Outside the South German city of Ulm, the Laupheim Planetarium and Observatory welcomes over 30,000 visitors each year to witnes the wonders of space at the Zeiss planetarium’s immersive Fulldome projection system.

A recent upgrade to the planetarium’s audio system to support 7.2 channels added two loudspeakers at the apex of the dome. In addition, the system needed to offer a tactile interface suitable for use in the dark by the in-house engineers, plus the ability to control the planetarium lighting via the same physical controller.

Overseeing the audio mixer upgrade and integration was Dr Max Rößner, a freelance planetarium and immersive media engineer who is familiar with the esoteric demands of this particular application.

‘The planetarium world is an exciting field, but it is also a niche field, particularly when it comes to technology,’ he says. ‘Therefore, it is essential that engineers can make use of interfaces that are open and well-documented, and to implement solutions that truly address the customers’ needs. The Allen & Heath AHM series and its ecosystem proved ideal for this.’

At the heart of the new system is an Allen & Heath AHM-64 Audio Matrix Processor fitted with a Dante card. The AHM-64’s rear panel analogue outputs are used to feed nine speakers and two subs in the planetarium, while a DT168 Dante Expander is used to provide localised analogue inputs to the system including wireless mic receivers, media players, and other auxiliary sound sources.

The building’s main sound source is a PC with a Marian Clara E Dante interface and running Reaper, which is synchronised to the projection system via SMPTE and sends audio over the Dante network to the AHM-64 for routing and control.

A pair of A&H IP8 remote controllers, each with eight motorised faders, eight OLED screens and 23 assignable SoftKeys, provide configurable, tactile mixing suitable for use in the pitch-dark environment. The controllers are configured such that ten of the faders are used to handle audio, with the remaining six dedicated to lighting control.

‘The IP8s integrated seamlessly during programming and commissioning,’ Rößner says. ‘The AHM’s underlying architecture is flexible enough to enable the integration of unconventional functionality, such as lighting control in our case.’

For lighting control from the IP8s, Rößner put the AHM’s TCP/IP control protocol to good use. He configured the system so that six channels on the AHM, with level controls assigned to six IP8 faders, transmit Midi NRPN data over Ethernet to the lighting computer where it is translated to DMX. When the lighting is controlled by the show automation system, the IP8’s motorised faders follow, ensuring the operator can always reclaim control if needed.

‘The AHM-64 offers features usually only found in open-architecture installed audio systems,’ Rößner says. ‘As an engineer, I feel comfortable with both closed and open architecture, but I appreciated how easy it was to implement and deploy advanced functionality in the AHM-64, especially as this was my first time using the system.’

‘The system was installed very quickly, and it has improved the sound quality significantly,’ adds in-house engineer, Alex Gölkel. ‘It is a great improvement now that all sources can be mixed and used simultaneously with a user-friendly control interface.’

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