SPHERICAL SOUND SOURCE FOR ACOUSTIC MEASUREMENTS US PATENT

SPHERICAL SOUND SOURCE FOR ACOUSTIC MEASUREMENTS US PATENT PENDING AUTHORS: Plamen Valtchev – UNIVOX, Dimitar Dimitrov – BMS PRODUCTION, Rumen Artarski – TRAX AUDIO � � � � PARAMETERS DEFINING OMNIDIRECTIVITY EVOLUTION OF DESIGN OBJECTIVES SPHERICAL SOUND SOURCE REALIZATION EXPERIMENTAL MEASUREMENTS DODECAHEDRON POLAR PATTERNS OMNIVOX VERSUS SPHEROVOX COMPARISONS SUMMARY AND CONCLUSIONS

PARAMETERS DEFINING OMNIDIRECTIONALITY � � � Omni is a Latin prefix meaning "all" or "every“ DIRECTIONS – BUT HOW MANY - 4, 5, 6, 12, 20, 120 or MORE –inf ISO-3382 – AS OMNI DIRECTIONAL AS POSSIBLE � � � � MONOHEDRON DIHEDRON TRIHEDRON TETRAHEDRON HEXAHEDRON – CUBE OCTAHEDRON DODECAHEDRON ICOSAHEDRON LETS OPEN THE FACE (HEDRA) – AND THINK OF IT AS BEENG MOUTH OF A HORN WITH ITS DRIVER INTO THE CENTER OF THE POLYHEDRON

MULTI-HORN vs. MONO-HORN � � � � � ICOSA-HORN DODECA-HORN OCTA-HORN HEXA-HORN (6 HORNS ON 6 SURFACES OF A CUBE) PENTA-HORN TETRA-HORN TRI-HORN DI-HORN MONO-HORN � � � BY REDUCING THE HORN NUMBER, INTERFERENCE ZONES ARE REDUCED THE LOWER THE NUMBER, THE LESS IS INTERFERENCE BY MATCHING -6 d. B POLAR PATTERN HORN ANGLE WITH SOLID SPHERICAL POLI-ANGLE, INTERFERENCES COULD BE MINIMIZED THE LONG WAY FROM PENTAHORN-THRU TRIHORN TO MONOHORN

PENTA-HORN � � � Three 100 x 100 deg Horns 120 deg apart, forming the cylindrical surface Two Conical Horns at the end of a Cylinder 5 Compression Drivers – 3 Horizontally radiated and 2 vertically (up/down)

PENTAHORN – OMNI-5 � � � Two 15” Coaxial Loudspeaker at the end of a Cylinder Three 100 x 100 deg JBL 2344 A Horns 120 deg apart, forming the cylindrical surface Two Bass reflex openings WEAKNESSES � � � ON-AXIS (ROOM) INTERFERENCES HARDLY POSSIBLE FOR 2344 A TO GO BELOW 630 Hz LACK OF FULL ROTATIONAL SYMMETRY (3 -fold Symmetry Only Available) FROM PENTA-HORN TO MONO-HORN / SPHEROVOX

SPHEROVOX MAIN FITURES � � � 3 PAIRS OF DIPOLES IN MONOPOLE CONFIGURATIONS EVERY LOUDSPEAKER COMPONENT HAS ROTATIONAL SYMETRY ALL LOUDSPEAKER COMPONENTS SHARE THE SAME (VERTICAL) AXIS THE TWO LOUDSPEAKERS IN EACH PAIR ARE AS CLOSELLY MOUNTED ONE TO THE OTHER AS POSSIBLE VIRTUAL POINT SOUND SOURCE

SPHERICAL SOUND SOURCE SIGNAL PROCESING

SPHEROVOX versus OMNIVOX (DODECAHEDRON)

