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[Christy L Manoppo (okky)]

David Sharp wrote on Thu, 22 April 2010 19:15

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

good job brother!
What my church is experiencing are:
Front row's are 95-100db average... peaks at 105db's. A-Weighted Slow. If I remembered correctly, peaks came from the vocals.
FOH position are around 90-95 db's.

Now, my problem is to tackle the stage sound. The musicians are experiencing louder than those numbers.

Btw... I experiment doing something that I believe, leads me to the result I told above.
After the new monitors are in (SRX712m), everybody in the stage can hear the Pastor, WL and singers very well now. Well, of course they are now happy.. but I'm not, why? Now the stage is somehow louder on vocals. That resulted on muddying the house a lot.

So, what I did was:
1. Turn down the volume on those new monitors. It did help, but not as I expect to be. Still too much bleed.
2. I think, what if I flip the polarity switch for the House Mix?... I give it a shot. Well... somehow it works quite well!
Does this cause some kind of phase cancellation effect to the stage sound? Because now the house mix are clearer.

[David Sharp]

Genius idea in switching the polarity on the monitors. I'll have to give it a try. Cant believe I havent heard of that till now.

Maybe this is for another post but shouldnt there be a distance from the source (monitor) to the reflection point (back wall of stage) back to the FOH speakers where reversing the polarity of the monitors would actually help reinforce the house sound provided that distance is not too great?

[Jonathan Johnson]

David Sharp wrote on Fri, 23 April 2010 01:09

Maybe this is for another post but shouldnt there be a distance from the source (monitor) to the reflection point (back wall of stage) back to the FOH speakers where reversing the polarity of the monitors would actually help reinforce the house sound provided that distance is not too great?

It depends on the frequency or, more specifically, the wavelength of the sound being reflected. I'm to tired to explain the math on this.  

[Arnold B. Krueger]

David Sharp wrote on Fri, 23 April 2010 02:13

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.

Fireproofing casually-chosen fabric is so easy and cheap that not doing so is like a crime, especially given the risk.

For example:

http://natfire.com/proddetail.php?prod=Flamex

http://www.firechemicals.com/?gclid=CNSYkJf4nKECFU3X5wodSzHZ xA

We treated several dozen yards of polyester fabric by rinsing and spinning out in a regular household washing machine. We recycled the liquid that got spun out by catching it in a bucket.

Our fabric test strips did anything but smoke, smolder or burn, even when placed over a direct gas flame for long periods of time.

[Keith Shannon]

Christy L  Manoppo (okky) wrote on Fri, 23 April 2010 00:00

David Sharp wrote on Thu, 22 April 2010 19:15 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 good job brother! What my church is experiencing are: Front row's are 95-100db average... peaks at 105db's. A-Weighted Slow. If I remembered correctly, peaks came from the vocals. FOH position are around 90-95 db's. Now, my problem is to tackle the stage sound. The musicians are experiencing louder than those numbers. Btw... I experiment doing something that I believe, leads me to the result I told above. After the new monitors are in (SRX712m), everybody in the stage can hear the Pastor, WL and singers very well now. Well, of course they are now happy.. but I'm not, why? Now the stage is somehow louder on vocals. That resulted on muddying the house a lot. So, what I did was: 1. Turn down the volume on those new monitors. It did help, but not as I expect to be. Still too much bleed. 2. I think, what if I flip the polarity switch for the House Mix?... I give it a shot. Well... somehow it works quite well! Does this cause some kind of phase cancellation effect to the stage sound? Because now the house mix are clearer.

Basically. By flipping polarity between two speakers, they produce sound waves that completely cancel. In practice they don't quite cancel because it's not a perfect world and you're dealing with reflections off of different surfaces at different times, but you get pretty darn close. Standing in front of just one monitor or the other, though, you probably can't tell anything was done even on the flipped monitor. That really is a stroke of genius there.

Our band averages about 85dBA slow; this last rehearsal, with another new vocalist (two additions to the group in as many months), we peaked out at 91dBA in the sanctuary playing as hard as we would ever realistically play. That's with no acoustical treatment, just good (conscientious at least) drummers and an iron-fisted control over mains and monitor levels. Gonna run out of mikes and loft space soon if the group keeps growing like this (we've got half the Youth group involved and - get this - the rest want to be roadies and sound techs), but that's a problem I'll take anyday if the alternative is not knowing if I'll have a bassist or female vocalist for this or that song.

[Christy L Manoppo (okky)]

God is Genius... not me  

it's the main speakers that are polarity flipped, not the monitors. The mains are proc'ed by a DSP, in which sit next to our mixing board.
I should have flipped the polarity on monitors though, but to do that I must walk all way down to the amp rack in the stage.
But the effect still remain (I believe) almost the same.

[Jonathan Johnson]

Christy L  Manoppo (okky) wrote on Fri, 23 April 2010 23:46

God is Genius... not me   it's the main speakers that are polarity flipped, not the monitors. The mains are proc'ed by a DSP, in which sit next to our mixing board. I should have flipped the polarity on monitors though, but to do that I must walk all way down to the amp rack in the stage. But the effect still remain (I believe) almost the same.

One potential problem with flipping the polarity of the mains (and maybe it's not a problem; I'm just conjecturing) is that you could get cancellation of the direct sound (the voice or instrument) by the reversed polarity of the amplified sound. In a large venue where most of the sound is from the main loudspeakers this probably won't be a problem, but in a small venue it could be an issue for folks sitting near the stage.

[Christy L Manoppo (okky)]

That's correct. So I advised everyone to be careful when taking this approach. If it's not working, then flip it back again.

In my case, the monitors are about the same placement of the subs
( i mean horizontally), and the mains are located up in the ceiling, approx. 15ft away from the subs, and the second mains (delay speakers) are approx 35ft away from the 1st main. So, our audio contractor put some delay (probably 35ms)for time alignment.
Maybe that's why the phase cancellation effect isn't subtle.

[David Sharp]

So this Sunday worked out great. I had several complements from both those on stage and in the audience. They managed to peak at 93db at the mix position and averaged around 87db (A slow). I ended up micing the snare, kick, & 1 overhead and on several occassion I really felt like I needed them to keep the drums up with the rest of the mix.

The kit, especially the kick, sounds much deeper and fuller with the insulation in front of it. Also, switching the drummer from a wedge to headphones made a significant difference in the stage volume.

The next order of business is to construct a 42" high wall where the shield is now and attach the shield to the top of that wall to extend its reach. I also purchased some 1x2's that will replace the plastic hinges the shields orginally came with.

Also, the band will need to get used to talking into a microphone when they need to communicate to the drummer.

@ $65 / 4'x10' sheet I would recommend it in a situation where you have a shield but no sound absorbtion in place.

[daniel hillis]

David,

Is there anyway you can get a picture of what you did and post it?  I think it would really help our sound if we could do this also but needs to look professional.

Thanks

[ProSoundWeb Community]