installation in performance halls

Transcription

1 Emplacement réservé pour une photo Isabelle Schmich The Carmen system and its installation in performance halls ACOUSTIC AND LIGHTING DEPARTMENT CARMEN SSA - 31 octobre 2008 PAGE 1

2 Reverberation Enhancement Systems - What For? Reverberation time for different types of performances Program Reverberation time (s) Popular music, Jazz 0,8-1,2 Lecture, Conference 0,7-1 Speech drama 1-1,2 Chamber music 1,3-1,5 Opera ,6 Symphonic Concert 1,8-2,5 Looking for control and variability of : > Reverberation Time (RT) > Sound Pressure Level (SPL) and Early Energy Distribution > Intelligibility, Envelopment, Clarity > Space-time impression ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 2

3 Reverberation Enhancement Systems - What For? Many auditoria suffer defects of various types, which are not always possible to correct architecturally. Too small volume, large overhang balconies, acoustically unsuitable shape, excess of sound absorbing materials, which create : dry acoustics, dead areas, remote and weak sound, lack of homogeneity, disturbed sound images Other halls need variable acoustics because of their performance program ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 3

4 Changing the Acoustics of a hall PASSIVE SOLUTIONS Movable absorbing/reflecting elements (curtains, panels, banners ) Movable ceiling or walls (change of the volume) Stage acoustic fittings (orchestra shell, panels, reflectors, orchestra risers) Cumbersome, limited efficiency, high cost ACTIVE C SOLUTIONS O S Installing a Reverberation Enhancement System (increases RT and SPL) ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 4

5 Reverberation Enhancement Systems Why? Can easily correct a lot of acoustic defects without undertaking heavy architectural works Can easily modify the acoustic c conditions o of an auditorium to correspond with the various types of cultural events. ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 5

6 Development of electroacoustic systems First electroacoustic system: 1929 by V.S. Kawanski General Synoptic ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 6

7 Basic equations Without system: With one active cell : S r = H sr. S s S r = H sr. S s +H hr. S h Open Loop Gain : G mh. H hm Gmh Signals: S h = G mh. S m = G mh. (H sm. S s + H hm. S h h) S h = (I - G mh.h hm ) -1. G mh. H sm. S s (I - G mh.h hm )< <==> rebouclage Source -> Receiver transfer function : H tot = S r / S s = H sr + H hr. (I - G mh. H hm ) -1. G mh. H sm = H sr +H ea S m S h H H hm sm S s H sr H hr S r ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 7

8 What is colouration? Each hall has its own tonal quality that can be characterized through the colour of the hall Colouration is due to a different time-decay of the sound energy at specific frequencies caused by room resonance effects. ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 8

9 Familles de systèmes Systèmes régénératifs (MCR, CARMEN, AS, AFC): rebouclage acoustique utilisé pour augmenter la réverbération Systèmes non-régénératifs (SIAP, ACS, ASR): rebouclage acoustique minimisé réverbération électronique Systèmes hybrides (LARES, Constellation/VRAS): couplage acoustique réverbération électronique - Absorption + Volume ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 9

10 Regenerative / In-line systems ADVANTAGES Regenerative systems > Natural sound >Space and time respect of sound source images > No use of electronic reverberation In-Line Systems > First reflections control > SPL / RT uncoupled > Very long RT possible DISADVANTAGES Regenerative Systems > Diffuse action on 1 st reflections > SPL / RT Coupling > Background HVAC noise increased In-Line Systems > Disturbance of sound images > Uneven stage covering >Frequent coloration due to electronic reverberation > Disturbing time variance effects ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 10

11 Specifications for choosing a R.E.S. Undetectable by listeners, natural sounding No change of the acoustic qualities of the walls and the geometry of the hall Large variation of RT (> +50%) over the full frequency range Control of early energy (clarity, intelligibility) ibilit Inaudible self-background noise No space-time disturbance of sound images and orchestra balance Long term reliability Easy to use Must not conflict with other equipment (lighting, ) ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 11

12 CARMEN is a French Acronym of : Contrôle tôl Actif de la Réverbération par Murs virtuels à Effet Naturel (Active control of reverberation by natural effect virtual walls) ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 12

13 Active Virtual Wall Principle A small number of active cells, each composed of a microphone close to the associated loudspeaker, spread all around the hall. Acoustic and electronic filters suited for controlling cells stability. Quasi-locally reacting cells behave as active reflectors/diffusers placed on walls and ceiling Reverberation builds up by natural acoustic interaction between the active virtual walls cells, just as natural reverberation. ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 13

