Lexicon PCM-90 Digital Stereo Reverb Processor

Version 1.01While some of the PCM-style reverb algorithms have been retained, the PCM90 also includes algorithms brought in from the high-end Lexicon 480L and 300L, perhaps the most notable being the 300L's Ambience algorithm. The dual Lex chips also allow the PCM90 to function in a true split mode, and one very flexible split algorithm taken from the 480L is included, enabling two different mono-in, stereo-out reverbs to be set up at once. Plans are in place for an expansion card offering further split reverb functions which utilise one Lex II chip per algorithm, and this is expected later in the year. There are five stereo reverb algorithms in total, and though the PCM90 isn't a multi-effects unit, there are additional parameters in some of the algorithms that take the effects further than basic reverb, by incorporating delay, modulation and EQ.

Like the PCM80, the PCM90 comes with a library of presets, and these cover all the usual acoustic spaces and plates, plus a few oddball effects. The presets are arranged as five banks of 50 patches, grouped into Halls, Rooms, Plates, Post and Split, with one bank per section. A new addition to the operating system is Keyword sorting, which allows you to tag your favourite patches so that they can be reviewed, database-fashion. Each preset comes with up to four Keyword tags, but you can change these in Edit mode if they don't meet your needs. In theory, if you want to pick a Drums/Percussion reverb, you can do a Keyword search to view only the patches you've tagged with Drums/Percussion. A full MIDI implementation is included for remote program selection, plus real-time control and a powerful set of tempo controls. This means that the rate of tempo-related effects can be tapped in from the front panel, effect tempo can be locked to an external MIDI device, and there's even the option to generate MIDI clock from the tempo you've tapped in. Tempo may be used to control LFO rates, delay parameters and so on, and there's provision to select different rhythmic tempo divisions for the various parameters in a patch. For example, the LFO might be set to run at twice or four times the delay rate. If a patch is designed to work with Tap Tempo, simply hitting the Tap button twice locks in a new tempo. The editing parameters are arranged as a matrix for easy access via the front panel plasma display, and the system includes comprehensive modulation facilities which have some parallels with the approach taken by some modular synths. For example, sources including LFOs, envelopes, switches, envelope followers and sample and hold can be assigned to various effect parameters, allowing the effect to either change with time or be in some way modified by the input signal itself. Up to ten modulation patches can be set up per effect, and you can control multiple destinations from a single source, or have several sources acting on the same destination parameter at the same time.