Damage Control Uses SHARC® for Superior Tone for Direct Recording, Pre-amp Guitar Products

In-demand rock guitar players and veteran multi-platinum producers alike sing the praises of Damage Control Engineering's direct recording, preamplifier, and floor-pedal guitar products designed for recording and performing. The list of Damage Control endorsers reads like the "Who's Who" of the rock guitar world, with names such as Yngwie Malmsteen, Robert Randolph, Matt Bachand (Shadows Fall), Michael Wilton (Queensryche), Earl Slick (David Bowie) and producer Sean Beavan, whose amazing production credits include Marilyn Manson, Depeche Mode, and Guns N' Roses, to name a few. The idea that crops up most frequently in any discussion with Damage Control President Lucian Tu is this: "Technology is there to serve guitarists in the art of making music." The company follows this motto by making products that leverage the best characteristics and performance benefits from both analog and digital technologies simultaneously or exclusively.

When Damage Control was developing its TimeLine and Glass Nexus line of hybrid analog/DSP products, the company performed a thorough investigation of the DSP market for audio processors. They wanted a processor that could excel in terms of audio fidelity and dynamic range to implement audio effects algorithms, one they could program using a high-level language. The company chose a SHARC® ADSP-21369 processor from Analog Devices (ADI) because, as Dave Fruehling, Damage Control's VP of Technology, simply stated, "ADI is the leader." Damage Control was also impressed with the SHARC's price/performance ratio, design flexibility, and development tools, as well as ADI's renowned support.

Best Sonic Performance
Damage Control's vision is about providing guitarists with products "that rule" in high-quality tone and range, style, and brand prestige, leveraging the best sonic performance out of analog, digital, and hybrid technologies. The company offers high quality yet reasonably priced products, comprising a range of tabletop, floor preamps, and effects. The company also plans to unveil a comprehensive brand and product line of premium amplifiers, effects, and rack equipment.

Damage Control recognized that many guitarists' "ears" have become more sophisticated over the years due to the fact that they've been exposed to a myriad of features through modeling products that came on the market in the 1990s. Today, many players want new equipment that performs better than vintage gear but offers a wider range of tonal refinements than previously existed. To that end, Damage Control creates unique algorithms based on vintage technology, such as tube-based delays, for example, by incorporating the strengths of the older gear but eliminating the undesirable weaknesses.

"When it comes to superior guitar tone, we all know that analog tube design reigns supreme. However, digital technology can enhance guitar tone," said Tu. Damage Control's hybrid analog/digital Glass Nexus and TimeLine products, which feature ADI's SHARC ADSP-21369 processors, are a departure for the company. Said Tu, "Our previous products have been totally analog in their architectures. Now we have the chance to show just how powerful the combination of great analog and great digital can be."

The company's TimeLine product is a stereo parametric delay that offers continuous controls to produce phrasing, chorus, flange, vibrato, slapback, long delay, reverse delays, and more. It offers endless possibilities with musically voiced filter, direct, and smear controls. It also offers the rich warmth of classic 12AX7 tubes, and an analog dry path. Plus guitarists can store and recall eight settings or use the MIDI functionality to take it to the next level of control.

Damage Control's Glass Nexus premium mod-effects pedal combines custom modulation effects with dynamics processing and reverb. The floating-point processing, combined with dual 12AX7 tubes, ensures the highest degree of fidelity and musicality. The Glass Nexus also allows for preset storage and MIDI functionality.

SHARC Allows for Creativity
All of Damage Control's employees are engineers and guitar players, so a signal processor that provided enough headroom and flexibility for Damage Control personnel to experiment with sounds was extremely important. "The SHARC platform allows us to approach the design of digital audio products using signal processing as art rather than technology," said Fruehling. "The power of the SHARC processor, in combination with the VisualDSP++ tools, allowed us to write code in 'C' rather than in assembly language. This allowed us more freedom and creativity in the development of our algorithms. We were able to spend more time trying out new ideas rather than worrying about the low- level workings of the processor. Later, we could optimize the algorithms as needed. Of course, the simplicity of the SHARC assembly language made this much easier."

