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Spatial loudspeaker configurations

Christophe Lengelé edited this page Jan 9, 2024 · 58 revisions

Spatial loudspeaker setups already implemented

Spatial configurations are defined in variable ~numChannelsConfig within initialisation the file loading the tool (_0B_Init_Config.scd) with the number of outputs and spatial distribution :

  • 2-Performance : Stereo Mix and effects
  • 2-MultiChannelSequencer : To get 8 seperated stereo tracks e.g. towards a sequencer
  • 4 : Clockwise Quad from Front Links
  • 5-Clock : Clockwise from Centre = 0
  • 5-Centre : Clockwise from Links (except Centre = 3)
  • 7 : Clockwise from Centre
  • 8-Centre : Clockwise from Centre
  • 8-PairClock : Clockwise from Front Links
  • 8-PairPair : Pairwise Links / Right
  • 16-PairClock : Clockwise from Links
  • 16-Dome-8-6-2-Pair : Pairwise Links / Right
  • 16-Dome-8-6-2-Clock : Clockwise from Front Links (+ 2 Subs) - Dome Hexa at Université de Montréal
  • 16-Dome-8-6-2-Clock-CC : IDEM (+ 4 Subs)
  • 22-8+Dome-8-4-2-Pair : Hall Claude at Champagne Université de Montréal with 8 additional speakers in the Hall
  • 16-UsineC-2Octo : 2 circles of 8 speakers + Subs
  • 24-UsineC-3Octo : 3 circles of 8 speakers + Subs
  • 32-Dome-12-10-8-2 : Clockwise from Front Links (+ 2 Subs) - Dome B-187 at Université de Montréal
  • 32-Dome-UQAM-11-11-9-1 : Clockwise from Front Links - Dome Hexagram at UQAM
  • 64-CentreClock : Test - Clockwise from Centre - not tested in real context
  • 96-CentreClock : Test - Clockwise from Centre - not tested in real context

If you want to add or change a spatial configuration, change ~numChannelsConfig within the files _1_Init_BuffersSynths_132.scd and _2_Init_GUI_225.scd. Although it is better to know the code and have a small training to do it quickly, you can copy from another spatial configuration and adapt it.


Loudspeaker assignation order

Loudspeaker assignation order within Live 4 Life is from Left to right and from bottom to top (in spiral), in order that some some spatial algorithms have some logic, like :

  • circular trajectories with equal-power panning with adjacent loudspeakers,
  • or static positions rotating (at each new event towards the adjacent loudspeaker).

I apply relatively the same logic of loudspeaker assignation order as the spatial specialist, developer and composer Jean-Marc Duchenne as explained in this Facebook post : series clockwise + from bottom to top + from outside to inside.

Examples of loudspeaker assignation order can be seen in representations of zones of loudspeakers for the domes at Université de Montréal in a later section on spatial modules or below with the dome Hexagram at Université du Québec in Montréal.


Loudspeaker configuration example of the 32-loudspeaker dome from Hexagram at UQAM

In the first image below, the figures within circles (beginning from 1) show the initial assignation of loudspeakers towards the RME MADI sound card on four different height levels. The figures within squares (beginning from 0) show my own assignation within the spatial performance tool Live 4 Life in Supercollider, as previously said : from Left to right and from bottom to top (in spiral). PlanDome_Hexagram

The second image shows the necessary matrix within TotalMix to match the initial assignation with my own assignation within SuperCollider.

Affectation_CarteSon_Hexagram

Why do I now prefer quadraphony ?

As I noticed during my studies, particularly after my doctorate and even during my post-doctorate, access to large-scale spatial configurations (greater than octophony) and to spatialised concerts is difficult and relatively rare, especially in the context of spatial improvisation, which requires some prior rehearsal time and sufficient preparation time in concert situation. During my doctoral studies, the only times I had the opportunity to play with more than 8 speakers were during concerts in universities or during a concert in Akousma Festival at Usine C thanks to a system based on the Dante protocol. During the concerts at the JIM in 2019 or the ICMC conference in 2018, only 8 loudspeakers could be used during the spatialisation of performances, due to technical constraints related to live, while 16 loudspeakers were available.

Since the initial purpose of the tool was to play real concerts in physical spaces with many loudspeakers, without having to pay the fees myself to play (travel expenses without even a beer), the development of new spatial forms is currently suspended in favor of rhythm and synthesis, due to the context and the current technical constraints of spatial performances. In the future, more standard and simple spatial configurations in 2D, such as octophony and quadraphony, will be mainly considered in composition and performance, in order to be able to experience space more easily in several places. The quadraphonic format will mainly be taken into account, but in a particular form, based on the spatial experiments of Wendy Carlos, and especially on a specific quadraphonic format, frontal in the shape of a diamond with two centers (near and far), to favor frontal width and depth to the detriment of immersion.

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