Live Sound

Dedicated Speaker Processors

Assuming that you've got the basics (decent speakers and solid amplification) in place, the best makeover for any live sound system can be a new digital speaker processor, a session with a fa 1/01/2004 7:00 AM Eastern

Assuming that you've got the basics (decent speakers and solid amplification) in place, the best makeover for any live sound system can be a new digital speaker processor, a session with a favorite speaker measurement system and some choice music tracks for tuning. And access to memory presets lets users store parameters to handle a variety of events in a fixed install or recall setups for different venues when touring.

Want more detailed info? Click here to see the "Specs at a Glance" chart (Adobe PDF format).

Many of the digital signal processors on the market can be used as full-function dedicated speaker processors. Most feature input delay for zone alignment and output delay for component and cluster offsets; parametric equalization of components on outputs; system and room EQ of inputs; onboard limiters for driver/system protection; and increasingly steeper crossover slopes and multiple user/factory presets.

These processors are primarily intended as full-featured crossovers, but live engineers often employ them for speaker zone control, taking the console's stereo mix and distributing it to main clusters, as well as subwoofers, frontfills and delays. For those who want to drive subs on an aux send, products with more than two inputs offer an advantage. While their main applications are live sound systems, these processors are increasingly found in studio control rooms where large-format reference monitors benefit from their use.

An entire class of products not included in this article are processors intended for installations with Phoenix or Euro-block analog connections on the back or those that are normally programmed from a computer. They generally have a bit less dynamic range, often lack front panel controls and typically include contact-closure inputs for use in ballrooms as room-combining processors. Most provide mic level inputs, offering complete microphone-to-amplifier solutions for contractors.

As more engineers use digital consoles in live sound applications, there's a growing interest in AES inputs, either standard or optional, which can increase a system's dynamic range. Some users prefer to tune a system with parametric filters, but a couple of brands permit graphic EQ to be used instead, or a combination of both.

Whether using a manufacturer's proprietary software or Device Control under SIA Software's SmaartLive, the ability to remotely program, operate and archive a processor from a computer makes it more powerful. Through use of wireless networking, this control can be extended, allowing a system tech to move throughout a venue and make adjustments from inside each zone. A wireless touchscreen device control is the new paradigm for pro sound EQ. There's no mouse on the bridge of the Enterprise.

With that in mind, let's check out a number of DSP boxes for sound system control from a variety of third-party suppliers. The following includes brief product descriptions; a chart later in the article provides more information and offers at-a-glance comparisons of features and functionality.

On the heels of its Intelli-Q stereo digital EQ, Belgian company Apex (dist. by Transamerica Audio Group, introduced the Intelli-X Equalizer and Speaker-Management System. Its four inputs can simultaneously provide a half-second of delay, eight bands of parametric EQ, two shelving filters, plus a 30-band graphic EQ. There are also two stereo AES/EBU digital inputs. Multiple Intelli-X processors can be networked with Windows software, allowing control of combinations of Intelli-Qs and Intelli-Xs from the same PC via a USB connection and the Apex RJ-45 serial bus. The Intelli-X has an optional one-rack-unit Intelli-Sense speaker-protection system that continuously monitors the true RMS power delivered to the speakers and adjusts the Intelli-X's internal limiters to prevent thermal failure of transducers.

Ashly Audio's 4.24C ( is the crossover model in the company's Protea System II line of digital processors. Like most processors in this roundup, the Protea C can be computer-controlled from an RS-232 connection via either Ashly's PC Graphic User Interface, SIA's SmaartLive or MIDI. The front panel's 2-line, 20-character display shows parameter, function and utility information.

The Behringer ( UltraDrive Pro DCX2496 is a 3-in/6-out unit with dynamic EQs and parametrics available on all inputs/outputs, along with limiter protection. Other features include four mono and stereo output operating modes; Butterworth, Bessel and Linkwitz-Riley crossover types; 6 to 48dB/octave slopes; individual delays; and an additional sum out signal. RS-232 and RS-485 interfaces enable single or multi-unit control via free Windows-based editing software, and presets can also be stored to a PCMCIA card slot.

BSS' ( Omnidrive Compact plus T is the newest version of the only top-shelf processor with three inputs. BSS' new FDS-366T provides a new crossover type from Australian audiophile company Whise, designed by Neville Thiele. His filters are comparable to Linkwitz-Riley topology, but with steeper roll-offs (36 and 52 dB/octave). The Neville Thiele Method filters maintain phase coherence thoughout the crossover region and sum for flat response. Speaker designers can use them to increase efficiency and widen a driver's bandwidth. Most programs employing L-R filters can substitute NTM filters without further changes, though steeper slopes can permit further optimization of crossover frequencies and out-of-band EQ.

The BSS MiniDrive FDS-336T is the newest version of the company's entry-level product. It now also includes the Neville Thiele filters recently added to the Compact plus, and older units can be flash-upgraded, as can the older 366s. While lacking a few features such as dynamic EQ, the third input, AES/EBU ports and the Alignment Assistant found on the plus, the 336T offers BSS quality to a wider audience. It's also available with four outputs as the FDS-334T, which is better suited to bi-amp monitor applications.

