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Discussion Starter · #1 ·
Ever since I discovered the exploding ball at the beginning of the Star War DVDs,

I've been using it to test the ability of whichever sub/subs that I may bring into my system. Sort of a make it or break it test.

Most subs, I've had, can't handle this "test" when the SPL meter starts approaching 100db. They either shut down or their driver/s start making some ugly noises. I take the measurements from my listening position about 12' from the sub.

My current subs, a pair of Revel B-15's, are the only subs I've had in my system that reproduce this exploding ball well into the 100s, 116+ is the highest I've dared to push the exploding ball, without a hint of breaking down or shutting down or worst, the drivers bottoming out. At that point I usually chicken out and lower the volume in fear of damaging the subs or the foundation of our house, as the entire room is shaking and rumbling.


Has anybody else here used the exploding ball as a measure of their subs performance?


dc
 

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Quote:
Originally Posted by DreamCatcher
Ever since I discovered the exploding ball at the beginning of the Star War DVDs,

I've been using it to test the ability of whichever sub/subs that I may bring into my system. Sort of a make it or break it test.


Has anybody else here used the exploding ball as a measure of their subs performance?


dc
You are referring to the THX Cavalcade Trailer. Here is a spectral color chart showing the frequency distribution.


The main hit is centered at 35 Hz, and the aftershock extends into the teens. I would expect the Revel B15 to handle the 35 Hz region well and provide a lot of felt impact.


Also interesting is the 20/40/60 Hz harmonics on the THX synthesized "tone" at the end. Unlike the older trailer, this newer tone has a solid 20 Hz component.
 

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Quote:
Originally Posted by kgveteran
I owned a laser disc that had an AC-3 (Dolby Digital) promo that was the bomb. Even back then with my garbage subs it sounded great.It was a train starting up and chugging along.Very cool.
I have that one, in two versions, on my computer along with many more :)
 

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It's just THX logo sequence at the beginning of a THX movie. It used be the wave of sound that come from the rear of the room forward with teh big THX logo on the screen, now it is thunder/lightning/rain followed by an exploding THX globe with "glass" hitting the ground.
 

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ohhh... I see... the Incredibles DVD has it as well... I've used it before to play with sub settings... it's a nice test :)
 

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Quote:
Originally Posted by DreamCatcher
My current subs, a pair of Revel B-15's, are the only subs I've had in my system that reproduce this exploding ball well into the 100s, 116+ is the highest I've dared to push the exploding ball, without a hint of breaking down or shutting down or worst, the drivers bottoming out. Has anybody else here used the exploding ball as a measure of their subs performance?


dc
Man, how hot are your subs or where did you have the volume?


Before work, I played that scene for a second and I hit a very clean 111db on the RatShack meter at the listening postion(11ft away) and the volume was at -2db on my receiver and my subs are 2db hot. Was your receiver's volume above reference level?


Anyways, I am sure I could have gone easily louder on that scene but I was scared:(
 

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Using the cd from Nemesis "To Hell And Back" (track 6) my SVS PB12 Ultra/2 maxed out my Rat Shack SPL meter (C/Slow) @ 1 meter. Pegged it hard.


The CD is out of print, so to get a new one, it will cost you!
 

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I have a copy of "Sound & Vision's Home Theater Tune-up", which in it's extra's section contains each and every one of the Dolby Digital intro's usually seen in theaters. I think there are 8 of them (Train, Aura, City Lights, Egypt, Canyon, etc.) There are also 3 different versions of the cavalcade THX trailer on it, 4:3, 1.66, and 2.35:1 ratios (Same audio, just more screen real estate).


I used them to demo the system to my friends. My wife groans every time I pull the disc out now. :)


I also used the intro to "Ice Age". When the squirrel pushes the nut into the ground, there is a very solid deep-bass "thump" that comes through.


Resident Evil has some incredibly deep bass on it, usually subltly placed to freak you out.


My favorite still is a CD, Techmaster P.E.B: Bass Computer ( http://www.amazon.com/exec/obidos/tg...glance&s=music )


Track 10 has amazing bass, and it's actually a fairly entertaining CD, not like the other Bass Head Cd's I've listend to in the past. At the 2:00 minute mark, it has tones that drop into the 15hz region. (Which the Eclipse subs in my car do a great job producing, but the Def Tech subs in my HT do not).


I also like Titanic. The southhampton scene where they introduce the ship for the first time has some swelling orchestral music that's quite impressive.
 

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I more a fan of test tones, since its only true fundamentals and no harmonics being produces, ti lets you know if your subs are distorting (more noticeable than a fundamental with oevrtones/other sounds). Besides, then you know that your sub has enough TRUE 10hz output to say...visibly flex your window/frame?
 

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Discussion Starter · #13 ·
Quote:
Originally Posted by UNICRON-WMD
Man, how hot are your subs or where did you have the volume?


Before work, I played that scene for a second and I hit a very clean 111db on the RatShack meter at the listening postion(11ft away) and the volume was at -2db on my receiver and my subs are 2db hot. Was your receiver's volume above reference level?


