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[Jonathan Johnson]

David Sharp wrote on Mon, 19 April 2010 19:09

My concerns with the iso pac is it would reduce the drum volume too much on stage and I would be putting them back into the wedges onstage for the rest of the musicians.

Isn't this essentially what you'd be doing if you went with an electronic kit (pads)?

[David Sharp]

Yes in a sense it is essentially the same which is why I am not going with electronic drums. Personally I cant stand them. My opinion: Do they sound better than they did 10-15 years ago? Yes. Do they sound better than a good acoustic kit? No. Are they right for some churches? Absolutley! I'm just not willing to drop $2500 for a set of rolands with mesh heads. We'll upgrade everyone to wired IEM's with hearback controllers before we spend $2500 on Edrums.

I did hook up an additional headphone monitor mix solely for the drummer, setup an overhead condesner, kick, and snare mic so they can hear themselves today and found a supplier to purchase some Johns Manville 814 insulation. From what I've read this stuff is comparable if not better than OC 703 and is slightly cheaper.

My plan this Sunday is to place the insulation around the base of the shield, on the walls, and hopefully suspend some from the ceiling above. This should give me a really good idea of how much of a reduction the finished product will bring.

[Brian Ehlers]

I'm not smart enough to do the math, but I really don't think you'll achieve the 10 - 15 dB of attenuation you've been talking about unless you use a booth which is almost completely sealed.  I'm thinking a couple inches max of air gap top and bottom to provide ventilation.  No amount of absorption inside the booth will overcome the transmissibility of a large air gap.  Think of a loud stereo playing through an open car window.

Of course, I'm not sure you really need 10 - 15 dB of attenuation.  Are you saying the drum kit really measures 110 dB SPL out in the congregation?  Or is that what you measured right next to the kit?  If your kit measures only, say, 95 dB SPL out in the congregation, then you may only need 5 dB worth of absorption to bring it down below the mix.

[David Sharp]

The drums are pretty constant 100-110db on stage which is driving the monitors, which in turns fills the room with reflective noise. I would be estatic if what I'm about to do cuts the drums about 6db on stage because then all the wedges can go down as well.

The drums are loud in the house mix but it would not be as noticeable if the reflection from the monitors wasnt messing with being able to hear the vocals.

I've already taken one wedge off the stage and replaced it with headphones for the drummer. So there is one truck load worth of mud off the stage.

So, if the drums go down 6db, one monitor is gone, and the other 2 monitors go down 6 db, I would put this project in the WIN column.

Here are the absorbtion coefficients for the product I'm using:

Type in mm 125hz 250hz 500hz 1000hz 2000hz 4000hz NRC
800  1½ 38 0.11  0.45  0.96  1.07   1.06   1.00   0.90

Yes there will be some air space but the majority of the sound will hit this or be reflected into it at some point. @ $1.58/sq/ft its worth a try.

[Keith Shannon]

David Sharp wrote on Wed, 21 April 2010 13:12

The drums are pretty constant 100-110db on stage which is driving the monitors, which in turns fills the room with reflective noise.

You're really rockin it out in there. Are your measurements A-weighted "slow", which is the standard for occupational safety, or are you using C-weighting "fast" to get true bass response and fast transients? Also, is that really only the drums, or was that the whole band with the drums at their normal level? Adding a 110dBA source to another 110dBA source will get you between 113-116dBA. If drums alone are 110dBA and you blend in other sources at similar volume, you could easily be topping 120dBA with the rest of the band mixed in. Those kinds of levels require hearing protection for at least your band and maybe your congregation (100dBA can be "safely" tolerated for 2 hours in a day; 110dBA for 30 minutes and 120 for less than 10 minutes; even then you are still risking permanent hearing damage).

