is there really such a thing as the "brown note"?

Servo-Drive Urban Legend ?

Hi travis,
is this the 'brown note' you mean ?. :D


http://oyt.oulu.fi/tbl/archive/VOL1/100-199/bl186.html#2

Has anyone out there had experience (on stage or as a spectator)
with these new servo-motor speakers? As I understand it, the
mechanism uses a small motor instead of the usual magnetic apparatus
to move the driver in and out (no nasty jokes, please). This is
supposed to make for a lot longer throw of the cones, resulting in
high output at *low* frequencies. I've heard that Billy Sheehan is
using one and a guitarist told me that he heard that at a Pink Floyd
show one was used and there was a bit of an incident because the
extreme low frequencies caused people in the first few rows to..um..
lose their bowels (so now we need to take Depends to concerts as
well as hearing protection?). But talk about playing with *power*!
I'm sure these things are incredibly and probably huge as well...

These guys are talking about Servo-Drive subs - good for 130 dBA
at 1% or so !. http://www.servodrive.com/

BTW http://www.epanorama.net/links/audiospeakers.html#subwoofer is a good resource for speaker and sub builders.

Eric.
 
Yes and no

Yes, low freq tend to be omni, but that does not mean that you cannot aim them. See Meyer, JBL, TurboSound and the other big guys in PA websites. Using stacks of drivers, they can adjust curve of stack, and vary phase (timing) in order to get the wave form that they want.

Same thing happens in the "extreme" end of car audio. In order to get the max SPL at the measure point, they vary phase on each driver so that its wave is additive, not subtractive.

(Wonder if the guys who are using stacks of Shivas in IB config, ala 12 Dancing Shivas, should take this in mind?)
 
I would think that the prevalence of high-dB boom-boom car stereos would indicate that this is indeed in the urban legend category. Many times I have heard people claim the potential for bodily harm (not counting hearing loss) or loss of sphincter control. When asked for data to back the claims up, the response is always couched in terms of,"Well, a friend of a friend of a friend said it once happened to their second cousin's next door neighbor's boyfriend's dog," or, worse yet,"Well, everybody knows it's true..."
Supposedly, there is a frequency somewhere around 10-12 Hz that is supposed to induce fear in folks. I tend to doubt this one, as I've played with my frequency generator down in that range (my subs are somewhat larger than the average) and can report that the only fear I felt was that the house might cave in.
I have no doubt that there is a limit to what the human body can take, SPL-wise, but I suspect that it's far beyond anything that you could stand to be in the same county with. Pain--a very identifiable sensation--would occur first, being more in the range of 120-130 dB. Bear in mind that whale calls are somewhere in the neighborhood of 170-180dB and of widely varying frequency. Elephants emit very loud infrasonic calls as well. In neither case do their organs pulp, nor do they explode. Maybe their eyes bulge a little bit, but that's about the extent of it.
The fellows who work with jackhammers are subjected to very high amplitude, very low frequency vibrations, yet they go home to their wives and daughters in pretty much the same condition as when they left for work that morning. Jets are extremely loud on takeoff, yet the flight crews on aircraft carriers manage to survive with only hearing protection. They don't go spastic, nor do they melt down into a puddle of amino acids.

<i>Dear Mrs. Jones,
We regret to inform you that your son was killed today on the flight deck of the USS Enterprise when a jet took off. We will forego the usual arrangements involving a casket; your son's remains will be returned in a Mason jar...</i>

Another factor to keep in mind is that bodily tissues are largely water, hence very well internally damped. They're also very elastic. Ever tried to resonate a water balloon to the point of structural failure? Further, no two internal organs are the same size (not even the lungs are the same--the left one is somewhat smaller in order to accomodate the heart), so any putative 'resonant frequency' would be different for each organ.
Etc. etc. etc.
In other words, a few moments spent in reflection will be sufficient to come up with some pretty decent counter-evidence to such claims. Rest assured, somewhere, someway, somehow, the human body is being subjected to massive vibrations at any frequency or SPL that you'd care to specify, even as we speak. Yet, there are never any news items about yet another jockey exploding as his horse rounded the final turn, pounding for all he was worth, to the beat of four cycles per second. Unless someone manages to crank out substantive data to support claims of exploding/pulped organs, or psychological effects, I'll continue to file this one under Urban Myth. Pain and hearing loss are about all you have to worry about.
And that should be enough to make you feel fear, right there.

Grey
 
When researching my sub system I contacted Bag End prior to purchasing the ELF system. In conversation with Henry ? (President/CEO I think) I remember inquiring about why the ELF system is rolled off at 8 hz when using the ELF-1 Integrator. His response was that it was done for two reasons. First, required power and the issues it created with driver design. Second, the fact that Cerwin Vega and Lucas Arts had done a lot of research on subsonic systems for theaters and Wickersham Labs (patent holder) was either familiar or involved in the work. They discovered that when freqs went below ~ 8 hz, the theater audiences tended to become restless and uncomfortable and a larger percentage of folks excused themselves to use the restrooms... I don't know if it was hype or not but that's what he said and he was very matter of fact about when I spoke with him...

I just searched google for info on the research that was done and didn't find anything so if anyone know more it'd be great if they posted about it...

There are also a number of articles and research papers related to the HAARP antenna array as well as the effects on humans of similar systems... Do a search on google for military related ELF research and incidents... Yes, I know the HAARP antenna is a HF array but they fire the array in such a manner that it creates an ELF pulse...

http://www.haarp.alaska.edu/haarp/HaarpSite.html

Lastly, on a personal note, it's very interesting having a system that goes down to 8 hz. No, you can't hear it. I don't know exactly how low some of my organ music and DVD's actually go but I can tell you that sometimes when listening I almost get a "creepy" feeling from the very low stuff. I don't know how else to describe it but the really low stuff tends to make me uneasy in a way that I've never experienced before.... No, I don't run to the restroom but it's more like the feeling when you're out hiking in the woods on a very black night and you're wondering if you're being watched... It's that kind of feeling in the base of your stomach... It just makes you uneasy... I could imaging that if the material actually went very low for extended periods of time that it might actually upset one's stomach. Hasn't happened to me though... That having been said, I wouldn't trade the low end response or speed for anything else that I've heard at any price. And yes, it take tons of power... It will clip 500 wpc at normal listening levels like it's nothing when the really low stuff is present... (no, I don't let it operate into clipping)...

Just my $.02,

Steve