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Watts per sqm

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bin juice24 View Drop Down
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    Posted: 05 August 2020 at 12:27pm
Hello. Is there a vague guide to how much output you need for varying sized outdoor areas? I appreciate there’s many variables, but was just wondering.
Playing modern dance music.
Cheers.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FOO Quote  Post ReplyReply Direct Link To This Post Posted: 05 August 2020 at 1:29pm
Short answer... No..

To many variables in play :)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 05 August 2020 at 2:02pm
The only rule of thumb that has any merit is that you need 2-4 times more equipment to get roughly the same performance as an indoor venue of the same size.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Crashpc Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2020 at 8:22pm
No, Watts produce heat, not SPL.
Too many variables. Also, if ypu have 1000 people and 5000 Watts, it doesn't meat that 1 human will be happy with 5 Watts.
Nikon and Canon people should not be married to each other. Why did you let this happen?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sonic the hedge Quote  Post ReplyReply Direct Link To This Post Posted: 15 August 2020 at 11:13pm
Very roughly, and keeping the maths simple, for basic floor stacked system, it's desired minimum dB level +6dB per doubling of distance from speakers. For each stack you gain +3dB for each doubling of drivers. Then factor speaker sensitivity to determine how many watts, this time +3dB per doubling of watts against the sensitivity at 1w/1m

Start with how loud, in decibels, you want it to be to achieve the desired effect over the area you want to cover. For dance I would suggest 90dB + as a minimum, but obviously depends on noise restrictions, neighbors etc.  

If you want to determine approximately how loud you want it, download a dB meter app to your phone and take it to a nightclub or event that has the kind of level you want to achieve. Find the spot that has the minimum level you think is ok and measure the dB level there.

Then for the furthest point in the area you want to cover, add 6dB per doubling of distance from the speakers, to determine how loud the speakers need to be, in decibels, at 1m. You can round the distance a little so it divides in, it's not an exact science!

e.g. 90dB@8m = 96db@4m = 102dB@2m = 108dB@1m. 

For a dance system can be useful to have four or more stacks pointing inwards i.e. rear stacks facing towards stage, like a nightclub, because this halves the distance to be covered by each stack for a given dB level of coverage, and will therefore also minimize overspill Vs a front only system.

Once you have determined how loud the speaker stack needs to be at 1m, then you can subtract 3dB for each doubling of drivers. This gives you the required dB level per driver. 

e.g. two drivers -3dB, four drivers -6dB etc.

 Then need to factor the speaker sensitivity, based 1w/1m again using 3dB per doubling of input power, to determine how many watts are needed per driver to achieve the required dB output. If the watts so required exceed the power handling of the driver, just add more drivers and repeat the calculations above.

e.g. 100db@1w = 103db@2w = 106db@4w = 109db@8w etc. etc.

In a multiway system will need to repeat this calculation for each band, bass, mid, top etc. making sure that you have a balance in dB level between the bands. Note also, the sensitivity of bass, mid, top etc will be different for each section. Most rigs are run with the bass/sub section pushed hardest,  because this requires they most power, and mid tops are run with plenty of headroom, for clarity. 

Depending on music genre you may want to add extra Sub/Bass, in this case each time you double the output watts/number of drivers it only adds 3dB, so you need a lot extra to make a significant difference to the overall tonal balance. But personally I think there is no such thing as too much bass...

Thats about the simplest approximation of how many watts, but not exactly a rule of thumb!




Edited by Sonic the hedge - 16 August 2020 at 9:26pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mk2_ginger_biscuit69 Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2020 at 1:28am
i aim to deploy a flux capacitor of power per metric ton of human flesh. Hope this helps. 
''Remember that the object of a subwoofer is to enhance the output of your main speakers, not overpower it''

''Dubstep - an elongated electronic fart''
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 4D Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2020 at 2:12pm
1kilowatt per 16m2 

Edited by 4D - 16 August 2020 at 2:13pm
DMZ. "The bass was intense. Girls were literally running up to stand next to the subs"
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Post Options Post Options   Thanks (2) Thanks(2)   Quote APC321 Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2020 at 3:19pm
bin juice24 asks: "Is there a vague guide to how much output you NEED for varying size outdoor arenas?"

Slightly off topic, but this drawing has always made me smile:

https://ibb.co/64nrR2T

Edited by APC321 - 16 August 2020 at 3:45pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Boxes-R-Blue Quote  Post ReplyReply Direct Link To This Post Posted: 19 August 2020 at 11:22pm
Unfortunately "watts" no longer have any part of pro audio...

D&B don't even get into the things, you buy the box, buy the amp, tell the amp what you plugging in and away it goes.

In the late 90s a Turbosound TMS-3 was about 1KW but a 350W Floodlight produced higher SPL and that is where Watts died...

Also program content, I'd want more system for a classical gig than a metal gig as I would need the headroom to cope with the extreme dynamic range where as DJ gigs have no dynamic range (or if they do the DJ removes it using the Boss DS-2 DJM distortion pedal) so you need less power than a metal gig....

Kinda Been there, Kinda done that, YOU COULDN'T handle my bar bill!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jacethebase Quote  Post ReplyReply Direct Link To This Post Posted: 20 August 2020 at 12:04pm
Originally posted by Boxes-R-Blue Boxes-R-Blue wrote:

Unfortunately "watts" no longer have any part of pro audio...

D&B don't even get into the things, you buy the box, buy the amp, tell the amp what you plugging in and away it goes.

In the late 90s a Turbosound TMS-3 was about 1KW but a 350W Floodlight produced higher SPL and that is where Watts died...

Also program content, I'd want more system for a classical gig than a metal gig as I would need the headroom to cope with the extreme dynamic range where as DJ gigs have no dynamic range (or if they do the DJ removes it using the Boss DS-2 DJM distortion pedal) so you need less power than a metal gig....


I find from personal experience DJ gigs require a fair bit of headroom.
You are right in the fact that what a mixer outputs is fairly even in terms of dynamics.
But when you got "Billy & Bob I've had 2 grams" shouting rewind down a 58 competing who can be heard the most. Forget it.

Unfortunately other than the free party type gigs, psy trance, house etc most of the larger dance events we do there are MC's to contend with.

No one really likes them, everybody wishes they would just be quiet and let you enjoy the music. But unfortunately they still exist.
www.wedding-production.co.uk

www.stage2sound.com
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