complicated, isn't it?

Add to that the question of MIDI and you'll see what a jungle the present reverb market can be. The early Roland SRV2000 reverb and Yamaha D1500 digital delays with MIDI simply offered patch change facilities - sometimes a particular effect could be assigned to a particular MIDI patch number, and sometimes (as on the Alesis MIDIVERB) you were stuck with one particular effect program always being called up by the corresponding MIDI patch command.

Now things are more versatile (ie. complicated). Most MIDI reverbs now allow you to assign effects to incoming MIDI patch commands and, after Lexicon first introduced the idea of dynamic or 'Performance' MIDI on their PCM-70, many other companies have followed suit. Performance MIDI enables you not only to change reverb effects from a MIDI keyboard or sequencer, but also to vary the level, reverb depth or other parameters according to (say) the velocity levels given with incoming MIDI data, or according to a modulation wheel or pitch bender setting.

On units such as the ART DR-1 (which received a major MIDI update soon after its initial release), Performance MIDI will allow you to change many of the unit's most important parameters from any one of a number of possible MIDI controllers.

The latest generation of Korg MIDI reverbs (DRV2000 and DRV3000) also excel in this area, offering all sorts of panning possibilities as well as depth and decay time control, and the Ibanez SDR-1000 (now updated to the SDR-1000+ specification) also offers some tremendous MIDI capabilities.

An alternative to Performance MIDI is a simple level detector on the input circuit which reduces the depth or decay of the reverb signal as the input signal becomes louder (as on the old MXR 01); this is a handy way of preventing 'cluttered' sounding mixes but, of course, isn't under the player's control as much as a full blown Performance MIDI system would be. But maybe MIDI isn't important to you at all - you may never need to change a reverb program during a mixdown and may not be interested in putting anything but a guitar or drum down your reverb channels.

However, the fact of the matter is that reverb units are going undeniably hi-tech (with MIDI now being offered on everything from the MIDIVERB II - see review this issue - to old faithfuls like the AMS RMX-16) and the way ahead for small studios seems to lie in MIDI automation of both mixing desks and effects units. If you buy a new reverb you're paying for those MIDI sockets on the back whether you like it or not, so you might as well use them to make your mixdowns slicker and more economically realised (automated patch changing with one reverb unit may save you having to buy a second).

Of course, this modern approach to the control of reverb involves running a MIDI sequencer synchronised to tape, using a MIDI master keyboard for programming, and so on. If you're simply interested in getting the best sound for your straightforward mixdown applications, hopefully you'll get some indication from the table of which units could fulfil your needs. And, don't forget, the ultimate test is to use your own ears and check out which reverb suits your own particular needs.