Calrec Audio unveils the secret of Bluefin

The high efficiency of field-programmable gate array chips proves perfect for high-density signal processing in audio consoles.
Calrec pioneered its high-density Bluefin processing technology through the use of console-specific FPGA architecture instead of typical DSP chips.

With the introduction of its new Omega audio console, Calrec has revealed some basics behind its award-winning Bluefin technology. Bluefin packs 480 channel processing paths onto just one card, resulting in huge potential power and space savings. At an NAB2007 press conference, the company explained the advantages of its approach.

Audio mixing consoles require only a few different mathematical operations, but these must be performed by the billions every second. Because traditional DSP chips are optimized to do a wide variety of mathematical operations, Calrec explored the idea of configuring field-programmable gate array (FPGA) chips specifically for use in console DSP applications. At the time, the company was already using FPGAs for mixing and gain control in its Alpha, Sigma and Zeta consoles.

During the course of two years, technical director Patrick Warrington and his team of engineers devised FPGA processing structures and logic resources dedicated to only doing those operations needed for audio. "The increases we saw in efficiency were breathtaking," Warrington says. "FPGAs allow the creation of a set of processing structures, each of which is designed to perform only one job, but with staggering efficiency. This means that processing power can be very precisely mapped onto the algorithmic framework, and logic resources tailored exactly to meet the required precision."

The FPGA design approach has realized so much efficiency that, in the Calrec Alpha console, a single Bluefin DSP card does more than double the work of 26 conventional cards, while a second Bluefin card provides 100 percent redundancy. Advantages to users include reductions in power usage, heat generation and component failure. In short, the FPGA base makes for a DSP system with huge advantages over conventional designs for about the same cost.

These efficiencies are particularly relevant at this time, with so many broadcasters moving toward 5.1 surround production and the need for more audio channels. Bluefin consoles allow full EQ and dynamics to all channels, and can provide 78 full 5.1 surround-sound channels. The system also allows for eight 5.1 groups with full EQ and dynamics, four main 5.1 surround-sound outputs, 48 multitrack outputs, 20 aux outputs and 19.6 minutes of delay.

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