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Could a stereo make the roof fall down?

The midrange was the downfall of the heritage Klipsches.
In all seriousness, I have a lot of admiration for PWK's iconoclasm, and I wouldn't be where I am today without the 1974 Cornwalls I bought ca. 1996 -- but Klipsch (the man and his company) had idiosyncratic tastes in sound reproduction, and seemingly still do.

On topic, I have a sense that some folks may not appreciate how big of a deal resonance can be.


There was a published claim by Steve Deckert ("Decware"* -- and speaking of idiosyncratic ;)) early in the company's history of a subwoofer made from the basement of their early HQ in Peoria, IL. Deckert claimed (and, if memory serves, showed a photo) of a foundation crack caused by his whole-house subwoofer experimentation.

Unfortunately, some quality time spent googling yesterday failed to turn up the original source link(s), but rather only my own invocations of the story :(
Deckert started out as kind of a wild-eyed subwoofer nut before he got into single-ended magic :rolleyes:, but that early Decware history seems to have been largely expunged from his website. EDIT: Well, some of the stuff of old is still there: Deathbox, Housewrecker, and Wicked One plans are, apparently, still available ;) Still lookin' for evidence of the cracked foundation...
_______________
* https://www.decware.com/newsite/homepage.html
I can pretty much guarantee y'all'll not care much for Deckert's spiel. ;) I will also cop, with some chagrin, to owning one of his amusing little "Zen" amps (SE-84B morph), one of many attempts to smooth over the oh-so-rough edges of the aforementioned Cornies. :rolleyes:
 
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Well -- OK -- I tracked down at least a reference to (mention of) the basement subwoofer from Steve himself:

On a happier note, despite the corner horns having perhaps the best bass ever... and extension to the mid 20's... Imagine the following: The house was over 150 years old. There was a basement. I build a concrete horn in the basement that wrapped around the furnace. It has a throat that was 3 inches x 48 inches and a mouth that was 10 feet by 48 inches with a total length of 18 feet. The wall thickness of the horn was 4 inches on one side and infinity on the other being underground. I estimate it weighed over 3000 lbs for just one side wall of the horn. (grin)

With a single 12 inch woofer I cracked my basement in 72 places in on the very first test. The bass from this sub when you were upstairs in the listening chair was so fast you perceived the kick drum coming out of your chest.... agh the good old days... when i was still crazy.

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72 places... well, at least he quantified the damage. :cool::facepalm:

I am nothing if not obsessive... sometimes. :cool:

... and enough from me on the topic of resonance. :)
 
Horns work!
I've even got a reference for that!

March around the city once with all the armed men. Do this for six days. Have seven priests carry trumpets of rams’ horns in front of the ark. On the seventh day, march around the city seven times, with the priests blowing the trumpets. When you hear them sound a long blast on the trumpets, have the whole army give a loud shout; then the wall of the city will collapse and the army will go up, everyone straight in.”
Joshua 6:3-5 (NIV)

Horns are acoustic transformers. :cool:
 
I was thinking about resonant frequency problems like the aforementioned Tacoma bridge. But your post does indirectly raise another point: what if I am listening to music whilst the roof (and thus the steel beam) is under heavy load, such as during high winds?! Would that increase the chance of the beam failing?

Another way to consider my OP question is: what is the "brown note" of my roof? lol

Ok, in all seriousness, these types of beams have their weaknesses. Which I think is described and demonstrated pretty good in this video:


But If we draw a conclusion from a worst case scenario, which would be poor manufacturing of the beam, poor construction with insufficient precision, too high of a load (or weather conditions), and then, too loud of a stereo on top of all of it, would the stereo be the one to blame?

For all I know, when I crank up my setup high enough, room gain and some modes are such to make the doors, windows and brick walls vibrate. But this subjectively is really a threshold of physical discomfort and not something I would enjoy for any extended amount of time. Nothing bad has ever happened to the house or the roof over the years and I think such destructive frequencies, as someone already said, are not contained normally in music. Or either too low for any subwoofer that would fit in your room and reproduce it with high enough SPL. Simply, you would be the first to feel the "brown note" and call it a day.