The DriveRack 480 from dbx Professional ( is the company's flagship, and can be used stand-alone, via PC or with the 480R DriveRack Remote, on which 32 instant-access buttons and 31 moving faders can control multiple units. Two slave models, the 481 and 482, lack front panel controls and offer a choice of XLR or Euroblock connectors. It features separate house and show input EQ with individual lockouts and dual RTAs for two of its four inputs that can be used for measurement mics.

dbx's DriveRack PA is a stand-alone, no-frills processor, offering graphic front-end EQ and 10 ms of transducer alignment delay. However, it has extras such as a classic dbx compressor, 120A Subharmonic Synthesizer, a dozen notch filters and a JBL/Crown setup Wizard. An RTA mic input, pink-noise generator and Auto-EQ with 28-band RTA make the DriveRack PA perfect for value-engineered installs or compact portable systems.

The newest dbx DriveRack for live sound, the DriveRack 260, picks up where the PA left off. Features include a full second of input delay for zone alignment, nine parametric input filters, PC control via DriveWare software or device control under SmaartLive. A line of five different wall-panel zone controllers can mount in standard electrical switch boxes and connect up to 1,000 feet away via Cat-5 cable. The 260 also has a full-time RTA for its pink noise and measurement mic input.

Australian firm DEQX ( offers the PDC-2.6 “ClarityEQ,” primarily intended as an active crossover upgrade for passive two- and three-way control room monitors and high-end consumer speakers. It comes with its own optimization software for making EQ and delay adjustments. It employs FIR filter technology to synthesize extremely steep crossover slopes. While not primarily intended for live sound, there may soon be a sound reinforcement spin-off.

Electro-Voice's ( Dx38 is the company-branded processor based on the Dynacord 244. It includes Real Acoustic Cluster Editor (RACE) software for controlling and programming the unit, which calculates and displays the free-field acoustical output when used with various E-V speaker products. Parameters can also be adjusted from the front panel controls. An optional RS-485 interface can be installed in place of the standard RS-232 port, allowing control over 650 feet of mic cable or six times that with Cat-5.

JBL Professional ( has given new life to its DSC260, upgrading it to 24 bits for higher dynamic range, adding new 2-stage limiters and renaming it the DSC260A. The 260 has been employed by more than a dozen other speaker manufacturers as a dedicated OEM system processor, and this will continue to be a widely used product.

Klark Teknik's ( DN9848 is the original high-density, 4×8, single-rackspace processor that was upgraded in Version 3.0 with Smaart compatibility and four additional parametric filters on its inputs, for a total of 96 filters. In addition to six user memories and 32 system programs, there are 99 factory presets. Summed inputs have a unique balance control. The RS-485 connections are conveniently provided on XLR connectors, while the front panel RS-232 port is an 8-pin mini-DIN.

Contour from Lake Technology ( set the live sound world on its ear with a new paradigm for speaker EQ that employs 96kHz resolution, low-propagation FIR filters and wireless Ethernet operation from a tablet PC. Its method of filter synthesis allows unlimited EQ overlays, and unique topologies such as “brick wall” and “mesa” filters are also possible. Lake's new plug-in provides integration between its Controller software and SmaartLive, showing RTA, spectrograph and FFT displays directly in Contour's software interface. For more, see the Lake Contour “Field Test” on page 100.

Sony's ( SRP-F300 is a little-known SR processor that's been living in the shadow of Sony's more glamorous pro audio gear. The F300 features 96kHz sampling, a choice of analog or AES inputs, and either graphic or parametric filters that can be chosen for input EQ. It has an internal pink-noise and sine wave generator, and its compressor can accept sideband EQ. It is programmed from Windows 95/98 software, and front panel controls allow only limited adjustment for security purposes.

At the recent AES show in New York City, Toronto's Xilica Audio ( introduced its new DLP4080, a full-featured, 4×8 1RU processor. Any combination of inputs can be summed as a source for an output. As with most DSPs today, its firmware is flash-upgradeable, and refinements like dynamic filters and feedback eliminators are in the works.

The DP226 from XTA (dist. by Group One Ltd., is an industry benchmark processor that's also been spun off into OEM versions for several speaker manufacturers, while being the processor of choice for others. Available with optional AES digital inputs and outputs, it's controllable from its AudioCore software and Smaart. Connections for RS-485, RS-232 and MIDI are standard. A front panel card slot provides convenient PCMCIA storage and backup of settings. A similar model — the DP 224 — has four outputs.

XTA's new DP6i has the same circuitry as its 226, but with a stripped-down front panel at a fraction of the cost. Parameters are not front panel-adjustable, but all of the rear panel connectivity of the 226 has been retained. Instead, there are four front panel push buttons for recalling four presets. An internal switch puts the unit into Safe mode where all front panel controls are disabled.

Mark Frink is Mix's sound reinforcement editor.

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