I'm new to this particular thread, but wanted to add my two cents worth (two hertz worth).
There is a mistaken impression that one only needs very deep bass response (say below 30 HZ or 20Hz) for that rare pipe organ recording or for movie soundtrack noises. Some people feel that the lowest frequency of interest ought to be the lowest note on a bass instrument, E1 (41.20Hz) and that 40 Hz response is therefore low enough for all but E. Power Biggs fans. Oh yes, the argument continues that 88-key pianos do go down to 27.5 Hz, but that the energy of that fundamental is very low due to inefficient sound board coupling (quite true). Well, 40 Hz may be low enough for some people, but this thinking, when professed as a fundamental truth for all others, reflects a misunderstanding of the physics involved, IMO.
Only steady state sine waves occupy a single frequency (in theory only those waveforms that started at –infinity and will continue through +infinity can be said to occupy a single discrete frequency). The transform of a 40 Hz tone that starts and stops abruptly (say, a plucked string) produces a frequency spectrum with variations on a sinx/x shape, which is to say that energy may be centered at 40 Hz, but that there is energy smeared well above and well below 40 Hz. (This should not be confused with sub-harmonics; that’s another matter.) We need to hear/feel that energy to recreate the full plucked or gated effect as if it were live. Energy from any transiently-gated bass waveform will show considerable energy down into the so-called infrasonic range. Drums combine periodic waveforms and some noise-like waveforms, but being transient in any case, also produce energy down very low, especially with bass drums, of course.
If you high-pass filter that original signal with a speaker that roll-offs below 40 Hz (and most do), especially with a steep roll-off like you’d have with a vented enclosure, then a part of the original spectrum is cut off, resulting in a changes to the transient envelop and time smearing. We're so used to it, we hardly notice most of the time.
The ear/brain/body can sense low frequencies even below levels where steady state sine waves cease to be audible. Call it a “feeling”. There exist plenty of decent recordings with some of this low frequency information left more or less intact. When played back on a truly wide range system, which is one that goes well below 20 Hz, there is a sense of openness, space and “being there”, more than the sensation of lots of bass tones. Too many people have really never heard a truly full-range system with good recordings.
Bag End makes subwoofers that are equalized down to 8Hz. Silly? Not at all; they understand musical physics. Their description follows: “The reason that the INFRA type subwoofers sound dramatically better than the others is because of their superior time domain performance. The INFRA subwoofer maintains the bass energy in a tight packet, aligned with the upper range signal, providing a seamless musical connection with the main loudspeakers. This is achieved by making the system have a very wide, very flat frequency domain response.” (I am not affiliated with bag End, nor do I endorse their products).
I am stepping off my soap box….right now! Comments?
There is a mistaken impression that one only needs very deep bass response (say below 30 HZ or 20Hz) for that rare pipe organ recording or for movie soundtrack noises. Some people feel that the lowest frequency of interest ought to be the lowest note on a bass instrument, E1 (41.20Hz) and that 40 Hz response is therefore low enough for all but E. Power Biggs fans. Oh yes, the argument continues that 88-key pianos do go down to 27.5 Hz, but that the energy of that fundamental is very low due to inefficient sound board coupling (quite true). Well, 40 Hz may be low enough for some people, but this thinking, when professed as a fundamental truth for all others, reflects a misunderstanding of the physics involved, IMO.
Only steady state sine waves occupy a single frequency (in theory only those waveforms that started at –infinity and will continue through +infinity can be said to occupy a single discrete frequency). The transform of a 40 Hz tone that starts and stops abruptly (say, a plucked string) produces a frequency spectrum with variations on a sinx/x shape, which is to say that energy may be centered at 40 Hz, but that there is energy smeared well above and well below 40 Hz. (This should not be confused with sub-harmonics; that’s another matter.) We need to hear/feel that energy to recreate the full plucked or gated effect as if it were live. Energy from any transiently-gated bass waveform will show considerable energy down into the so-called infrasonic range. Drums combine periodic waveforms and some noise-like waveforms, but being transient in any case, also produce energy down very low, especially with bass drums, of course.
If you high-pass filter that original signal with a speaker that roll-offs below 40 Hz (and most do), especially with a steep roll-off like you’d have with a vented enclosure, then a part of the original spectrum is cut off, resulting in a changes to the transient envelop and time smearing. We're so used to it, we hardly notice most of the time.
