Symetrix Manages Audio Speaker and Mixing Systems with SHARC®, from Boardrooms to Broadway

What do these audio installations have in common?

• A huge system of fiber-optic lines and roughly 213 speakers distribute play-by-play audio to 40,000 Kansas City Royals baseball fans at Kauffman Stadium in Kansas City, MO.
• The 500-seat Christian Life Center of Stockton, CA, is home to a large speaker-management system that processes audio feeds to five main speaker clusters, four delay rings, and distributed speaker systems that are preset according to the format of each worship service.
• Broadway's Tony award-winning musical, Hairspray, combines great acting, world-class choreography, and memorable music. But that's not all. The pit orchestra musicians use in-ear monitors and AMX control to create a personalized mix, reducing the need for on-stage engineers and traditional monitor consoles.

While these audio installations all seem quite different, they have something in common – all are based on SymNet audio systems from Symetrix, a Washington state-based company. Symetrix designs and produces electronics for the management of audio in a wide variety of situations, from boardrooms to Broadway, from houses of worship to home theaters, from major theme parks to major league sports venues.

Another thing the SymNet installations have in common is that they leverage the flexibility and power of SHARC® processors from Analog Devices, Inc. (ADI). With SHARC 21065L and SHARC 21161N processors on board, software modules emulate analog audio processing functions and implement new, digital-audio capabilities. The result? Better quality sound and outstanding configurability.

Plus SHARC processors let SymNet users make changes to processing schemes so they can accommodate multi-purpose venues for increased flexibility. "It's exceedingly important for our customers to be able to reconfigure the building blocks of the processor within an audio I/O box," said Nathan O'Neill, Chief Technical Officer, Symetrix, "SHARC processors enable that kind of flexibility."

More Processing Bang Per Buck
Another reason Symetrix chose ADI's SHARC family of processors was because of their 32-bit fixed and 40-bit floating-point math, which O'Neill said is "a step above other processor designs." The SHARC (Super Harvard Architecture) offers the highest levels of performance and memory integration of any 32-bit processor in the industry. It is also the only processor that offers both fixed- and floating-point capabilities without compromising precision or performance.

The Symetrix modules, which include complex audio software algorithms that run on the SHARC processor, must be written in the most efficient manner possible. "Price/performance is fairly important in our market in terms of dollars/MIPs," said O'Neill. "Being able to share SDRAM, and to use 40-bit floating-point math allowed us to give the customer much more processing bang per buck..."

The multi-processing ability of the SHARC processors allowed Symetrix to use two or four processors per box. "Each processor is part of a pool of resources that we used in a graphical user interface (GUI)," said O'Neill. "We could easily drag and drop processor modules into a design. Hardware and software integration was important, though we wrote our own dynamic linker for the pooled processor allocation."

Symetrix SymNet is a modular system that utilizes a variety of hardware I/O configurations that allow audio system designers to tailor both features and price points to their client's needs. The company's SymLink hardware supports up to 64 audio channels and 16 SymLink devices. To route audio over longer distances, Symetrix CobraLink hardware interconnects multiple SymLink rings and provides direct Ethernet access, enabling sound system control from a facility's LAN. Express Cobra units comprise up to eight channels of audio and can also be controlled over a LAN. SymNet Express hardware is for standalone applications.

The SHARC processors are featured on nine SymNet multi-channel audio processing products. The first two SymNet models – the 8x8 DSP and the DigIO 12x12 DSP feature four SHARC ADSP-21065L processors and two SHARC ADSP-21065L processors respectively. The SHARC ADSP-21065L processor is a powerful member of the SHARC family of 32-bit processors optimized, for cost-sensitive applications, and "provides plenty of performance for the application," said O'Neill. The remaining seven SymNet models – the Express 12x4 Cobra, the Express 8x8 Cobra, the Express 4x12 Cobra, the Express 4x4 Cobra, the Express 12x4, the Express 8x8, and the Express 4x12 – feature two SHARC ADSP-21161N processors each. Symetrix was very impressed with ADI's SHARC 21161N processor, which incorporates the Single-Instruction-Multiple-Data (SIMD) architecture and is often helpful for stereo modules. The SHARC ADSP-21161N, which is a low-cost derivative of the ADSP-21160, can double cycle performance versus the ADSP-2106x on a range of signal processing algorithms by using two computational units (by virtue of SIMD).

Best Peripheral Set
For I/O, Symetrix needed enough serial ports to support TDM serial audio I/O to interface A-D converters to the audio processor devices. They also needed link ports for communication between processors and an FPGA and host microprocessor interface. The memory features that Symetrix required included external SDRAM controllers for memory expansion, and a decent amount of on-chip SRAM.

The SHARC processors were equipped with the memory and I/O features Symetrix wanted. The SHARC ADSP-21065L processor combines a floating-point core with integrated on-chip features, including 544 Kbit SRAM memory; a host processor interface, which provides an easy connection to standard microprocessor busses; a direct memory access (DMA) controller, which allows non-intrusive data transfers without processor intervention; and an SDRAM controller, which enables the processor to transfer data to and from SDRAM at a high throughput. "The on-board SDRAM controller helped reduce bill of materials (BOM) costs," said O'Neill. The SHARC ADSP-21065L processor also includes enhanced serial ports that provide an inexpensive interface to a wide variety of digital and mixed-signal peripheral devices.

The SHARC ADSP-21161N processor combines a high-performance 32-bit core with integrated on-chip features, including 1 Mbit dual-ported SRAM memory, a host processor interface, an I/O processor that supports 14 DMA channels, four serial ports, two link ports that provide additional I/O capabilities and an SDRAM controller, a serial peripheral interface (SPI) that enables an SPI-compatible port to communicate with other SPI-compatible ports, an external parallel bus, and glueless multi processing powerful features tailored for multiprocessing systems. "There were other processors on the market, but not with the same peripheral set," said O'Neill.

For development tools, Symetrix used the ADI command line assembler but wrote its own linker and software debugger. Symetrix said its time-to-market was faster because ADI's assembly language format, which is based on an algebraic syntax, is easier to read than any other they've seen. Symetrix also said that the assembler is well supported in the integrated development environment (IDE), ADI's VisualDSP. "We wanted an easy design approach, and ADI's assembly tools are very easy to use," said O'Neill. "The presence of JTAG [the test access port used to monitor and control the target board during emulation] was also important as it gave us flexible debugging options."

Following its SymNet experience with the SHARC processors, Symetrix also went on to update its "AirTools" broadcast-industry audio processing product line with the ADI devices.

For more information about Symetrix, visit the company's Web site at www.symnetaudio.com.

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