Max SPL numbers at data-bass - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 14 Old 05-29-2016, 04:22 AM - Thread Starter
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Max SPL numbers at data-bass

I was looking at the max SPL numbers for various subs here

http://www.data-bass.com/data?page=systems&type=0

The max SPL numbers increase towards right (higher freq) of the table, which is expected.
But in a setup with flat FR, will the higher SPL capacity at the higher frequencies be of any use if lower frequencies will decide the max SPL ?
And with equal loudness contour, wouldn't the sounds at lowest freq be mixed at higher SPL than higher freq ones ? Which means that headroom, even if available will go unused ?

@Ricci

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post #2 of 14 Old 05-29-2016, 05:32 AM
 
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Quote:
Originally Posted by Hifisound View Post
in a setup with flat FR, will the higher SPL capacity at the higher frequencies be of any use if lower frequencies will decide the max SPL ?
Not really. Most subs are displacement limited, and since displacement requirements go up as frequency goes down that's why maximum SPL tends to go down with frequency.
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post #3 of 14 Old 05-29-2016, 06:40 AM - Thread Starter
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Originally Posted by Bill Fitzmaurice View Post
Not really. Most subs are displacement limited, and since displacement requirements go up as frequency goes down that's why maximum SPL tends to go down with frequency.
I am not questioning as to why max SPL goes down with freq, which is obvious.
I am wondering if that "extra" SPL at higher frequencies, above the SPL at say 20Hz (or whatever lowest one wants the FR to be flat upto), is of any benefit in a flat FR setup...

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post #4 of 14 Old 05-29-2016, 07:54 AM
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Your correct. The producers and sound designers are well aware of the boundaries and limitation of a sub. Music and movie soundtracks are mixed accordingly. But there's a few of these individuals that stand above the rest and you can feel the difference in their soundtracks.
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post #5 of 14 Old 05-29-2016, 09:39 AM
 
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Your correct. The producers and sound designers are well aware of the boundaries and limitation of a sub. Music and movie soundtracks are mixed accordingly. But there's a few of these individuals that stand above the rest and you can feel the difference in their soundtracks.
??? Non sequitur.
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I am wondering if that "extra" SPL at higher frequencies, above the SPL at say 20Hz (or whatever lowest one wants the FR to be flat upto), is of any benefit in a flat FR setup...
None I can think of. That's just the nature of how speakers work.
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post #6 of 14 Old 05-29-2016, 12:40 PM
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Quote:
Originally Posted by Hifisound View Post
I was looking at the max SPL numbers for various subs here

http://www.data-bass.com/data?page=systems&type=0

The max SPL numbers increase towards right (higher freq) of the table, which is expected.
But in a setup with flat FR, will the higher SPL capacity at the higher frequencies be of any use if lower frequencies will decide the max SPL ?
And with equal loudness contour, wouldn't the sounds at lowest freq be mixed at higher SPL than higher freq ones ? Which means that headroom, even if available will go unused ?

@Ricci
I have long wondered this very same question! It always seems to be explained away with about as much rationale as when the wife tries to explain that me wanting to have sex with her doesn't tell her I love her lol
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post #7 of 14 Old 05-29-2016, 02:39 PM
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The higher capability in the frequencies can often be correlated with higher efficiency. That means when eq'ed flat you'll save some amp power there. Other than that theres no advantage. You'll always be limited by how capable the low end is with SEALED subs. Ported subs aren't tested as often on database, but they'll generally have a little more capability down around tuning. So they're generally output limited a little above the tuning and very limited below tuning.

The graphs are most useful in deciding which sub to use if you'll limiting the bandwidth. Such as if you are using above 30hz instead of 20hz. Then a ported sub with a 30hz tune or a horn tuned there will have better output and those graphs help show that.

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post #8 of 14 Old 05-29-2016, 04:58 PM
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Originally Posted by Bill Fitzmaurice View Post
??? Non sequitur.
None I can think of. That's just the nature of how speakers work.
Bill's gonna make me earn it. I don't re eq my flat eq setting but I watch Interstellar a lot louder than WOTW. It's hi passed. I listen to 40hz bass music a lot louder than 7hz bass music. In a lab doing measurements, your correct, of course. Real world is we crank the volume to max excursion whatever that frequency is and the power will deliver. So if I have an amp that will give me 3 or 5db more at 40hz than max at 20hz I'm using it.
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post #9 of 14 Old 05-29-2016, 05:01 PM
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There is only 1 case that I can think of that would allow both flatness and louder highs, and that would be: DEQ

Where you limit the amount of boost to the ULF, so that it is flat at lower SPL's, and as the SPL increases... the system becomes more and more mid-bass heavy as the ULF boost is automatically deactivated.

To my knowledge Velodyne has used this extensively for the last 20 years, and now even SVS and several other DSP-equipped subs have this sort of thing too. (It's almost expected these days... in fact.)

