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Find good line array system

khachai44

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#1
Making line array theory work in the real world inevitably introduces compromises that deviate to a degree from the desired ideal behaviour.

I believe the argument for divergence shading has significant merit. I'm not entirely convinced it's as big an issue as is implied in white papers written by advocates such as Dave Gunness, due to other compromises inherent in most implementation of loudspeaker arrays. There is considerable debate over the issue, but I'm not qualified or sufficiently conversant with the technicalities to summarize it here!

Aside from the issues around imperfect summation from differing sound pressure levels, one real world practical benefit of divergence shading over amplitude shading, is that fewer separate processing and amplifier channels are required - the same amplitude is sent to the downfill elements as is sent to the boxes above, in order to ensure the neighbouring sound pressure levels are equal. Hence in an array of cabs where one pass band has a resistance of 16R, one http://amthanhthudo.com/loa-line-array processor and amp channel could feed up to 8 boxes - a helpful practical benefit similar to many other points of view that favour line arrays in general.

Another benefit is scalability - where by adding additional identical inventory, providers can scale up according to changing coverage requirements.

The predictable sightline impact allows them to easily be factored in to set designs.

Many significant attractive line array qualities have nothing to do with the much-hyped inverse square law-beating properties of an idealized line source.

I agree that line arrays are a useful tool to have, but I don't believe they've become so popular due to their sound quality. Their primary benefits are related to the many and varied logistical costs associated with large scale sound reinforcement.
 

DonH56

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#2
I keep thinking it'd be neat to take one of the Dayton kits or a DIY scheme, mate it to a bunch of little amplifiers (one per driver), and put a DSP behind it that would allow you to play with the transfer function to each speaker. I used to piddle with phased-array radars (and other ESA's) so this should be easy right? Riiigghhhhtttttt... Maybe when I retire after winning my second Lotto (still waiting on the first).
 

amirm

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#3
I keep thinking it'd be neat to take one of the Dayton kits or a DIY scheme, mate it to a bunch of little amplifiers (one per driver), and put a DSP behind it that would allow you to play with the transfer function to each speaker. I used to piddle with phased-array radars (and other ESA's) so this should be easy right? Riiigghhhhtttttt... Maybe when I retire after winning my second Lotto (still waiting on the first).
I saw one of these built and shown although I don't recall where (may have been an AES meeting). The designer had used university students to build the whole thing and said in no way, no how would he get into manufacturing it!
 

amirm

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#4
First, welcome aboard. :) And good topic!
Many significant attractive line array qualities have nothing to do with the much-hyped inverse square law-beating properties of an idealized line source.
In home theater applications this is an important benefit for surround speakers. Without it, someone sitting on the right would get far higher volume from right surround than left surround (or sides). They are also nice for outdoor use for the same reason (i.e. not being too loud for people close to it). Here is an example install my company did at the Seattle Wheel: http://audiosciencereview.com/forum...ransducer-speakers-in-commercial-project.310/





The other benefit is wider sweet spot due to similar reasons.

That said, you are right that for pure fidelity reasons, this factor is immaterial. Many "arrays" are not line arrays either. They just put a number of drivers together which then causes lobing requiring one to sit pretty far back relative to their height for them to integrate.

How about explaining more about this topic? I sense that you know fair bit about it. :)
 

iridium

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#6
Line arrays must be Just Right:
A logarithmic spaced, articulated spiral array in a horizontally asymmetric configuration employing frequency tapering and divergence shading, which includes isophasic high-frequency and mid-frequency apertures, hyper-cardioid low-frequency transducer sections, is controlled by finite-impulse response filtering digital signal processing, and works well with a psychoacoustic infector.
Very simple.

iridium.
 

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