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Old Tuesday, March 17th, 2009, 08:03 PM
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Request for help with speaker placement

Hello everyone. I am new to the site and must say I am impressed with the level of expertise and the willingness to help the less educated.

I definitely qualify as an uneducated member and would appreciate advice on speaker placement for our sanctuary.

My Church:
The sanctuary is 80 ft in length, 32 ft wide and has a cathedral ceiling at 17 ft high. The walls are drywall. The ceiling is wood planking. There are 5 wooden arch ceiling supports between each end of the sanctuary. The span between the arches is approx. 16 ft. The stage is about 17 ft deep and just under 2 ft high. The sanctuary is carpeted, as is our stage. There are two sections of pews. Generally we have about 150 - 180 people in attendance but somtimes draw 225+.

Our music ministry is a live band including acoustic and electric guitar, acoustic drums, electric bass and a mic'd piano. We play mostly contemporary music such as Tomlin, Brewster, Redman but also put a traditional hymn in the song list for good measure.

We desire to optimize our sound to provide more uniform coverage. Our current logic is to mount 2 existing QSC 122i active speakers in the apex of the roof just in front of the stage. We also have a QSC 118i active subwoofer sitting on the stage, but located in the corner. There are also 4 EAW JF60 speakers we think could be mounted on each side of the sanctuary. Two JF60's per side. We plan to mic the drums and perhaps the electric guitar amp and bass amp.

Lastly, we are a small Church with very limited funds. I would appreciate knowing how we can utilize the speakers we have in the best configuration. If other equipment is definitely required, I am certainly interested in knowing where we lack.

I am concerned that our logic is flawed. I am only a musician and make no claims of being a sound engineer. I would greatly appreciate some advice from the knowledgeable people frequenting this site.

I look forward to reading all responses.

Best regards,
Paul in Cincinnati
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Old Monday, March 30th, 2009, 12:51 PM
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A couple of practical considerations to start, such as can you get power and cabling to where you are thinking about mounting the HPR122i and how would you fly the speaker? Those may be easy to address or might make it less practical.

I have not looked at it in any detail but with a nominal 75 degree conical pattern, I'm not sure that you would need/want two QSC HPR 122i boxes flown together for that room. Using 122i one to cover the front of the room and the second flown as a delay fill to cover the back part of the room might work better but would require the appropriate processing.

I would not use the JF60s as part of the house system unless they also could have dedicated processing and amplification and even then they would most likely be used for front or side fills rather than long the sides of the room.
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Old Monday, March 30th, 2009, 02:46 PM
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Les might know, but I lost track of how many JF60s we blew up at the hall as frontfills. Use them in a delay or down/front fill application, sure, but not main PA.

Here's what I'd do: First, figure out what it takes to cover the room properly. Then see how much of what you have could be used in that. Also worth considering, is a center array the best fit for the room and application?
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Old Tuesday, March 31st, 2009, 07:05 PM
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Thank you for the responses. They are very timely being that we have scheduled a rigging crew to install the speakers this weekend. The flying hardware was purchased from the manufacturers (QSC & EAW).

The plan is to vertically fly the QSC 122i speakers in the center of the vaulted ceiling, just beyond the stage. Is comb filtering effect an issue? Can someone offer recommendations on angle of verticle and horizontal tilt?

Also in the plan was to only use two of the EAW JF60 speakers, also flown center about 32 ft further down. We have a 275W per channel power amp for the EAWs. We checked the SPL at front row and rear and found a 10 dB delta. This is the reasoning for the second center cluster. If a delay is required, how many milliseconds? Also, we do not have a delay unit or speaker management module. I think we would only need to delay the second center pair. Can someone recommend an inexpensive unit?

I really appreciate everyone's recommendations. If our plan has some serious flaws, please kindly point them out. We want to do the best we can with what little we have.
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Old Friday, April 3rd, 2009, 11:06 AM
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It looks like we will delay our installation until after Easter.

I would like to add that our current set up has only the 4 EAW JF60s speakers. Two in the center, just after the stage, and the other 2 on left and right sides, also just after the stage. We measured the 10 dB delta with this configuration. The new QSC 122i speakers are intended to replace the center EAWs and we plan to move the 2 EAWs 32 ft further down, but remain in the center location. The left side and right side EAWs would be removed. The QSC subwoofer is expected to provide the low freq. that we are currently missing.

The existing EAW only solution is quite lackluster in performance, mainly due to the absence of low frequency. Can we expect an improvement with the new configuration?
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Old Friday, April 3rd, 2009, 11:25 AM
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Radio Design labs RU‑ADL2 is a suitable delay unit for your purposes.
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Old Friday, April 3rd, 2009, 01:35 PM
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FWIW, I did a quick EASE model with the two HPR122i arrayed together with a 60 degree splay between them (located 16' into the room, which should be at a beam and near the front of the stage, and as high as I could get them) and it shows significant lobing. A single HPR122i at the same location doesn't provide the desired coverage, it drops off at the front corners and rear at some frequencies, but actually looks much better.
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Old Friday, April 3rd, 2009, 09:09 PM
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I've only got a minute but here is my thoughts on the JF60's.

They are a great sounding speaker and excellent for fills, but not so much for mains...

We used them in one room as a center/front fill application and we kept having problems with them blowing, well, really it was only 3... I think. We had 3 problems with that setup, that we later corrected.

First, our high pass was set too low. I don't know what EAW recommends, but we bumped it up to a 24db/octave at 180Hz.

Second, our limiter wasn't set hard enough so guest engineers would push the front fills up because they couldn't hear them... from mix position (which, they weren't supposed to be heard from mix position)

Which brings to the 3rd problem, they were originally fed on an Aux so guest engineers could monkey with it. We decided to move it off of the aux and just use the system processor to set the level once and for all.
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Old Friday, April 3rd, 2009, 11:17 PM
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Quote:
Originally Posted by mrprogers View Post
I would like to add that our current set up has only the 4 EAW JF60s speakers. Two in the center, just after the stage, and the other 2 on left and right sides, also just after the stage.
Wow, so the entire PA is four JF60s. I don't understand how somebody could think that's a good idea. I think they're a great box, but not for a main array -- frontfill like we had at The Hall they're great for.

Les brings up a good point, the system processor. You want a good processor in there that will be able to keep you from blowing up JF60s and will also keep everything sounding good, and stupid-proof.
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Old Saturday, April 4th, 2009, 09:40 AM
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Thanks for the good information.
Would flying the QSC 122i speakers horizontally reduce lobing? Can a processor reduce lobing?
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Old Saturday, April 4th, 2009, 10:06 AM
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Quote:
Originally Posted by mrprogers View Post
Thanks for the good information.
Would flying the QSC 122i speakers horizontally reduce lobing? Can a processor reduce lobing?
Not really in this case. For one thing, the HPR122i horns are conical and are the same pattern in either direction. A processor could help but primarily by lowering the level or applying filters to reduce the contribution of one of the speakers for the frequencies where lobing occurs, thus limiting any benefit of having two speakers.

I really think that one HPR122i up front, the other HPR122i delayed partway back in the room and the JF60s for side fill up front might be the best solution with the speakers you have but would require at least a three, probably four, output processor.
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Old Saturday, April 4th, 2009, 10:47 AM
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Quote:
Originally Posted by Brad Weber View Post
I really think that one HPR122i up front, the other HPR122i delayed partway back in the room and the JF60s for side fill up front might be the best solution with the speakers you have but would require at least a three, probably four, output processor.
I agree, that sounds about right.
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