EXPERIMENTAL MEASUREMENTS � � � MEASURING SIGNAL – FREQUENCY MODULATED SINEWAVE WITHIN 1/3 oct DR. BENJAMIN BERNFELD CD UNDER PIERRE VERANY LABEL -1984 400 Hz, 500 Hz, 630 Hz 1/3 Oct FMPN 500 Hz 1/1 Oct FM-PN – MIXING 400, 500, 630 Hz 1/3 MEASURING ROOM – SEMI ANEQOICK CHAMBER 150 m 3 PINK NOISE VS FM-SINE WAVE EQUIVALENT SIGNAL

FM-SINE WAVE VS PINK NOISE � ADVANTAGES � FAST MEASUREMENT TIME EXITE ALL ROOM MODES WITHIN THE BAND � � � DON’T NEED HUGE POWER AMP TO CARY PEEKS HIGHER DYNAMICS OF MEASUREMENTS VERY PRECISE FOR TURN TABLE MEASUREMENT AT LOW FREQUENCY ADVISABLE FOR ANY ACOUSTIC MEASUREMENT AS PINK NOISE ALTERNATIVE

SPHEROVOX LOW-FREQUENCY 1/1 OCTAVE POLAR PATTERNS � � 125 Hz (OUTERMOST) 250 Hz 500 Hz 1 k. Hz (INNERMOST)

SPHEROVOX – ONLY ¼ OF A VERTICAL POLAR PLOT NEEDED

SPHEROVOX POLAR PATERN � 2 k. Hz oct (outermost)– 1. 6 k/2 k/2. 5 k, 1/3 oct-RGB HF Co-Axial Drivers Switched off

SPHEROVOX POLAR PATERN � VERTICAL � � HORIZONTAL ALL HORIZONTAL POLAR PATTERNS ARE IDEAL CIRCLES FOR ALL FREQUENCY, AT ANY FREQUENCY BAND – 1/1 oct, 1/3 oct, PURE SINE WAVE

SPHEROVOX POLAR PATERN � 4 k. Hz oct (outermost)– 3. 2 k/4 k/5 k, 1/3 oct-RGB HF Co-Axial Drivers Switched off

DODECAHEDRON � � � There an infinite number of different polar pattern planes of measurement across the dodecahedron center Four axes, however, determine particular dodecahedron symmetry These two planes of measurement don’t coincide with any loudspeaker axis There are 10 such 3 -fold symmetry axis There are 6 such 5 -fold symmetry axis

DODECAHEDRON CURRENT AXES OF MEASUREMENT � � � This first “vertical” plane of measurement crosses 4 LS acoustic centers This second “eccentric” axis uses plane of measurement trough 2 LS acoustic centers These two planes of measurement share common mic axes equally distant to 2 pairs of LS at a time, and another ones equally distant to 5 LS centers There are 15 such 2 -fold symmetry axis There are 30 such axis

DODECAHEDRON “HORIZONTAL” POLAR PATERN - LF vs HF LOW FREQUENCY LOUDSPEAKERS–RED CURVES HIGH FREQUENCY COMPRESSION DRIVERS – BLUE CURVES

DODECAHEDRON POLAR PLOTS Edge Axis versus “Eccentric” Axis � 2 k. Hz oct (outermost)– 1. 6 k/2 k/2. 5 k 1/3 oct-RGB

DODECAHEDRON POLAR PLOTS Edge Axis versus “Ecsentric” Axis � 4 k. Hz oct (outermost)– 3. 2 k/4 k/5 k 1/3 oct-RGB

DODECAHEDRON MIMICRICS � � MEASURING IN A PLANE, IN WHICH NO LOUDSPEAKER AXIS LIE – SO CALLED “HORIZONTAL PLAIN” GIVEN IS SOUND POWER LEVEL FREQUENCY RESPONSE INSTEAD OF POLAR PATERN SMOOTHING ANGULAR RESOLUTION, AS DONE IN ISO 3382 PAPER STANDARD BY “GLIDING” CONCEPT – PRESENTING SO CALLED “DEVIATION FROM OMNIDIRECTIVITY” GIVING MISLEADINGLY GENUINE SPHERICAL SHAPE – EVEN WITH SPHERICAL PROTECTING GRILS