The ear/brain/body can sense low frequencies even below levels where steady state sine waves cease to be audible. Call it a “feeling”. There exist plenty of decent recordings with some of this low frequency information left more or less intact. When played back on a truly wide range system, which is one that goes well below 20 Hz, there is a sense of openness, space and “being there”, more than the sensation of lots of bass tones. Too many people have really never heard a truly full-range system with good recordings.
Bag End makes subwoofers that are equalized down to 8Hz. Silly? Not at all; they understand musical physics. Their description follows: “The reason that the INFRA type subwoofers sound dramatically better than the others is because of their superior time domain performance. The INFRA subwoofer maintains the bass energy in a tight packet, aligned with the upper range signal, providing a seamless musical connection with the main loudspeakers. This is achieved by making the system have a very wide, very flat frequency domain response.” (I am not affiliated with bag End, nor do I endorse their products).
I am stepping off my soap box….right now! Comments?
Right on!
I do believe this goes for the other direction as well. Even if most of us only hear up to 18k listening to sine waves I think we need DSD or 24/192 to even approach truly realistic sound. The sharp roll of down low and the brickwall shape at the upper limit of 16/44.1 PCM is a phenomena that never happen in nature.
5Hz-50kHz BW is a realistic goal for a high performance rig IMO.
One must also not forget that not only our speakers are BW limited, but also some electronics, the microphones and lots of intermediate stages and all of this accumulate which is very detrimental to natural sound. -1dB here and -3dB there soon creep down well into the audible range, resulting not only in decreased amplitude but also as a phase distortion, a distortion in time domain as you mention.
/Peter
I do believe this goes for the other direction as well. Even if most of us only hear up to 18k listening to sine waves I think we need DSD or 24/192 to even approach truly realistic sound. The sharp roll of down low and the brickwall shape at the upper limit of 16/44.1 PCM is a phenomena that never happen in nature.
5Hz-50kHz BW is a realistic goal for a high performance rig IMO.
One must also not forget that not only our speakers are BW limited, but also some electronics, the microphones and lots of intermediate stages and all of this accumulate which is very detrimental to natural sound. -1dB here and -3dB there soon creep down well into the audible range, resulting not only in decreased amplitude but also as a phase distortion, a distortion in time domain as you mention.
/Peter
Hi,
IMO you are in the wrong forum. Audio ranges from 20Hz to 20kHz although at my age it stops at 14kHz. This is DIYaudio.
Find a forum called DIYfeeling(infra) to DIYultra and ask them.
Sorry you asked for comment, I'm not feeling too helpfull tonight.
I agree but for a different reason. To get a flat response over the full range you need to ensure the reproducing system is frequency and phase accurate and this necessarily requires the system to reproduce well outside nature's audio range.
I believe that most listeners will agree that our limited range systems are a compromise that try to meet value, space and partner/neighbour demands.
IMO you are in the wrong forum. Audio ranges from 20Hz to 20kHz although at my age it stops at 14kHz. This is DIYaudio.
Find a forum called DIYfeeling(infra) to DIYultra and ask them.
Sorry you asked for comment, I'm not feeling too helpfull tonight.
I agree but for a different reason. To get a flat response over the full range you need to ensure the reproducing system is frequency and phase accurate and this necessarily requires the system to reproduce well outside nature's audio range.
I believe that most listeners will agree that our limited range systems are a compromise that try to meet value, space and partner/neighbour demands.
Peter,
Good point about needing top-end extension for similar reasons! Now, this is not a subwoofer topic, but my first posting sure was.
Good point about needing top-end extension for similar reasons! Now, this is not a subwoofer topic, but my first posting sure was.
In addition to what you've said, it would be good to point out that extended low frequency response has to be accompanied by a good power bandwidth in order for it to be useful. You have to move a lot of air. That's the part of low frequency cabinet and driver design that's hardest to accomplish.
And you're right. Too many people haven't heard this kind of low end.
And you're right. Too many people haven't heard this kind of low end.
I agree with you, we will probably be able someday to go to 1 Hz - 100 kHz. With Diamond drivers and the like we are near the 100 kHz, but the low end is causing more problems.
