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Sep 29, 2019

Re: Steerable Array

Hi @Oldghm,
Thanks for your comments.
I did try to explain what I meant about beam shaping in the following paragraph:

"Apart from a steerable beam, the advantage of the MSA12X is that the beam can be shaped. What this means is the persons sitting close to the speaker would experience lower sound pressure than would normally be the case. Similarly, persons sitting towards the rear of the auditorium would experience higher sound pressure than would normally be the case."

To achieve the outcomes described in the above paragraph requires more than simply inclining the speaker column. 

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Sep 29, 2019

Re: Steerable Array

Hi @Rob Wright, The reason I an L1 Model 1SA is to reduce the reverberance you seem to be hinting at.
Later today I will be uploading a model of the interior of a church created using Sketchup. I will also post a link to the corresponding mdr file for Bose Modeler.
My intention is to use this basic model to create another two models, one with a tilted L1 Model 1S (as suggested by @Oldghm) and the other with an L1 Model 1SA.
Following that, I will run a simulation for each and post the results here.
How long will all this take? If I do it, probably a few months as I'm on a steep learning curve. If someone at Bose is willing to pitch in (which I hope they will), it would probably take them less than a day. 
 

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May 25, 2004

Re: Steerable Array

@Uncle John posted:

Hi @Oldghm,
Thanks for your comments.
I did try to explain what I meant about beam shaping in the following paragraph:

"Apart from a steerable beam, the advantage of the MSA12X is that the beam can be shaped. What this means is the persons sitting close to the speaker would experience lower sound pressure than would normally be the case. Similarly, persons sitting towards the rear of the auditorium would experience higher sound pressure than would normally be the case."

To achieve the outcomes described in the above paragraph requires more than simply inclining the speaker column. 

Hi Uncle John,

Could you link to the documentation for the quote I highlighted in red? 

All of the portable line arrays lose dB at a lessor rate than typical point source speakers. I think the Model II loses volume by 3db per doubling of distance vs a typical two way speaker losing at a rate of 6db per doubling of distance.

O..

 

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Re: Steerable Array

Hi @Oldghm, I was quoting myself from earlier in this discussion ( https://www.bosepro.community/...96#56492378163831796 
I used to work as a technical author. The understanding expressed here is based mostly on what I took away from the Bose online education center course material at:
https://pro.bose.com/en_us/res...learning-center.html

Course: Bose Array Tool.
5. Vertical Beam Shape Types  

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Nov 7, 2018

Re: Steerable Array

Hi All

WOW!!

What an interesting thread. I wonder where the S1 Pro stands in all these technical analogies?

Or does it?

Harpo

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May 25, 2004

Re: Steerable Array

Hi Harpo,

The S1 is the shortest of the Bose speakers with "line arrays". Length of throw and how well the array carries volume are both relative to the length, (among other factors) or height of the array. A Model II will carry more volume a longer distance than a Model 1s, a 1s will carry more volume a longer distance than a Compact, and the Compact will carry more volume a longer distance than a S1.

O..

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Re: Steerable Array

@Uncle John posted:

Hi @Oldghm,
Thanks for your comments.
I did try to explain what I meant about beam shaping in the following paragraph:

"Apart from a steerable beam, the advantage of the MSA12X is that the beam can be shaped. What this means is the persons sitting close to the speaker would experience lower sound pressure than would normally be the case. Similarly, persons sitting towards the rear of the auditorium would experience higher sound pressure than would normally be the case."

To achieve the outcomes described in the above paragraph requires more than simply inclining the speaker column. 

Hi Uncle John,

Please understand my comments come from a very basic layman's understanding of the principles of line array technology. I am not an engineer  or highly skilled technical person.

After spending a fair amount of time looking, I failed to find documentation to support the hypothesis you have presented.

While I believe it is true that "beams", when there are at least two, from one or more stacked modules can have separate gain, the property that you speak of about sound pressure levels is not unique to, or directly related to the steerable beam feature of the MSA12X. If I am wrong I am open to being corrected.

When compared to traditional style speakers, the Bose L1 and MA series all offer a more even sound field, front to back. This even sound is a product of the line array, a stack of speakers arranged very close together, not a product of the steerable feature.

The steerable feature allows the narrow vertical coverage of the array to be directed to an audience that is seated in an arrangement that exceeds the normal vertical coverage of the MA 12 series.

It is my understanding that line arrays present problems that are overcome by DSP. When placing speakers close together there is both constructive and destructive interference between the output of individual transducers. Using DSP to modify this interference is what makes the line array usable. I'm just guessing here, but I suspect the steerable feature is born from the continued research of how to make line arrays work better in the most difficult of venues.

I believe that if, or when, this steerable feature of a line array becomes consumer usable in a portable system, Bose will be the first to include that feature in their products.

O..

 

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Re: Steerable Array

I've been thinking about any possible negatives of a DSP speaker such as the MSA 12X as compared to say the L1 Model 1S.
Here are two which I'd like to explore:
1. DSP introduces a delay of 5.7 ms. As I understand it this would mean that sound from the DSP speaker would seem to be coming from about 7 ft (2m) further back when compared to a non-DSP speaker. Are there any significant negative aspects related to this if a DSP speaker is placed where an L1 speaker is intended to be placed, ie. behind the performer?
2. The L1 Compact has a line-level input impedance of 800 kohm (1/4 inch). The MSA 12X has an input impedance of 20 kohm. Can the L1 Compact line-level output be used successfully as a source for the MSA 12X? I'm proposing to operate such a setup with the array section of the L1 Compact disconnected.    

 

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May 25, 2004

Re: Steerable Array

Hi Uncle John,

 

Latency is a product of digital signal processing. I don't think that there is a fixed number for latency in a digital speaker system. Some might be more, some less. Generally speaking latency of 10 milliseconds or less is not detrimental to a vocal performance.

 

Problems occur when there are multiple sound sources different distances from a listeners ears. Then distance and delay must be managed.

 

The MA 12 series of speakers like many other of Bose products require active eq controllers to provide best results.

I am not familiar enough with the X series to offer an opinion on using the Compact line out to feed one. I'll read some and return If I learn something worth sharing.

 

O..

 

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May 25, 2004

Re: Steerable Array

Hi Uncle John,

Well, the MSA 12X has an analog, line level input so I see no technical reason that the Compact cannot be used as an interface.

 

I have to ask, why?

 

O..