postalrat said:
Ah, some welcome reality.
I'm not convinced anybody can really waft enough of the air in their room at 20 Hz at a level that can be heard. There's an enormous difference between the air movement needed to hear midfrequencies and the outrageous amount of air movement needed to produce detectable 20 Hz sounds (if they can be heard by ear at all). It may not take a lot of energy to shake windows and furniture, those rattles are no evidence.
Of course, many of us have put big 20 Hz signals into speakers and heard some very low tone start as we did so. But what I think is happening is that we are hearing distortion products. I suspect that even 2% harmonically related distortion products would produce the illusion of the basic note, in the absence of any such basic note really being present. Tough thought, I know.
Next time you try that, ask yourself this, "Can I hear some stuff that isn't really 20 Hz?" If such stuff is present (and I bet it is), maybe your brain has created that 20 Hz tone... and that can be fully satisfying.
BTW, the same is true of those 16 Hz organ pipes thinking you really were hearing 16 Hz during a pipe organ demo. Spine tingling is another matter entirely and I think there are all kinds of different viscera resonance points (and differently for different bodies too) and the threshold for excitation may be far below hearing levels.
That argument certainly holds true for low piano notes where the amount of base tone present is miniscule in hearing effectiveness compared to the overtones that let your brain reconstitute the base frequency.
Hmmm... 0.01Hz results in a cycle time of 1/0.01Hz=100 seconds.
Assuming a driver with a 20mm peak-to-peak Xmax, that means 40mm traveled for one cycle. Therefore the driver would be moving at a rate of 40mm/100s=0.4mm per second.
It might *just* be visible. Can't think there's the slightest chance it would be audible to a human.
Assuming a driver with a 20mm peak-to-peak Xmax, that means 40mm traveled for one cycle. Therefore the driver would be moving at a rate of 40mm/100s=0.4mm per second.
It might *just* be visible. Can't think there's the slightest chance it would be audible to a human.
Don't sell your ears short.
Obviously, some of us have never been in an airplane.
The atmospheric pressure varies (sound) with altitude.
This "sound" is detectable with the ears.
and yes, I can notice the change over 100 seconds or even more.
There are even earplugs made to reduce the loudness.
http://www.amazon.com/EarPlanes-Flight-Protection-Pressure-Discomfort/dp/B000FI7D8E
Not at all musical, but certainly audible!
Obviously, some of us have never been in an airplane.
The atmospheric pressure varies (sound) with altitude.
This "sound" is detectable with the ears.
and yes, I can notice the change over 100 seconds or even more.
There are even earplugs made to reduce the loudness.
http://www.amazon.com/EarPlanes-Flight-Protection-Pressure-Discomfort/dp/B000FI7D8E
Not at all musical, but certainly audible!
Is it neccessary?
It's not needed to survive and it's not for the betterment of human kind. So it's not neccessary.
Is ist neccessary for Music and HT. You only need the frequency range to understand what is being said and what happens, for music maybe a little more. But the bandwith of a telephone is sufficient. So also not neccessary.
I have done the Dan Wiggins approach and build me a 6th-order Bandpass with 2 relatively cheap 15" long-throws capable of making itself be felt down to 12 Hz.
- For about 50% of my CDs it does nothing
- To 40% of my CDs it adds a little weight, a little size to the bass, a little awe here and there.
- On 10% of my CDs it reveals something formerly hidden, unearthes some ultradeep drones or wall shaking movements. It makes the differenz between impressive and awe-inspiring bass.
- For movies it is even more important, there are a lot of movies with bass below 25 (And Trucks and Trains without infrasonics just ain't "sound" real. Pay attention to it the next time a big one lets its engine roar...)
The infrasonics may be subtle effect when originating from big hall reverbations, but they sure aren't a subtle effect on the brink of conciousness when the Balrog comes stamping...
It's totally up to ones taste if the infras are worth the efford (and space!). My friends e.g. think it's not... but they still like to come over for a movie or two
Boom Shakar
Danny
It's not needed to survive and it's not for the betterment of human kind. So it's not neccessary.
Is ist neccessary for Music and HT. You only need the frequency range to understand what is being said and what happens, for music maybe a little more. But the bandwith of a telephone is sufficient. So also not neccessary.
