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Discussion Starter · #1 · (Edited)
Hi folks. It's my first time owning a DIY sub. It's 2 18" Ficar driver.

I have a question/clarrification or soliciting your comments. There were a lot of claims that the sound right after the guy said "Irene" from the movie Black Hawk Down was below 10Hz. I do believe that it was below 10Hz because I saw my drivers cone move very slowly forward and backward. It was the same movement that I saw when I was playing a test tone of 10hz.

However, I didn't feel anything at all. The only time I would feel bass pretty badly/insanely is that when it's above 18Hz. So guys, please let me know what you think about that 7Hz from Black Hawk Down's Irene scene. Do you really feel it? I want your honest experience please. :)
 

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What kind of spl are you getting with a 10hz test tone? In my experience it takes a lot of spl to feel 10hz strong enough to notice it during a movie.
 

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Discussion Starter · #3 ·
I did not measure. I can try again. But like what I said, I wasn't feeling anything at all. I guess, I'll just have to wait until I move my manifold to the false wall. Someone told me that I can fry my drivers with the way my manifold is setup now.
 

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First off, even with two high-displacement 18"ers there is still a limit to how much energy the drivers are making at 10Hz. 10 Hz requires four times the energy as 20Hz to make the same amount of sound.

Secondly you can't hear 10 Hz. Down that low all sound is, as you say, felt. I believe there is some misconception as to how and where you should feel low bass. Here is my take;

Everything has a natural resonance frequency. Much of the "slam" that comes from bass isn't actually super low, it just happens to be the resonance frequency of your chest cavity or guts. I've heard some different statements of what frequency that is at - probably depends on the person - but I believe it is more mid-bass (chest) down to about 20 - 25 Hz (guts). Unless there is a part of your body that resonates at 10Hz you won't feel much. There is a good chance that major parts of your house resonate at 10Hz. What is your room doing when you play that tone?
 

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Discussion Starter · #5 ·
What is your room doing when you play that tone?
It does nothing to the room. I found out that I shouldn't be playing 10hz until I move my IB modified driver to a real false wall. I will find out 3rd quarter of this year once I finish my theater.

Thanks. I really appreciate it.
 

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Secondly you can't hear 10 Hz. Down that low all sound is, as you say, felt. I believe there is some misconception as to how and where you should feel low bass.
Well, few of us ever get to experience a system that can reproduce 10Hz at a sufficient level of output. But folks who have heard a thigpen say you can hear 10Hz, although one can't discern pitch.

But yeah, one would need a lot more displacement than even a pair of high excursion 18" drivers to 'hear' 10Hz or lower.
 

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Discussion Starter · #7 ·
yeah, from most of the articles I've read, anything below 15hz cannot be heard. That's why I said, "I can't feel it." Well, I've got a response from an IB master that my 18" drivers are capable. I'll just have to be patient. I should start working on the home theater room design.
 

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I can feel the room shaking, I can feel the breeze created by the drivers, and there is some audible cone movement. I think you will need a lot more drivers and amps to get much of a 10hz "sense".
 

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..., please let me know what you think about that 7Hz from Black Hawk Down's Irene scene. Do you really feel it? I want your honest experience please. :)
My experience ... I have two small subs (Velodyne VRP1000 and Infinity TSS750), their lowest response is 35HZ :sad: ... but my experience with this movie was :yay: ... I have a pair of buttkickers installed on my seats, so I can feel anything below 60Hz (that's the crossover on the buttkicker amp), I think the lowest response is 1Hz ... :bigsmile::bigsmile:
 

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A 10Hz signwave will make walls or dishes rattle (thunder or a sonic boom) so in a way you can hear it but like others have said below about 18Hz its all about air movement if your drivers cant move enough air you wont notice it at all. I have tower speakers that easily go down to 25Hz and frequencies below that will move the drivers back and forth like you said but you just cant move enough air to feel anything.
 

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Also (correct me if i am wrong) but the port is fighting the output at everything below its tuned freq. So the port itself is restricting output.

10hz is low and takes much more energy to achieve at a sufficient level that it really impacts you.

Although my mom gets headaches whenever i play sub 20 hz test tones even with it barely turned up. Then again thats prolly just something weird with her thats causing it.

Also remember that because you cannot hear it pressure makes a huge difference. Larger room with the same sub will create less pressure, a sealed room will be much greater. For example I am currently living in a 120 year old house with plaster walls and double paned windows. I have my 15" LLT in my room that is 14x11ft and when i do a 10hz test tone you feel it, higher freqs have a bit more output but still when i close my vent and door it gets intense.
 

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yea when I play 10hz tone I don't get much output but things are sure shaking around the room, let's share some vidz of what your sub-setup is capable of at 10hz
 

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It's not necessarily the speaker alone that makes the low notes noticeable but a combination of amplifier power AND cubic feet of air being moved by the cones that produces the pants flapping and floor/wall/ceiling movements.
My grand mother, "rest her soul" would have a loose bowel movement every time we watched "Master and Commander". I always thought it was because she was in love with the Captain of the ship. But I recently read where long loud subsonic sounds or abrupt loud explosive sounds can induce vomiting and stomach upset. I'll bet those canon shots in the movie excited her colon and "whoooosh", there she went!!!
 

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There are some low frequency tones in Blackhawk Down's Irene scene, I think 5-7Hz or something. However it's not a whole lot. If you turn it way up, you'll sort of feel a little bit, but not much.

You're better off playing around with War of the Worlds or Hitchhiker's Guide to the Galaxy, or there's one scene where a Griffin flies overhead in Narnia that gives you one pant flap.

Do you have flat output to something below 10Hz? If you're like -6dB at 10Hz or something, you won't feel so much.
 

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Discussion Starter · #17 ·
There are some low frequency tones in Blackhawk Down's Irene scene, I think 5-7Hz or something. However it's not a whole lot. If you turn it way up, you'll sort of feel a little bit, but not much.

You're better off playing around with War of the Worlds or Hitchhiker's Guide to the Galaxy, or there's one scene where a Griffin flies overhead in Narnia that gives you one pant flap.

Do you have flat output to something below 10Hz? If you're like -6dB at 10Hz or something, you won't feel so much.
I got a confirmation that my 2 drivers are capable of 10hz from CIB forum, ThomasW. However, the reason why I wasn't feeling it is because of the way it's currently setup. I'll be working on my theater this year. I'll do more 10hz below test in the future but not right now so as not to fry/ruin my drivers. Right now, I'm very happy with the performance on 20hz and above.

Oh, for the War of the Worlds, that movie is insane! I love its LFEs. :)

Thanks guys for all the help.
 
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