Be Flexible

The digital signal processor has become common in the drive racks of sound reinforcement systems. The next step in the application of this technology is the application (finally) of digital mixing consoles. However, the fully programmable DSP unit offers the greatest boon to the creative talents of the industry. These devices offer the ability to make use of signal processing in ways that were too expensive, complex, cumbersome or reliable in their analogue counterparts. Combining the flexibility of a digital mixer with a fully user-configurable signal processing path can extend the creative abilities of the live sound technician, if he or she has the patience, time and interest.

Live sound technicians have always developed favorite processing chains for vocalists, drums, guitars, etc. that gave them creative control over the signal and, sometimes, a personal trade-mark sound to set their work apart. This can be extended dramatically with the application of signal processing (from BSS, IED, Peavey, Yamaha and a few others) that can be built from basic functional components. These powerful DSP boxes offer a drop-down menu of every conceivable (at least to the manufacturer) processor. From a "blank slate", a chain of processing that would have filled several FOH processing racks can be dedicated just to the lead vocal. Other chains can be created to handle any other featured or difficult instrument. Once a suitable processing chain is created, it can be saved as a unit and used as though it were a single (albeit complex) processor. While these processors are in routine use in installed sound reinforcement systems, we can expect to see a growing awareness of the power they offer touring sound applications.

Innovative analogue devices, such as the BSS 901 dynamic EQ, can be emulated and built upon. Imagine having a vocal processor that removes the screech of the vocalists loudest moments without loosing the high frequencies needed to make the rest of the vocal cut through the mix, combined with the same type of processing for the backup vocals to improve their dynamics and tonal balance. Using mixing devices, stereo parametric EQ devices and dynamic devices; a chain can be created that controls the signals individually and collectively; reaching far beyond the capability of the traditional side-chain. Taking each of the single-channel sources and processing them with stereo-linked dynamics devices, you can build a monster side chain that can be equalized (like the aforementioned dynamic EQ) and more. As the side chain path is audio and not just a control signal, you can pass the audio through other dynamic processors, such as noise gates, that allow you to determine when the chain of processing is linked between mic channels and when it is acting only on the main input signal.

Another advantage of the digital domain is that you have complete control over the relative timing of these signals. You can build dynamic processing that has no overshoot or even have the level reduced before the peak arrives. This is accomplished by inserting the delay in the main channel and not in the side chain. Of course, it is "live" sound and you will only have a few milliseconds to play with before the delay becomes noticeable to the audience. However, even that is enough time to warn of impending peaks and have the processing already on.

The programmability extends to the selection of a control interface. Once a complex signal processing chain has been created, a user interface can be constructed. This allows the user to build a control surface that includes only those adjustments and indicators that are needed during the show. In necessary, several levels of control surface can be created to allow for the regular shows and then for those days when the vocalist is really, really tired and every last threshold will need to be adjusted. Unlike analogue gear, you can create controls that change parameters on many different processors with a single knob (of course, it was possible to a lesser degree with MIDI control) and the range and even the nature of the control can be defined. You could build the "tired" control that handles all the dynamics thresholds from a single knob.

All this programming sounds like a lot of work, but once you have built your own processing system in one of these universal DSP devices you will find it is less time consuming than loading and wiring up the FOH rack. Of course, you can cut and change whenever you want. No need to have the shop FedEx a new processor to the next venue; it's just a mouse click away. While your sitting in the tour bus, you can get out your laptop and rebuild your FOH rack while the rest of the crew watches Spinal Tap for the 200th time. You know when to look up to see the highlights, anyway.

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