Stair Cardioid Subwoofer Array
- Thread starter Sebastian Rivas Godoy
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Stair Cardioid Subwoofer Array
Hi i just posted this article.
http://soundforums.net/hub/2386-stair-cardioid-subwoofer-array.html
Abstract
The advantages of cardioid sub configurations are well known, however they also have some drawbacks. Because of the nature of the arrays in their 2 in line and inverse stacked variations, cardioid systems reduce the acoustical pressure not only on the stage- but also at FOH, the most important area! This is in front of the array, where the audience is located. Level can be decreased by greater than 3-6 dB when compared to a simple mono cluster. This makes the technique unviable in situations where maximum SPL is needed. Measurements are presented to show and explain the problems here. Next we introduce a new way to create a cardioid array. In this new method, we achieve the same output levels as a mono cluster through most of the subwoofer’s bandwidth, while keeping the benefits of a cardioid configuration.
Enjoy...
Hi i just posted this article.
http://soundforums.net/hub/2386-stair-cardioid-subwoofer-array.html
Abstract
The advantages of cardioid sub configurations are well known, however they also have some drawbacks. Because of the nature of the arrays in their 2 in line and inverse stacked variations, cardioid systems reduce the acoustical pressure not only on the stage- but also at FOH, the most important area! This is in front of the array, where the audience is located. Level can be decreased by greater than 3-6 dB when compared to a simple mono cluster. This makes the technique unviable in situations where maximum SPL is needed. Measurements are presented to show and explain the problems here. Next we introduce a new way to create a cardioid array. In this new method, we achieve the same output levels as a mono cluster through most of the subwoofer’s bandwidth, while keeping the benefits of a cardioid configuration.
Enjoy...
re: Stair Cardioid Subwoofer Array
Just skimmed your article, Sebastian. Thanks for post the abstract here.
Just skimmed your article, Sebastian. Thanks for post the abstract here.
re: Stair Cardioid Subwoofer Array
Quite an interesting article and an equally interesting "solution". Hopefully you or someone else will be able to test your zig-zag setup at a later date.
That stair array looks quite imposing as well!
Quite an interesting article and an equally interesting "solution". Hopefully you or someone else will be able to test your zig-zag setup at a later date.
That stair array looks quite imposing as well!
re: Stair Cardioid Subwoofer Array
Cool article, I've never been able to sell the cardioid array to the other guys at work, even though we typically stack our subs 2 or 3 high, every time we've tried it in the back the negatives never outweighed the positive.
First person to build a stair end-fire that is four+ subs high gets a gold star.
Cool article, I've never been able to sell the cardioid array to the other guys at work, even though we typically stack our subs 2 or 3 high, every time we've tried it in the back the negatives never outweighed the positive.
First person to build a stair end-fire that is four+ subs high gets a gold star.
re: Stair Cardioid Subwoofer Array
Hey Sebastian, great article, really in depth! Explains a lot about traditional cardioid and end-fire setups that almost nobody knows. Awesome of you to put it here, first.
Just for your amusement, this is current SFN server CPU load (7:55 p.m. EST) now that this got posted on PA Of The Day on Facebook! Nice to have friends in high places. Thanks to the volunteer backend team - Phillip Graham and Jeff Knorr - for making it possible for us to take this kind of demand.
Hey Sebastian, great article, really in depth! Explains a lot about traditional cardioid and end-fire setups that almost nobody knows. Awesome of you to put it here, first.
Just for your amusement, this is current SFN server CPU load (7:55 p.m. EST) now that this got posted on PA Of The Day on Facebook! Nice to have friends in high places. Thanks to the volunteer backend team - Phillip Graham and Jeff Knorr - for making it possible for us to take this kind of demand.
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re: Stair Cardioid Subwoofer Array
Well now, here's a little something I tried in a particularly difficult outdoor city centre festival location a couple of years back…
Sadly I can't find the accompanying measurements I took at the time but it definitely worked very well, they even had a yoga and meditation seminar in the building closest behind the stage during the show!
Quite an interesting article and an equally interesting "solution". Hopefully you or someone else will be able to test your zig-zag setup at a later date.
That stair array looks quite imposing as well!
Well now, here's a little something I tried in a particularly difficult outdoor city centre festival location a couple of years back…
Sadly I can't find the accompanying measurements I took at the time but it definitely worked very well, they even had a yoga and meditation seminar in the building closest behind the stage during the show!
Re: Article: Stair Cardioid Subwoofer Array
I hope it's ok to post a few links to some sub array's i did during a few seminars i did last year @Sebastian Rivas.
These are end fired configurations where i measured the level and frequency response in the back of the array per part of the array in order to get max cancels at the back when tuning the array.
http://timobeckmangeluid.files.wordpress.com/2013/08/img_1665.jpg
An article at my blog on a gradient set-up where i use 2 subs at the front and 1 at the back:
Gradient or reversed end fired sub array first with delay then with All-pass filters Updated 04-09-2013 . | Timo's World all around the globe
and a end fired where i first used delay and after that the same thing but with allpass filters:
End fired sub array first with delay then with 2nd order all-pass filters | Timo's World all around the globe
So in order to get the level to match at the back of the cardioide array i put in more subs at the front row. After that match frequency response of sections of the array and then start to align via delay or allpass filters to get the max cancel at the back and max level in front of the array. It's about the same as described in the article. (the end fired of 6 is an idea coming from the guy's @ ampco pro rent from the netherlands as far as i know
I hope it's ok to post a few links to some sub array's i did during a few seminars i did last year @Sebastian Rivas.
