Is infrasonic output with authority possible with dynamic drivers?

[TheWarrior]

You listed a wind turbine article. I don't see the relevance to our discussion. 20hz is plenty of extension. If you want below that you'll need a rotary sub

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That concluded:

1. Hearing perception, mediated by the inner hair cells of the cochlea, is remarkably insensitive to infrasound.

Bass response in a room is dictated by the room below 200 hz. That has to be accounted for and no high power sub or enormous driver will change that, when the goal is to get everyone listening to hear the same sounds.

 

[shadyJ]

You listed a wind turbine article. I don't see the relevance to our discussion. 20hz is plenty of extension. If you want below that you'll need a rotary sub

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Much of the research done on the effects of infrasound has been done to see if the sound of wind turbines can cause health problems. That motivation of the research does not invalidate the results of the research. The results shown here are pertinent to this discussion. Also, extension below 20 does not require a rotary sub by a long shot. Sub 20 Hz sound can be achieved by a much more modest system, but of course, the lower you want the system to dig, the more powerful it has to be.

 

[Auditor55]

A couple of points. Extremely deep bass can be heard, or at least sensed by the ears, and we are talking about stuff down to single digit frequency sound. And it can be heard more easily than it can be felt. A study was done on bass in this region, with normal healthy hearing vs profoundly deaf people. The hearing people were able to detect extreme deep bass frequencies much more easily than deaf people. But I would agree that such frequencies are not terribly important because we can not discern the difference in pitch down there, it is all just vague stuff. No way to tell the difference between 9 Hz and 12 Hz, although at high enough sound pressure levels and low enough frequencies you can actually tell by counting the individual cycles per second. Personally I would aim for 16 Hz extension, since there is some, although very little musical content that does dig that deep, such as a 32 ft stop on a pipe organ.

One thing in your post I would emphasize is that, as you said, it does not take a lot of power to vibrate and rattle stuff around the house. Some people thing their system is amazing because it can shake their windows, but it doesn't take much power at all to rattle stuff at their resonant frequency. I have seen regular bookshelf speakers do that. And that vibration will, more likely than not, be the real bottleneck to good low-frequency playback as well. Some people seem to like making their houses shake from subs though, and if that is what makes you happy, that is fine. It's not high-fidelity sound though.

They seem to like it for big budget summer action movies, those with a lots of explosions and gun fire. Kind of like that myself, however I'm concerned with the sound of music, popping, snapping, articulate bass.

 

[ATLAudio]

I don't care what anyone says. Among a litany of other things, a premium HT system (the best ever) will need to produce clean reference quality LFE (95 dB, 20 dB of headroom) at 16hz, at the MLP, using CEA 2010 distortion limits to meet my independent seal of approval for a premium top shelf HT system. You are absolutely free to disagree and consider my seal of approval to be hot garbage, be my guest, but I'm not changing my mind, nor do I insist to change yours. That is to say, an HT which can only present the same max at only 20, or 25hz sound bad, that's not true, I'm sure those can and do sound incredibly epic, but there's room for improvement. Conversely, demanding the same max capability at lower than 16hz involves seriously diminishing returns, and a lot more investment. If this is your approach to the hobby, that's great! Go on with your bad self! But, I don't find this to be particularly rewarding.

Caveats:
1. Almost any 15"+ vented sub on the ID market, corner loaded, should be able to do this in all but the most cavernous rooms due to 6-18dB room gain. There's some 12 and 13" subs that should also qualify.
2. You'll likely want 2 subs (occasionally 3, or 4) to smooth out response across the target listening area.

 

[TLS Guy]

I don't care what anyone says. Among a litany of other things, a premium HT system (the best ever) will need to produce clean reference quality LFE (95 dB, 20 dB of headroom) at 16hz, at the MLP, using CEA 2010 distortion limits to meet my independent seal of approval for a premium top shelf HT system. You are absolutely free to disagree and consider my seal of approval to be hot garbage, be my guest, but I'm not changing my mind, nor do I insist to change yours. That is to say, an HT which can only present the same max at only 20, or 25hz sound bad, that's not true, I'm sure those can and do sound incredibly epic, but there's room for improvement. Conversely, demanding the same max capability at lower than 16hz involves seriously diminishing returns, and a lot more investment. If this is your approach to the hobby, that's great! Go on with your bad self! But, I don't find this to be particularly rewarding.

