Holy Crap! Sounds to make the sub go baaaaarf... (1 Viewer)

This is the only forum I could thing to post at since people here have the drivers to appreciate it, and possibly the equipment to measure it as well.
Black Hawk Down. Ok, I am sure most of you have seen this and can appreciate the killter audio track. ...and most of you with good subs can have some fun with the helicopter with an ~18hz rumble. (ok...if you have an ok "sub"...you can only get the ~30hz overtone )
...but am I the only one to notice the low beyond belief sub-sub bass?
Boot up the DVD and go to 35min 20sec. This is right when the Helicopters start up to head into Mogedishu (sp?) and a pilot says "f*&en Irene".
My 12" HE sealed system is dancing on what looks to be 3-5hz ultra-sub-bass!!!!!!
If you are running on an amp with a rumble filter, you probably will not "experience" this.
I hae TrueRTA and this is below its 10hz low end, though I can see the start of a hill there. Does anyone have the tools to measure below 10hz?

Chris,

There are a lot of things which happen when you have a system with flat response to well below 20Hz, besides just being able to produce those frequencies. There are all sorts of things with respect phase and transient response which come along with it. Thomas's 12 Shivas can certainly produce some output below 20Hz, and while synthesized frequencies can leave you a bit uneasy, there is ultra-low frequency content associated with real world sounds.

Anthony

What RTA do you have/use and are you measuring calibrated mic in room or direct souce feed?

Curious
Geoff

I have the WM-61A and TrueRTA, but I didn't measure in-room on this. The frequency was so low that I could literally count the cycles!!! and at about 1-1.5" p-p it wasn't to hard to see
I could probably put a stop watch to it to find out the "real" frequency since trueRTA only goes down to 10hz.

I love the bass from We Were Soldiers R3 DTS

When I watched BHD in the theaters I noticed a lot more bass especialy in CHP 4 or whenever the chopperes were going. There was this wave of low sound that I couldn't recreate at all in my HT. In the sceen where the choppers are flying on the beach going to mogadi. When the camera pans through the line of blackhawks theres this ultra low rumble from Left to right and back. Does anyone hear that in there HT? The bass had so much energy it felt like you were right in front of the blackhawks.

My floor was beating with the beats of the blades. I couldn't believe it at first so i rewound and sure enough the floor was pulsing with each blade beat. I love my SVS.

---
jay

Hey Anthony,

Did you ever get a measurement on this? I've found a couple of old threads that I read awhile ago, but can now participate since I got my Tempest up and running.

I also noticed this moment at 35:20. I have a fake plant that is sitting on top of my sub and I noticed it bouncing right at that point when it cuts from the pilot's face to the hangar, WOW! I took a flashlight and got down next to my Sub (down-firing) and you're right, there is 3-5Hz bass there. I could count the cycles, too.

Anybody else experience this?

JKS

I have nothing that measures below 10hz. I did have a gathering at my house in december and we had an "oh shit" moment when I showed it to the guys for the first time. only someone with a sealed/IB system with NO sort of typical rumble filter will be able to experience it. I have a 3rd order at 8hz, so I wonder how strong it REALLY is

Anthony,

What kind of sub do you have?

Couldn't what is being interpreted as 3-5 Hz bass actually be 3-5 20Hz "bass hits" per second? If you can see the cone moving 4 times in a second, and the heli blades come by 4 times in that same second, then I'd say it's not 4 Hz... it's 4 instances of a 20Hz (or whatever) heli blade sound.
Just my guess, though. I'm probably not qualified to enter my 2 cents here.

Sealed 12" XBL2 prototype drivers.

no...it is around 4hz. you see it "spin up" with the rotor till it reaches about 18hz (measured)

Jeff,
If you can see your driver, you can tell the difference. My driver (Tempest) is noticeably moving at 20Hz, but it is FLAPPING during this BHD scene. I also have a 100-1Hz sweep that gets the driver flapping in a similar manner well below my enclosure's tuning point (17.5Hz).
Now, I'm not saying that I can hear or even feel 5 Hz from my sub, but I can see my plant bouncing on top of my sub and I can see my driver flapping. Now this is at 15dB below reference, so maybe at full reference . . . well, maybe at full reference, my driver would be bottoming to the point of destroying itself. Regardless, I don't think I'd try to push this scene too hard without some kind of subsonic filtering in place.
I have wondered though, would what Jeff describes (4 20Hz "hits" per second) be an effective way of faking a subsonic sound? Any sound design experts out there??
JKS

Anthony,

I am looking for a new amp for the BP 1503's, any suggestions? I have only put about 20 minutes play time on this set-up since I brought them home on a QSC amp. We watched a bit of LOTR and about shook the stucco off the walls. The QSC works but I am looking for something to get the optimal performance from these drivers.

Thanks,
Jason

For power amps, my favorite is still the Crown K2. Pricey, but one hell of a nice amp.

If you are looking into plate amps, the HS500 is a pretty nice way to go. Anyway you look at it, you will still need a parametric EQ for the inductance hump.

For a pair of 1503's, you will need a pair of plates since very few are 2ohm stable. John at stryke was looking at some low impedence amps, but I have no idea if that will even materialize.

In regards to the single digit hertz, i am confident it is not a "20hz multiple" thing.

I need to get a hold of a digital camara with video capabilities and I can show you all what I am talking about.

I also noticed this.. scared the shit out of me. I have my Tempest forward firing with the driver visible (about 5 feet in front of me). As soon as I saw the driver moving like that I jumped up and turned the volume down in fear that I would wreck my brand new tempest. Never heard it bottom though.