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[Ivan Beaver]

Here is a good example of what happens when you don't understand what is happening and just do it because somebody said it was "cool"

Take a look at the center sub

https://www.facebook.com/PAotD/photos/a.173817121282.132706.173813726282/10154271001041283/?type=3&theater

[Tim McCulloch]

Here is a good example of what happens when you don't understand what is happening and just do it because somebody said it was "cool"

Take a look at the center sub

https://www.facebook.com/PAotD/photos/a.173817121282.132706.173813726282/10154271001041283/?type=3&theater

The umbrella & table should be a little more to the stage left...

And I'm betting the directional sub setup was Not a Thing of Happiness.

[Dave Garoutte]

But subs have a 360 radiation pattern, right?

[Ivan Beaver]

But subs have a 360 radiation pattern, right?

No.

It depends on the particular sub and the freq.

As with other loudspeakers, they get narrower as they go higher.

Yes, most are "generally" omni, but not always.

Some are VERY directional-without the use of electronics

[Jeremy Young]

Just so I'm clear, the issue with their setup is the lack of distance behind the subs to allow for the cardioid array to perform correctly?  Or did I just fall victim to the same lack of knowledge?

[Ivan Beaver]

Just so I'm clear, the issue with their setup is the lack of distance behind the subs to allow for the cardioid array to perform correctly?  Or did I just fall victim to the same lack of knowledge?

That is the biggest problem.

Also the distance from the "radiating areas" of the front and rear subs are not far enough apart to provide cancelling down very low.

You physical distance-in both the front to rear distance and also be away from any boundaries that would reflect parts of the signal.

When you have reflections, you introduce all new signals that are out of phase (YES that is the correct use of the term-NOT polarity in this case) which will cancel at various freq, depending on the distance of arrival from the original signal and the reflected signal (plus any delay that might have been applied to the "directional" speaker.

Directional subs work best outside-free of reflections.  Indoors they need to be a good distance away from reflections.

[Jay Barracato]

Just so I'm clear, the issue with their setup is the lack of distance behind the subs to allow for the cardioid array to perform correctly?  Or did I just fall victim to the same lack of knowledge?

Another way of thinking of this is if the front of the sub is three feet in front of the boundary, the reflection can be considered as another source three feet behind the boundary at a slightly lower level.

So in this case, out front, you have the direct signal from the two front facing subs, the reflection from the surface, the signal off the back of the back facing sub, plus it's reflection, all at slightly different times, smearing the signal.

Add in the low height of the boundary which will allow the air above it to move freely, which will create more smearing.

Sent from my XT1254 using Tapatalk

[John Roberts {JR}]

When you have reflections, you introduce all new signals that are out of phase (YES that is the correct use of the term-NOT polarity in this case) which will cancel at various freq, depending on the distance of arrival from the original signal and the reflected signal (plus any delay that might have been applied to the "directional" speaker.

Directional subs work best outside-free of reflections.  Indoors they need to be a good distance away from reflections.

If a reflected waveform is phase shifted, is that phase lead, or phase lag? 

JR

[Ivan Beaver]

If a reflected waveform is phase shifted, is that phase lead, or phase lag? 

JR

Relative to the original signal (from the loudspeaker) the reflected signal would be lagging-due to the later arrival, by whatever the difference of arrival times is.

[Jelmer de Jong]

Here is a good example of what happens when you don't understand what is happening and just do it because somebody said it was "cool"

Take a look at the center sub

https://www.facebook.com/PAotD/photos/a.173817121282.132706.173813726282/10154271001041283/?type=3&theater

Lets assume someone out of your control decided the subs should be against the wall. Would you place them alle facing forward or alle facing backwards?