With music and the spoken word at the heart of the modern worship service, any renovation of a church sanctuary calls for a critical appraisal of the performance of the fixed audio system. In the Bethlehem Church in Gothenburg, Sweden, just such a renovation resulted in the installation of a new NEXO GEO M6 compact line array, after careful analysis of the church room’s acoustics and a shoot-out between manufacturers’ solutions.
Tech 4 Event AB has specialised in church installations over recent years, and was called in to assess the needs of the Bethlehem church, and its 800-strong congregation. Björn Carlsson, the CEO of Tech 4 Events, and his colleagues looked at a number of different sound reinforcement systems for the installation, considering the aesthetic appearance of the audio solution as well as its sonic performance.
The church called for a demo and comparison between two brands, a clean shoot-out which was welcomed by Björn Carlsson. “Such a test is rewarding for the customer, in this case the assembly. In this way, they get an opportunity to listen to different systems before choosing what to install. Not only to experience that one system sounds better than anything else, but above all in order to determine whether the systems fit into their premises and the activities that are going on there.”
In the end, the choice rested with the assembly, and they chose the NEXO GEO M6 compact line array. Steps were taken to improve the building acoustics, such as replacing the ceiling, which helped Björn Carlsson and his team as they set about examining the design of the sanctuary, and how its acoustics worked.
“We used one of our most important tools, the NTI XL2 Acoustic Analyzer, which enables us to document acoustics, frequency, sound pressure and STIPA value, the assessment of speech comprehensibility in the room. We used this measurement tool before, during and after a completed installation. Through these metrics, we could ensure a range of parameters to gauge which improvements have been made, and to verify that the requirements in the preliminary study were achieved.”
“We did several computer simulations early in the project to see exactly where the speaker system elements would be placed to get the best results. All measurements from the room were added to the system, along with data from the drawings of the church from the architect. Then we got a 3D model of the whole church room, and in this case we used NEXO’s own software, NS-1, which is a powerful and intuitive system configuration and simulation tool with a smooth drag and drop interface.
“The NS-1 program enabled us to configure and optimize performance of any NEXO system by simulating its behaviour in the current location. Measured speaker data is processed together with complex mathematical data to predict SPL and delay in three dimensions. Then we could quickly and efficiently see how different speaker systems behaved in the room and how they would sound. We also found out how many speakers we needed of a particular model to solve the assignment and reach the desired end result, but above all we found out where in the room we would need to install the selected speakers for the best results. It is a very smooth and extremely useful piece of software.”
Acoustics are often a tough challenge in a church building, but one of the key requirements of the congregation was for as discreet a speaker system as possible, one which would not visually affect the church environment more than necessary.
“We know from experience that, using the right technology, it is possible to create good sound systems which can also look nice and blend into the church room. In this case, we mounted the speaker system on a heavy concrete beam between floor and ceiling, and the assembly wanted the speakers to pick up the colour from the concrete beam. So the loudspeakers and flyware were specially painted in the RAL colour we received from the architect to blend in perfectly.”
The NEXO GEO M6 is a relatively new system that made it a little easier for the team to make an aesthetic fit with the church’s interior.
“The GEO M6’s lightweight polyurethane composite cabinet measures only 191 x 373 mm x 260 mm and is therefore ideal for installation in design-sensitive environments. In addition, this line array also performs very well when it comes to both sound pressure and sound quality. Not only is there a wide range of mounting accessories, the system offers us as an installer and audio rental company a reliable, TÜV-certified system with very good performance. The Bethlehem system uses 18x GEO M6 modules in two arrays of 9 cabinets, supplemented by 2x NEXO LS18 subbass. The entire system is powered by 3x NEXO NXAMP4x1, which brings the built-in, advanced processor that makes the system sound so good.”
Carlsson concludes, that “we, and more importantly, the congregation is very pleased with the results in the Bethlehem Church. Of course, the sound quality has become much better with a steady frequency range from bass to treble, but above all speech comprehensibility has become significantly better. Every seat in the whole church must enjoy the same sound and we have managed to achieve that. In fact, there is only 2 dB between the highest and lowest points in the whole church, which is a very, very good result.”
With thanks to Peter Fredberg, and MONITOR magazine for this article.
All photos © Peter Fredberg.