Lexicon PCM80

Lexicon's PCM70 reverb has been widely acclaimed as a modern classic, a ubiquitous component of pro studios worldwide. Paul White tests out its successor, the PCM80, falls deeply in love with it, then has to give it back!

The new PCM80 takes the concept of the legendary, industry‑standard PCM70 into the mid '90s by offering a wealth of highly sophisticated reverb and delay‑based effects and effects combinations, in an accessible, easy‑to‑use package. Its price falls somewhere near the middle of the Lexicon range (it's not cheap, in other words), but at the risk of giving too much away too early, the quality of its effects is comparable with that of the most elite Lexicon processors.

Lexicon have incorporated two or three new ideas into their operating system to make the PCM80 easy to use, even though the more dedicated effects programmer still has access to an almost unbelievable wealth of parameters, options and control functions. One of my own crusades has been trying to convince more synth designers to incorporate such ideas, so I'm delighted to see that a major player like Lexicon is thinking along similar lines.

User Friendly

The PCM80's first base of user‑friendliness has got to be the 200 factory presets which are divided into four logically‑demarcated groups of 50. OK, presets aren't exactly new, but in the case of the PCM80, there's a front panel Adjust knob which provides instant, real‑time access to the most important parameter of whichever preset (or user patch) is loaded. Next is a dual‑level operating system which Lexicon call Go or Pro. The unit first boots up in Go mode, which means that when you start to edit a patch, you're presented with up to 10 of the most important parameters and no more. In many instances, this will be all the editing that's required, but switching on Pro mode permits full user access to all available parameters — up to a maximum of 100 per patch! Finally, once in Pro mode, you can create your own key Go parameters and Adjust knob destinations for the user patches.

As delivered, the PCM80 has 200 presets and 50 user memories, but its user memory can be expanded very simply by means of standard PCMCIA SRAM memory cards of up to 1Mb capacity, enabling up to 2350 further patches to be stored. Another thoughtful feature is that the unit's internal RAM can be expanded using standard computer SIMMS, to increase the basic maximum delay time from 2.6 seconds to more than 42 seconds. We've also just heard that Lexicon will be introducing a series of algorithm cards for the PCM80, to further expand the unit"s sonic potential in the future.

Though the available effects are all based on reverb, modulated delay and basic EQ, the PCM80 has a few tricks up its algorithmic sleeve, aimed at wringing the maximum creativity out of these now‑standard forms of audio manipulation. Perhaps its most powerful feature in this respect is the internal modulation patching system, which is roughly analogous to the Matrix Modulation system devised by Oberheim for use in their synths. Here, internal modulation sources such as LFOs, envelopes, envelope followers, latches and time switches, can be patched to just about any meaningful effect parameter, providing incredible scope for dynamically evolving effects. Up to 10 patches of this kind may be created within each effect setup, and in addition to one‑to‑one patching, multiple sources can be mapped to single destinations and vice versa.

Another very friendly feature is a kind of simple on‑line help; most of the button functions are applied when the button is released, but if you push and hold a button, you get a helpful prompt message instead of the usual button response.

The Hardware

The PCM80 looks almost understated when you consider what's inside it. The 1U case follows traditional Lexicon styling, a two‑line, 20‑character display dominating the clearly‑designed front panel. Aside from the input level control, there are just two rotary controls, both continuously‑variable knobs, dedicated to the Adjust and Select functions. Adjust is normally used in edit mode to change the value of selected parameters, while Select scrolls through patches, parameters and so on. To Lexicon's credit, the control panel has been kept very simple, with just a dozen buttons, which all have clearly‑defined, dedicated functions. To the extreme right of the panel is the card slot, which takes both preset ROM cards and user‑programmable RAM cards.

The rear panel reveals stereo ins and outs on balanced jacks, further jacks for a foot switch and a foot controller (pedal), and a full complement of MIDI In, Out and Thru sockets. The audio operating level may be switched to match semi‑pro/instrument levels or pro studio/broadcast levels, and as you might imagine, the PCM80 also has a very thorough MIDI implementation, including the ability to dynamically control effect parameters over MIDI.