Earthquakes 😀
A well built cinema made to handle the new Movie, San Francisco, with 1 Hz 130 dB blasts!
Well, we need at least 5 Hz I guess... to reproduce most of the spectral content of the 8.2 Hz organ pipe.
1 Hz - 100 kHz sounds good too, "my system handles 5 decades" or maybe 1 Hz - 131 kHz, "my system handles 17 octaves"...
A well built cinema made to handle the new Movie, San Francisco, with 1 Hz 130 dB blasts!
Well, we need at least 5 Hz I guess... to reproduce most of the spectral content of the 8.2 Hz organ pipe.
1 Hz - 100 kHz sounds good too, "my system handles 5 decades" or maybe 1 Hz - 131 kHz, "my system handles 17 octaves"...
I have to agree with IMO.
Recently I listened to a concert in a park and it was a percussion
group from china. There were huge drums, the biggest I've
seen so far. The PA sound system was adequate with big
speakers like in rock concerts. I compared the sounds emitting
from the huge speakers and from the sounds coming from
the huge drums by going back in forth to the 2 sound sources.
The sound coming from the big speakers paled in comparison
from the sound coming from the huge drums! With these drums
it's so much better to listened with both the ears and our bodies!
It was obvious too that the SUB-frequencies from different
directions were mixing and the resultant AUDIO frequencies
were being produced.
We live on planet earth and we do hear the sub and ultra
ranges but we audiophile unconsciously know it's very
expensive to extend our current systems!
Peace
sonda
Recently I listened to a concert in a park and it was a percussion
group from china. There were huge drums, the biggest I've
seen so far. The PA sound system was adequate with big
speakers like in rock concerts. I compared the sounds emitting
from the huge speakers and from the sounds coming from
the huge drums by going back in forth to the 2 sound sources.
The sound coming from the big speakers paled in comparison
from the sound coming from the huge drums! With these drums
it's so much better to listened with both the ears and our bodies!
It was obvious too that the SUB-frequencies from different
directions were mixing and the resultant AUDIO frequencies
were being produced.
We live on planet earth and we do hear the sub and ultra
ranges but we audiophile unconsciously know it's very
expensive to extend our current systems!
Peace
sonda
I'm all for low bass response, but there's a few problems.
First, there isn't much down there in the vast majority of recordings. Sure there's something now and then that's worthy, but most of my CD's I have pretty sucky bass. I've dabbled with a subharmonic synthesizer a bit, and that's frequently a benefit on the really sucky recordings.
Second, (and I think this is the bigger problem) reproducing really low frequencies with any reasonably low amount of distortion is really hard and/or expensive. I heard a Bag End system in a club a long time ago during the day. I tossed in a cd with a 20 Hz sine wave. It really wasn't all that impressive, especially considering there was a wall of 18's and a downright stupid amount of power. 18" woofers in a small sealed boxes with a F3 of 80Hz. So if you're 98 dB/W at 80 Hz, then you're around 74 dB/W at 20 Hz. And by the time you're putting enough power into the poor things to be getting some decent 20 Hz output, you're hearing way more harmonic distortion than anything. It'd be one thing if they were using some quality woofers (JBL, McCauley, etc), but instead it's likely (slight guess here) some marginal Eminence stuff (not bad for the money, but...). So it may be time-correct and "flat to 8 Hz" but overall I thought it sucked.
I've got a couple dayton titanic 15's in 3 ft3 sealed boxes. I need a bit of EQ boost to get things flat down to 20 Hz. The subs are very close to my listening position, so any distortion tends to draw attention to them. I've mounted one of them inverted to cancel the even order harmonics which worked well (measured and confirmed it the trueaudio 1/24th octave rta). But odd order distortion is still pretty high. Just today I was putting a 20W 20Hz sine wave into both. Third harmonic was down just 5.5 dB from the fundamental.
I realize these aren't the best drivers out there, but I think this goes a ways to show the problem. Has anyone else measured distortion like this?
I've been considering making some new subs for a while. First I'd be curious to hear the titanics in a big ported box, so I don't need to EQ the bottom end. If that fails, something like a JBL 2226 or 2241 or TAD stuff looks reasonable. I'm kicking myself for missing out on PE's JBL Sub1500 (Revel) closeout deal a year or two back. I suspect those would have worked very nicely.