Or maybe you have this type of setup http://web.tiscali.it/royaldevice/custom3.htm

Edit: this page shows photos of total of 16 x 18" woofers in situ http://web.tiscali.it/royaldevice/custom4.htm
 
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But If we draw a conclusion from a worst case scenario, which would be poor manufacturing of the beam, poor construction with insufficient precision, too high of a load (or weather conditions), and then, too loud of a stereo on top of all of it, would the stereo be the one to blame?
Good post. But regarding the quoted portion;
1) The beam should be fine from a manufacturing stand point as it would be to standards, but they do seem to put them in untreated, so perhaps corrosion over time could reduce its performance? But I don't think that is worth considering.
2) "Poor construction and insufficient precision", well that is a guarantee from cheap home builders! I think these steel beams just bear on some timber that is bearing onto the top of the wall. There might be a few fixings to keep it roughly in place, but there certainly isn't a proper bolted moment/shear-plate connection or anything. But I doubt this "sloppiness" is a problem either (as it is fit for purpose in supporting the roof against the elements)
3) "Too high of a load", is not a problem here because modern roofs are designed to engineering standards that cover the extremes, so the roof should be fine (and it's not worth considering increasing extremes for this discussion).
4) "too loud of a stereo on top of all of it, would the stereo be the one to blame?" - yes, lol. The roof is designed to handle the various weather related loads, but they don't consider a potential "weakening of performance" due to resonant frequencies induced by a subwoofer.

If jsilvela's post is correct, 29Hz is an easily producible frequency. This post was sort of tongue in cheek, not a true concern of mine, but at the same time there is a nugget of truth to it. I presumed the frequency might be single digit too, but apparently not. It might actually be a benefit that roofs like mine are made from timber and without tight tolerances, because that way they maintain a sort of flexibility. Some houses are made from light gauge steel though.

But anyway, if this were a real problem, I'm sure someone's roof would have fallen down at least once before!
 
Back of the envelop calculations:
  • The pressure amplitude to give 120 dB SPL is 20 Pa (= 0.42 lbf/ft^2).
    Reference: Wikipedia
    For a 4 m X 5 m roof, the amplitude of the load is 20 * 4 * 5 = 400 N (= 90 lbf). The pressure force is far insufficient to lift the roof.
  • Roofs are usually required to support a minimum live load of 20 lbf/ft^2.
    Reference
  • Natural frequencies of light wood frame structures are usually <10 Hz, at which point the output of the sub(s) will be weak.
    Reference
I'd conclude my answer to OP's question is the likelihood is going to be very very very small.
 
  • Natural frequencies of light wood frame structures are usually <10 Hz, at which point the output of the sub(s) will be weak.
    Reference
Good info, thanks.

Will read through that thread now. The 1st response is already on point!

It almost doesn't matter how strong the structure is if you excite a resonance as that will maximize the amplitude of the vibration, if undamped. What frequencies do houses resonate at? I don't know but its a critical question if you are going to take this seriously.

Edit: There were some decent posts in that thread, but just like this one, there are people only thinking of the "physical" pressure and how that possibly couldn't be enough. The resonant frequency is another problem. If a structural member begins resonating, it could buckle or shift or something, and that could cause failure.

User lukeamdman had this to say;
Before I beefed up the main supporting wall in my house, it would resonate violently between 15-20hz. When I say violently, I mean moving more than 1" peak to peak.
and when another user questioned if it was a non-load bearing "floating" wall, he replied;
This is a load bearing wall...holding up the floor above. All floor joists rest on it...
The top and bottom of the wall stays in the same place, but the center is flexing over 1" peak-to-peak...
In the right circumstances, that could be a huge problem!

Also, many places in the USA have earthquake codes/requirements, so their houses are meant to handle some level of vibration/movement. But that's not the case here, as we rarely get anything, and I don't think the housing codes have any particular requirements. I also don't think you would build rigid brick houses with steel beams basically just "resting" in position if earthquakes were a concern. Also the steel beam is just a "lazy solution" that enables "stick built" roofs to be built, rather than proper timber trusses being fabricated. So this particular problem might be unique to my part of the world.
 
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Good post. But regarding the quoted portion;
1) The beam should be fine from a manufacturing stand point as it would be to standards, but they do seem to put them in untreated, so perhaps corrosion over time could reduce its performance? But I don't think that is worth considering.
2) "Poor construction and insufficient precision", well that is a guarantee from cheap home builders! I think these steel beams just bear on some timber that is bearing onto the top of the wall. There might be a few fixings to keep it roughly in place, but there certainly isn't a proper bolted moment/shear-plate connection or anything. But I doubt this "sloppiness" is a problem either (as it is fit for purpose in supporting the roof against the elements)
3) "Too high of a load", is not a problem here because modern roofs are designed to engineering standards that cover the extremes, so the roof should be fine (and it's not worth considering increasing extremes for this discussion).
4) "too loud of a stereo on top of all of it, would the stereo be the one to blame?" - yes, lol. The roof is designed to handle the various weather related loads, but they don't consider a potential "weakening of performance" due to resonant frequencies induced by a subwoofer.

If jsilvela's post is correct, 29Hz is an easily producible frequency. This post was sort of tongue in cheek, not a true concern of mine, but at the same time there is a nugget of truth to it. I presumed the frequency might be single digit too, but apparently not. It might actually be a benefit that roofs like mine are made from timber and without tight tolerances, because that way they maintain a sort of flexibility. Some houses are made from light gauge steel though.

