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Author Topic: [UPDATED] Need advice on given design for new facility  (Read 28253 times)

Lee Buckalew

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Re: Need advice on given design for new facility
« Reply #20 on: April 03, 2013, 07:10:36 am »

"The risers being covered, was a simple aiming correction on the drawing.  It was changed by accident when i was copying the models over.  It has been corrected.  Please see the attached file.  Please note, the front of the seating area on the floor doesn't look as well covered, but this mapping doesn't reflect the stage fills adding sound to the front chairs."

What do you guys think now?

As with Brad's comments, your design team knows more about the whole project than we do.
That said:
The color legend for SPL is different for the two frequencies shown.  It needs to be kept constant in order for you to derive more easily understood differences in SPL at various frequencies. 
Even with the coverage angle being changed it is my opinion that you will not have even coverage all the way to the back row.  It is my opinion that, were you to plot half octave centers from 100Hz to 16kHz you would be able to see a progressively increasing directionality as frequency increases.  This will cause a drop in coverage at the frequency ranges required for good intelligibility of English language.  This will be a problem not only in the areas indicated in the on axis plot of the speaker arrays but, as was mentioned in another post, it will be problematic for an even larger area off axis.  In my opinion you don't have enough coverage from the line array design and you either need additional cabinets in the arrays, you need delay fill speakers for the upper tier or you need to rethink the design to point source.

Lee
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Justin Philip

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Re: Need advice on given design for new facility
« Reply #21 on: April 03, 2013, 01:44:04 pm »

As with Brad's comments, your design team knows more about the whole project than we do.
That said:
The color legend for SPL is different for the two frequencies shown.  It needs to be kept constant in order for you to derive more easily understood differences in SPL at various frequencies. 
Even with the coverage angle being changed it is my opinion that you will not have even coverage all the way to the back row.  It is my opinion that, were you to plot half octave centers from 100Hz to 16kHz you would be able to see a progressively increasing directionality as frequency increases.  This will cause a drop in coverage at the frequency ranges required for good intelligibility of English language.  This will be a problem not only in the areas indicated in the on axis plot of the speaker arrays but, as was mentioned in another post, it will be problematic for an even larger area off axis.  In my opinion you don't have enough coverage from the line array design and you either need additional cabinets in the arrays, you need delay fill speakers for the upper tier or you need to rethink the design to point source.

Lee
Here's the rest of the frequencies. I have talked with another designer who has access to our building CAD files (AV director at one of the biggest churches in the US)..and he didn't seem to think we would have trouble reaching the back rows.

His issue though was adding real subs to the system since the 4883 are merely a LF extender to the top cabs.
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ThomasKielhofner

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Need advice on given design for new facility
« Reply #22 on: April 03, 2013, 02:09:38 pm »

Here's the rest of the frequencies. I have talked with another designer who has access to our building CAD files (AV director at one of the biggest churches in the US)..and he didn't seem to think we would have trouble reaching the back rows.

His issue though was adding real subs to the system since the 4883 are merely a LF extender to the top cabs.

It's already been said, but these additional pictures confirm it. You either need a couple more 4886 boxes a side, or a different design. 8 boxes a side can't evenly cover that space.

Another possible issue is how they plan on using the 5 macro techs to power the main system. From what I can tell they would pretty much be stuck using three of them in stereo for the 6 subs (they're 4 ohms per box with the drivers wired in parallel), and the remaining two on the 4886s (4 per channel). That doesn't give you much flexibility to shade/tune the rig with only 2 zones per hang.
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Justin Philip

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Re: Need advice on given design for new facility
« Reply #23 on: April 03, 2013, 07:20:20 pm »

I got to run something else by everyone.

Right now it's:
16 x 4886 (FR: 75 Hz - 18kHz)
8  x  4883 (40 Hz - 300 Hz)

I know that alone WON'T get me the "punch" I am looking for in the kick/bass heavy music. I got a recommendation to add 4 x S28 from the VTX line (FR 27-300 Hz). That seems like overkill to me (at least cost wise).

Would it work just to have:
16 x 4886
4  x S28

http://www.jblpro.com/BackOffice/ProductAttachments/JBL_VT4886_v3.pdf

http://www.jblpro.com/products/tour/vtx/specs.html
« Last Edit: April 04, 2013, 09:53:36 am by Justin Philip »
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Lee Buckalew

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Re: Need advice on given design for new facility
« Reply #24 on: April 04, 2013, 06:57:54 am »

I got to run something else by everyone.