- Robert
First, there isn't much down there in the vast majority of recordings. Sure there's something now and then that's worthy, but most of my CD's I have pretty sucky bass. I've dabbled with a subharmonic synthesizer a bit, and that's frequently a benefit on the really sucky recordings.
Second, (and I think this is the bigger problem) reproducing really low frequencies with any reasonably low amount of distortion is really hard and/or expensive. I heard a Bag End system in a club a long time ago during the day. I tossed in a cd with a 20 Hz sine wave. It really wasn't all that impressive, especially considering there was a wall of 18's and a downright stupid amount of power. 18" woofers in a small sealed boxes with a F3 of 80Hz. So if you're 98 dB/W at 80 Hz, then you're around 74 dB/W at 20 Hz. And by the time you're putting enough power into the poor things to be getting some decent 20 Hz output, you're hearing way more harmonic distortion than anything. It'd be one thing if they were using some quality woofers (JBL, McCauley, etc), but instead it's likely (slight guess here) some marginal Eminence stuff (not bad for the money, but...). So it may be time-correct and "flat to 8 Hz" but overall I thought it sucked.
I've got a couple dayton titanic 15's in 3 ft3 sealed boxes. I need a bit of EQ boost to get things flat down to 20 Hz. The subs are very close to my listening position, so any distortion tends to draw attention to them. I've mounted one of them inverted to cancel the even order harmonics which worked well (measured and confirmed it the trueaudio 1/24th octave rta). But odd order distortion is still pretty high. Just today I was putting a 20W 20Hz sine wave into both. Third harmonic was down just 5.5 dB from the fundamental.
I realize these aren't the best drivers out there, but I think this goes a ways to show the problem. Has anyone else measured distortion like this?I've been considering making some new subs for a while. First I'd be curious to hear the titanics in a big ported box, so I don't need to EQ the bottom end. If that fails, something like a JBL 2226 or 2241 or TAD stuff looks reasonable. I'm kicking myself for missing out on PE's JBL Sub1500 (Revel) closeout deal a year or two back. I suspect those would have worked very nicely.
- Robert
For low distortion low bass with decent level there are good alternatives from TC sounds, Aura and Adire for example. The XBL2 from Adire is very nice for extreme applications.
/Peter
/Peter
A lot of people say there isn't much bass down at 20 Hz, but I wonder if they have actually looked at a RTA with a range of different music and movies. I think they might be surprised. I have an RTA permanently running in my system on all the time. I can tell you that the bass often goes deeper than you think. Even music that doesn't appear to have much deep bass.
* a lot of action / sci fi movies have bass at 20 Hz a lot of the time equal to the output in the midrange, where you have a bass heavy deep boom (heavy door slamming shut, someone getting clobbered in a fight scene, avalanch, big rocks falling, concrete doors slamming etc), this is often the case with boost centred around 40 Hz which tapers off either side
* some movies with a dark, forboding feel (especially blade) have a rising amount of output down to 20 Hz (below that my RTA doesn't display), I think it actually extends down well below that
I often wonder what that content below 40 Hz actually is, and sometimes I wonder how useful it is. I should try rolling off the response below 40 Hz to see how much difference there is. My system is eq'd flat from 20 - 20k, with the exception of part of one dip at 80 Hz due to a room mode.
I think once you go below 20 Hz, the law of diminishing returns sets in. The impact of the lower bass diminishes but the cost escalates. To continue to get the same output lower you need 4x the displacement/octave. To get down from 20 Hz to 10 Hz you need to spend 4x as much. To then get down to 5 Hz you need to spend 16x as much as 20 Hz. You budget has just gone from $1000 to $16,000!!! (who needs a car anyway!)
If you have a driver with quite a bit of excursion to spare, that you can't use with an affordable amp, or without the thermal power limit being found ... then you might consider an EBS and use the spare excursion to go A LITTLE lower. You might get down to 15 Hz in room or lower, without giving up significant SPL or spending more.
However, at the same time, as you go lower the threshold of hearing goes up. Not only does it cost you more to go lower, but it does not have the same effect.