But anyway, if this were a real problem, I'm sure someone's roof would have fallen down at least once before!

Sound pressure itself, as some of us pointed in this thread, is hardly going to be a problem. Resonances may be, but, as most of us here care about sound quality, resonances by definition we like to minimize.
When I built my DIY system, in room I had a problem with floor resonance. It was literally vibrating under my feet. It had nothing to do with SQ, but at higher SPL, the surrounding stuff which were coupled to the hardwood floor (kitchen utensils included), had started singing by itself and were subjectively annoying. During transients, stuff like beforementioned, including windows and doors were louder than the program material. To me the solution was acoustic suspension, basically elastic feet to suspend tower speakers and the sub.
I can confirm that this did absolutely nothing to further improve sound quality, but the floor born resonances are very much attenuated and no longer a problem. Interestingly enough, stuff which are on the vertical plane (walls), do still vibrate on high SPL itself which is no surprise, but they don't buzz anymore. From that experience I can't help but come to a conclusion that resonances are more complex than we may think, possibly need force on both vertical and horizontal plane and leading to a some kind of interference which may even pulsate at an entirely different, lower frequency. Like in listening tests, when we play two frequencies which are close enough together and suddenly hear a pulsation at the differential frequency. In that sense, I don't know, but maybe it can be possible that the surface ratio of in room horizontal and vertical planes not only creates the room modes of sound pressure, but also resonances containing frequencies we can't audibly perceive because they are masked by the actual music.

I remember back in the day when I had one of those cheap downfiring subs. It was producing a dreadful one note bass through the ports and when cranked, at lower frequencies it started jumping up and down on it's plastic spikes. The resulting resonances were such that, below port tuning and high excursion it produced barely any SPL, but in turn was shaking the floor vigorously. Once I got out on the balcony when a bass heavy song was playing and the experience was scary to say the least. I thought it was going to collapse under my feet. Temporary solution was to flip the damn thing on it's side, suspended on some books, because that's what most of the students have. Long term solution was to get rid of it.

So, as I said before, you need a lot more moving mass, and a complex resonance, like throwing a brick in a washing machine, or, if you like it to be a bit more musical, an orchestra of cheap downfiring subs, for a multitone resonance, pointed the right way. This could possibly bring your entire house down.

To further illustrate, I can't help but thinking of Tesla's earthquake machine. For those that aren't familiar with this concept, it is easy to google it. But here's a working model:


Note the multitude of resonant frequencies.

EDIT: To me it's funny that subs I described sound quite similar to this machine. They have a very high port velocity and have more than 100% THD, so for one frequency input, they play many more. And they shake surrounding stuff like this.

Sorry about the long post, but I must conclude that if you care about sound quality, and are moderate in SPL, there's nothing to worry about.
 
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When is bakelite due a come back under the vintage fad? Some of it looks quite pretty in its own right...isn't it about time for a bakelite renaissance, hipsters. BTW, does anyone know what this thing does?
It's already started. Have you looked at glasses frames lately?
 
If anything could it would likely be something similar to the Eminent Technology rotary subwoofer. I heard one of these being demonstrated about 15 years ago at CEDIA. It was impressive and at times extremely unpleasant. This thing puts out extremely high SPLs between 20Hz and down into the single digits... as in 1-2Hz.

In the demo I experienced, the projector and screen were bouncing around and the ceiling tiles were dropping out of their tracks.


Screen Shot 2023-03-10 at 2.10.29 PM.png
 
When is bakelite due a come back under the vintage fad? Some of it looks quite pretty in its own right...isn't it about time for a bakelite renaissance, hipsters. BTW, does anyone know what this thing does?

17120153_2_lg.jpeg
It's a radio, from back when the ADC and DSP were in glass bulbs.
 
It's a radio, from back when the ADC and DSP were in glass bulbs.
I think from back when the D in both ADC and DSP didn't exist.
 
A bit off to the side... but if one wants to destroy things with bass;




JSmith
 
A bit off to the side... but if one wants to destroy things with bass;




JSmith
I suspect there are some mid or inner ears being destroyed there also.
 
I suspect there are some mid or inner ears being destroyed there also.

I predict the bright future of EV's in this pointless line of business, since battery power here is the limitation, and they have plenty of it. Who knows, one day, maybe everything blows up. Where do they keep the spare windscreens, I wonder...
 
I predict the bright future of EV's in this pointless line of business, since battery power here is the limitation, and they have plenty of it. Who knows, one day, maybe everything blows up. Where do they keep the spare windscreens, I wonder...
Well... you know... the Cybertruck will have that covered. Eventually. :cool:


Tesla-Cybertruck-window.jpg
 
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