"The SHARC platform allows us to approach the design of digital audio products using signal processing as art rather than technology."
Dave Fruehling     
VP of Technology
Damage Control   

The SHARC ADSP-21369 processor is a member of the Single-Instruction Multiple-Data (SIMD) family of signal processors that feature ADI's Super Harvard Architecture. It is a 32-/40-bit floating-point processor optimized for high-performance audio applications with 2Mb on-chip of SRAM and 6Mb of mask-programmable ROM, and multiple internal busses to eliminate I/O bottlenecks.

The processor uses two computational units to deliver a significant performance increase over previous SHARC processors on a range of signal-processing algorithms. With a 400 MHz (2.5ns) core instruction rate, the SHARC ADSP-21369 performs at 2.4 GFLOPS/800 MMACS. The SHARC ADSP-21369 processor's floating-point capabilities and performance gave Damage Control's designers flexible control over the gain and dynamic range in the algorithms they developed for their products.

Audio Peripherals Included
SHARC audio processors feature audio-specific peripherals and on-chip factory-programmed ROM. "All of Damage Control's IP is custom," said Fruehling, "although we did take advantage of ADI's math library functions." SHARC audio processors also integrate audio-specific peripherals designed to simplify hardware design, minimize design risks, and quicken time to market. Grouped together, and broadly named the Digital Audio Interface (DAI), these peripheral blocks may be connected to each other or to external pins via the software-programmable Signal Routing Unit (SRU). The SRU is an innovative architectural feature that enables complete and flexible routing amongst DAI peripherals. "The rich peripheral set and the tools allowed us to avoid the use of a host processor for interface and system chores," said Fruehling. "This system-on-chip (SOC)-approach saved us money and development time."

Specifically, Damage Control took advantage of the SHARC ADSP-21369 processor's SRU, eight serial ports (SPORTs) that provide an inexpensive interface to a wide variety of digital and mixed-signal peripheral devices, and the 32-bit wide external port that provides a glueless connection to both synchronous SDRAM and to asynchronous memory devices — all part of the DAI, described earlier. The company also leveraged some of the digital peripheral interface (DPI) features, including the DPI SRU, the two Universal Asynchronous Receiver/Transmitter (UART) ports that provide a simplified interface to other peripherals or hosts, and two serial peripheral interfaces (SPIs), which are industry-standard synchronous serial links. "The DPI and DAI routing allow great flexibility and help to recover from those simple schematic errors that inevitably find their way into printed circuit board (PCB) prototypes that often leave a designer saying, 'We'll fix it in the code.'"

In addition, Damage Control utilized ADI's AD7908, an 8-bit high-speed, low power, 8-channel, successive-approximation analog-to-digital converter (ADC), and an AD5207, a dual-channel, 256-position, digitally controlled variable resistor (VR) device, in the signal chain.

Running in a Day
The SHARC ADSP-21369 processor is supported with a complete set of CROSSCORE software and hardware development tools, including ADI's emulators and the VisualDSP++ integrated development environment (IDE). The VisualDSP++ project management environment lets programmers develop and debug an application. It includes an easy-to-use assembler that is based on an algebraic syntax, an archiver (librarian/library builder), a linker, a loader, a cycle-accurate instruction-level simulator, a C/C++ compiler, a C/C++ runtime library that includes a signal processor, and mathematical functions.

ADI offers a range of EZ-KIT Lite evaluation platforms to use as a cost-effective method to learn more about developing or prototyping applications with ADI's processors, platforms, and software tools. Each kit includes an evaluation board and an evaluation suite of the VisualDSP++ environment as well as sample application programs, a power supply, and a USB cable, for use only with the EZ-KIT Lite product.

"The VisualDSP++ IDE and EZ-KIT Lite are great tools. Though not perfect — and no tools are — I believe that they are the most robust tools in the signal-processor market today. They got us going quickly and facilitated the transition over to our custom hardware. We made our very first board revision from the development kit and the tools got us running in a day," said Fruehling.

Ultimately, Damage Control sees its products in the hands of guitar players and producers who want high-quality sounds and results. Because of its floating-point performance, audio-specific peripherals, and ease of use, ADI's SHARC platform is the signal processor of choice for now and into the foreseeable future for the refined tastes of the musicians/engineers at Damage Control.

For more information on Damage Control, please visit Damage Control.

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