SPHEROVOX vs. OMNIVOX � SPHEROVOX - 2 k. Hz � OMNIVOX – 2 k. Hz

SPHEROVOX vs. OMNIVOX � SPHEROVOX - 4 k. Hz � OMNIVOX – 4 k. Hz

SPHEROVOX vs. OMNIVOX � SPHEROVOX - 4 k. Hz Coaxial Drivers Switched off � OMNIVOX – 4 k. Hz

SPHEROVOX vs. OMNIVOX � SPHEROVOX - 4 k. Hz Coaxial Drivers Switched off � OMNIVOX – 4 k. Hz

SPHEROVOX vs. OMNIVOX � Free Field Directional SPL Differences - d. B

SPHEROVOX vs. OMNIVOX � � SPL Frequency Response at 3 random, 15 deg apart, off. Axis Steps – 2 m Mic Distance Spherovox – Verical 15 deg Steps � Omnivox – Horizontal Plane 15 deg Steps

NEXT GENERATION SHEROVOX � � � Two 15” Coaxial Loudspeaker Double Dual Diaphragm Large Format CD Mono. Horn US Patent 5, 878, 148 – 1997 Inventor – D. Dimitrov ADVANTAGES � � � REDUSED HORN CUT-OFF FREQUENCY WITH THE SAME EXTENTION RATE CROSSOVER FREQUENCY DOWN TO - 250 Hz THD PERFORMANCE АТ 125 d. B/1 m <-40 d. B (2 nd), <-50(3 th) – 50 Hz-10 k. Hz

SUMMARY AND CONCLUSIONS � � It is impractical to have HR dodecahedron 3 -D polar pattern measured. Maximum directional SPL deviation in any band however could easily be evaluated by a single polar pattern in a plane, determined by at least two loudspeaker axes. 30 d. B L/R 1/3 octave band maximum SPL variation values, and about 20 d. B octave ones for 2 k. Hz to 4 k. Hz bands could be expected in rooms with dodecahedron measurements in horizontal plane. Spherovox will give 2 -3 d. B maximum L/R variations under the same conditions, which is 10 times better. � � Spherovox has about 10 d. B higher SPL sensitivity and about 10 db higher Power handling capabilities than marketed Dodecahedrons – meaning about 20 d. B higher SWL Capabilities. Spherovox exhibit perfectly circled horizontal polar patterns for all frequency 50 Hz-10 k. Hz, and for all frequency bans including pure sine wave, and “ 3 or 5 equally rotational steps” during measurements are misconception. Some spatial parameters measured with dodecahedrons are hardly usable after “ 3 or 5 equally rotational steps” averages. Both Omnivox and Spherovox are fully ISO 3382 compliant , which is deeply erroneous.

REFERENCES � � � [1] Hak, Wenmaekers, Hak, van Luxemburg - The Source Directivity of a Dodecahedron Sound Source determined by Stepwise Rotation, FORUM ACUSTICUM 2011/27. June - 1. July, Aalborg, Denmark. [2] ISO 3382 -1 International Standard ISO/DIS 3382 -1: Acoustics Measurement of room acoustic parameters–Part 1: Performance rooms. International Organization for Standardization, 2009. [3] Angelo Farina, Advancements in impulse response measurements by sine sweeps, Presented at the 122 nd AES Convention 2007 May 5– 8 Vienna, Austria. [4] Leo L. Beranek, Acoustics pp 103, 104. [5] T. W. Leishman, S. Rollins, and H. M. Smith, “An experimental evaluation of regular polyhedron loudspeakers as omnidirectional sources of sound, ” J. Acoust. Soc. Am. 120, 1411– 1422 (2006).

AUTHORS CONTACTS � � � Plamen Valtchev – plamen@spherovox. com Dimitar Dimitrov – dimo@spherovox. com Rumen Artarski – rumen@spherovox. com www. spherovox. com