Caveats:
1. Almost any 15"+ vented sub on the ID market, corner loaded, should be able to do this in all but the most cavernous rooms due to 6-18dB room gain. There's some 12 and 13" subs that should also qualify.
2. You'll likely want 2 subs (occasionally 3, or 4) to smooth out response across the target listening area.

That is not an unreasonable position. Certainly going below 16 Hz is a worthless pursuit.

That I think will get you anything audible. The previous referenced article is pretty much all BS and full of conjecture. If some one shows me a response from the 8th cranial nerve to an auditory stimulus in the 5 to 14 Hz range I will change my mind. Until then I won't.

TLs have an advantage as roll off is 12 db per octave and cone movement limited due to high pressure in the pipe at driver location and no need for power boost.

This is a subless system and has good output to 20 Hz and would obviously still have good output to 16 Hz.

 

[shadyJ]

Among a litany of other things, a premium HT system (the best ever) will need to produce clean reference quality LFE (95 dB, 20 dB of headroom) at 16hz, at the MLP, using CEA 2010 distortion limits to meet my independent seal of approval for a premium top shelf HT system.

CEA 2010 distortion limits are nowhere near good enough for a high-fidelity system. They can permit almost as much as 40% THD.

 

[panteragstk]

CEA 2010 distortion limits are nowhere near good enough for a high-fidelity system. They can permit almost as much as 40% THD.

That seems high...

 

[ATLAudio]

CEA 2010 distortion limits are nowhere near good enough for a high-fidelity system. They can permit almost as much as 40% THD.

I believe it's around 25-35% in ultra-low range, but THD alone doesn't tell me enough. In addition to THD CEA-2010 evaluates each harmonic differently, which tells me a better story. It’s far more likely the system will fail at particular harmonic order than reach THD max allowed. Moreover, in most cases it will only take another dB or two to take a system from 10% THD to 25-35%, or even higher than that. For my demands, I want LFE to perform at 95 dB with 20 dB of head room. So, hypothetically, at 95 dB, and 17 dB of head room I’m within 10% THD, but at 20 I’m around 30%. To each his own, but I certainly won’t pay a premium for that extra 2 dB to be at 10%.


Do what you like, but I'm more than comfortable with the CEA-2010 thresholds when it comes to distortion evaluation. There are some other considerations to be sure, but if you want 95 dB with 20 dB head room into the single digits AND 5-10% THD max, by all means, rock on with your badness.

 

[shadyJ]

I believe it's around 25-35% in ultra-low range, but THD alone doesn't tell me enough. In addition to THD CEA-2010 evaluates each harmonic differently, which tells me a better story. It’s far more likely the system will fail at particular harmonic order than reach THD max allowed. Moreover, in most cases it will only take another dB or two to take a system from 10% THD to 25-35%, or even higher than that. For my demands, I want LFE to perform at 95 dB with 20 dB of head room. So, hypothetically, at 95 dB, and 17 dB of head room I’m within 10% THD, but at 20 I’m around 30%. To each his own, but I certainly won’t pay a premium for that extra 2 dB to be at 10%.


Do what you like, but I'm more than comfortable with the CEA-2010 thresholds when it comes to distortion evaluation. There are some other considerations to be sure, but if you want 95 dB with 20 dB head room into the single digits AND 5-10% THD max, by all means, rock on with your badness.

There is no difference in the thresholds with respect to frequency range, unless you are using CEA-2010-B, which no one does, so that doesn't matter. You can achieve something like 39.75% THD for any frequency under CEA-2010 (and even more under CEA-2010-B) and still pass the test. CEA-2010 shouldn't really be used as a guide for distortion audibility, but more like at what point a subwoofer is pushed past its linear operation.

 

[yepimonfire]

CEA 2010 distortion limits are nowhere near good enough for a high-fidelity system. They can permit almost as much as 40% THD.