In DIY subs it is less common, unless the person knows about it, has the equipment to implement it, and chooses to implement it.
I know I do, and a few others have said they do as well...

A lot of subs just make-do with a HPF and a limiter, no DEQ is ever applied, just PEQ (if that) and that is noticeable when they get tested since the mid-bass is of equal-loudness up to the natural limits of the sub's ULF, as explained above. (So they never use the full mid-bass capability of their subwoofer system.)

Signal limiters, power limiters, and soft-clip limiters (and/or actual clipping) will ultimately limit even the amount of mid-bass that is possible (thermal-compression of the voice coil will too! )
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Last edited by BassThatHz; 05-29-2016 at 05:27 PM.
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post #10 of 14 Old 05-29-2016, 05:47 PM
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Quote:
Originally Posted by Docethic View Post
It always seems to be explained away with about as much rationale as when the wife tries to explain that me wanting to have sex with her doesn't tell her I love her lol
She is correct, but unfortunately... those girls charge us by the hour. Where as... the wife charges us MORE and over a LONGER time span. Like 10years and half your total possessions!
Sex without love is theoretically possible in an unhappy marriage

That is what you get for not ever reading any startup directions, instruction manuals, contract fine-print, or even so much as the warning labels! (The only thing you opened was a beer... )

Well that's all I got! I'm now off to the strip club...because NOTHING says "I love you" to the stage girl MORE than a plate of wings, heck the wife might even tag along... LOL

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post #11 of 14 Old 05-29-2016, 07:55 PM - Thread Starter
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Quote:
Originally Posted by tuxedocivic View Post
The higher capability in the frequencies can often be correlated with higher efficiency. That means when eq'ed flat you'll save some amp power there.
So multi tone tests should reveal this ?

Quote:
Originally Posted by tuxedocivic View Post
The graphs are most useful in deciding which sub to use if you'll limiting the bandwidth. Such as if you are using above 30hz instead of 20hz. Then a ported sub with a 30hz tune or a horn tuned there will have better output and those graphs help show that.
This is true, and what I meant by "or whatever lowest one wants the FR to be flat upto" .
Though , I guess, it should still limit the upper freq to something like 40Hz ?

Quote:
Originally Posted by BassThatHz View Post
There is only 1 case that I can think of that would allow both flatness and louder highs, and that would be: DEQ

Where you limit the amount of boost to the ULF, so that it is flat at lower SPL's, and as the SPL increases... the system becomes more and more mid-bass heavy as the ULF boost is automatically deactivated.
This is to compensate for equal loudness contour at lower SPLs ? But even at higher SPLs, the ULF SPL need is quite higher, and would set the upper limit ?

Speaker drivers and ears have opposite behavior as freq increases
Former starts providing more SPL and the latter starts needing less of it. So its kind of two extras here : one upto the SPL set by ULF, and other, the driver's capability above that. Both unused !!
Unless I am misunderstanding something..


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post #12 of 14 Old 05-31-2016, 02:33 PM
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Originally Posted by BassThatHz View Post
She is correct, but unfortunately... those girls charge us by the hour. Where as... the wife charges us MORE and over a LONGER time span. Like 10years and half your total possessions!
Sex without love is theoretically possible in an unhappy marriage

That is what you get for not ever reading any startup directions, instruction manuals, contract fine-print, or even so much as the warning labels! (The only thing you opened was a beer... )

Well that's all I got! I'm now off to the strip club...because NOTHING says "I love you" to the stage girl MORE than a plate of wings, heck the wife might even tag along... LOL
Rotflmao!!!!!
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post #13 of 14 Old 05-31-2016, 04:52 PM
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post #14 of 14 Old 05-31-2016, 04:58 PM
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Quote:
Originally Posted by BassThatHz View Post
There is only 1 case that I can think of that would allow both flatness and louder highs, and that would be: DEQ

Where you limit the amount of boost to the ULF, so that it is flat at lower SPL's, and as the SPL increases... the system becomes more and more mid-bass heavy as the ULF boost is automatically deactivated.

To my knowledge Velodyne has used this extensively for the last 20 years, and now even SVS and several other DSP-equipped subs have this sort of thing too. (It's almost expected these days... in fact.)

In DIY subs it is less common, unless the person knows about it, has the equipment to implement it, and chooses to implement it.
I know I do, and a few others have said they do as well...

A lot of subs just make-do with a HPF and a limiter, no DEQ is ever applied, just PEQ (if that) and that is noticeable when they get tested since the mid-bass is of equal-loudness up to the natural limits of the sub's ULF, as explained above. (So they never use the full mid-bass capability of their subwoofer system.)

Signal limiters, power limiters, and soft-clip limiters (and/or actual clipping) will ultimately limit even the amount of mid-bass that is possible (thermal-compression of the voice coil will too! )
Did you mean apply more boost at lower frequencies at lower volume and decrease the boost as you reach max output of your sub? Fletcher Munson compensation. The equivalent of a rev matching trans on modern exotic cars so you stay in the power band!
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