Bose Panaray MA12 Technical Foundation & Discussion - Page 20

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Also for Bose Panaray MA12: User Manual (2 pages), Installation Manual (16 pages), Installation Manual (8 pages), Installation Manual (7 pages), Service Manual (11 pages)

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APPLYING LINE SOURCES TO SOUND SYSTEM DESIGN

3 dB per doubling behavior of cylindrical waves is of special interest in sound system

design because it is so much more gradual than the 6 dB per doubling behavior that

motivated us to hang and tilt speakers. On the other hand, so was the 0 dB per doubling

behavior of plane waves, but unfortunately, producing them was impractical in real life. Is it

more practical to produce cylindrical waves? Or are there problems that will rule this out too?

If such a source can be realized, would it really do a good job at meeting customer

requirements?

Source shape and sound output capability

begin, a source that produces cylindrical waves does not have to be rejected for the same

reasons a plane-wave source was rejected. A cylindrical-wave source must be as tall as the

audience, but not as wide, since the wide horizontal radiation pattern can be relied on to

cover an audience distributed side to side; a tall, slim source, resulting in wide side-to-side

radiation, can cover a typical audience.

Second, with modern transducer technology, there is no reason that a line source can not

produce a balanced frequency response at the kind of output levels required in many

applications. Major improvements in transducer technology (including many introduced by

Bose) mean that it is no longer true that the small transducers needed to fit into a slim line-

shaped source lack the correct balance of frequencies or necessary output capacity. A full,

balanced frequency response and very high output is now possible from speakers no larger

that a tea cup. Therefore, concerns about frequency response and output are also not reasons

to reject the line source.

Meeting the primary customer requirements

principal – in other words without regard to the specifics of any particular implementation

– would a line-shaped source radiating cylindrical or near-cylindrical waves be a good choice

for meeting the major customer requirements listed earlier?

Re-examination of the side view of the radiation pattern of a line source, shown in Figure

11, reveals that sound does not radiate up and down, but rather is confined to a region

between a plane perpendicular to the top of the array and one perpendicular to the bottom.

When such a source is placed in a room, it means that sound will not radiate up and down and

therefore will not radiate to the ceiling and upper walls, where reflections contribute to the

amount of reverberation and therefore to the degradation of music clarity and speech

intelligibility. Such a source would be therefore ideally suited to environments with longer

reverberation times such as churches, auditoriums, airports, hallways and so on.

Bose

MA12™ Modular Array: Technical Foundation & Discussion

Page 20 of 36