In order to maintain optimum audio quality, the conversion system is 18‑bit and may be set to run at either 44.1kHz or 48kHz sampling rates, yielding a 100dB signal to noise ratio and a frequency response extending from 10Hz to 20kHz within half a dB. The delay time through the system (other than any deliberately imposed ones) is just over 1mS — which is about as good as you can get, given current converter technology. In addition to the analogue ins and outs, the PCM80 also features S/PDIF digital I/O linked to a wide range of editable user parameters. This can run at either sample rate, can be sync'ed internally or externally, has options for the way in which SCMS (Serial Copy Management System) is handled, and provides key information on digital errors.

I should say at this point that this review can't possibly cover all the fine detail of the PCM80, so I'll apologise in advance to both Lexicon and the reader for points necessarily omitted or glossed over. The manual for the PCM80 is almost as thick as this magazine, and even that's been written as concisely as possible. However, I must stress that the overall operating system is very straightforward, and you only need to dip as far into the techno‑horrors of advanced effects programming as you want to.

Effect Organisation

A system of Banks, each containing 50 patches, is used for patch storage. As supplied, the PCM80 has four preset Banks and one user Bank. Individual Banks may be accessed directly over MIDI, and MIDI Bank Select messages may be used to hop from one Bank to another. An assignment table can be constructed, allowing up to 128 patches, taken from any combination of Banks (preset, user or internal) to be mapped to any MIDI program number. A further mode, called Chain, allows a single MIDI program change to load in one of 10 possible effects chains, which can be navigated using a MIDI controller mapped to the Pgm + and Pgm — (program increment/decrement) parameters.

Patches are normally loaded manually by selecting the desired Bank, and then using the Select knob to find a specific patch within that Bank. Finally, the Load button is used to replace the existing patch with the new one, though somewhere, deep in the operating system, the mode of operation may be changed to provide direct loading of selected patches.

Patch loading is the only area in which I have misgivings about the PCM80, because the process takes a second or so, during which the audio output is muted. It would have been nice to see a system that allowed seamless transitions to be made between one effects patch and another; though this may be wasteful on memory, I still feel it would be worthwhile, especially where MIDI is being used to change patches during a mix. As it is, you have to pick your moment carefully.

Again I'm going to have to skip some of the subtleties — like the various bypass mode options that allow you to decide whether an effect dies naturally or is cut off abruptly — but one area that needs mentioning in more detail is the way in which the PCM80 can utilise tempo information. A front‑panel Tap button allows tempo information to be banged in, in real time, but things go a lot further than this. Any delay parameter (and some effects have 10 different ones!) can be set either as a time value or as a tempo, and in tempo mode can be linked to incoming MIDI clock so that the effect will follow tempo changes. Tap information may also be entered remotely using a designated MIDI controller, and it's even possible to link the rates of the internal LFO modulators to tempo.

When it comes to patch editing, edit parameters are arranged in the form of a matrix of up to 10 lines, with up to 10 parameters per line. The Go parameter line, or Soft Row, appears first; the parameters in this line are simply duplicates of parameters available in following rows. In other words, this line doesn't provide you with anything new or unique — it simply gathers together up to 10 selected parameters from various parts of the matrix, so that you can access them from one place. For example, in a reverb algorithm, parameters like 'Decay Time', 'Pre‑delay' and 'Effects Mix' are obvious candidates for quick access, whereas you might not be quite so worried about getting to 'Diffusion' in a hurry.

Algorithms

The PCM80 isn't a conventional multi‑effects unit that tries to do everything — instead it combines delay/modulation effects with reverb in a number of creative ways. Each effect is based on one of 10 possible algorithms, which are further sub‑divided into four‑voice and six‑voice algorithms. The four‑voice algorithms are:

• Concert Hall
• Plate
• Chamber
• Infinite
• Inverse

The idea is that a specific reverb type is teamed with a flexible combination of delays. The six‑voice algorithms are:

• Glide>Hall
• Chorus+Rvb
• M‑Band+Rvb
• Res 1>Plate
• Res 2>Plate

These comprise a specific reverb type teamed with a six‑voice, delay‑based effect such as multitap delay, resonator, and so on.

All the four‑voice algorithms have many parameters in common, and where possible, these always appear in the same positions in the edit matrix, which makes it easy to find your way around, regardless of which algorithm you're using. The four‑voice algorithms all have a similar structure, but because the way in which the reverb and delays are combined and routed is quite complex, a block diagram will probably explain the arrangement better than I can. Just remember that the signal flow follows the arrows and you won't go far wrong (see Figure 1).

