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Understanding Basics of LIne Array vs Point source

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Masis Ingilizian:
I am an amatuer when it comes to PA, and have read a little on the difference between line array vs point source. I am also new to this forum but have been around other forums for a while. My goal is to match the acoustic treatment for the large venue I am working on with the intended speakers. Put it this way, I don't trust the audio engineer(they just sell PA systems, not experts) and am making sure we or shall I say he chooses the right dispersion pattern.

The room is 17 metres from front to back and 23 metres left to right with the lowest part of the ceiling height 5m closer to the stage with it inclining to 9.6m to the back of the hall like a vaulted ceiling. It is intended for live music as well as DJ, it a wedding hall.

I am considering toeing in the speakers to criss cross the room, to get later reflections from the opposite side walls which might or might not have diffusion on the wall. The back is glass in the middle and on the sides concrete but I will fill up on that part of the back wall with heaps of absorbtion.

My understanding is a 80 to 90 degreee horizontal coverage will aim the speaker to the opposite side covering the dance floor and reducing or essentially getting rid of the closest side wall reflection. A line array has 100 degree horizontal pattern plus from what i understand it throws the music as far as it can, and with a glass wall on the back it wont be ideal. The room is about 3000m3 and defenitely has a higher RT60 of 5ms but im not experienced enough to take a decent guess, the place was an echo chamber. I will be bringing that down to at least 2ms, well I am going to try.

https://photos.app.goo.gl/aFRBTeQxeBpMNrRi7

Let me know if the attached link for the photos work. When clicking on the insert image, all i got was a quoted "img" and was not sure how to attached them into the post.

Steve-White:
Butter heating up and Popcorn popping.

Welcome to the forums sir - fasten your seatbelt and stow all items.

Masis Ingilizian:

--- Quote from: Steve-White on November 28, 2021, 08:10:47 AM ---Butter heating up and Popcorn popping.

Welcome to the forums sir - fasten your seatbelt and stow all items.

--- End quote ---

Thanks mate, I was attracted here by the quality articles on the website. I am actually into small room acoustics althouh I have read enough internet available papers on larger venue acoustics still getting my head around the differences. I also have a triamped DSP system for home but as I am the acoustic "expert" in town I get odd jobs regardng acoustics and on this occasion promised the owner I check up on the audio engineers choice for the hall. The audio engineer recommended the JBL VRX series which line array or a concave curvature array and my knowledge tells me that a point source will be a better option for this particular hall. So hopefully some of the experts can chime in and tell me what I am looking for.

Matthias McCready:

--- Quote from: Masis Ingilizian on November 28, 2021, 11:29:22 AM ---Thanks mate, I was attracted here by the quality articles on the website. I am actually into small room acoustics althouh I have read enough internet available papers on larger venue acoustics still getting my head around the differences. I also have a triamped DSP system for home but as I am the acoustic "expert" in town I get odd jobs regardng acoustics and on this occasion promised the owner I check up on the audio engineers choice for the hall. The audio engineer recommended the JBL VRX series which line array or a concave curvature array and my knowledge tells me that a point source will be a better option for this particular hall. So hopefully some of the experts can chime in and tell me what I am looking for.

--- End quote ---

That is a small space for a line array, which would certainly cost more without necessarily offering better performance.

Regarding the engineers suggestion of VRX boxes. That is a constant curvature box (ie no adjusting angles between boxes). The tonality of them is not great, and their coverage pattern is quite inconsistent (Horizontally in the boxes coverage the horn/mid driver is not even). They are not "delightful" to work on, the best I can give them, is that they "get the job done."

An appropriate point-source product (pick your brand) would probably work well for this venue; if they are deadset on the look of an "array" the room is more sized for a constant curvature box (again much more money than point source).

The only constant curvature product I have worked on that I have enjoyed (good tonality, even coverage, nice handoff between boxes) is the install version of L'Acoustics A series (I did not like the tour version of that product, as the handoff from box to box had problems).

Jeremy Young:
I am by no means an expert, but I spent a lot of time asking questions until I finally picked up and read Bob McCarthyís book Sound Systems: Design and Optimization.  Iíve read several other resources, but none as complete and detailed as that one.  Literally every question I used to ask was answered in detail.  I canít recommend it enough.   Go grab a copy, read it start to finish, and you will find the exact answers to your question with formulas and charts to do the calculations, along with real world venue examples.

This forum is great, but to truly understand (to the level needed to provide counter arguments to an engineer on a permanent install) everything from the basics to optimization, thereís a lot of reading needed to get there. 

Line arrays (should) be designed through the manufacturers prediction software so that you can implement the necessary splay angles and processing.  Line arrays and point source both come in a range of available horizontal dispersion angles, and placement / trim height needs to be calculated for both based on numerous details not included in your original post. 

Since weíre in a virtual environment, my tone is meant in a helping way, not trying to cut you down for asking good questions or not including the right data.  I just canít help but preach how many ďah-haĒ moments I had reading that book and am convinced it will help you. 

Good luck on your project !

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