When I first heard about the PCM70 I thought that it was going to be just another MIDI digital reverb but there turned out to be much more to it than that.

The Lexicon PCM70 isn't really a digital reverb. True it can produce a wide range of reverb sounds, but it's capable of performing so many other functions that reverb must be considered as just one facet of its capabilities.

An overview would seem appropriate at this point, but where to start? Well, it's black and lives in a 1U rack mounting case so we're on familiar ground so far, but the rest is uncharted waters with the possible exception of the mains lead and power switch.

I've already mentioned reverb, which incidentally includes gated and infinite effects, but the PCM70 will also produce flanging, chorus, echo, multi-delay and resonant chord programs, all in stereo. Most of this will probably be familiar to you but you would be quite justified in asking; what the zark is a resonant chord program? You might think that I'm now about to launch into a dissertation on said resonant chord feature but you'd be wrong... you'll have to wait until the appropriate section, so don't hold your breath.

The unit comes with around 40 preset reverb and delay effects and there is room to store around 50 more of your own edited versions. The exact number varies slightly depending on the current software version.

This being a MIDI-compatible unit, you might reasonably expect to be able to change programs using MIDI program change information generated by your synth or sequencer, and of course you can, but there's more. The PCM-70 recognises note number, note on velocity and pitch bender information so that reverb or other effect parameters may be dynamically varied from the controlling synth. An example of this might be changing the reverb decay time according to the note played, or perhaps altering the feedback of a delay patch from the bend wheel.

So having whetted your appetite, let's see what this box looks like in the control department.

Layout

For a box that does so much, this unit is remarkably uncluttered and features relatively few controls. To the left of the front panel is the obligatory Input Level control and a 6-segment LED level meter for optimising the input to the processor. To the right of this is a multi-purpose display unit of which more will be said later, and to the right of this is one of those rotary controllers that turn indefinitely and this is referred to as the Soft Controller. Elsewhere in the text they have shortened this to Soft Knob, but as this might invoke a prurient response in certain of our readers (and contributors), I will continue to refer to it by its former name. This can be used to alter nearly anything that's alterable and it's used in conjunction with the two rows of buttons to its right.

There is a pair of increment/decrement buttons and a set of push button switches numbered 0 to 9 and these are used to access presets, user programmes and parameters to be edited so they come in for quite a lot of use.

Further to the right is a cluster of four switches and these determine what mode the machine is in. PRG selects the preset programs, Reg calls up the user programs and Load as its name implies lets you load up any selected effect ready for use. Load can be switched out so that the programs can be changed instantly and this switch exists in software and is accessible in Row-7 which we will talk about later.

"...the only obvious omission is that there is no reverse reverb preset and no way that I could find of simulating one."

Lastly comes Byp which is of course bypass and is used to mute the effects part of the output signal.

Turning now to the rear panel, we find that in addition to the usual mono input (balanced) and unbalanced stereo outputs (all on ¼" jacks), there are DIN sockets for MIDI In, Out and Through. Additionally, there are a further two jacks for remote control of bypass and program step using optional footswitches. The programs are arranged in rows of 10 and this step function only allows you to step through the programs in the row currently selected. Of course you can access any program from the front panel or via MIDI.

In order to be compatible with both professional and semi-professional equipment, rear panel switching of input and output levels is provided giving a choice of +4dB or -20dB and the range of the input level control ensures that anything between these limits can also be accommodated.

Operation

The handbook is very comprehensive so I won't examine the unit in too great a detail but essentially there are three modes of operation: Program Mode, Register Mode and Parameter Mode. Program mode is used solely to select one of the preset effects which are arranged in six banks of ten. As there are only around 40 preset effects, some locations are invalid and the display reads Not Available when you try to access one of them. Using the numeric keys with the PRG button illuminated, any one of the presets can be called up and this is implemented by pressing the Load button. Until this is done, the previous effect remains active. Reg functions in exactly the same way but only acts on the user programmes.

Parameter mode is called up when you want to create new effects and the system works rather like the REV7 where you call up a preset and then modify it except the PCM70 gives you the opportunity to change more parameters. The actual parameters depend on the patch called up but for reverb, you can select from plate or room simulations and alter pre-delay, reverb time, high and low frequency damping, dry/FX balance and level. Additionally you can alter the attack time of the initial reflections, the reverb density and even add chorus and gating to the reverb treatments. There's much more, depending on which preset you start out with but if I mentioned them all, the list would end up as long as this review! The best bet is to describe some of the effects in each category and to comment on any outstanding features as we go along.

Edited programs may be stored in Reg locations but if a slot is already inhabited, you won't be able to overwrite it unless you disable the memory protect system, again in Row-7.

Effects

Row-0 contains the Chorus, Flange and Delay effects including several Multi-tapped Delay treatments which are very effective. Patches here include Spin Echo, Swarble and Psycho Echoes, all of which seem quite appropriate once you've heard the effect. In this row, it's possible to alter the delay time of each of six taps and these taps have individually adjustable delay time, feedback and pan position. The maximum delay time is 432mS.

Row-1 contains what are referred to as Multi-band Delay programs. Again these have six available taps which have independent level, delay, pan and HF/LF filtering, but the first two voices or taps have further control over feedback and a master diffusion control affects all the taps. The maximum delay time in this instance is 936mS.

"A single drum machine can be made to sound like an entire backing track in any key of your choice and you can change the pitch of the chord/arpeggio via MIDI to produce viable musical arrangements."

