Funny specs provided for show I'm doing this weekend.

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Brian jojade

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Jan 15, 2011
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Wausau, WI
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A tournament supplied house sound system will be provided by the host team of any National Show Tournament for the use of all participating teams. Said sound system shall meet, but not be limited to, the following minimum specifications:*

A. Loudspeaker cabinets sufficient to provide clear, intelligible coverage of the entire spectator and judging area. Sound pressure level (SPL) at the judging area should be at least 70 db.*

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So, I brought 40,000 watts for the show. :D

A little overview, this is an outdoor show for a waterski tournament with about 5000 in attendance. 26 show teams throughout e weekend patch in their random assortment of crap gear, and I have to make sure it works within 10 minutes for their hourlong show. Then they have full control of their board. So, I do bring plenty of extra horsepower because invariably some idiot will do something stupid. If I didn't have the headroom, stuff would be blown up. Overall, it's a pretty fun gig.
 
Re: Funny specs provided for show I'm doing this weekend.

Brian jojade said:
A tournament supplied house sound system will be provided by the host team of any National Show Tournament for the use of all participating teams. Said sound system shall meet, but not be limited to, the following minimum specifications:*

A. Loudspeaker cabinets sufficient to provide clear, intelligible coverage of the entire spectator and judging area. Sound pressure level (SPL) at the judging area should be at least 70 db.*

----

So, I brought 40,000 watts for the show. :D

A little overview, this is an outdoor show for a waterski tournament with about 5000 in attendance. 26 show teams throughout e weekend patch in their random assortment of crap gear, and I have to make sure it works within 10 minutes for their hourlong show. Then they have full control of their board. So, I do bring plenty of extra horsepower because invariably some idiot will do something stupid. If I didn't have the headroom, stuff would be blown up. Overall, it's a pretty fun gig.
Click to expand...

Watts does not say a whole lot. While 70dB may not seem to be very loud-it depends on how far the loudspeakers are away from the listener-the sensitivity of the loudspakers and so forth.

When you start to look at distances of say 1000' can result in losses of at least 50dB-some football stadiums have listeners further way than that from the loudspeakers. Once you throw in air absorbtion-the highs could lose another 50dB.

So you are looking at up to 100dB of loss at that distance.

We don't know-but 40Kw may not really be all that loud where it needs to be. 40Kw is 46dB of gain.

So if you look at a little bit of "math"- to provide 70dB (we are not assuming any headroom here-which will require more output) + 100dB loss=170dB. Take away the 46dB gain in power and you have 124dB. So the speaker system should produce 124dB with 1 watt of power to meet the "minimal spec of 70dB @ say 8Khz.

Of course at lower freq the air absorbtion-or in a more humid climate- will be less-AND there will be a lot of other factors to take into consideration-but it is always a good idea to do a little bit of quick math to see if the system will perform as desired.
 
Re: Funny specs provided for show I'm doing this weekend.

70dB is barely above normal speaking volume. A crowd of 5000 will be creating far more than 70dB on its own. The point is that the spec was artificially low. For fun, I set the pre-show music this morning at 6 am to 70db ad the judging area, which is about 100 feet back from the beach and then asked the judges if they though that would be loud enough for the tournament. The look on their faces when they realized how quiet 70 dB was when a boat drove by and completely drowned out the sound was priceless.

My suggestion to them, and one that I generally use, is that you want a system that can produce at least 15dB above the ambient sound level of the venue. This doesn't mean you have to run it that loud, but you should be able to.

In this case, 40kw is more than enough. The area being covered is a beach about 300 ft wide and 100 feet deep. Yeah, if I had to produce sound 1000 feet from a speaker, that would be a different story, but that would be a totally different system.
 
Re: Funny specs provided for show I'm doing this weekend.

Ivan Beaver said:
When you start to look at distances of say 1000' can result in losses of at least 50dB-some football stadiums have listeners further way than that from the loudspeakers.
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Ivan,
Do you mean futball? or can you do some name dropping? Not that I am nit picking...but I don't know of any stadiums with 1000ft throws, but i haven't seen them all.
 
Re: Funny specs provided for show I'm doing this weekend.

David Sturzenbecher said:
Ivan,
Do you mean futball? or can you do some name dropping? Not that I am nit picking...but I don't know of any stadiums with 1000ft throws, but i haven't seen them all.
Click to expand...

Some of the larger ones (100,000ish seats) have that type of throw-between where the loudspeakers are mounted and the furthest listener-give or take a few feet.

At that distance-100' or so one way or the other doesn't matter-in terms of SPL and distance loss.
 
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