* a lot of action / sci fi movies have bass at 20 Hz a lot of the time equal to the output in the midrange, where you have a bass heavy deep boom (heavy door slamming shut, someone getting clobbered in a fight scene, avalanch, big rocks falling, concrete doors slamming etc), this is often the case with boost centred around 40 Hz which tapers off either side
* some movies with a dark, forboding feel (especially blade) have a rising amount of output down to 20 Hz (below that my RTA doesn't display), I think it actually extends down well below that
I often wonder what that content below 40 Hz actually is, and sometimes I wonder how useful it is. I should try rolling off the response below 40 Hz to see how much difference there is. My system is eq'd flat from 20 - 20k, with the exception of part of one dip at 80 Hz due to a room mode.
I think once you go below 20 Hz, the law of diminishing returns sets in. The impact of the lower bass diminishes but the cost escalates. To continue to get the same output lower you need 4x the displacement/octave. To get down from 20 Hz to 10 Hz you need to spend 4x as much. To then get down to 5 Hz you need to spend 16x as much as 20 Hz. You budget has just gone from $1000 to $16,000!!! (who needs a car anyway!)
If you have a driver with quite a bit of excursion to spare, that you can't use with an affordable amp, or without the thermal power limit being found ... then you might consider an EBS and use the spare excursion to go A LITTLE lower. You might get down to 15 Hz in room or lower, without giving up significant SPL or spending more.
However, at the same time, as you go lower the threshold of hearing goes up. Not only does it cost you more to go lower, but it does not have the same effect.
Makes sence what you say Paul.
My thoughts.. Even if (as you say) we need 4x the excursion we go down one octave, the content in music is low down there so we probably do not need flat power respons.
Indeed the threshold of hearing changes as we go down in frequency, but the question is if the studies that prooved this used sine waves and/or dynamic material.
Possibly a flat response with low gropdelay and phase shift makes difference with music and possibly it´s very worthwhile and audible.
There´s a world of difference between a music only rig and a theater rig as you mention, since there are tons of power down low in movies. In music the power is often not high down low, but still there is information down there and it needs to be intact in level as well in time to be perceived as fully realistic.
For serious low bass like this it almost only makes sense to use corner placed subs with EQ/DSP becasue the enormous gain in a room, in a corner makes it possible to get this without fridge sized boxes and a price tag of $16.000. as you mention.
One of the better sounds I´ve heard was in a small room from a pair of speakers using TC sounds 10" in closed boxes of 30 liters and a big bass absorber in one corner. The subs was EQ´ed flat to 10Hz.
/Peter
My thoughts.. Even if (as you say) we need 4x the excursion we go down one octave, the content in music is low down there so we probably do not need flat power respons.
Indeed the threshold of hearing changes as we go down in frequency, but the question is if the studies that prooved this used sine waves and/or dynamic material.
Possibly a flat response with low gropdelay and phase shift makes difference with music and possibly it´s very worthwhile and audible.
There´s a world of difference between a music only rig and a theater rig as you mention, since there are tons of power down low in movies. In music the power is often not high down low, but still there is information down there and it needs to be intact in level as well in time to be perceived as fully realistic.
For serious low bass like this it almost only makes sense to use corner placed subs with EQ/DSP becasue the enormous gain in a room, in a corner makes it possible to get this without fridge sized boxes and a price tag of $16.000. as you mention.
One of the better sounds I´ve heard was in a small room from a pair of speakers using TC sounds 10" in closed boxes of 30 liters and a big bass absorber in one corner. The subs was EQ´ed flat to 10Hz.
/Peter
For somebody that listens to Chinese music from time to time, I can understand what efren sabio of Hong Kong means. One of the attractions of classical Chinese music to me is the rhythm and dynamics. Western music has always been about harmonics (originally only one harmony).
Having that said, I still enjoy Chinese music very much on my Mårten Design Minguses, which go down to 36 hz. I'm not saying I wouldn't like my speakers to go deeper. But a sub wouldn't add to my enjoyment. It would impress the surround crowd and car audio fans, though.
In short, I have no answer. But from experience, frequency range isn't one of my main priorities when it comes to speakers. And my preference of floor-standing speakers has more to do with their ability to play with power and authority at low volume than anything else. Small speakers, in contrast, tend to die at low volumes.
Having that said, I still enjoy Chinese music very much on my Mårten Design Minguses, which go down to 36 hz. I'm not saying I wouldn't like my speakers to go deeper. But a sub wouldn't add to my enjoyment. It would impress the surround crowd and car audio fans, though.
