Lexicon Dual Reverb

When it comes to cloning people, or even sheep, there's always an outcry, but where do you stand on the issue of a plug‑in card that effectively turns your Lexicon PCM90 into two Lexicon PCM90s? Paul White feels that first in the queue would be the appropriate location!

One of the better things about high‑end products is that the manufacturers generally leave room for expansion, via either software upgrades, or plug‑in cards like this one. As those of you who read the Lexicon PCM90 review in SOS May '96 will know, the machine is built around a pair of Lexi Chip II dedicated reverb processors and, though some of the algorithms require them to work together, they are sufficiently powerful to work individually, making it possible to generate two entirely different reverb programs at the same time. Indeed, the reverb for the Lexicon PCM80 is handled by a single Lexi Chip II.

The Dual Reverb read‑only card provides 10 new reverb algorithms comprising various combinations of Chamber, Inverse, Room2 and Surround Chamber (Matrix), which, in isolation, will already be familiar to PCM90 owners. Six of the new algorithms are splits, where the PCM90 can be used as two separate reverbs fed from two different aux sends; the remaining four are cascades, allowing one reverb effect to be placed in series with another. The effect parameters are set out in the same way as their standard PCM90 single‑effect counterparts, and full routing and modulation support is maintained — in fact, the Inverse algorithms function has been given a few new parameters. And, of course, the input routing arrangements have been changed so as to allow the dual algorithms to be used effectively. The dual effects may be routed as Stereo Split, Mono Split or Reverse Mono Split, whereas Cascade offers the choice of Left Cascade, Right Cascade or Stereo Cascade.

Few busy professionals ever seem to find the time to program new Lexicon effects from scratch, so 200 new presets come with the card. The four banks of 50 effects are broadly divided into Studio, Live, Post and Surround, and these are further broken down into application groups, each extension memory bank being denoted by an X.

To use the card, you must either power up your machine with the card installed, or follow a load routine if you installed the card after power‑up. The card may be removed from the machine once it's loaded, but any new algorithms will be lost when the machine is switched off. User patches based on the card will be saved, but you can't access these unless the card algorithms have been loaded. Obviously, if another PCM90 card has already been loaded, it won't be possible to load a second card.

Routing

The InRouting control determines the routing, which differs depending on whether dual or cascaded algorithms are selected. Mono Split enables the PCM90 to be used as two separate mono in/stereo out processors, where two aux sends feed the two inputs. RevMono does exactly the same, but swaps the two inputs over — great for those people too lazy to swap a couple of patch leads, I suppose! Stereo Split is stereo in, stereo out, so both reverb blocks are heard in parallel.

When the cascade options are selected, the effects can either have mono or stereo inputs, and the output of the first effects block feeds directly into the input of the second. Each preset has a pre‑configured routing setting and symbols are provided in the preset titles to provide clues as to what routing system has been used.

The Effects

The effects blocks need little description, as they're very similar to those found in the unexpanded PCM90 — though the Inverse algorithm has been enhanced somewhat. Using this block, reverbs with varying attack and decay rates can be combined with variable time intervals to create gated, reverse or normally decaying reverb patterns with pre‑delay and discrete left and right delays. Sadly the Ambience algorithm isn't included in the dual programs, presumably because it takes up too much processing power.

For around 10% of the cost of a PCM90, this card effectively doubles the capability of the machine in many routine (and a few less routine) mix situations, and, on top of that, it provides 200 new presets.

The surround chamber is similar in character to the one in the PCM90, but this has a mono output designed to be added antiphase to the output of another reverb block, so as to force the result to appear in the surround channels of a surround mix. The manual warns that this algorithm must be used with a surround decoder, as it's quite possible that the entire effect will be cancelled out if it's used in mono.

As far as I can tell, none of the reverb effects suffer in any audible way from being handled by one Lexi Chip II rather than having both at their disposal; for most routine mixing jobs, the split 'two mono ins, one mixed stereo out' option is perfectly fine. The combinations on offer provide adequate flexibility as regards which effects may be used together, and the cascade programs offer a number of creative possibilities that an unexpanded PCM90 can't quite match, not least because they double the number of delay paths that can be included in the overall patch.

Summary

For around 10% of the cost of a PCM90, this card effectively doubles the capability of the machine in many routine (and a few less routine) mix situations, and, on top of that, it provides 200 new presets. The card comes with a full‑size manual, which includes block diagrams of all the algorithms, and all the presets are described in reasonable detail. There's also a representation of the parameter matrix below each algorithm, so you can see exactly where to find the various adjustments. Ultimately I see this as a must‑have accessory for any PCM90 owner who dreams of being able to use two units on the same mix.