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when to delay FOH

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when to delay FOH

Postby hopscotch44 » Fri Apr 21, 2017 1:17 pm

i've been turning this question over in my mind planning a big mixed school concert next week (Zimbe)
A main adult & upper school choir (100+) on risers will have in front of them 250+ young children and a Jazz band. There will be solos from a number of timid youngsters to the front of the affair.
Originally i was to simply record the concert. I have been asked to provide P.A. reinforcement to the main choir & the soloists.

There are fire exits down either side & adjacent to the main choir. I will be splitting signals to recorders and FOH desk.

If i have to place FOH speakers well foward from the choir (fire exits)...when do i start considering FOH delay?
The soloists may well be closer (horizontal) to the speakers then!

Is it maths simply?
there will be little/no time for major experiment.

any thoughts?

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Re: when to delay FOH

Postby Hugh Robjohns » Fri Apr 21, 2017 1:59 pm

As a rough rule of thumb, I'd suggest when the speakers end up being 20 or more feet in front of the sound source. At roughly 1ms/foot (3.4ms/metre), anything less than 20 feet means less than 20ms delay and the brain tends to cope with that, fusing the direct and speaker sound into one (see Haas Effect). More than 20ms and the two become separate sources and aural confusion kicks in. The speakers are perceived as the real source and the real performers as echos... which isn't very natural or helpful.

So, if the speakers end up more than about 20 feet in front of the performers, dial in the appropriate delay, and err on the side of slightly longer than the maths dictates. In practice, just dial up the delay until your brain recognises the stage sound as being the focus.

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Hugh Robjohns
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Re: when to delay FOH

Postby hopscotch44 » Wed Apr 26, 2017 4:47 pm

thank you Hugh
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