Know-how

Master Class in Cologne

Today, many theater and opera productions in Germany could not be accomplished without CANTUS and NEXUS. This seems a somewhat bold statement but there is proof as well. The latest example is the Cologne Opera. Here, the former digital desk was replaced with a CANTUS to give the audio engineer the flexibility he needs in a world of ever-increasing demands set by producers.

Being a decentralized system, NEXUS is perfect for a location such as the Cologne Opera. The base devices can be installed right where audio signals are generated: On stage, in the production studio or playback studio. In a standard CANTUS/NEXUS setup, a number of converter boards installed in the base devices convert the signals to the digital domain and distribute them via fibre-optic cables. This is a huge benefit where long cable distances have to be spanned as hum and noise are completely avoided using fibre-optics. However, a different solution was chosen in Cologne: The existing cable network was only three years old; replacing it with fibre-optic cables was not an option. Therefore, the NEXUS has been installed just behind the existing analog patchbay – a pragmatic and economic approach. Thus, NEXUS manages all of CANTUS's input signals such as microphones, analog tape, Tascam DA-88, and Augan OMX 8.

Format Conversion Included

Once converted, the signals may be accessed by all components connected. There are, of course, analog and digital outputs plus one or more CANTUS desks. In this setup, NEXUS acts not only as a digital patchbay but also as an integrated digital split box and as format converter. A standard Windows PC that can be connected anywhere in the system controls the whole setup.

Reliability First

The Opera's senior audio engineer Burkhardt Henschel and his colleagues primarily appreciate the reliability of the CANTUS/NEXUS system, which is quite different to what they had previously experienced. Stage Tec achieves this level of reliability and stability through a rugged and fit-for-live design on the one hand and through comprehensive system monitoring on the other one. This system-monitoring facility does three things:

• If an external sync source fails, one of the NEXUS base devices will spread this news to all other components.
• All devices are equipped with redundant power supplies that automatically substitute one another in case of failure. Any such case is instantly displayed on the control computer and logged so it can subsequently be diagnosed.
• In addition, the fibre-optic connections can be made with built-in redundancy. Therefore, if a connection fails, the system changes to a redundant line within one clock cycle.

In Cologne, everybody feels comfortable with the system's reliability, and there is no need for this third option. Burkhardt Henschel is happy to demonstrate this ruggedness to visitors: while the system is in operation, he disconnects a channel board from the frame and pulls all electrical connections. The CANTUS remains completely unimpressed – even the audio signal of the removed channel remains present in the mix. This feature is exciting even for seasoned engineers.

104 Signals in a Tiny Place

104 input signals are handled in the playback studio of the Cologne Opera. As the studio is just a few square meters in size, another one of CANTUS's features comes in handily: each physical channel strip handles up to 10 different audio signals, thus drastically reducing the space required for the console. The Opera's main desk provides 40 physical channels driven by 13 DSP cards.

In addition, a slave board provides another 20 channels that communicate with the main desk via fibre-optics. The growing market of musical productions necessitates a slave console in the audience room. Unlike a classical opera, such modern productions often feature untrained actors and rock musicians using wireless microphones that have to be mixed from the audience position.

Strong Together

Main and slave consoles can collaborate in two basically different ways: in split or in parallel mode. In split mode, every signal assignment is made using only one of the two consoles. Much more often, however, customers choose the parallel mode where all signals are accessible on both consoles. This also applies to Cologne. The slave console is not only used for live mixing but also as a recording desk in the production studio.

Four different places in the building are equipped for slave-console connection. However, the story still goes on: through a special modification, even the main console can be used in the concert hall. To achieve this customer requirement, Stage Tec moved the console's power supply to the tub, away from the console stand where it is normally mounted. Thus, two people can quickly move the main console to the concert hall and use it as a large FOH mixer. An elegant and efficient solution.

Installation

Although the installation was timed to be done during the Opera's summer break, it had to be accomplished in a very short time since audio was urgently needed for rehearsals. An installation within only two days was made possible by excellent planning. After four more days, Burckhardt Henschel and his crew were trained and fit for serious business.

CANTUS's premiere was celebrated six weeks later with »Master Class«, a piece dedicated to the great Maria Callas.