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Author Topic: FOH DB limits  (Read 9503 times)

Jay Brett

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FOH DB limits
« on: December 12, 2016, 01:21:57 pm »

I'd like to get some opinions on standard FOH DB restrictions. I'm going from a smaller Meyer PA where I didn't really need to enforce a DB/SPL limit to a new D&B rig that can easily outperform the Meyer rig. I'm in a downtown outdoor environment and we have brand new high-end residential towers just outside of the venue. 

I see a ton of artist riders, but not many venue tech packs as I've been off the road and at this same venue for 4 years now. It seems like I use to see 105Dba at FOH on the regular.

What does everyone recommend? 105, 100 ??? A,C weighted?
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Nathan Riddle

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Re: FOH DB limits
« Reply #1 on: December 12, 2016, 01:29:36 pm »

I would say it depends on the length of the show. You can go louder for shorter. Quieter for longer.

I'd go with NIOSH or OSHA limits.

A weighted, when weighing SPL that damages human hearing, C gives unrealistic answers.
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Ivan Beaver

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Re: FOH DB limits
« Reply #2 on: December 12, 2016, 02:50:55 pm »

Technically, A weighting should never be used above 80dB.

C can give high numbers if people are used to using A.

Basically it depends on what you can get away with.

On a city street, lots of vibrations can get into buildings through the structure.

So they may not be able to "hear" it, but they can feel it.

It is also not only the scale, but also the response time.  Slow and fast can give a wider or narrower range.

At one recent EDM show I did, the difference between A slow and C peak was 32dB.

HOWEVER-when you look at the difference below 100Hz to above 200Hz, the difference was around 42dB.

So-once again- a simple single number does not give an accurate easy answer.

So-it depends---------------

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John L Nobile

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Re: FOH DB limits
« Reply #3 on: December 12, 2016, 03:02:51 pm »

When I'm mixing on my rig I max out at 105 dbC and don't get any complaints. This weekend the BE ran at 112 dbC and I had to leave the room periodically. Staff was telling me it was too loud as well and asked me to get it turned down.

But the crowd was into it and the system was clean so I didn't say anything to the BE.
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Nathan Riddle

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Re: FOH DB limits
« Reply #4 on: December 12, 2016, 03:08:50 pm »

Technically, A weighting should never be used above 80dB.

Then why are NIOSH & OSHA using it and their charts don't start until 85dB?

https://www.cdc.gov/niosh/topics/noise/reducenoiseexposure/regsguidance.html

Yes I realize they are for a 8hr work day using loud equipment. Yes I know we assume no prior exposure during the day when we run shows. But its what we got.

If you metered things with C at a edm/rock concert you would absolutely be way higher on the meter than the only published source of spl restrictions we have. So to be inside the margin you would be forced to run things quite a bit quieter and the promoter/band might not be having you back.

Also, I'm not saying use the chart for peaks, I'm saying use it for an average level. If said concert is 1hr then the average level should be below 94dBA which is pretty easy given how much luls there are in music.
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David Buckley

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Re: FOH DB limits
« Reply #5 on: December 12, 2016, 04:23:14 pm »

So-it depends

You do know they're gonna put that on your tombstone, yeah?
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Ivan Beaver

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Re: FOH DB limits
« Reply #6 on: December 12, 2016, 04:47:39 pm »

Then why are NIOSH & OSHA using it and their charts don't start until 85dB?

https://www.cdc.gov/niosh/topics/noise/reducenoiseexposure/regsguidance.html


OK, I was wrong.  The upper limit for A is supposed to be 60dB, not 80dB.

Just because some people use it does not mean that it is proper or correct.

I was simply stating the level of the original intended curves were.

Here is some more reference if anybody is interested

http://www.acoustics.asn.au/conference_proceedings/AAS2013/papers/p39.pdf
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Jay Brett

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Re: FOH DB limits
« Reply #7 on: December 12, 2016, 04:48:57 pm »

Technically, A weighting should never be used above 80dB.

C can give high numbers if people are used to using A.

Basically it depends on what you can get away with.

On a city street, lots of vibrations can get into buildings through the structure.

So they may not be able to "hear" it, but they can feel it.

It is also not only the scale, but also the response time.  Slow and fast can give a wider or narrower range.

At one recent EDM show I did, the difference between A slow and C peak was 32dB.

HOWEVER-when you look at the difference below 100Hz to above 200Hz, the difference was around 42dB.