Row-2 brings us onto the mysterious Resonant Chord programs. To explain what these sound like requires a little thought. You may be familiar with the effect achieved by setting a delay unit up to give a very short delay and then applying feedback. On feeding a drum beat or other percussive sound into the unit, the delay line will resonate and produce a distinctive note, the pitch of which can be varied by changing the decay time. If six such delays were set up but tuned to the notes of a chord and then sequenced in some way, an input would create an arpeggio as the different resonances were excited in sequence. This is in fact what the PCM70 achieves, and each of the six resonators may be edited to alter level, pitch, duration and high frequency cut off. In addition, there's a master resonance control which increases or decreases the resonance of all six sections simultaneously. Several effects available within this unit contain the letters BPM in their names, these Resonant Chord settings included, and in this case BPM stands for beats per minute. What this feature enables you to do is to program the rate at which the effect occurs in beats per minute, so you can match the tempo of the effect to the piece of music you are working on. Though this effect works well on drum parts or the output from drum machines, it's also effective on voices and instruments providing that the notes of the arpeggio don't clash with the key of the song. To this end, this selection of treatments contains major, minor, seventh and thirteenth chords to get you started, and the overall pitch may be controlled in semi-tone steps.

Row-3 contains a selection of Concert Hall programs and consequently these exhibit a fairly low reverb density. All the reverb parameters may be changed to produce a wide range of user reverb effects which can then be stored away for future use.

Row-4 is designated as Rich Chamber. This might sound like Paul Getti's loo but in fact it's another selection of reverb settings. This is a good general purpose reverb treatment where several instruments within a mix need to be processed at once.

Row-5 presents us with a selection of Rich Plate programs which are the ideal basis for percussion treatments as they are bright and have a high level of initial diffusion. All reverb programs have around 20 user-variable parameters which the manual lists in the form of a set of tables and gating may be applied to any reverb setting via the editing system.

MIDI

Row-6 does not contain any new effects as such but is used to store existing programs such that their patch parameters may be set to utilise the MIDI compatibility aspect of the system. Patches exist for controls that feature on many popular synths in common use but don't worry if you need something a little bit different because you can edit the patch parameters to suit your own needs. For example, Mix is patched to operate from the data entry control fitted to most synths but you can change this if your synth doesn't use a data entry controller.

All these pre-programmed patches are fully detailed in the manual and editing isn't too difficult once you know what you want to achieve.

Row-7 contains the software equivalent of the memory protect switch the auto-load switch and MIDI Mode and Channel assignment. The PCM70 will transmit and receive on 16 MIDI channels with Omni, Poly or Mono status and note numbers in the range 0 to 127 are recognised as are program changes over the same range.

Performance

The system comes with a fairly high technical spec in terms of dynamic range, bandwidth and distortion, the figures being 80dB, 20Hz to 15kHz and 0.05% respectively for the effected sound. As is common with this type of equipment, the memory is backed up by a lithium battery which should last for several years and the unit does have a battery low warning to let you know when your time is nearly up.

The reverb programmes are good and very flexible and the only obvious omission is that there is no reverse reverb preset and no way that I could find of simulating one. To be honest, the new generation of digital reverbs is so good that there is very little to choose between them, although they all sound subtly different when compared directly. Digital reverb always sounds artificial and obviously digital under test conditions but this sound has become accepted as the norm and as a testimony to this, various manufacturers are now busy cooking up programs to capture the endearing artificial traits of their rival's products. No problems then in the reverb department but that's hardly surprising when you consider that Lexicon have been in the reverb game for some time now.

"...there's the facility to enter your own name for the patch which is a sensible idea..."

The delay effects, particularly the multi-delay effects can be used in all sorts of interesting ways and the ones that can be set up in beats per minute are useful when you are working with drum machines and sequencers. Also the chorus and flanging effects are up-to a very high standard, but you may do well to record these effects onto tape at the track laying stage. It's unlikely that the unit will be free to do these tasks at mixdown as you'll probably be using one of the reverb programs.

What about this resonant chord business then? At first I thought it was a bit of a gimmick but you can certainly produce sounds that no other machine can generate. A single drum machine can be made to sound like an entire backing track in any key of your choice and you can change the pitch of the chord/arpeggio via MIDI to produce viable musical arrangements. Used on a guitar the effect is quite disturbing and the intensity of the resonant effects varies depending on your playing technique. Soft notes produce slightly coloured echoes whilst hard ones invoke an effect not unlike a Stravinsky meets Brian Eno concert. This is definitely a must for anyone doing atmospheric or film music; the more you play with this section, the more you discover. The only danger is that this effect is so distinctive, it is in danger of being done to death in a very short time if everyone starts to put it on their records.

Conclusions

The machine is surprisingly easy to use insofar as you don't have to keep going back to the book to find out what the controls do but there are so many parameters to edit that you could get bogged down if you feel obliged to alter every one of them. This is in no way a criticism as the operating system is very logical, but you do get a very large choice of things to twiddle.

The sound quality is good on all the effects and as I mentioned earlier, the only real omission is that of a reverse effect which I quite like to use on occasions.

In the Reg mode which is used to store edited programs, there's the facility to enter your own name for the patch which is a sensible idea; on the Yamaha REV7 you just get the name of the original patch from which the new one was generated.

Finally of course comes the inevitable comment on the price which sets this unit a bit above the budget sector of the market and in all honesty, I could only recommend this model if you have a real need for the other effects as you can get a good digital reverb-only device for about half the price of this machine.

The MIDI controllability should make this a popular unit in electronic music studios and certainly the ability to dynamically control various reverb or delay parameters from a MIDI keyboard is going to provide an irresistible attraction for some people. It's definitely an innovative product and it's time we saw something new.

The Lexicon PCM70 costs £2127.50 including VAT, and further details from Scenic Sound Equipment Ltd, (Contact Details).