The six‑voice algorithms are a little more varied in structure, the first being 'Glide Hall', where the delay times may be modulated to create a pitch‑gliding effect (subtle pitch glides are useful for setting up dynamic flange effects as well as more obvious pyrotechnics). Reverb comes last in the signal chain so that it may be added to the delay effects already created.

In Chorus+Rvb mode, the reverb is in parallel, with six independently adjustable modulated delays, each of which can be panned anywhere in the stereo soundstage. M‑Band+Rvb is similar, except that the delays work as independent delay taps, each with its own high/low cut EQ and feedback amount.

I must admit to being infatuated with the Resonant Chord algorithms, in which the six delays are configured as MIDI tunable resonators. When excited by a percussive source, these resonators ring at whatever musical note they're set to; depending on the parameter settings, the result can be anything from the effect of tuned log percussion to playing inside a piano with the sustain pedal permanently down. In the first of the two algorithms, the six resonators accept chromatic pitch information in such a way that when all six have been used up, the next pitch re‑uses the first resonator, rather like synth voice allocation. In the second version, the resonators are tuned to a harmony of the incoming note information, based on the key, scale and root note set by the user. The resonated sound, in both instances, may then be treated by the reverb block.

Each of the PCM80's two audio inputs has its own pan control, which enables the unit to work in true stereo mode or to synthesize a stereo effect from a mono input.

The Effects

No matter how many parameters there are to tweak, the real crunch for an effects procerssor is the quality of its effects: I can only say that the PCM80 is stunning in this respect. Particularly impressive is the effect of the Stereo Width parameter, which can not only be adjusted to give anything from mono to a wide reverb that reproduces surround systems, but also allows you to dynamically sweep the width using any of the available modulation facilities. The reverb and chorus patches are the widest, deepest effects I've heard from any effects unit under the price of a new car; indeed, the reverb wraps round you so convincingly you could almost wear it as a coat. Lexicon have a knack of creating a reverb that you can really ladle on without killing the original sound, and that's something that's been carried through to the PCM80. I don't know if their reverb algorithms are the nearest thing to a real‑life situation, but they're still the nicest to listen to. If you want the classic Lexicon reverb sounds, (including Lexicon's own Spin parameter), you don't really need to look any further than the PCM80. The non‑linear and infinite reverbs are also excellent.

The chorus patches have a rare clarity and transparency, while the PCM80's modulation capabilities enable incredibly fluid, evolving effects to be set up. Similarly, the resonator effects are clean, focused, punchy and magical. In the delay department, there's an almost dizzying range of multi‑tap treatments on offer and, because the modulation possibilities are so far reaching, many of these stand out as being quite different from the run‑of‑the‑mill effects we're all used to. Of course, some of the presets are designed more to show what is possible than to offer a musically useful effect, but most will set your imagination working.

I could go on about how wonderful this unit sounds, but the only way to appreciate it is to check it out for yourself, preferably in an A/B comparison with something you already know. There are many excellent reverb units on the market, but a Lexicon still has that indefinable magic that sets it apart from the rest. Incidentally, the release of the PCM80 doesn't mean curtains for the classic PCM70; Lexicon will still be supporting the older unit, and will still build them for as long as there is sufficient demand.

Summary

The PCM80 is so much more than just a reverb unit, yet the Lexicon reverb sound is central to the overall sound. When it comes to creating truly three‑dimensional textures, this little box takes some beating, not only in terms of its subjective effects, but also for its supreme audio quality. There are so many creative possibilities that it's obvious that the PCM80 won't date easily, and will grow alongside you as you get deeper into it.

Operationally, this unit is exceptionally straightforward, thanks to the dual‑level operating system, the in‑built prompts, and the way in which the Adjust knob lets you change an effect without having to go into edit mode. My only negative comment, as mentioned earlier, is the time it takes to change from one effect to another.

For those who simply must push any piece of equipment to its limit, the parameter pool is about as deep as you could possibly want it to be, and it is worth mentioning that the possibilities for MIDI, as well as internal control are enormous. ROM cards have been catered for, enabling the introduction of additional patches from Lexicon and/or third parties, and the use of standard RAM cards means that you can save personal patches into a very portable and robust medium.

As pointed out at the outset, quality like this doesn't come cheap, but then neither is the PCM80 unduly expensive when you consider the quality and scope of the effects it makes possible. Actually I'm rather glad it's not any cheaper — because if it was, I would simply have to buy one, and that's something I can't really afford to do — at the moment!