These are end fired configurations where i measured the level and frequency response in the back of the array per part of the array in order to get max cancels at the back when tuning the array.
http://timobeckmangeluid.files.wordpress.com/2013/08/img_1665.jpg
An article at my blog on a gradient set-up where i use 2 subs at the front and 1 at the back:
Gradient or reversed end fired sub array first with delay then with All-pass filters Updated 04-09-2013 . | Timo's World all around the globe
and a end fired where i first used delay and after that the same thing but with allpass filters:
End fired sub array first with delay then with 2nd order all-pass filters | Timo's World all around the globe
So in order to get the level to match at the back of the cardioide array i put in more subs at the front row. After that match frequency response of sections of the array and then start to align via delay or allpass filters to get the max cancel at the back and max level in front of the array. It's about the same as described in the article. (the end fired of 6 is an idea coming from the guy's @ ampco pro rent from the netherlands as far as i know
Re: Article: Stair Cardioid Subwoofer Array
Sabastian great work. I noticed in effect in my measurements deviations from expectations. During the time I thought and experienced, even without precise measurements, a number of alternative carodioid configurations to limit the damage of ordinary configurations. For example, in the in-line configurations often I could not have the expected spl in front as you explained (except in those cases, if I remember correctly, of sub with not very long depth and low crossover frequencies, so with a large distance between the subs).... knew the damage that caused the obstruction of the front sub together with other factors (I read a your previous document about in the past) that now you have well analyzed. these ideas, were right to limit the problem of obstruction, were at the time posted on my FB profile where you can find them (sorry for my bad English)
of course we must consider the alternatives that can actually be achieved logistically.
Sabastian great work. I noticed in effect in my measurements deviations from expectations. During the time I thought and experienced, even without precise measurements, a number of alternative carodioid configurations to limit the damage of ordinary configurations. For example, in the in-line configurations often I could not have the expected spl in front as you explained (except in those cases, if I remember correctly, of sub with not very long depth and low crossover frequencies, so with a large distance between the subs).... knew the damage that caused the obstruction of the front sub together with other factors (I read a your previous document about in the past) that now you have well analyzed. these ideas, were right to limit the problem of obstruction, were at the time posted on my FB profile where you can find them (sorry for my bad English)
of course we must consider the alternatives that can actually be achieved logistically.
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Re: Article: Stair Cardioid
Nice work
Are all the subs in a stair cardioid in polarity with each other or are there some polarity reversals in your measurement data?
Nice work
Are all the subs in a stair cardioid in polarity with each other or are there some polarity reversals in your measurement data?
Re: Article: Stair Cardioid
Awesome work! It would be interesting to further study the effect of the floor boundary spacing in relation to the subs that are raised in the stair configuration.
Awesome work! It would be interesting to further study the effect of the floor boundary spacing in relation to the subs that are raised in the stair configuration.
Re: Article: Stair Cardioid Subwoofer Array
Looking at the pattern thumbnails it seems that this still results in a similar pattern problem...the front lobe is very narrow and gives uneven coverage across the width of the listening area.
Looking at the pattern thumbnails it seems that this still results in a similar pattern problem...the front lobe is very narrow and gives uneven coverage across the width of the listening area.
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Re: Article: Stair Cardioid
In your article you wrote:
"It’s very important to note that in both traces only sub 1 is working. The only change made was placing sub 2 (turned off) in front of sub 1, just like in a cardioid configuration. In this special case, the only purpose of sub 2 is to act as a passive obstacle... Results were very significant, we even saw 5 dB attenuation at some frequencies."
"Just like in a cardioid situation" would require the sub to be driven by an amplifier, but it appears from your text it was not in this case.
You did not mention if the "obstacle" sub was shorted out at the cabinet input terminals, or connected to an amplifier (turned off or on). Each of those three cases would result in a different frequency response, assuming the amp disconnects it's load when turned off.
A cabinet shorted out at the input terminals acoustically appears pretty much like a box, the other two possibilities turn the obstacle sub in to various versions of "bass traps", which may largely be responsible for the measured frequency response deviations.
Which of the three options was the test case?
If the cabinet was not shorted, what is the resistance measured at the cabinet end when the amp is "off" or "on"?
Art
Sebastian,
In your article you wrote:
"It’s very important to note that in both traces only sub 1 is working. The only change made was placing sub 2 (turned off) in front of sub 1, just like in a cardioid configuration. In this special case, the only purpose of sub 2 is to act as a passive obstacle... Results were very significant, we even saw 5 dB attenuation at some frequencies."
"Just like in a cardioid situation" would require the sub to be driven by an amplifier, but it appears from your text it was not in this case.
