e-spools ease PA speaker array manoeuvring in university venue

The largest of these is Mountford Hall, Liverpool's second-largest concert space, with a capacity of 2300 people which is used for live events and conferences. It also has its own bar, which has been moved to a more central and accessible location as part of the refurbishment. The Hall is in heavy, regular use by both day and night. It runs a full programme embracing Students' Union activities and all genres of music and performance, including the BBC's "˜Question Time'. This has been presented here as recently as March 2016; the university will host the show here again in June.

A significant part of the upgrade budget for the Hall has been invested in a permanent PA and lighting installation. Performers can just "˜plug and play' while audiences enjoy a high-quality audio-visual experience. Any potential delays and increased costs often arising when performers bring in their own, temporary PA and lighting systems have been managed and minimised.

The new L-Acoustics sound system comprises amplifiers, cabling and suspended (or flying) speakers chosen and set up using acoustic modelling to give optimal clear sound and sonically uniform coverage around the venue. However, some flexibility is required within the fixed installation, to allow for the different audio projection needs of visiting performers. This can be provided by raising and lowering four independent main PA Loudspeaker speaker arrays to achieve the best sound balance for differing performances.

Traditionally this speaker manoeuvring was carried out manually - a more labour-intensive procedure that was not only costly and time-consuming but also potentially dangerous as it involved staff working at height and also within the roof void to access cable routes and rigging. On occasions this could also lead to untidiness with the venue, in the form of unsightly trailing speaker cables overhead.

Fixed and moveable audio elements

Another solution that has been adopted in many situations is to interconnect the fixed and moveable audio elements through slip rings. These allow flexibility in extending and retracting both electrical signal and power cables, however their operation depends on a break in the conductive paths. This is undesirable in high-power, high-quality systems such as the Mountford Hall installation because of its adverse effect on both reliability and potentially signal quality.

A similar situation existed for the overhead lighting trusses, which also needed to be raised and lowered to rig equipment to suit different event requirements.

Adlib Audio, the sound and lighting designers, suppliers and installers for the entire upgrade project, turned to igus for a superior alternative. For the speakers, this was delivered in the form of four custom e-chain and e-spool cable management systems, one for each of the four main speaker arrays. These provided no-break connections between the amplifiers and the speakers, eliminating reliability and signal quality issues. It also meant that speaker raising and lowering became a simple, automated procedure that could be conducted at will prior to rehearsals and sound checks. The delays, costs and health and safety issues associated with calling on extra crew and working at height for manoeuvring were eliminated.

The e-spool system is also very compact while being able to carry many cables in a confined space. Its interconnection of the amplifiers and speakers is described as unique. An e-chain carrying the cables from the amplifiers is guided by one roller, and always maintained at exactly the correct length and tension by an integrated retaining spring. In the start position, the e-chain is completely rolled up to save space. The twisterband connects the roll to the shaft block, which acts as the interface to the speaker cables. There is never any tensile load on the cables, while cable droop is eliminated to save space and keep working areas clear.

A similarly flexible and robust system for the lighting trusses was used. Known as "˜zig-zag' e-chain, it uses a space-saving and unconventional approach facilitated by the modular design of the e-chain. When the trusses are at maximum trim height, the collapsed e-chain is stored in a "˜basket' above each lighting truss. If the truss is lowered, the e-chain automatically unfolds. When the truss is raised then the e-chain is stored automatically into its default position into a basket over the truss.

Different cable types

Adlib Audio had not used e-chain or e-spool products previously, but after reviewing the alternatives was convinced they would prove beneficial to the project's success. The e-spool's ability to carry a large number of cables, including different types - for power, signal and data - was a significant factor in the decision.

Roger Kirby, installations director at Adlib Audio comments: "We were able to work closely with the igus engineers at all times. They attended regular meetings and visits to site, and were always available for advice and support. They also helped us select the best of multiple designs, and spent time in testing the lift and drop actions, chain pitch and chain basket position. This turned out to be time well spent, as everything continues to run excellently. The system looks neat, and can cope with pressure and frequent movement.

"Overall we felt that igus offered us a large catalogue range of high-specification items coupled with the knowledge and skills to develop specific solutions for our needs. After this first project, we will definitely consider using the e-spool technology again. From a cabling and reliability point of view it works brilliantly."

For more information about igus products, visit the website at www.igus.co.uk.