I have done the Dan Wiggins approach and build me a 6th-order Bandpass with 2 relatively cheap 15" long-throws capable of making itself be felt down to 12 Hz.
- For about 50% of my CDs it does nothing
- To 40% of my CDs it adds a little weight, a little size to the bass, a little awe here and there.
- On 10% of my CDs it reveals something formerly hidden, unearthes some ultradeep drones or wall shaking movements. It makes the differenz between impressive and awe-inspiring bass.
- For movies it is even more important, there are a lot of movies with bass below 25 (And Trucks and Trains without infrasonics just ain't "sound" real. Pay attention to it the next time a big one lets its engine roar...)
The infrasonics may be subtle effect when originating from big hall reverbations, but they sure aren't a subtle effect on the brink of conciousness when the Balrog comes stamping...
It's totally up to ones taste if the infras are worth the efford (and space!). My friends e.g. think it's not... but they still like to come over for a movie or two
Boom Shakar
Danny
dazydee -
All very interesting and nicely expressed but a few issues arise. First, I'd provide roughly the same stats for when my woofer amp is off and I am talking about 40% and 10% of my eclectic "serious" music collection at 140 Hz cutoff... not 12 Hz.
A Klipschorn waffs more bass air in a room than any other method I know of and hard to imagine how other methods can truly waff as much air as genuine CD reality calls for. But sadly, the output is pretty much gone fast below maybe 35 Hz. I know how that must sound terrible and in fact a worse low bass than an AR-1 from 1955.
But then there is my old recording of railcars bumping into one another - gotta be over 40 yrs old and then went into and through and out of my computer into a CD burner. Sure shakes me and the whole room violently, rattles selected window panes each at its resonant frequency (not necessarily all that low), but nothing there under 35 Hz.
So, first question. My audio generator stops at 20 Hz... what makes you think you are putting "sensible" sound out anywhere near 12 Hz? (I use the word "sensible" to encompass both audible and visceraly detectable.)
It also isn't clear what the acoustic levels are in your listening room? Perhaps some others would find the bass cranked up to levels intolerable for most sources and way way out of balance? After all, you can always add a sub-sub-woofer covering, say, 12-24 Hz and set it at 40 dB louder than the rest of the system. And just how would you know if that sub-sub-thunderer is set at a "correct" level?
All very interesting and nicely expressed but a few issues arise. First, I'd provide roughly the same stats for when my woofer amp is off and I am talking about 40% and 10% of my eclectic "serious" music collection at 140 Hz cutoff... not 12 Hz.
A Klipschorn waffs more bass air in a room than any other method I know of and hard to imagine how other methods can truly waff as much air as genuine CD reality calls for. But sadly, the output is pretty much gone fast below maybe 35 Hz. I know how that must sound terrible and in fact a worse low bass than an AR-1 from 1955.
But then there is my old recording of railcars bumping into one another - gotta be over 40 yrs old and then went into and through and out of my computer into a CD burner. Sure shakes me and the whole room violently, rattles selected window panes each at its resonant frequency (not necessarily all that low), but nothing there under 35 Hz.
So, first question. My audio generator stops at 20 Hz... what makes you think you are putting "sensible" sound out anywhere near 12 Hz? (I use the word "sensible" to encompass both audible and visceraly detectable.)
It also isn't clear what the acoustic levels are in your listening room? Perhaps some others would find the bass cranked up to levels intolerable for most sources and way way out of balance? After all, you can always add a sub-sub-woofer covering, say, 12-24 Hz and set it at 40 dB louder than the rest of the system. And just how would you know if that sub-sub-thunderer is set at a "correct" level?
MaVo said:
There exists an esoteric technique called measuring. I think one can find out if two signals are equally loud with it.
Nice joke but I gather your are virginal as to the realities of measuring low bass - not to mention infra-sonic - sound.
Even the most masterful of Finnish woofer mavens doing trick measurements in some farmers broad field are meticulous in not suggesting what the results would be in anybody's living room. True, you can hang a mic in your living room and read the output, but then you can move it and get something different or change the test signal in some way....
I'm mostly in the measurement camp, you seem to be endorsing. So your point is a good one. But in practice, very hard to do, even for the best instrumented companies.