Right now it's:
16 x 4886 (FR: 75 Hz - 18kHz)
8  x  4883 (40 Hz - 300 Hz)

I know that alone get me the "punch" I am looking for in the kick/bass heavy music. I got a recommendation to add 4 x S28 from the VTX line (FR 27-300 Hz). That seems like overkill to me (at least cost wise).

Would it work just to have:
16 x 4886
4  x S28

http://www.jblpro.com/BackOffice/ProductAttachments/JBL_VT4886_v3.pdf

http://www.jblpro.com/products/tour/vtx/specs.html

I may have missed it but:
What musical style?
What instrumentation?
What anticipated SPL need?

The 4886 is a cute little box but it is little.   It may get loud enough for your needs but may not actually move enough air to provide the sound quality and punch that is expected.  The problem with this is that the typical response to this problem is to just urn it up when the real problem is moving enough air to have impact.  In a 1000 plus seat space, if looking for rock show/Christian contemporary music style needs, it is my experience that 10" bass drivers are the minimum that can typically be successful for your main cabinets.  Sometimes it's possible to push this to 8", especially if you go 5 way rather than 4 way as long as you keep your bass modules as LF extension of the arrays placed at te arrays.

My experience, YMMV.

Lee

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Brad Weber

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Re: Need advice on given design for new facility
« Reply #25 on: April 04, 2013, 07:32:50 am »

Here's the rest of the frequencies. I have talked with another designer who has access to our building CAD files (AV director at one of the biggest churches in the US)..and he didn't seem to think we would have trouble reaching the back rows.
Those plots may be a good starting place but they only show the vertical coverage on axis of the arrays in an infinite space.  What happens to the coverage when you factor in both the horizontal and vertical patterns as well as the physical space?  The variations in overall level and/or response throughout the entire seating in the space may be greater than is shown in the plots provided.  In fact simply toeing the arrays in to perhaps better cover the seating in plan view would change the resulting on-axis vertical section.

I got to run something else by everyone.

Right now it's:
16 x 4886 (FR: 75 Hz - 18kHz)
8  x  4883 (40 Hz - 300 Hz)

I know that alone get me the "punch" I am looking for in the kick/bass heavy music. I got a recommendation to add 4 x S28 from the VTX line (FR 27-300 Hz). That seems like overkill to me (at least cost wise).

Would it work just to have:
16 x 4886
4  x S28

http://www.jblpro.com/BackOffice/ProductAttachments/JBL_VT4886_v3.pdf

http://www.jblpro.com/products/tour/vtx/specs.html
Any chance the original three VT4883 per side were intended to be used in a cardioid configuration?  Have you looked at the rigging hardware required to fly the VT4886 with the VTX-S28?  You've gone from the original three dual 8 Ohm boxes per side to four dual 8 Ohm boxes per side, have you looked at the associated amplification and sensitivities to see just how much more output you'd actually expect to get with this approach?  Just trying to understand what you are actually proposing and what you are trying to achieve.

I believe that a struggle here is commenting on the system without having any defined specific goals or results combined with a hesitancy to contradict the work of an unidentified system designer that is apparently already involved in the project.
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David Sturzenbecher

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Re: Need advice on given design for new facility
« Reply #26 on: April 04, 2013, 08:22:03 am »

Those plots may be a good starting place but they only show the vertical coverage on axis of the arrays in an infinite space.  What happens to the coverage when you factor in both the horizontal and vertical patterns as well as the physical space? 

Similarly, I would ask the AV installer for 3-D plots, ie. EASE maps.  If they can't produce these for you, I would start to doubt their chops in the install business.
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Justin Philip

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Re: Need advice on given design for new facility
« Reply #27 on: April 04, 2013, 01:44:10 pm »

That section and the coverage shown in the array software seem to only address on axis of the two arrays but what happens off axis?  Did the system designer do any prediction beyond the on-axis vertical coverage shown?  And did they look at any frequencies other than 500Hz and 1kHz?  It would be interesting to see how well each array covers the entire seating if the system is stereo and how much combiltering and power alley you might get for mono sources as well as things like the resulting intelligibility.

Will the EASE model show all this? They did do the higher frequencies that I posted in one of the follow up posts above.

I don't know what the ceiling material is but does the system designer expect any issues from the distance the LF boxes are from the ceiling?

