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Calrec Sigma 100 Console

The Sigma 100 (custom priced, starts at approximately $150,000) is an all-digital production console for use in high-end broadcast applications. The Sigma is a close relative to the larger Alpha 100, with sacrifices coming only in size and features, as component choice is nearly identical for both consoles, and in fact several modules are interchangeable between the two.

In the rarefied world of high-end broadcast consoles, one factor reigns supreme: reliability. For facilities that broadcast around the clock for months on end to audiences that can run into the millions, just several seconds of downtime a year is unacceptable. Imagine the voice of Peter Jennings going mute just as election returns are finalized to get a sense of the stakes involved. Hardly less important are input and routing flexibility, ergonomic and rapidly configurable control elements, and of course, the highest level of audio fidelity.

For years, British manufacturer Calrec has catered to this specialized market with purpose-built analog broadcast consoles, and more recently with its flagship all-digital Alpha 100, currently in use at several BBC facilities and U.S. network sports and news divisions. I recently had the opportunity to check out the newest addition to the digital line (Alpha’s little brother if you will), the smaller Sigma 100 console, at Studio Consultants, Inc., a New York-based systems contractor that distributes Calrec in the northeast U.S. and Canada.


The Sigma 100 (custom priced, starts at approximately $150,000) is an all-digital production console for use in high-end broadcast applications. The Sigma is a close relative to the larger Alpha 100, with sacrifices coming only in size and features, as component choice is nearly identical for both consoles, and in fact several modules are interchangeable between the two. The frame can be equipped with up to 64 faders (or as few as 32) controlling up to 48 stereo and 24 mono (or 60 stereo) channels; each fader module is capable of controlling two discrete signal paths on A and B layers.

The I/O matrix is configurable for a variety of analog and digital sources, and befitting the unit’s all-digital architecture, I/O is fully matrixed, meaning all inputs and outputs can be routed via any channel or console module patch point, with inserts available via the same matrixing conventions. Up to 24 MT outputs are possible, in addition to two main and two submain outputs, each either in stereo or 5.1 surround.

Channels can be grouped in eight stereo or mono groups with dynamics, with unlimited additional VCA subgrouping possible as well. Each channel is routable to each bus, without restrictions, and direct inputs are possible to all group, main, aux and mix-minus busses. Future expandability enabling full pooling is said to be in the works, which when offered will add to this routing ability by enabling larger facilities to share I/O across multiple consoles and rooms via networked connections.

The Sigma’s I/O and DSP take place on outboard rackmounted modules, with analog racks holding up to eight input and eight output cards, and a digital rack holding up to two bulk I/O cards (which link the console into the analog racks), or up to seven digital I/O cards. The digital rack has an additional 12 slots for DSP modules.

The unit is linked to a dedicated PC, with an interface appearing on an integrated monitor. As Calrec is quick to point out, the PC is used for setup only, and the console is capable of running without the PC in the event of failure. The mentioned DSP cards are independent from both the PC and each other – outboard processing is “pre-allocated,” meaning each channel and module has dedicated processing power with no sharing. Unlike many DAWs and digital consoles, this architecture makes it possible to max out every EQ and dynamics control on every channel without reaching DSP limits.

Channels are controlled via assignable strips, with two “wild” soft knob controls quickly assignable as well. Each channel comes equipped with four-band parametric EQ, compressor, expander/gate, mix-minus and direct output facilities. Backlit LCD readouts indicate channel name, and amply-sized buttons control the A and B layers, cut, AFL and PFL.

Each channel strip displays an impressive level of information on well-laid-out indicators. Next to each fader is a small bar-graph level display, switchable to reflect input, output or dynamics control level, which serves in addition to the main level indicators on the meter bridge. Soft knobs and additional LCD displays can reflect EQ and panning data amongst other data. Small LEDs reflect a wealth of information , from group and routing assignments to engaged EQ and dynamics.

In Use

As mentioned, reliability is the all-important prerequisite in broadcast applications, and the Sigma’s design addresses this in the obvious way: with heavily redundant architecture. Each console ships with hot spares for DSP and control cards – and even power supplies – all of which are rigged for automatic takeover in the event of failure. All cards and power supplies are hot-swappable, making the goal of 100 percent uptime at least theoretically possible.

Like most digital consoles at this level, the entire frame functions as a control surface, with audio routed through control modules and DSP on the attached rack, rather than the console itself. Reliability is addressed with rapid initialization – the Sigma boots up from a cold start in approximately 10 – 15 seconds.

Control of dynamics and EQ is accomplished in the same way as most digital mixers, by selecting a channel and making adjustments on a master EQ module, though in the Sigma’s case dedicated buttons allow selection of bandwidth, shelving and the like. Conspicuously absent – thankfully are multilevel menus. Channel and dynamics parameters are accessible directly, or in no more than one step, from the control surface.

This philosophy carries over to nearly all functions on the console. Though the unit does make use of a monitor, generally its function is to control routing, setup and global operations. When adjusting audio, the operator is rarely looking at a screen, but rather accessing parameters through dedicated controls and reading data via the large number of small and strategically placed LCD screens.

The Sigma displays several signs of its broadcasting focus, most notably it does not contain fader automation functions though snapshots can be stored in the 99 Flash ROM settings, or offloaded into an unlimited number of saved programs via the PC. The channel interrogation function allows the engineer to instantly track a specific audio path through the console. Talkback is selectable to any combination of aux, main and external outputs in addition to a slate function to all tracks.

Monitoring control is very extensive, with multiple controls for the source selection and surround and stereo monitoring. The unit is designed to be compatible with the Dolby E standard, and decoder control is integrated into the monitoring module. In addition to bargraph meters for each channel, the main output meters are adjustable to display stereo, 5.1 or downmixed outputs. Third party metering options are supported, with the continental height allowing European-spec bargraphs, and an open panel usable for a surround scope/master stereo display.


Calrec designs consoles for the broadcasting market. It is clear that Sigma’s designers had a hurdle to overcome when convincing jittery engineers to move to an all-digital environment for critical applications, and they have done their best to address the issue via hot-swappable, highly redundant components. Ergonomics and layout are equally purpose-built, and top notch; I especially liked the way information was displayed creatively, and typically right next to the relevant control element.

Sound quality and DSP are identical to the Alpha 100, and are top quality, though additional options for digital formats (and a higher sampling rate option) would be a nice touch [Calrec says a MADI option will be available soon – Ed.]. This high degree of integration (and many shared spare parts) between the Sigma and the more established Alpha will be a selling point for larger facilities. In short, the Sigma is a welcome addition to Calrec’s line, adding a new set of options for broadcasters in the market for a bulletproof audio console.

Contact: Calrec/Studio Consultants at 212-586-7376, Web Site.