I'm not entirely sure what the cea 2010 limits permit, but I can tell you, at least from an amplification standpoint, with musical or movie content, I can't tell the difference between 1% and 10% thd, in fact, I don't notice anything until the amplifier hits hard clipping and it becomes very obvious.

With speakers, the pair of Klipsch r-15m I own started showing 20-30% THD below 50hz at levels above -15dB (90dBc at 3m), yet I can't hear that distortion when running them full range and playing excessively bass heavy music and movies at 90dB.

I certainly wouldn't want a sub to be rated as being able to perform to a specific level with 40% thd, but our ability to hear distortion when it comes to low frequencies isn't that good. IIRC, doesn't the 2010 cea rate it based on psychoacoustic perception?

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[yepimonfire]

They seem to like it for big budget summer action movies, those with a lots of explosions and gun fire. Kind of like that myself, however I'm concerned with the sound of music, popping, snapping, articulate bass.

In all reality, majority of movies lack significant content below 30hz. I have done several spectrum analysis graphs of LFE tracks, and most of the big "earth shaking" sounds are centered between 30-50hz. That kick in the chest bass comes from content centered around 40-50hz anyways.

You have to take into account that both Dolby and the SMPTE specifications for low frequency response call for a response from the front three channels of ~45hz, and 31hz for the subwoofer. When creating a mix for a movie, engineers generally take this into account, analyzing the spectrum of the LCR and LFE channels reveals that. Movies that dip down into 20hz and below are very very rare. THX calls for a response of 20hz I believe, but not everybody has built their cinema to THX specifications, and a quick look at the specifications of a majority of professional cinema subs will reveal most of them outside of THX certified subs have a -3dB point of around 30hz.

For music, outside of pipe organs, the lowest note on a piano is 28hz. For rock music, a response down to 40hz is more than adequate, since open e on a bass guitar is around 40hz (can't remember the exact frequency) and the fundamental frequency of a kick drum is around 50hz. My speakers have an in room response of 50hz, listening to rock, I can switch back in for between direct, which disables the subwoofer, and stereo and hardly hear a difference in bass.

The whole infrasonic thing is really just a curiosity of mine, considering the difficulty involved and expense of going below 20hz, it's not practical. I do listen to pipe organ music frequently, but the 32' stop still shakes my house with a sub that has an f3 of 25hz.

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[mtrycrafts]

...

With speakers, the pair of Klipsch r-15m I own started showing 20-30% THD below 50hz at levels above -15dB (90dBc at 3m), yet I can't hear that distortion when running them full range and playing excessively bass heavy music and movies at 90dB.

...

That is what research shows for detecting distortion from subs. Ever wonder why they are meassured at 10% distortion?
It just doesn't register in your brain. And, I think Toole may have mentioned, that in some case not even 100% on those lows.

 

[William Lemmerhirt]

In all reality, majority of movies lack significant content below 30hz. I have done several spectrum analysis graphs of LFE tracks, and most of the big "earth shaking" sounds are centered between 30-50hz. That kick in the chest bass comes from content centered around 40-50hz anyways.

You have to take into account that both Dolby and the SMPTE specifications for low frequency response call for a response from the front three channels of ~45hz, and 31hz for the subwoofer. When creating a mix for a movie, engineers generally take this into account, analyzing the spectrum of the LCR and LFE channels reveals that. Movies that dip down into 20hz and below are very very rare. THX calls for a response of 20hz I believe, but not everybody has built their cinema to THX specifications, and a quick look at the specifications of a majority of professional cinema subs will reveal most of them outside of THX certified subs have a -3dB point of around 30hz.

For music, outside of pipe organs, the lowest note on a piano is 28hz. For rock music, a response down to 40hz is more than adequate, since open e on a bass guitar is around 40hz (can't remember the exact frequency) and the fundamental frequency of a kick drum is around 50hz. My speakers have an in room response of 50hz, listening to rock, I can switch back in for between direct, which disables the subwoofer, and stereo and hardly hear a difference in bass.

