Film-Tech Forum ARCHIVE: "toe-ing in" L R screen ch. speakers

This is topic "toe-ing in" L R screen ch. speakers in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by James Larden (Member # 5594) on 08-16-2010, 01:15 PM:

Hi All,

According to the JBL white paper for specifying theater loudspeakers, it is a recommended practice to angle the L,R screen channels towards the center of the room (specifically that their on-axis extensions converge 2/3 of the distance to the back wall of the cinema). I have never seen this in practice, albeit I've worked in special/academic venues pretty much my whole career. Is it still done or is their some debate in the installer/tech field as to the efficacy of this speaker placement.

Thanks

Posted by Ian Parfrey (Member # 5122) on 08-16-2010, 01:32 PM:

It is a sound practice to aim the L & R speakers as per the recommendations suggested by your source. The object is to mainly prevent excess spill and spurious reflections from the side walls emanating from those speakers but there is conjecture as to whether comb effects are more noticable in the centre of the auditorium. This shouldn't be a problem with constant directivity horns and the like, but it is important to get the physical phasing of the pressure units as close as possible.

Posted by Mark Gulbrandsen (Member # 72) on 08-16-2010, 02:30 PM:

THX always had all three of the 4675 horns aimed just above the rear center seat on sloped floors. With stadium it varied depending on the exact type of stadium it was. Some houses have mixed slope/stadium seating..

Mark