ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: [1] 2 3   Go Down

Author Topic: Importance of basic understanding & fundamentals  (Read 4369 times)

Ivan Beaver

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 8166
  • Atlanta GA
Importance of basic understanding & fundamentals
« on: March 22, 2017, 05:18:21 pm »

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

Logged
A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Tim McCulloch

  • SR Forums
  • Hero Member
  • *
  • Offline Offline
  • Posts: 17645
  • Wichita, Kansas USA
Re: Importance of basic understanding & fundamentals
« Reply #1 on: March 22, 2017, 08:34:31 pm »

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.
Logged
"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Dave Garoutte

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 618
  • San Rafael, CA
Re: Importance of basic understanding & fundamentals
« Reply #2 on: March 23, 2017, 01:05:59 pm »

But subs have a 360 radiation pattern, right?
Logged
Events. 
Stage, PA, Lighting and Backline rentals.
Chauvet dealer.
Inventor.

Ivan Beaver

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 8166
  • Atlanta GA
Re: Importance of basic understanding & fundamentals
« Reply #3 on: March 23, 2017, 06:52:18 pm »

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
Logged
A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Jeremy Young

  • Full Member
  • ***
  • Offline Offline
  • Posts: 140
    • Brown Bear Sound
Re: Importance of basic understanding & fundamentals
« Reply #4 on: March 23, 2017, 09:11:47 pm »

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?
Logged
Brown Bear Sound dot CA
Victoria BC Canada

Ivan Beaver

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 8166
  • Atlanta GA
Re: Importance of basic understanding & fundamentals
« Reply #5 on: March 23, 2017, 09:24:10 pm »

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.
Logged
A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Jay Barracato

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1811
  • Solomons, MD
Re: Importance of basic understanding & fundamentals
« Reply #6 on: March 24, 2017, 07:12:50 am »

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

Logged
Jay Barracato

John Roberts {JR}

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 15605
  • Hickory, Mississippi, USA
    • Resotune
Re: Importance of basic understanding & fundamentals
« Reply #7 on: March 24, 2017, 09:32:39 am »



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?  8)

JR
Logged
On the internet people tell you everything "they" know, not the answer to "your" question.

Ivan Beaver

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 8166
  • Atlanta GA
Re: Importance of basic understanding & fundamentals
« Reply #8 on: March 24, 2017, 01:33:54 pm »

If a reflected waveform is phase shifted, is that phase lead, or phase lag?  8)

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.
Logged
A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Jelmer de Jong

  • Full Member
  • ***
  • Offline Offline
  • Posts: 159
Re: Importance of basic understanding & fundamentals
« Reply #9 on: March 24, 2017, 02:33:34 pm »

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?
Logged
Pages: [1] 2 3   Go Up
 


Page created in 0.089 seconds with 19 queries.