Daveis said:
Umm, I smell a fallacy here and the answer is yes and no. The sound at 20 Hz would have to be monumental to be heard even if you could ever hear it at all, as you correctly say. So, assuming an undiddled recording, to hear thunderous bass, you'd have to crank up the whole spectrum a LOT (but not as much to feel a thunderous bass). But what would be the point of that (assuming proper reproduction (?) is your goal)?
BTW, if you check out some of those tests, you'll find woofers producing 30% distortion tones at frequencies and volumes where the fundamental tone is unhearable, at least by me. Which means you are hearing the fundamental "tone" in your mind composed from the harmonics (which is normal) but it really isn't there... but you are sure it is.
MaVo said:
Granted, that is kind of like measuring and a good strategy in light of the challenges to doing any kind of definitive (or fantasy) measurement. But to illustrate the problems with that method, what you need to do is slam a car door in your living room and compare the spectrum to your reproduction and/or convene a listening panel to say that one sound bears a reasonable resemblance to the other. As a first step.
Another way to judge for your self is to listen to your music with high grade headphones. My Maggie 1.6QR's roll off around 36hz and I can still hear tones down to about 34hz with them. Switching over to my Sennheiser HD650's, the experience is similar to what Danny mentioned in post #209 of this thread.
Sennheiser HD650 headphones reproduct sound down to something 5hz. That's way beyond human hearing, but you feel the rumble and vibration down that low. The added context is nice.
-David
Sennheiser HD650 headphones reproduct sound down to something 5hz. That's way beyond human hearing, but you feel the rumble and vibration down that low. The added context is nice.
-David
bentoronto said:
Excuse me for being sceptical. But a cutoff of 140 Hz should be an obvious lack of all bass.
Do you have an 140 Hz highpass before your ESLs? For what I know, some of the Dayton-Wright ESLs can actually do bass.
and still it's qualities make it preferable to almost any other subwoofer...even I would sacrifice a few Hz for a Klipschhorn.
I don't get the point. Sure the bumping railcars produce enough SPL over 35 Hz to shake the room, even without the bottom octave.
Well,...because.... my PC software sine generator stops at 10 Hz
And i got a test CD with a sweep from 0 - 100 Hz with a pace of 2 Hz per second, so the CD timer tells you the current frequency.
I have set the level by trial and error, tweaking and listening (plus complaints and comments of my wife), so that the tones from 14 to 100 Hz give the same impression of loudness (like most people wiith a subwoofer and without measuring eqipment do). I have settled having 2 EQ setiings for loud and quiet listening. And i am aware that probably both settings give a big boost to the infras, but since I rarely listen at reference levels a little "loudness boost" ist permitted, i think.
For the next planned infra sub currently in building (new bandpass for music, tapped horn for the HT) measurements will be taken, as good as possible for this frequency range at least.
"Skeptical" is gracious way to express it. Appreciated. First, everybody should try it. Second, yes, the missing band is fairly obvious on a lot of music (although not on string quartets and a lot of good stuff). I think I earlier used the term "detectable" as a more helpful way to characterize the situation than "obvious" or not. Yes, generally detectable, but surprisingly modest consequences for most music unless you live and die by the viscera-shaking content.
For example, yesterday I played one of my favourite show-off CDs, the Holst Band Suites, Fennel/Cleveland/Telarc. Big side drum hit hard, much loud brass, even an anvil in band three The Blacksmiths Song (the ultimate orchestral square wave). Do my guts and the walls shake with a big boom with the Klipschorn (cut off 37 Hz): yes, lots, wow. But with the Klipschorn off, can I "hear" a big drum but not feel it: yes, not so bad even if this is the worse-case example. I am certainly not arguing that this is good, only saying "you'd be surprised how much you hear when the low range is restricted."
As an ESL guy for the last 31 years, a secret is to limit the frequency range (esp bottom) since hard to drive them well down there and tricky at the highest Hz too for various reasons. They have great bass, sort of rolls off below maybe 65 Hz, but as I said above.....
