One Box or Two

Live sound systems may only be inching towards a fully digital audio path, but at least now the signal processing chain that follows the mixer is often entirely digital. Unfortunately, this is not because the format for multi-channel digital audio has become standardized within the live sound industry. It's simply a case of DSP-based system processors providing everything necessary to condition a live sound signal, and they are now more functional than their analogue counterparts. The ubiquitous DSP-box has the processing and the feature set to meet even the most demanding needs for equalization, gain management, signal distribution and crossover functions.

The development of these processors has reached the point where you must have a good reason to select analogue signal processing for this task, because cost is no longer an issue. Perhaps, you require something with knobs on, simply to satisfy those instantaneous needs that arise during a live event. You may have found a match between a specific analogue processor and a troublesome performer (the BSS 901 comes to mind). It might simply be a case of needing that very personal silken sheen that only something like a Manley Variable-Mu compressor can achieve. Whatever your reason, it is no longer simply a factor of cost or basic audio quality. Unless your sound system is married to a particular analogue loudspeaker processor or you don't want (or need) any processing, the DSP-based system processor is the least expensive route between mixer and power amplifier.

This is great news for the roadies that must lug the drive rack up the back stairs, and these same racks take up less space in the crowded venue and in the truck that brought them there. The system tech doesn't have to worry about the warm-up band's expert doing a bit of tweaking on the crossovers, or that accidental brush that undoes the system's graphic EQ. Now the front panel may brightly display the name of the tour and the drive rack preset, or simply offer the blank stare of a few status LEDs. Not only do the settings remain constant from night-to-night but, when a unit does go up in smoke, all of the settings can be loaded into a spare unit from a little palmtop computer.

Last winter, Harry Witz proudly showed me the way his company, db Sound, was using the XTA processor on the most recent Rolling Stones tour. Using a tiny notebook computer with a wireless LAN card, the system tech was able to walk, untethered, throughout the venue and adjust any parameter of any loudspeaker component in the array. The system processors were connected to a network and Harry had worked with XTA to develop a comprehensive software package that could address single processors or groups of processors, as required. The result was a powerful way to trim a large-scale loudspeaker array from the only place you could be sure it's right: the audience. This has long been a major problem in touring large venues, where there is never the time or enough crew to enable the system to be perfectly balanced for each venue. Now, the odd-shaped venue can be accommodated with the combination of a powerful DSP unit to handle all of the signal processing, and comprehensive remote control of the critical parameters (level, equalization and signal delay) via remote control. No one in the audience has to suffer because tonight's arena has shallow corner seating but last night's had extremely deep corner sections. Of course, tweaking will still take time, but at least you don't have to shout at one another through radios to get the high-frequency horn in Column B Row 2 or the left side array raised by 3 dB. That has to save some time!

There are now products that offer digital signal processing at every level of cost and capability. There are the low-cost units, such as the Biamp MSP22e that features 28 bands of parametric EQ and more gain management than any analogue crossover I've ever seen. There are high-end units (such as the BSS Soundweb and Peavey MediaMatrix) that provide flexible signal routing that can be personalized beyond anything that was ever possible in analogue devices. In between are some excellent sounding devices that provide so many choices in filters, dynamics and delay processing that your major limitation might be the ability decide on a final configuration. There will be plenty of time to think it over, because you don't have build the cable harness that connects all those stages of processing. It will be even better when we finally get to the point where the whole sound system being connected together with a little bit of fiber-optic cable, but for now at least the drive rack is handled.

United Entertainment Media Inc.
460 Park Avenue South, 9th Floor
New York, NY, 10016
Ph. 212-378-0400
FAX 212-378-2160

page construction