What is large, warm, ideal for vocalists and lasts for 1.4 seconds? Well, among other things, the number 19 setting on the Alesis Midiverb. One of 63 presets on one of two new and highly desirable effects devices from America.

The Midiverb and its recently released sibling the Midifex represent a new departure for digital processors in so much as they are preset devices. The economics of designing such products is that you probably have to pay as much for control mechanisms as for the printed circuits that actually do the work and create the sounds. By selecting 63 options and eliminating the D.I.Y aspect of getting a reverb or delay sound, they have been able to produce two remarkably inexpensive machines which sound like top studio gear. The only thing is — no knobs to twiddle. The options are all tabulated on the front of the device like the menu of a Chinese takeaway — except that for example No 60, instead of being Chicken and Cashew nuts, is 300 msecs Reverse Reverb on the Midiverb and 'Stereogen Ambient' on the Midifex. This last effect, incidentally, is a kind of artificial stereo with reverb or diffusion: it is not the name of the next Brian Eno project.

Both units are flat, moulded plastic boxes which together fit into a £10 adaptor designed for a 19" rack. The adaptor is worth getting because they're very light (the power supply is separate), and small light boxes of electronics especially when attached to heavy shielded cables and put on top of things, tend to be accident prone.

In terms of controls, they're spartan in the extreme. A rubber press-stud selects (bypass), another three select Down, Up and MIDI channel. To choose a patch you just press Down or Up and run through the patch numbers which display themselves in a seven segment LED display window. And that's it, apart from a 'Mix' pot on the back in case you're using the unit inline with an instrument rather than from the mixing desk. Green and red LEDs tell you when the correct signal is being received. Connects are phonos for left and right in and out with standard 5 pin DIN MIDI In and Through sockets, which allow the machines to be controlled from a keyboard, sequencer or other MIDI command device.

The MIDIVERB

No other effect makes so much difference to a recording or performance as a decent reverb unit correctly used. Being a preset device it would be fairly difficult to use the Midiverb incorrectly, and its sound is excellent.

Reverb is the perfect effect for a pre-programmed device. When naturally occurring, reverb is a product of a slight delay (pre-delay) followed by a whole complex interaction of sound waves reflecting off surfaces at different planes and distances from the sound sources. Even the major variables of pre-delay, reverb time, and tone envelope require a fair amount of experience to set up in such a way that they produce a natural sound. There is very little to lose and a great deal to be gained by leaving the tortuous experimentation to the people that programme the memories in the Midiverb, and concentrating instead on remembering the chords right. The Midiverb reproduces, cleanly and without fuss, the sounds of some fifty rooms plus thirteen 'special effect' processes.

The rooms take in everything from a small booth to the Albert Hall with an impressive range in between; you'll find Church Halls, Tube Stations, Subways, Lecture Theatres, British Rail Waiting Rooms and Underground Caverns. They are not, of course, labelled as such: you are given the reverb time plus Bright, Warm, or Dark and Small Medium or Large. In practise, you will probably end up with four or five favourites for different instruments and applications. The time range goes from 0.2 seconds to 20 seconds (less like a room than a high-sided valley or gorge). The uncluttered nature of the digital process means that longer reverb times can be used without swamping the music as much as, say, a spring reverb would. It's perfect for giving a natural depth to vocals and it would be true to say that nothing else can do this for the same price: a spring reverb has too much colouration and delay machines will almost always sound artificial. Effective with any instrument, the Midiverb is, as the world's most economical digital reverb, the most cost-effective way of effectively processing drums. Snare drums, in particular, don't respond well to spring devices. The MIDIVERB has nine Gated settings, so suddenly a home studio can produce the big, rich snare sounds that have until now been the preserve of large studios with effects racks like the control panel on Concord.

And then, finally, the MIDIVERB has a reverse gear. The four reverse settings produce a kind of gulping delay produced by the sound being sectionised and re-assembled backwards, and no doubt this is enormously useful for something. In fact it's probably the setting you use most when you're fiddling with the machine in a frenzy of post-purchase experimentation, and least when you're actually playing.

The MIDIFEX.

The Midifex like the Midiverb is a multi-tap processor. This means that the delay circuit can be tapped or interrupted at more than one point. Digital Delay lines in the lower price brackets do not have this facility — you only get one echo, and all the various sounds that can be created by repeating and modulating that echo. With the Midifex, different echos can be generated to interact with one another, or a clean echo can be thickened and diffused by simultaneous reverb. In other words, the Midifex can create sounds which otherwise would have to be created by using a conventional delay line plus a reverb plus a parametric equaliser to vary the tonal characteristics. This technology gives a family of effects quite distinct from those offered by the conventional DDL — which the Midifex would supplement as well as replace.

The lower numbers in the bank of programmes, all echoes of various types up to around 500 Msecs, are with options on the filters and the ambience. There are usable ADT effects (in fact, thicker and therefore perhaps better than ordinary DDL versions). Sharp echoes that can be regenerated infinitely are out, however — this has no pretentions to sampling and is strictly a signal processor tending to be non-extreme. Next on the menu are 2-tape and 3-tape delays, and the stereo outputs come into play with the effect panned across the stereo image. Medium and Short regeneration effects and five Slap effects are next, and then five reverb effects from a short gated reverb to panned reverb, a long drawn out 'bloom' and a reverse reverb: special effects reverb for the most part and not seriously competing with the Midiverb for a range of ordinary working reverbs. There follow Multi-tap effects 'Thickener and Dense Thickener' and stereogen effects.

A real box of tricks! And the truth is the Midifex really has to be listened to if you want to discover what its unique character and colour of effects can do for you. If possible, it should be listened to in stereo because so many of the effects create, exploit or develop a stereo image. For its price, (which makes it the most inexpensive digital multiprocessor by a margin of a couple of hundred pounds) its range is amazing. And there is a repertoire of effects that cannot be created even using the higher-priced rivals. As well, inevitably, there are gaps — because if you have a machine that will replicate the combined processing power of DDL, Reverb, and Parametric, you are going to discover that 63 presets won't quite allow you to store all the sounds you might wish. But there are enough to be going on with...

ALESIS MIDIVERB/MIDIFEX £395