Lambda Labs professional acoustics

“Sonus Loci” Multi-Channel Concert in Ulm’s Minster

The visible parts constitute the form of a work. Its value lies in that which remains unseen. (Lao Tse)

If there is anyone who knows the sound of the ‘Münster’, then it is Tabea Frey. After all, as minister, it is part of her work to ‘spread the word’ to the church on a regular basis. The nave, she explains, has a long reverberation time. “But the choir-room is a space for preach, to me it is like butter.” This is why she did not speak from the pulpit on the evening of the concert, but rather from this ‘intimate room’. Voice and space were to form a very special bond on this evening, a joint effort of the clergywoman and five comrades in arms. Or rather in sound, for voice was to be only one element of the four part concert “Sonus loci”, conceived to mark the Minster’s 125 year jubilee. “A room already rich with sound is given voice,” explains Frey.

The idea, according to project manager Elisbath Haselberger, comes from composer Klaus Hollinetz, who already had some previous experience with this kind of concept. During the concert’s musical part, the recorder flutist shared the stage with percussionist Jürgen Grözinger and organist Alexander Moosbrugger. Andreas Usenbenz did take care of Sound Engineering and Design, while composer Hollinetz stood in as a sort of spiritual DJ. The results of the ‘Acoustic Measurements’ taken by Hollinetz in advance form the basis, explained Haselberger. Recordings with the participants were processed into 20 channel soundtracks on which the musicians in turn would be playing and improvising. “These are no rigidly prescribed modules, we have the opportunity of engaging them on creative grounds,” says Haselberger. The ‘grounds’ can indeed be taken literally, since the music lead the audience around four different locations within the Minster, each with its very individual response.

For the Minster to articulate itself in such a versatile fashion, a battle array of dimensions seldom seen in the chapel was mustered. Thousands of metres of cable were laid down to carry the signal into the individual sound zones. In order to achieve a rather homogeneous sound reproduction of the respective musical parts, identical speakers typ TX-2A, 20 pieces in number, were positioned and triggered in accordance with the previously executed acoustic measurements. In his work, Klaus Hollinetz, composer, sound artist and associate professor at the Institute for Electronic Music in Graz, tends towards perfectionism. “I am not satisfied with quick results,” he said in 2005, having received the cultural award from the state of Upper Austria.

“I have been approached several times after the concert and asked, how this almost unearthly clear sound could have been achieved. In matters of composition, this is of course due to the algorithms employed in editing the sound and to the quality of the original material or rather the choice and positioning of microphones” explains Klaus Hollinetz, and goes on to say: “When it comes to live performances however, it is first and foremost a matter of the quality of the technical material that is involved in the acoustic reproduction, a matter of the loudspeakers that are used.”

“For the Sonus Loci project in the Ulmer Münster we employed 14 loud­speakers in the main room and further 6 inside the choir, which were all individually driven,” the composer remebers. “What this also means is that in an extreme case, every single loudspeaker has to be able to take the entire PA’s weight practically on its own. Strictly speaking the Sonus Loci concept does not envision a PA system in its classical sense, it is rather a genuine location-based electro-acoustic instrument in itself and meant to be ‘played’ as such.”

Klaus Hollinetz gladly recalls: “We were lucky to be able to employ Lambda Labs’ TX-2A, which are relatively small and easy to handle loudspeakers. They also possess the advantage of two different angled bevelling, that allow for the positioning the speakers in such a way as to ‘radiate’ in an ascending angle as a floor monitor with its own preset for that. For the Sonus Loci concert the speakers which were placed on the floor, were not pointed directly towards the audience, but rather aligned to stimulate the room through indirect radiation. The outer walls were ‘radiated’ at different angles by 8 speakers from a distance of about 10m and the further 6 speakers put the thick interior columns, several of which are concave, to good use as refraction and dispersion surfaces. These arrangements created quite different acoustic zones that were taken into consideration during composition. So was the church interior’s rather long but clearly defined reverberation used in quite different ways,” as Hollinetz elaborates.

Despite these very unusual and unaccustomed arrangements, we were able to create a very clear and yet almost magical sound thanks to Lambda Labs’ speakers. Many loudspeakers can create the desired sound pressure level just under struggling pressure. This is a phenomenon that is perceived quite severely and that may leave the listener with an impression of ‘fatigue’, says the man from Upper Austria.

“Loudspeakers that are employed within the field of PA, often have very characteristic features, which may however limit their suitability for specific purposes. For an ‘instrument’ like the one designed for Sonus Loci, I need speakers that display the same precision and effortless ease as well in the low as in the high level range,” as Klaus Hollinetz qualifies. “There is nothing worse, than the feeling that the low meticulous passages are swallowed up in ‘technical fog’. Unfortunately, this seems rather to be the rule with most loudspeakers these days.”

“The ease with which the TX-2A fulfill the tasks put before them, never gave rise to this sense of effort, of strain. Rather the contrary, one might suppose that dynamics were something quite natural. The sound image remained absolutely stable, regardless of the desired volume,” emphasizes the academic sound artist.

“It may well be that the TX-2A employed in full range mode and also carrying the entire low frequency range, were not tasked to exhaustion, that they may have indeed gone much further in terms of volume, and perhaps that scope of dynamics I demand is of little importance when it comes to matters of classical PA, but it is precisely this ability of finding the necessary areas of acoustic play, without being hampered by the speakers’ limitations that remains with me a measure of quality that can hardly be set high enough,” says Hollinetz.

“In addition to the dynamic scope, there is the effortless ‘speed’ with which these loudspeakers are able to follow the dynamic movements. Here too, the clarity of the impulses is maintained intact without ‘squeezing’ them, as is so often the case nowadays. I was impressed that despite the classically conventional technology there was so much know-how poured into these speakers, that a new level of sound quality could be attained,” notes Klaus Hollinetz. “Do I still need to mention, then that noise, static, crackling or any other of the typical side effects of usual PA systems were completely off the cards for our Sonus Loci setup?”

Technical Details

What 20 x TX-2A
Wo Ulmer Münster, Münsterplatz 21, 89073 Ulm, Germany
System Supervision Klaus Hollinetz, Andreas Usenbenz