In short, I have no answer. But from experience, frequency range isn't one of my main priorities when it comes to speakers. And my preference of floor-standing speakers has more to do with their ability to play with power and authority at low volume than anything else. Small speakers, in contrast, tend to die at low volumes.
I assume you mean frequency response as power response is another thing altogether ...
I think this is in fact quite well established and quite logical. If at some point the ear can no longer hear sounds due to it being too low in frequency, then it follows that the sensitivity of the ear either drops gradually, or suddenly, the latter being very unlikely.
My observation is that music NEVER only "goes down to x Hz" - there is always some content at 20 Hz as shown on the RTA. The question is what is the level relative to the rest of the spectrum. Is that statement based on observation / measurement or subjective opinion?
IMO accuracy means useable output down to 20 Hz.
That's a matter of personal taste. But I would say also that it's a matter of having heard a well integrated quality sub setup. Without having experienced this, which most haven't, you can't really know what you like. Many who don't like subs haven't heard it done right.
That's most likely true. But I can only speak from experience. And, as said, I wouldn't mind for my speakers to go down to 20 hz, or 1 for that matter. I just don't think it's as important as some other things. Of course, when you have those other things...
Paul,
I wrote:
"My thoughts.. Even if (as you say) we need 4x the excursion we go down one octave, the content in music is low down there so we probably do not need flat power respons."
You wrote:
"I assume you mean frequency response as power response is another thing altogether ...
quote"
I know what frequency respons and power respons is. What I mean is that we do need flat frequency response, but not necessarily flat power response, since the power at sub frequencies are relatively low in music.
I wrote:
"Indeed the threshold of hearing changes as we go down in frequency, but the question is if the studies that prooved this used sine waves and/or dynamic material."
You wrote:
"I think this is in fact quite well established and quite logical. If at some point the ear can no longer hear sounds due to it being too low in frequency, then it follows that the sensitivity of the ear either drops gradually, or suddenly, the latter being very unlikely."
My point is; if we do only hear down to 20Hz at SINE WAVES that doesn´t mean that we can not perceive and also hear energy well below that in a complex dynamic waveform.
Same goes for upper limits of hearing. We say that normally we only hear up to 20k sine waves, but that does not mean we can not hear or perceive higher spectral components in a transient.
That was my concern. I wonder how these tests are done, with static or dynamic signals.
Or maybe we do not hear jack sh_t outside 20Hz-20k but are very sensitive for distortion in time domain. This would imply we need a flat response well outside the audible range in order to have flat accurat phase response IN the audible range.
/Peter
I wrote:
"My thoughts.. Even if (as you say) we need 4x the excursion we go down one octave, the content in music is low down there so we probably do not need flat power respons."
You wrote:
"I assume you mean frequency response as power response is another thing altogether ...
quote"
I know what frequency respons and power respons is. What I mean is that we do need flat frequency response, but not necessarily flat power response, since the power at sub frequencies are relatively low in music.
I wrote:
"Indeed the threshold of hearing changes as we go down in frequency, but the question is if the studies that prooved this used sine waves and/or dynamic material."
You wrote:
"I think this is in fact quite well established and quite logical. If at some point the ear can no longer hear sounds due to it being too low in frequency, then it follows that the sensitivity of the ear either drops gradually, or suddenly, the latter being very unlikely."
My point is; if we do only hear down to 20Hz at SINE WAVES that doesn´t mean that we can not perceive and also hear energy well below that in a complex dynamic waveform.
Same goes for upper limits of hearing. We say that normally we only hear up to 20k sine waves, but that does not mean we can not hear or perceive higher spectral components in a transient.
That was my concern. I wonder how these tests are done, with static or dynamic signals.
Or maybe we do not hear jack sh_t outside 20Hz-20k but are very sensitive for distortion in time domain. This would imply we need a flat response well outside the audible range in order to have flat accurat phase response IN the audible range.
/Peter
Electricity being (relatively) cheap, I wonder why some genius hasn't diy'ed a more robust electromechanical device for generating the lowest frequencies? More robust than say, a paper cone. Something on the order of a carefully suspended and damped false wall of stiff fiberglass coupled with a massive 120v "bass shaker" device.
Is this just completely WIBNI domain?
Is this just completely WIBNI domain?
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