The whole infrasonic thing is really just a curiosity of mine, considering the difficulty involved and expense of going below 20hz, it's not practical. I do listen to pipe organ music frequently, but the 32' stop still shakes my house with a sub that has an f3 of 25hz.

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Just though I'd add that dropped D bass as well as 5 string basses are lower than that. Around 30hz. Kick drums also can be tuned anywhere from 40 to 100(although I personally don't like the higher kick tunings like jazz. Btw, try switching your subs on/off while listening to Korn. Bet you'll notice that.
Also, dig through here a little. http://data-bass.ipbhost.com/index.php?/forum/4-bass-content/
I'd disagree that movies dip into the 20's are "very very rare". The reason most cinema subs f3 at 30 is because going below that takes a lot more than it's worth for most cinemas, and considering that 30hz is amazing for most casual movie goers, it mostly doesn't matter. There's also a lot of feel at 30hz. Think car audio. I think too if your subs f3 was more like 18-20 it might be eye opening for you.

 

[shadyJ]

I'm not entirely sure what the cea 2010 limits permit, but I can tell you, at least from an amplification standpoint, with musical or movie content, I can't tell the difference between 1% and 10% thd, in fact, I don't notice anything until the amplifier hits hard clipping and it becomes very obvious.

With speakers, the pair of Klipsch r-15m I own started showing 20-30% THD below 50hz at levels above -15dB (90dBc at 3m), yet I can't hear that distortion when running them full range and playing excessively bass heavy music and movies at 90dB.

I certainly wouldn't want a sub to be rated as being able to perform to a specific level with 40% thd, but our ability to hear distortion when it comes to low frequencies isn't that good. IIRC, doesn't the 2010 cea rate it based on psychoacoustic perception?

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The research behind CEA-2010 kind of references the few studies of psychoacoustic perception in this area, but it doesn't really heed them as a guideline. It has more to do with ascertaining the mechanical limits of the subwoofer or speaker. When the sub is approaching the thresholds, the distortion is clearly audible. For your reference, here is the distortion limits:

If you want to gauge your ability to detect distortion with typical content, you will need to be very familiar with the source content, otherwise there is nothing to judge it against.

 

[Steve81]

That is not an unreasonable position. Certainly going below 16 Hz is a worthless pursuit.

That I think will get you anything audible. The previous referenced article is pretty much all BS and full of conjecture. If some one shows me a response from the 8th cranial nerve to an auditory stimulus in the 5 to 14 Hz range I will change my mind. Until then I won't.

To offer a different perspective, the question of audibility is entirely irrelevant as to whether or not extension into the infrasonic realm is worthwhile. People aren't buying subs like the aforementioned JTR Cap 4000ULF to play 10Hz sine waves in hopes that they hear the fundamental. They buy them because they can add significantly to a home theater as it relates to the tactile experience.

Is it worthwhile? To each his own. If you're primarily concerned with classical music like the good doctor, and if your movie collection doesn't have a distinct tilt towards action blockbuster type films, then seeking extension beyond 16 or 20Hz may well be fruitless. As Mark notes, it may even be a serious distraction. OTOH, if those blockbusters make up a significant chunk of your screen time, being able to reproduce a soundtrack that can literally move you might well etch a smile on your face.

 

[ATLAudio]

There is no difference in the thresholds with respect to frequency range, unless you are using CEA-2010-B, which no one does, so that doesn't matter. You can achieve something like 39.75% THD for any frequency under CEA-2010 (and even more under CEA-2010-B) and still pass the test. CEA-2010 shouldn't really be used as a guide for distortion audibility, but more like at what point a subwoofer is pushed past its linear operation.

You can use it to determine how much max headroom you'll have, but what I'm saying isn't about "distortion audibility." Again, most of the time, a sub will fail at specific harmonic before it fails THD. If a sub fails at 3rd order, THD can still be relatively low, and or well below 40%. Also the difference in 30%+ THD and 10% (inaudible with source material) is usually 1-2 dB.

This is all good for prior to purchase, but what the room does can be a huge unknown. Among other things, at this point a good run of compression sweeps will be in order.