Anyways, I am sure I could have gone easily louder on that scene but I was scared:(
I'm not running my subs "hot" at all.

Denon Audyssey set the sub level (-2.5) and I've left it there.


Volume level on my 5805 was at -9 when I also "got scared" and stopped.

I'm not sure but I think the level one can achieve on the "exploding ball", has more to it then just volume.

Probably how deep your sub/s can go, before rolling off, has a lot to do with it as well, since as previously mentioned there is alot of good stuff going on below 20hz when that ball goes off.


But my main concern or what I'm looking for from the sub/s, is how they act when the ball explodes.

Do they shut down,

Do the drivers start rattling, bottoming out,

Or just run out of steam,

and at what level do these bad things start happening?


dc
 

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Discussion Starter · #14 ·
One more important note I forgot to mention.....

I turn off all other speakers when I'm doing the "exploding ball" test.

That way I'm only measuring the sub/s and

I don't put my other speakers at risk :D


dc
 

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Quote:
Originally Posted by DreamCatcher
I'm not running my subs "hot" at all.

Denon Audyssey set the sub level (-2.5) and I've left it there.


Volume level on my 5805 was at -9 when I also "got scared" and stopped.

I'm not sure but I think the level one can achieve on the "exploding ball", has more to it then just volume.

Probably how deep your sub/s can go, before rolling off, has a lot to do with it as well, since as previously mentioned there is alot of good stuff going on below 20hz when that ball goes off.

dc
Hum, weird. If 2 systems are setup "properly", they both should hit close to the same SPL.


I set my system up with AVIA at 85db at the listening position with my RS meter. my subs are set to 84db so they are about 2db hot. Also, my subs in my room are pretty damn flat to 17-18hz. I also use a DEQ-2496 to help make a flat FR.


Now, from what little I know, which is very little, if 2 systems are setup properly and have a FR from 20hz - 20kz while watching a movie at reference level, they both should have a SPL that is very close. It just seems kinda odd you are hitting 116db at -9 while I am hitting 111db at -2.


Anyways, I am not trying to compare systems or sub, it is just the numbers seem a little off. Have you calibrated your system manually before? Maybe your receiver set your subs a tad hot?
 

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Discussion Starter · #16 ·
Quote:
Originally Posted by UNICRON-WMD
Hum, weird. If 2 systems are setup "properly", they both should hit close to the same SPL.


I set my system up with AVIA at 85db at the listening position with my RS meter. my subs are set to 84db so they are about 2db hot. Also, my subs in my room are pretty damn flat to 17-18hz. I also use a DEQ-2496 to help make a flat FR.


Now, from what little I know, which is very little, if 2 systems are setup properly and have a FR from 20hz - 20kz while watching a movie at reference level, they both should have a SPL that is very close. It just seems kinda odd you are hitting 116db at -9 while I am hitting 111db at -2.


Anyways, I am not trying to compare systems or sub, it is just the numbers seem a little off. Have you calibrated your system manually before? Maybe your receiver set your subs a tad hot?
Maybe....

I've ran AVIA to double check how well Audyssey set the levels and they are pretty much right on.

"I am not trying to compare systems or sub",

Exactly that's why I didn't mention the other subs that I've had in my system.


Room nodes are probably involved in the measurments as well. This makes it hard for two different systems in two different rooms to be compared. But my room hasn't changed from sub test to sub test. Subs are placed in the same front corner of the room. So anyone can use the "exploding ball" to test their subs ability or lack there of.


dc
 

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Monty Williams,

Quote:
122db C/Slow with my current calibration (sub levels calibrated +3 hot) with 2 M&K MX-350's



Those are amazing figures. I'm curious to know, what is your room size? Because unless you have a room the size of a closet, it would be physically impossible for you to be hitting those numbers with two M&K MX-350's with the THX exploding ball scene.


--Sincerely,
 

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ACtually, it's quite possible to hit those levels with a pair of M&K's.


The misleading part is that the majority of the SPL's are coming from the >35hz reproduction. You may see 122db on the meter but compared to another sub setup where the majority of the SPL is coming from
 

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Yes, it's possible to achieve 122 dB's at 35hz (if that) measured at the dust cap in a small to medium size room. That is indeed possible. But at the seats, I have a difficult time believing that the pair would achieve levels in excess of 120 dB's (perhaps at 50hz).


--Sincerely,
 

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Discussion Starter · #20 ·
Really the point I was trying to get across with this thread was not "mine's louder than your's" but more of a TEST of one's subwoofer setup.

Putting the THX exploding ball on a continuous loop and slowly increasing the volume of your processor (I usually start around -20 on the volume display and increase the volume by 4 each time through) you can see and hear and measure how your sub/s will react to this very demanding track.

I've had too many subs that either shut down or their driver/s start bottoming out (rattling, slapping) or distortion becomes very audible, rather quickly when trying to reproduce the exploding ball.


dc
 
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