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Directing Audio Traffic

The recent AES Convention in New York brought contractors news of major advancements in digital audio networking over Cat-5/6 cable. Digigram announced its next-generation Gigabit-EtherSound protocol, which offers a four-fold increase in the channel count over EtherSound while adding increased data flow capabilities, Sony Pro-Audio Lab named new licensees to its similarly powerful SuperMAC/HyperMAC technologies, and Cirrus Logic introduced DSP Conductor, a graphical programming tool designed to speed up the design and implementation of new CobraNet products.

In announcing the Q1 2006 launch of the Digigram-licensed Gigabit-EtherSound data transmission scheme, business development manager Jimmy Kawalek noted that the new protocol signals a similar industry transition to that experienced during the introduction of CobraNet, when 10 baseT was superceded by 100 Mbps technology. It's now affordable to look at Gigabit versus 100 Megabit, he noted.

Gigabit-EtherSound supports 512 channels-256 bi-directional-at 48 kHz/24-bits, an increase from the current 64-channel limit, and increases control and data capacity to 100 Mbps. The new protocol also offers the low 125-microsecond (6 frames) latency of the previous protocol and introduces fault tolerance through support of ring topologies.

"We have found such a wonderful response from the live sound community, including installations," observed Kawalek, who noted that console manufacturers in particular have embraced EtherSound. But, he added, "Everybody knows the console guys want more channels."

The inability of EtherSound to pass large quantities of data due to the bandwidth restrictions of running 64 audio channels are eliminated with Gigabit-EtherSound, he continued. "By limiting the channel count to 256 x 256 we overcome that limitation. If you run [Harman's] HiQnet, say, we can handle all that IP traffic."

Current licensees include DiGiCo, InnovaSON, Allen & Heath and AuviTron (therefore, Yamaha); and Whirlwind has now added EtherSound to its CobraNet-enabled E Snake. Existing products are unlikely to be re-engineered to comply with the new protocol, according to Kawalek. "So we're being considered for new products and new platforms for the future. We're looking at a whole new stream of products that will adopt this quickly."

That contractors have embraced SuperMAC/HyperMAC appeared to surprise Michael Page, Sony Pro-Audio Lab's engineering project leader for the product. "I thought they all wanted to use regular Ethernet switches, they don't mind about the latency, and they have CobraNet serving the market very well. It transpires that the use of the same regular Ethernet switches is not tremendously important. The piece of infrastructure which it must use and which is hard to change is the cabling that has been installed. Changing a box in a wiring closet is not tremendously difficult."

That bodes well for SuperMAC, which is based on the existing Ethernet physical layer transmission structure (and has been adopted in the AES50-2005 standard), as well as its more capable cousin, HyperMAC. SuperMAC carries a maximum of 48 bi-directional, 48 kHz/24-bit audio channels plus 5 Mbps of generic Ethernet control data and handles DSD as well as PCM audio. HyperMAC offers 384 bi-directional channels (48k/24) and 100 Mbps of data transport over Cat-5/6 or optical fiber and will support up to 48 channels of 384 kHz PCM audio or 96 channels of 128fs DSD. Both protocols produce a latency of just 62.5 µsec (three samples).

As Page noted, CobraNet's advantage is that it can be run over exactly the same infrastructure in place for the IT system. But in practice, he noted, "The IT guys won't let the audio guys touch their equipment. They end up being completely separate systems with separate switches."

Euphonix announced that it would license SuperMAC/HyperMAC, joining Midas, who signed up in September. Merging Technologies, maker of the Pyramix DAW and the control software for DiGiCo's DiGiTRACS hard-disk recorder, is also now onboard.

Cirrus Logic's DSP Conductor graphical programming tool announced at AES for its CS4961XX CobraNet-based audio system processors will allow audio system architects to quickly develop new products that take advantage of distributed audio processing to implement innovative solutions for audio network systems. DSP Conductor simplifies the design process by providing pre-formulated drag-and-drop audio algorithm "building blocks" along with the ability to tune the system in real time.

Said Keith Cheney, vice president of the Embedded Products Division, Cirrus Logic. "This powerful combination of audio networking and rapid software development provides networked audio system designers greater design flexibility, the tools to create unique and innovative audio system products and the ability to offer incredible value-added system features and benefits."

Two new CobraNet-enabled products made an appearance at the AES Convention. Crest launched the new Nx CobraNet-8 control module and CM Series power amps, which support the Crest NexSys 4 and Peavey MediaMatrix MWare software programs. Nx CobraNet-8 supports all NexSys functions, DSP functions and CobraNet digital audio I/O on a single Cat-5 cable. Rane Corporation introduced the NM 1 network mic preamp, a versatile, single-channel CobraNet I/O box. The mic signal can be transmitted over CobraNet, and the amplifier input can be driven by any CobraNet audio channel.

Steve Harvey ( is editor-at-large for Pro Sound News and also contributes to TV Technology, MIX, and other Future titles. He has worked in the pro audio industry since November 1980.