what db/Hz combinations actually DO cause house damage?

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infrasound
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what db/Hz combinations actually DO cause house damage?

#1 Post by infrasound » Fri Mar 03, 2017 3:09 am

This may sound slightly silly in a way in that people talk about subwoofers that will "break your house" but i'm never sure if that's more a figure of speech, or a literal truth.

Some people have reported throwing a bunch of DJ bass bins into a house and having dust and ceiling plaster particles starting to come down, that's clearly there. Steve Meade did the same thing with his truck in a massive indoor trade show type area apparently. People with infinite baffle arrays suggest 120-125db will cause damage but dont mention frequencies other than they play lower than anything. It sounds like even 115db THX levels will not do it, but the movie Earthquake from the 70's did I think and the horn systems they had playing was reported to damage theaters - if I remember what I read it sounded like they pushed 120db at 25hz and 35hz.

At what combination of volume and lower frequency does damage (even if slower cumulative damage) actually start to become an issue? The kind of level that "if you live in a rented place for 10 years with THAT system you wont be getting your deposit back".

I include HZ as well as db because i'm a fan of pipe organ music - i'm pretty sure the system i'd like to reproduce 16hz fundamentals would cause damage at a lower level than a guy blasting 60hz techno sinewave.


At what point do people want custom built home theater rooms not just for acoustics but even for handling the pressure? :)

Will two Tuba HT's produce volume/frequencies leading to house damage or would I need four??

gzc_stageTech
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Re: what db/Hz combinations actually DO cause house damage?

#2 Post by gzc_stageTech » Fri Mar 03, 2017 8:46 am

infrasound wrote:...At what combination of volume and lower frequency does damage (even if slower cumulative damage) actually start to become an issue?...At what point do people want custom built home theater rooms not just for acoustics but even for handling the pressure?
It depends if your house is built with straw, sticks, or bricks "little piggie".

The energy can either resonate or attenuate the building and contents. Glass window panes will rattle with 60Hz at 90-95db, especially if the panes are large. Shelves full of small objects will jump and dance too.

Mass helps to lower the resonant frequency and stiffness aggravates it (flexible structures absorb the energy better...soft pillows compared to the coffee table).

If you're trying to create an earthquake to cause damage, then certainly 20Hz and lower will do it, especially if you can get there with SPLs around 100db. So, if playing "the big, bad wolf", push your lows up there and you'll see the dust and other small objects fly.

But why? Instead of trying to drive the subharmonic frequencies to that extent, why not use tactile transducers to shake your theater chairs? My theater has shakers in the Lazyboys and there is no doubt when the sound track has LFE....you feel it. Of course, subwoofers help your ears "hear" it. But the sonic "perception" of the movement from the shakers brings it to life. And, the theater isn't destroyed.
infrasound wrote:Will two Tuba HT's produce volume/frequencies leading to house damage or would I need four??
Room size, acoustic treatment, windows and other breakable objects??? Go ahead and build 4...go insane if you want. But I hope your insurance is paid up.

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BrentEvans
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Re: what db/Hz combinations actually DO cause house damage?

#3 Post by BrentEvans » Fri Mar 03, 2017 2:41 pm

gzc_stageTech wrote: It depends if your house is built with straw, sticks, or bricks "little piggie".
Maybe.

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Re: what db/Hz combinations actually DO cause house damage?

#4 Post by appo1999 » Fri Mar 03, 2017 7:25 pm

I have 3 tht's with Lab 12's 1 tht with a Dayton 15 and 2 tt's with 10's... have 3,200 watts rms on tap for the bottom end thru a dbx subharmonic synth. the HT room is 26 ft by 22 ft ....I use it all up and haven't knocked my walls down yet...
Have given guests ptsd however

infrasound
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Re: what db/Hz combinations actually DO cause house damage?

#5 Post by infrasound » Sat Mar 04, 2017 5:37 am

gzc_stageTech wrote:If you're trying to create an earthquake to cause damage, then certainly 20Hz and lower will do it, especially if you can get there with SPLs around 100db. So, if playing "the big, bad wolf", push your lows up there and you'll see the dust and other small objects fly.

But why? Instead of trying to drive the subharmonic frequencies to that extent, why not use tactile transducers to shake your theater chairs?
infrasound wrote:Will two Tuba HT's produce volume/frequencies leading to house damage or would I need four??
Room size, acoustic treatment, windows and other breakable objects??? Go ahead and build 4...go insane if you want. But I hope your insurance is paid up.
Thats a good point! I'd forgotten about tactile transducers for years honestly... how well do they honestly work? Do people "feel them as transducers" or do they just think the bass from your speakers is unreal? (if they also think it's unreal i'm assuming you A/B/X'ed it - having heard of but never experienced it i'd always worried if it would actually work as described or just be gimmicky)

It's not so much a desire to break anything as much as wanting to push the audio as far as I can without a custom constructed room. In the future I will eventually have a custom home theater room and probably an infinite baffle system - but that's years off. So i'm trying to decide "how much is enough" to max what I am interested in now. I'm guessing it's probably two or four Tuba HT's though to last me until then.

I will freely admit that I love pipe organ music and the 16hz fundamental tones - that is a bit below where the THT's are designed for as far as I know/never seen a chart below 20hz but I can see it ramping down. It's more i'm aware at some point house damage is likely to ensue at some level i'm just not sure where. Also into some crazy electronic music which plays lower than anything. (even if i'm not sure why I can see 2.5hz waves on the mixing console when i've listened to it through pro headphones at a friends place... lots of true infrasonic content)


appo1999 wrote:I have 3 tht's with Lab 12's 1 tht with a Dayton 15 and 2 tt's with 10's... have 3,200 watts rms on tap for the bottom end thru a dbx subharmonic synth. the HT room is 26 ft by 22 ft ....I use it all up and haven't knocked my walls down yet...
Have given guests ptsd however
Can you tell me about the synthesizer? I've always been fascinated by those things and wondered how well they work in the real world to beef up the sound... esp if everyone says true infrasound doens't matter and i'm pretty sure the THT's wont be putting out that much under 16hz except with room gain though I could be wrong.