I would seriously look at what you could do to get your levels down to about 90-95dBA for a HoW setting (which can be tolerated "safely" for 4-8 hours). Our praise band uses unisolated acoustic drums and we average about 85dBA, which is comparable to our pipe organ (for good reason) and right at the OSHA limit for unprotected hearing long-term. Ear bud monitors replacing wedges, some sort of real isolation for those drums, and a general turn-down. Spec some equipment, come up with a budget and plead your case to any who will listen to you; if the SPLs stay that high you could end up giving one of your band members or congregants tinnitus or other permanent hearing damage.

[David Sharp]

The measurements I took were C-weighted slow standing behind the drummer with the meter about 6" from his ear (trying to plead my case). They ranged from 100-110db on their faster song they practiced that evening. For obvious reason I didnt stand back there very long. For the rest of the stage it ranged from 95-105 around the guitar amps and monitors.

I've had peaks of 103db (C slow) at the mixing position (at the back of the sanctuary (but its not all that deep) which is nearly a half circle.

I've plead my case to the band, worship leaders, & pastor. Unfortunately, I get very little response from the worship leaders to control the band members (there are more issues here than just volume). The pastor is supportive but they won't give me the budget to even get everyone on WIRED IEM's.

I did have a nice breakfast with the pastor this past weekend which prompted the acoustic insulation for the drums. I believe if I can "show them the light" so to speak and they some hear difference they will be more inclined to continue in a safer and quieter direction.

I've run out of ways to say, "The louder you get, the worse it sounds in the house. Why won't you turn down?"

[Keith Shannon]

David Sharp wrote on Wed, 21 April 2010 15:47

I've run out of ways to say, "The louder you get, the worse it sounds in the house. Why won't you turn down?"

First, SPLs are usually measured A-weighted for regulatory purposes, and second, stage sources will be louder on stage. I would place the meter at your desk, set to A-weighted slow, and compare the time-weighted average (if you can get one, otherwise just keep an eye on the meter) to OSHA regs. If the average volume in that room exceeds OSHA regs for any set "exposure time", your congregation is suffering permanent hearing damage. If you EVER record a peak value 140dB or above, that indicates immediate permanent damage (though I would wonder why those volume levels haven't cleared the house; 140dB is serious pain).

If you have that kind of volume problem and you can't get anyone to listen to you, quit the soundman position, and go over your pastor's head to either regional church leadership or OSHA's local office. Seriously; your church is liable for damages at that point, and you as soundman will be the first person pointed to if and when a complaint is made to someone who cares. If you don't have the clout within the church to effect a permanent change in volume levels, you're just a scapegoat.

If things aren't quite that bad yet (say 100dBA-slow at the desk while the band's playing, and the pastor's sermon's significantly lower) then I would look for some mutual friends or authority figures to help lean on the band before it gets to that point. The pastor's supportive; maybe the worship team will listen to him. After all, he is THE worship leader when it comes right down to it. Find some respected members of the congregation who say it's too loud. If you're not the only voice of dissent, then prove it.

[David Sharp]

So I roughed in the insulation today. I ending up for OC703 from a local HVAC supplier. Other than the itching Im experiencing now, I really like the results.

I placed 4' high sections between the drums and the shield, a 5'x4' section on one of the walls behind, and suspended a 5'x4' section above the drums.

A weighted slow, pounding as hard as I could, I was only able to achieve 90db at the mix position hammering the crash, snare, and kick. Front row was 98db again drumming harder than anyone typically would in our service. When I stopped, my ears were ringing for a couple of seconds so you I know I was trying.

The pastor has spoken to the worship leaders regarding the volume issues and really reinforced what I've been trying to achieve. He does agree that it is too loud and would like to see a change as well. I believe its just an issue now of consistent enforcement and with the pastors backing I hope they just take me at my word when they are too loud. We are aiming for service with peaks of 92db and an average around 87db. We'll see what this Sunday brings though

[George S Dougherty]

Put some cloth covering over that insulation ASAP.  Otherwise, looks like you're headed in the right direction.

[David Sharp]

Wrapped in burlap. Ironcially the fire inspector was there for a surprise inspection. I wasnt sure what he would think of the burlap since it is flammable but he let it slide. Good man. Maybe it just doesnt matter because of the way its mounted or whatever.

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