 

[yepimonfire]

Just though I'd add that dropped D bass as well as 5 string basses are lower than that. Around 30hz. Kick drums also can be tuned anywhere from 40 to 100(although I personally don't like the higher kick tunings like jazz. Btw, try switching your subs on/off while listening to Korn. Bet you'll notice that.
Also, dig through here a little. http://data-bass.ipbhost.com/index.php?/forum/4-bass-content/
I'd disagree that movies dip into the 20's are "very very rare". The reason most cinema subs f3 at 30 is because going below that takes a lot more than it's worth for most cinemas, and considering that 30hz is amazing for most casual movie goers, it mostly doesn't matter. There's also a lot of feel at 30hz. Think car audio. I think too if your subs f3 was more like 18-20 it might be eye opening for you.

Yeah I can notice it on that.

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[panteragstk]

To offer a different perspective, the question of audibility is entirely irrelevant as to whether or not extension into the infrasonic realm is worthwhile. People aren't buying subs like the aforementioned JTR Cap 4000ULF to play 10Hz sine waves in hopes that they hear the fundamental. They buy them because they can add significantly to a home theater as it relates to the tactile experience.

Is it worthwhile? To each his own. If you're primarily concerned with classical music like the good doctor, and if your movie collection doesn't have a distinct tilt towards action blockbuster type films, then seeking extension beyond 16 or 20Hz may well be fruitless. As Mark notes, it may even be a serious distraction. OTOH, if those blockbusters make up a significant chunk of your screen time, being able to reproduce a soundtrack that can literally move you might well etch a smile on your face.

You hit it on the head. This very much matches my logic. I have tons of different types of movies and music. I want my system to be accurate for all of them. I have tons of blockbusters that dig VERY deep and if my subs weren't capable I'd miss out. I also have some non-blockbuster stuff (wife movies as I call them) that has no need for a sub at all. The sounds aren't what make the movie cool.

I've always said that if you don't have a capable system you are missing out on what some movie soundtracks offer. It really is eye opening to have more capable bass than most theaters. Kinda makes you not want to go to the movies any more.

 

[Auditor55]

You hit it on the head. This very much matches my logic. I have tons of different types of movies and music. I want my system to be accurate for all of them. I have tons of blockbusters that dig VERY deep and if my subs weren't capable I'd miss out. I also have some non-blockbuster stuff (wife movies as I call them) that has no need for a sub at all. The sounds aren't what make the movie cool.

I've always said that if you don't have a capable system you are missing out on what some movie soundtracks offer. It really is eye opening to have more capable bass than most theaters. Kinda makes you not want to go to the movies any more.

Unfortunately for you, as the gentlemen noted above, very few movies, even so-called block busters, contain low frequency information below 30 Hz let alone 20 Hz. If you're spending money of equipment with intent on reproducing below 20 Hz (infrasounds) content, you are seriously experiencing the point of diminishing returns.

Also, sound isn't the only reason to enjoy a movie at the cinema. I went to see the Dunkirk in 70 mm and it was beautiful, movie was mediocre, but it looked and sound great. Btw, it won't coming to a home theater any time soon.

 

[Auditor55]

Just though I'd add that dropped D bass as well as 5 string basses are lower than that. Around 30hz. Kick drums also can be tuned anywhere from 40 to 100(although I personally don't like the higher kick tunings like jazz. Btw, try switching your subs on/off while listening to Korn. Bet you'll notice that.
Also, dig through here a little. http://data-bass.ipbhost.com/index.php?/forum/4-bass-content/
I'd disagree that movies dip into the 20's are "very very rare". The reason most cinema subs f3 at 30 is because going below that takes a lot more than it's worth for most cinemas, and considering that 30hz is amazing for most casual movie goers, it mostly doesn't matter. There's also a lot of feel at 30hz. Think car audio. I think too if your subs f3 was more like 18-20 it might be eye opening for you.

Its true. There was a guy that use to frequent the AVS forum and he was sound mixer for film and he pretty much agreed that few films are mixed with sound below 30 although there are some.