14 Active Virtual Wall Principle Each cell is composed of : a loudspeaker an electronic processing unit a microphone insensitive to the loudspeaker acoustic radiation Pi A/D Pc DIGITAL SIGNAL PROCESSING Pr =r(pi= r.(pi - Pc) D/A Several independent cells behave as a virtual wall ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 14

15 CARMEN - Block Diagram ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 15

16 CARMEN Tuning Parameters 6 parametric filters 22 tuning parameters for one wall Cell 1 G τ GFWS G,F,W,S GFWS G,F,W,S Cell 2 G τ G,F,W,S G,F,W,S Wall 1 5 parametric filters G τ G,F,W,S G,F,W,S Cell m G τ G,F,W,S G,F,W,S Cell n G τ G,F,W,S G,F,W,S Wall n G τ G,F,W,S G,F,W,S Cell p G τ G,F,W,S G,F,W,S 26 tuning parameters for one cell ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 16

17 CARMEN Main Points Virtual positioning of the ceiling and walls Reverberation enhancement produced by natural energy exchange between the virtual walls elements (no artificial reverberation). ΔRT: [50%,100 %] for 125 Hz Hz Space-time coherence of the sound field is preserved Reinforced early reflections Fully natural sound picking up from stage (no source image shift). Good subjective perception of the volume Public Address possible ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 17

18 Some examples of working CARMEN Systems ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 18

19 Grimaldi Forum, Monaco Multipurpose auditorium with: -Theatre - Chamber music - Ballet - Opera - Symphonic Concert Salle des princes: V = m 3 N = 1900 seats T R = [ 1.2 s s] ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 19

20 Grimaldi Forum, Monaco 29 cells 14 lateral cells 15 cells in the ceiling 3 forestage microphones ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 20

21 Grimaldi Forum, Monaco ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 21

22 Acoustic Results in the Salle des princes, Monaco Reverberation Time TR20 (s) 4 3 Preset 6 Preset 5 RT (s) 2 sans conque avec conque Preset 4 Preset 3 Preset 2 1 Preset 1 Inactif Frequency (Hz) ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 22

23 Salle des princes, Monaco Config0=Passif Config1=Théatre Config2=Opéra Config3=Concerto Config4=Symphonique Config5=Grand Symphonique 1 Config6=Grand Symphonique 2 ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 23

24 Salle des princes, Monaco ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 24

25 Brighton Dome, UK 1900 seats 30 cells : 6 in the tier front 12 in the columns below the balconies (2x6) 8 in the dome 4 over the stage ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 25

26 Acoustic Results in the Brighton Dome, UK Reverberation Time Tr 20 (s) Tr (s) 2.0 conf 0 conf conf 2 conf conf Frequency (Hz) ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 26

27 Norwich Theatre Royal, UK 1280 seats cells : 14 cells on the lateral wall 3 cells below the balcony 6 cells in the ceiling 4 cells in the dome 2 forestage microphones ' ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 27

28 Acoustic Results in the Norwich Theatre Royal, UK Echograms Chorus Symphonic Concerto Chamber Music System off Gain (db B) Time (s) ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 28

29 Acoustic Results in the Norwich Theatre Royal, UK Reverberation Time Passive Chamber Music Opera Concerto Symphonic Chorus RT30 (s) Frequency (Hz) ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 29

30 Questions? ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 30

31 CARMEN at Berlioz Festival (La Côte Saint-André, France)? 24 cells : 8 lateral 11 in the ceiling 5 on stage ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 31

32 Acoustic Results in the covered market of Côte Saint-André Reverberation time TR20 (s) 4.00 Tr (s) Preset 1 Preset 2 Preset 3 Inactif Frequency (Hz) ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 32

33 Covered market of Côte Saint-André ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 33

34 Théâtre Mogador, Paris 1800 seats 31 cells : > 18 lateral cells (2x9) > 7 cells in the dome and balcony ceiling > 6 double cells in balconies soffit 2 forestage microphones ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 34

35 Acoustic Results in the Théâtre Mogador Reverberation Time RT Tr (s) Conf 4 Conf 5 Conf 3 Conf 2 Conf 1 Passif Frequency (Hz) ACOUSTIC AND LIGHTING DEPARTEMENT CARMEN SSA - 31 octobre 2008 PAGE 35