I respect your intellectual powers reflected in your approach to measurement. But there are many pitfalls. For example, what is the harmonic content of your PCs 10 Hz tone? And then that goes into your sub-sub-woofer where maybe 95 dB at 20 Hz (a pretty modest level at that freq in terms of human hearing threshold) leads, in many woofers, to 30% distortion. Could it be that you are really hearing the 5% second harmonic and 1% fourth when you think you are hearing the 95% fundamental? That 1% may be far more hearable than the 94%, even if there is any 10 Hz air motion in your room at all. And we really are talking more 30% not 5% and 1%.
For example, yesterday I played one of my favourite show-off CDs, the Holst Band Suites, Fennel/Cleveland/Telarc. Big side drum hit hard, much loud brass, even an anvil in band three The Blacksmiths Song (the ultimate orchestral square wave). Do my guts and the walls shake with a big boom with the Klipschorn (cut off 37 Hz): yes, lots, wow. But with the Klipschorn off, can I "hear" a big drum but not feel it: yes, not so bad even if this is the worse-case example. I am certainly not arguing that this is good, only saying "you'd be surprised how much you hear when the low range is restricted."
As an ESL guy for the last 31 years, a secret is to limit the frequency range (esp bottom) since hard to drive them well down there and tricky at the highest Hz too for various reasons. They have great bass, sort of rolls off below maybe 65 Hz, but as I said above.....
I respect your intellectual powers reflected in your approach to measurement. But there are many pitfalls. For example, what is the harmonic content of your PCs 10 Hz tone? And then that goes into your sub-sub-woofer where maybe 95 dB at 20 Hz (a pretty modest level at that freq in terms of human hearing threshold) leads, in many woofers, to 30% distortion. Could it be that you are really hearing the 5% second harmonic and 1% fourth when you think you are hearing the 95% fundamental? That 1% may be far more hearable than the 94%, even if there is any 10 Hz air motion in your room at all. And we really are talking more 30% not 5% and 1%.
Found this text at Linkwitz Lab.
After presenting the familiar dramatic curves showing the mamoth vibrations needed to hear at 20 Hz (and over 15 kHz), he comments (inadvertently supporting my post above):
"This means that if the 40 Hz 2nd harmonic of a 20 Hz tone is at a 24 dB lower level, then it will sound equally as loud as the fundamental. This corresponds to 6% 2nd harmonic distortion. The 3rd harmonic distortion would have to be below 1%, or over 38 dB down, in order that it is less loud than the 20 Hz fundamental. It all leads to very low distortion requirements. The fundamental frequency sound pressure level needs to be above 70 dB to even become audible and it should not be masked by higher frequency distortion products.
For a detailed investigation of requirements see: Louis D. Fielder & Eric M. Benjamin, "Subwoofer performance for accurate reproduction of music", JAES, Vol. 36, Number 6, pp. 443 (1988)."
Sooo, some folks who think they are hearing 20 Hz are really hearing the distortion... and you may not be able to tell the difference by ear, no kidding.
BTW, anybody have a copy of that Fielder and Benjamin paper to "loan" me? They also have a very long sub-woofer patent application worth reading, some weekend. As per the Iron Law, their patent indicated 2700 watts amp power (and a large air conditioner?).
After presenting the familiar dramatic curves showing the mamoth vibrations needed to hear at 20 Hz (and over 15 kHz), he comments (inadvertently supporting my post above):
"This means that if the 40 Hz 2nd harmonic of a 20 Hz tone is at a 24 dB lower level, then it will sound equally as loud as the fundamental. This corresponds to 6% 2nd harmonic distortion. The 3rd harmonic distortion would have to be below 1%, or over 38 dB down, in order that it is less loud than the 20 Hz fundamental. It all leads to very low distortion requirements. The fundamental frequency sound pressure level needs to be above 70 dB to even become audible and it should not be masked by higher frequency distortion products.
For a detailed investigation of requirements see: Louis D. Fielder & Eric M. Benjamin, "Subwoofer performance for accurate reproduction of music", JAES, Vol. 36, Number 6, pp. 443 (1988)."
Sooo, some folks who think they are hearing 20 Hz are really hearing the distortion... and you may not be able to tell the difference by ear, no kidding.
BTW, anybody have a copy of that Fielder and Benjamin paper to "loan" me? They also have a very long sub-woofer patent application worth reading, some weekend. As per the Iron Law, their patent indicated 2700 watts amp power (and a large air conditioner?).