I will check on this.

Has anyone verified that the AC15 front fills can physically fit in the locations shown?  Unless the speakers actually sit exposed on top of the steps you are probably going to need some type of enclosure that is larger than the speaker while also having to work within the step height.  And which plan is correct, the seven stage fill locations shown on the speaker plan seem to not work with the Platform front shown on the overall floor plan (the center location is bumped out while the two extreme side speakers would appear to be aimed at the walls).

The front steps are straight. That bump has been taken out.

Speaking of steps, any access to the platform seems to involve four steps.  ADA access is not a requirement but not having one or more ramp access paths to the Platform could prevent limiting the potential use of the space and make getting things on and off the Platform easier.

I mentioned this to the building coordinator and they had to cut the ramp to avoid the higher cost.

Are you planning on all the amplifiers and processing being located at FOH?  It would seem to make sense to have an amp room closer to the speakers.

I will check on this. My understanding is the electrical room is where the amplifiers will be located

Is anybody addressing acoustics and not just room finishes but also aspects such as room shaping and dimensions, sound isolation and mechanical system noise?

The architect and the designer have been in communication to address those issues.

A purely architectural issue but in terms of keeping the cross aisle clear and sightlines it seems like it would make more sense to move the floor level seats just behind the cross aisle to the front of the cross aisle and have the first seats behind the aisle elevated so they can see over people using the cross aisle.

I don't think the seating/sections have been finalized, so I will pass this information along
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Justin Philip

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Re: Need advice on given design for new facility
« Reply #28 on: April 04, 2013, 01:54:05 pm »

Another possible issue is how they plan on using the 5 macro techs to power the main system. From what I can tell they would pretty much be stuck using three of them in stereo for the 6 subs (they're 4 ohms per box with the drivers wired in parallel), and the remaining two on the 4886s (4 per channel). That doesn't give you much flexibility to shade/tune the rig with only 2 zones per hang.
2 Amps For 6 Lf Extenders (L/R)
1 Amp For Top 3 Array Boxes L/R
1 Amp For Center 3 Boxes L/R
1 Amp For Bottom 2 Boxes L/R

I may have missed it but:
What musical style?
What instrumentation?
What anticipated SPL need?
The 4886 is a cute little box but it is little.   It may get loud enough for your needs but may not actually move enough air to provide the sound quality and punch that is expected.  The problem with this is that the typical response to this problem is to just urn it up when the real problem is moving enough air to have impact.
It's christian rock music like you mentioned. I don't know the exact SPL needs though. Not concert loud..but enough to get you moving. :-)
Kick, bass guitar, couple of electric, acoustic, keyboards etc.

Any chance the original three VT4883 per side were intended to be used in a cardioid configuration?
"In the initial design there were (5) macrotechs total powering the 4886ís and 4883ís.  The low frequency extenders (4883ís) were connected in a cardioid design."

Similarly, I would ask the AV installer for 3-D plots, ie. EASE maps.  If they can't produce these for you, I would start to doubt their chops in the install business.
He will give me the EASE models by next week. Not sure if it's the right way to do it but here's their reasoning:
"Due to the timelines expressed to us, we have been trying to work to finalize all of the necessary details for everything the church needs installed in the project (fine tuning the details of equipment/functionality) therefore, since we knew the hanging points from the Sound Mapping and JBL Calculations, finishing the design/EASE model was pushed back to try not to hold up the project and occupancy date."
« Last Edit: April 04, 2013, 01:56:01 pm by Justin Philip »
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Adam Robinson

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Re: Need advice on given design for new facility
« Reply #29 on: April 04, 2013, 03:36:20 pm »

Here's the rest of the frequencies. I have talked with another designer who has access to our building CAD files (AV director at one of the biggest churches in the US)..and he didn't seem to think we would have trouble reaching the back rows.

His issue though was adding real subs to the system since the 4883 are merely a LF extender to the top cabs.

What's with the massive gap between the 3rd and 4th box?  I entered your approximate dimensions (gathered from looking at the LAC drawings) and was able to get a much smoother response in my calculations.  I will still agree that you're definitely looking at an array that's too small.  I got it looking pretty decent with 3 4883 over 12 4886 (and had the ability to hit closer seats with the array).  I also got it looking not to terrible with just 6 VTX. 

And I'd personally add a few ground subs.
« Last Edit: April 04, 2013, 03:39:03 pm by Adam Robinson »
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