So-once again- a simple single number does not give an accurate easy answer.

So-it depends---------------

I've always been confused by people's choice of A or C weighting. "A" makes sense to me, considering I'm more worried about what people are hearing as opposed to getting truly scientific data. For example, I had a local guy who thinks he's an audio guy post something on social media after a show at my venue. The headliner actually brought their own PA for that show, but regardless he was posting on social media that the show was 137DB, even posting a picture of his phone app he says he calibrated in his studio. He was using C-weight and was about 16 feet from 8 SB1000's. Had he used A-weight, it would likely have been closer to 110 or lower, still too loud but fairly normal in regards to concert audio.

I'm wanting to find a good compromise where I can keep the SPL at a reasonable level while at the same time not restricting visiting engineers into a unrealistic set of rules. I'm not worried about system protection, as I'll have tons of headroom and the ability to clamp anyone down who may be pushing it too hard.

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Tim McCulloch

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Re: FOH DB limits
« Reply #8 on: December 12, 2016, 05:11:20 pm »

I've always been confused by people's choice of A or C weighting. "A" makes sense to me, considering I'm more worried about what people are hearing as opposed to getting truly scientific data. For example, I had a local guy who thinks he's an audio guy post something on social media after a show at my venue. The headliner actually brought their own PA for that show, but regardless he was posting on social media that the show was 137DB, even posting a picture of his phone app he says he calibrated in his studio. He was using C-weight and was about 16 feet from 8 SB1000's. Had he used A-weight, it would likely have been closer to 110 or lower, still too loud but fairly normal in regards to concert audio.

I'm wanting to find a good compromise where I can keep the SPL at a reasonable level while at the same time not restricting visiting engineers into a unrealistic set of rules. I'm not worried about system protection, as I'll have tons of headroom and the ability to clamp anyone down who may be pushing it too hard.

You're trying to prevent problems with neighbors who have more political and monetary capital than your venue is willing to risk.  Good luck, because if you fail the City Commission will have your Board reading a "nastygram" from a bunch of lawyers.

The easy answer is to use whatever SPL level was not objected to previously.  If the old rig got no complaints at (arbitrary number for discussion) 95dBA, slow, then use that until you feel more adventurous and/or have a better feel for the neighbors attitude.

As far as BEs... most of them get it when you tell them about the SPL limit.  A few will scoff and a few will ignore it and you.  I've worked a restored historic theater with a 95dBA fast limit.  The national acts simply ignore the theater director unless they're already performing that way...  Others will do their best to accommodate the limit but they struggle.

The potential for over-limit use starts with booking.  Ricky Lee Jones or the Man o' War tribute?   8)
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Jay Brett

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Re: FOH DB limits
« Reply #9 on: December 12, 2016, 05:35:25 pm »

You're trying to prevent problems with neighbors who have more political and monetary capital than your venue is willing to risk.  Good luck, because if you fail the City Commission will have your Board reading a "nastygram" from a bunch of lawyers.

The easy answer is to use whatever SPL level was not objected to previously.  If the old rig got no complaints at (arbitrary number for discussion) 95dBA, slow, then use that until you feel more adventurous and/or have a better feel for the neighbors attitude.

As far as BEs... most of them get it when you tell them about the SPL limit.  A few will scoff and a few will ignore it and you.  I've worked a restored historic theater with a 95dBA fast limit.  The national acts simply ignore the theater director unless they're already performing that way...  Others will do their best to accommodate the limit but they struggle.

The potential for over-limit use starts with booking.  Ricky Lee Jones or the Man o' War tribute?   8)

Well, the good thing is the company I work for owns everything around the venue, including the residential towers. So that makes life a little easier as I'm getting info directly from the source and we have to compromise between being respectful of tenants, but also making sure they understand they are moving into what's labeled as the "Midwest's #1 Entertainment District".

While I took measurements with the old PA, I never attempted to establish a SPL limit for multiple reasons. I do know the D&B rig I have coming can cruise at 115DB all day, as I've done the testing with it this summer.

I'm more dealing with whiners too, not really anything that can legally hold up. I've done testing during a concert and on the 22nd floor, the SPL would spike by 1-4 DB with the music, never getting past 62dbA in the unit's bedroom and living room.

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Re: FOH DB limits
« Reply #9 on: December 12, 2016, 05:35:25 pm »


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