SPL Prediction?
Jul 29, 2009 9:14:20 GMT -7
Post by flyingv74 on Jul 29, 2009 9:14:20 GMT -7
As I mentioned in my previous posting, I come from a live sound/PA background where high sensitivity loudspeakers are the absolute king. So this IB thing is really throwing me for a loop! 
In the world of PA systems, you can use the rated sensitivity and the power handling of given loudspeaker to calculate a "theoretical" prediction of how loud the speaker will be. You also can use the inverse square law to calculate theoretically how loud the speaker will be at any point within a given room.
In the world of infinite baffle subwoofers, it seems that these theories are "out the window". The sensitivity ratings of the drivers are extremely low when compared to PA speakers. And you guys talk about the Xmax and the volume displacement of the woofer cone. And this kinda makes sense since we are trying to move a large volume of air using a "piston". Is there a way to use these specs and calculate the maximum SPL for a given loudspeaker at a certain distance from the loudspeaker?
Also, in the world of PA systems, excessive cone motion is generally looked upon negatively as it creates distortions and timing issues. Thus the preliferation of horn loaded designs in the PA world. A horn loaded driver moves very little and produces extremely high SPL levels with minimal power input. In the infancy of PA systems, this is the way that things had to be done due to the fact that there was no such thing as a 1000W power amplifier.
In the world of IB subs, it seems that huge Xmax seems to be king! I would think that too much cone motion would cause timing issues when listening to music. I have heard loud sloppy subs before in the world of car audio. But much of what I have read on the forum indicates that IB subs produce excellent sub bass for music listening applications.
Are you beginning to see why I am confused? It seems that everything that we desire in the world of PA systems is the exact opposite in the world of infinite baffle subwoofers!
Ultimately my question is how do you predict how loud an IB subwoofer system will be in a given size room? How do you know how many IB sub drivers will be required based on their Xmax and volume displacement of the cone? Are two 15" enough? Or will four 15" be required? Or would two 18" be better? Or perhaps even more!
Why did I have to be an engineer? Why couldn't I have just been a dumb rich guy that can afford to blow up woofer after woofer until I find the ones that will work for me?
In the world of PA systems, you can use the rated sensitivity and the power handling of given loudspeaker to calculate a "theoretical" prediction of how loud the speaker will be. You also can use the inverse square law to calculate theoretically how loud the speaker will be at any point within a given room.
In the world of infinite baffle subwoofers, it seems that these theories are "out the window". The sensitivity ratings of the drivers are extremely low when compared to PA speakers. And you guys talk about the Xmax and the volume displacement of the woofer cone. And this kinda makes sense since we are trying to move a large volume of air using a "piston". Is there a way to use these specs and calculate the maximum SPL for a given loudspeaker at a certain distance from the loudspeaker?
Also, in the world of PA systems, excessive cone motion is generally looked upon negatively as it creates distortions and timing issues. Thus the preliferation of horn loaded designs in the PA world. A horn loaded driver moves very little and produces extremely high SPL levels with minimal power input. In the infancy of PA systems, this is the way that things had to be done due to the fact that there was no such thing as a 1000W power amplifier.
In the world of IB subs, it seems that huge Xmax seems to be king! I would think that too much cone motion would cause timing issues when listening to music. I have heard loud sloppy subs before in the world of car audio. But much of what I have read on the forum indicates that IB subs produce excellent sub bass for music listening applications.
Are you beginning to see why I am confused? It seems that everything that we desire in the world of PA systems is the exact opposite in the world of infinite baffle subwoofers!
Ultimately my question is how do you predict how loud an IB subwoofer system will be in a given size room? How do you know how many IB sub drivers will be required based on their Xmax and volume displacement of the cone? Are two 15" enough? Or will four 15" be required? Or would two 18" be better? Or perhaps even more!
Why did I have to be an engineer? Why couldn't I have just been a dumb rich guy that can afford to blow up woofer after woofer until I find the ones that will work for me?