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Re: what db/Hz combinations actually DO cause house damage?

#6 Post by appo1999 » Sat Mar 04, 2017 10:31 am

Have to be VERY careful not to over exert the woofers. It can add aw-sum bass but at a cost. Google the DBX sub-harmonic syn. for the details

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Radian
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Re: what db/Hz combinations actually DO cause house damage?

#7 Post by Radian » Sat Mar 04, 2017 1:50 pm

IME
120hz will vibrate/massage practically anything
40hz bursts will easily knock stuff off the walls
15hz is dangerous with mirrors, windows, or anything made of glass

~10hz is the natural frequency of most structures and at sufficient SPL (albeit nearly inaudible) can pull apart a house. Not cool.

Usually anything above 105 dB spl is were things get "tactile".
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Re: what db/Hz combinations actually DO cause house damage?

#8 Post by gzc_stageTech » Sun Mar 05, 2017 10:19 am

infrasound wrote:...I'd forgotten about tactile transducers...how well do they honestly work? Do people "feel them as transducers" or do they just think the bass from your speakers is unreal? (if they also think it's unreal i'm assuming you A/B/X'ed it - having heard of but never experienced it i'd always worried if it would actually work as described or just be gimmicky)
Not a gimmick at all. The transducers are like speakers (fixed field magnet + electro-magnetic voice coil), but instead of a suspension mounted cone to move air, they have a mass which moves. This "inertial" movement is translated in vibrations. Low frequencies travel well in solids, so the vibrations are easily felt in the surrounding structure (lazyboy chairs, in my example).

Years ago there was a product marketed call, "the Bone Fone" that was similar to a portable media player, but it didn't have speakers. Instead, it had resonating vibrators (tactile transducers) in a sock-like case that draped around your neck. The resonators located over your clavical bones and the sounds were literally felt inside you, not through the ears as sound. Of course you could "hear" the sounds because your ear bones would resonate as a part of the skelatal structure.

So tactile transducers work very well for the LFE (low frequency energy) present in movies and some musical instruments. But, I would still recommend an acoustical subwoofer simply because there are sounds in the SW bandwith that are better "heard".

The tactile transducers simply augment the LFE reducing the dB's you "think" you need for those frequencies. Plus, you won't destroy your theater and home.

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Re: what db/Hz combinations actually DO cause house damage?

#9 Post by Bruce Weldy » Sun Mar 05, 2017 11:40 am

Drummers have used these for years....yes, they work.

http://www.thebuttkicker.com/pro-audio

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infrasound
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Re: what db/Hz combinations actually DO cause house damage?

#10 Post by infrasound » Sun Mar 05, 2017 12:00 pm

Radian wrote:IME
120hz will vibrate/massage practically anything
40hz bursts will easily knock stuff off the walls
15hz is dangerous with mirrors, windows, or anything made of glass

~10hz is the natural frequency of most structures and at sufficient SPL (albeit nearly inaudible) can pull apart a house. Not cool.

Usually anything above 105 dB spl is were things get "tactile".
Thanks for the factoids. :) Should I assume that the Tuba HT's probably play "as low as any human in any normal house actually wants to go", ie yet another reason Bill hasn't designed an alternative to the Gjallerhorn (16hz horn sub) and similar?

Should I be concerned about the THT in general injuring my house? :) Or even if I have it I should be lowering the 16hz EQ setting anyways despite my love of pipe organ music... (and hopefully the tactile transducers will take it over seamlessly)

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Re: what db/Hz combinations actually DO cause house damage?

#11 Post by infrasound » Sun Mar 05, 2017 12:03 pm

gzc_stageTech wrote: So tactile transducers work very well for the LFE (low frequency energy) present in movies and some musical instruments. But, I would still recommend an acoustical subwoofer simply because there are sounds in the SW bandwith that are better "heard".

The tactile transducers simply augment the LFE reducing the dB's you "think" you need for those frequencies. Plus, you won't destroy your theater and home.
Which do you think would be the better experience, a couple Table Tubas with buttkickers in the couch, or just a Tuba HT, for the purpose of playing super deep electronica music, 16hz pipe organ fundamentals, AC3 soundtracks, and dubstep? (not that the answer I expect will sway me off building a THT, it's a when more than an if honestly)

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Re: what db/Hz combinations actually DO cause house damage?

#12 Post by Bruce Weldy » Sun Mar 05, 2017 5:55 pm

infrasound wrote: (not that the answer I expect will sway me off building a THT,
Then it's time to stop asking and start making sawdust.

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4 - OT12 2512 Melded/NSD2005
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2 - XF210


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Re: what db/Hz combinations actually DO cause house damage?

#13 Post by Tom Smit » Mon Mar 06, 2017 1:18 am

Bruce Weldy wrote:
infrasound wrote: (not that the answer I expect will sway me off building a THT,
Then it's time to stop asking and start making sawdust.
+1

Enjoy your builds! :clap:
TomS

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Re: what db/Hz combinations actually DO cause house damage?

#14 Post by gzc_stageTech » Mon Mar 06, 2017 1:54 am

Bruce Weldy wrote:
infrasound wrote: (not that the answer I expect will sway me off building a THT,
Then it's time to stop asking and start making sawdust.
+2.

Enuf talking about it...time to hear for yourself.

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