You did not mention if the "obstacle" sub was shorted out at the cabinet input terminals, or connected to an amplifier (turned off or on). Each of those three cases would result in a different frequency response, assuming the amp disconnects it's load when turned off.
A cabinet shorted out at the input terminals acoustically appears pretty much like a box, the other two possibilities turn the obstacle sub in to various versions of "bass traps", which may largely be responsible for the measured frequency response deviations.
Which of the three options was the test case?
If the cabinet was not shorted, what is the resistance measured at the cabinet end when the amp is "off" or "on"?
Art
Re: Article: Stair Cardioid Subwoofer Array
certainly John. but I do not think that the narrowness of the field is the subject of the discussion.
certainly John. but I do not think that the narrowness of the field is the subject of the discussion.
Re: Article: Stair Cardioid Subwoofer Array
Yeah I get that. In longer venues this is a good thing anyway.
Yeah I get that. In longer venues this is a good thing anyway.
Re: Article: Stair Cardioid
Dear Art.
The cabinet used as obstacle was not even connected. The point was to illustrate that this frontal sub will act as an obstacle to the rear produced waves. So, that is part of an explanation about why the level is lower at front in a Cardioid array versus a mono cluster.
Dear Art.
The cabinet used as obstacle was not even connected. The point was to illustrate that this frontal sub will act as an obstacle to the rear produced waves. So, that is part of an explanation about why the level is lower at front in a Cardioid array versus a mono cluster.
Re: Article: Stair Cardioid
I think Art's question comes down to: was the obstructing speaker electrically shorted during your tests?
I think Art's question comes down to: was the obstructing speaker electrically shorted during your tests?
Re: Article: Stair Cardioid
The unconnected cabinet will reduce level at some frequencies, and add level at others, affecting frequency response of the powered cabinet.
The frontal sub will present a quite different obstacle if it is powered or shorted than if it is not connected.
In the chart below, the three traces illustrate the same cabinet tested three ways:
1) Green trace- 18" tapped horn cabinet alone.
2) Blue trace- 18" tapped horn with the same type of cabinet along side, the input terminals shorted.
3) Purple trace- 18" tapped horn with the same type of cabinet along side, the input terminals not connected.
The adjacent cabinet when shorted acts as a boundary, uniformly increasing level by one to two dB.
The adjacent cabinet when left open increases level as much as 3 dB around the low tuning and also decreases level by almost 3 dB in two other frequency ranges.
If you electrically short your "obstacle" speaker cabinet, the frequency response of the powered cabinet will look quite different than your test results, and would be more indicative of an actual cardioid array response.
Art
Sebastian,
The unconnected cabinet will reduce level at some frequencies, and add level at others, affecting frequency response of the powered cabinet.
The frontal sub will present a quite different obstacle if it is powered or shorted than if it is not connected.
In the chart below, the three traces illustrate the same cabinet tested three ways:
1) Green trace- 18" tapped horn cabinet alone.
2) Blue trace- 18" tapped horn with the same type of cabinet along side, the input terminals shorted.
3) Purple trace- 18" tapped horn with the same type of cabinet along side, the input terminals not connected.
The adjacent cabinet when shorted acts as a boundary, uniformly increasing level by one to two dB.
The adjacent cabinet when left open increases level as much as 3 dB around the low tuning and also decreases level by almost 3 dB in two other frequency ranges.
If you electrically short your "obstacle" speaker cabinet, the frequency response of the powered cabinet will look quite different than your test results, and would be more indicative of an actual cardioid array response.
Art
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Re: Article: Stair Cardioid
Dear Art.
Thanks for the toughtfull response. I did not know of the effect this kind of "passive" device could have on the measurement. So the turned off acts like a resonator, or pasive device. In this case the obstacle box was not conected, and not shorted. So new measurements are required. I was trying to get the effect of the obstacle just as a phisical solid obstacle, but didn`t remember that it could resonate/vibrate, affecting the response.
On the measurement you showed, where was the mic located ? Is that a local effect near to the obstacle sub, or a general change in the farfield ? I ask you this because when the obstacle sub was located at some distance, there was no change in the 12m response.
Dear Art.
Thanks for the toughtfull response. I did not know of the effect this kind of "passive" device could have on the measurement. So the turned off acts like a resonator, or pasive device. In this case the obstacle box was not conected, and not shorted. So new measurements are required. I was trying to get the effect of the obstacle just as a phisical solid obstacle, but didn`t remember that it could resonate/vibrate, affecting the response.
On the measurement you showed, where was the mic located ? Is that a local effect near to the obstacle sub, or a general change in the farfield ? I ask you this because when the obstacle sub was located at some distance, there was no change in the 12m response.
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Re: Article: Stair Cardioid
The amplifiers act as "brake" on the cone movement. Not as good as shorting out the cabinets-but better than leaving them open-as they would be if the amps were off.
That is the reason when I take a system into a venue that has a house system-I ask the house guys to turn their system on and mute the DSP.
The amplifiers act as "brake" on the cone movement. Not as good as shorting out the cabinets-but better than leaving them open-as they would be if the amps were off.