Is infrasonic output with authority possible with dynamic drivers?

[yepimonfire]

Let's assume we want 15hz at 100dB with minimal distortion. Outside of turning your basement into a giant folded horn enclosure, can it be done with regular dynamic drivers in ported enclosures? Most of the subs I've modeled with tuning frequencies that low start rolling off until a peak at the tuning frequency, even with massive box volumes, and I have yet to find a driver with an fs that low.

Is it possible?

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[its phillip]

These are outdoor measurements. Output should be higher in room with lower distortion for the most part.

http://data-bass.com/data?page=system&id=135&mset=151

 

[ATLAudio]

Of course

All but the most enormous rooms will give cabin gain or 6-12 dB at 15hz, which would be on top of their outdoor ground plane measurements. Corner loading will help even more.

There's no shortage of ported systems which will give clean reference presentation (ie 95 db with 20 db of headroom; 115dB) at 15 hz in room at the MLP.

 

[rojo]

Let's assume we want 15hz at 100dB with minimal distortion. Outside of turning your basement into a giant folded horn enclosure, can it be done with regular dynamic drivers in ported enclosures? Most of the subs I've modeled with tuning frequencies that low start rolling off until a peak at the tuning frequency, even with massive box volumes, and I have yet to find a driver with an fs that low.

Is it possible?

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The Stereo Integrity HST18 mk II will reach nearly 10Hz at 100dB in an 8ft³ box tuned to the driver's Fs of 15.6 Hz, driven with 1000W of power. To achieve that tuning, you'd need to fold a slot port 3" x 20" to a length of over 76" to keep the vent velocity under 20m/s.

 

[lovinthehd]

@yepimonfire What's your definition of minimal distortion?

 

[shadyJ]

@yepimonfire What's your definition of minimal distortion?

In my opinion, anything below 5% THD is negligible. From 5% to 10%, that is tolerable, but it does mean the device is at or close to its maximum linear operation, its best not to use the sub in this range for too long. If the sub is being driven to over 10% frequently, it is time for either another sub or a bigger sub.

 

[TLS Guy]

Let's assume we want 15hz at 100dB with minimal distortion. Outside of turning your basement into a giant folded horn enclosure, can it be done with regular dynamic drivers in ported enclosures? Most of the subs I've modeled with tuning frequencies that low start rolling off until a peak at the tuning frequency, even with massive box volumes, and I have yet to find a driver with an fs that low.

Is it possible?

Sent from my 5065N using Tapatalk

There is a lot of nonsense and wasted time and effort on this. If it is infrasonic, it means just that. It means you can't heat it! By definition it is below the bandwidth of the human ear.

Now you might feel it. I have no idea what level of distortion the bones of your ass can detect, nor do I care.

If you have s sub with good performance to the 20 Hz region, there will be sub audible content, unless the sub requires a steep high pass filter to prevent damage.

If the sub is standard ported then it will roll off 24 db per octave. In theory a sealed design will roll off 12 db per octave, but a cone alone is not going to effective at these frequencies.

My TLS roll off 12 db per octave. Driven from a signal generator I know there is content below hearing by the physical effects on the room.

That brings me to the last point. If you can reproduce those frequencies you seem to be obsessed with, the limitation will not likely be the speaker, but the physical construction of the room. When an organist does use the 32 ft stop at power, the problem is not from my TLs but the physical properties of the room, making the pictures shake and the windows rattle. I can assure you it does not have to be loud to do that.

So the bottom line is you don't hear it, and if you do produce it, the room will react in a way that is a distraction. So if you want it you will have to start with a room that is not stick construction with standard windows.

There is a house going up next door to me that will be all concrete. With special attention to windows that just might fit your requirements.

 

[shadyJ]

There is a lot of nonsense and wasted time and effort on this. If it is infrasonic, it means just that. It means you can't heat it! By definition it is below the bandwidth of the human ear.

Now you might feel it. I have no idea what level of distortion the bones of your ass can detect, nor do I care.

If you have s sub with good performance to the 20 Hz region, there will be sub audible content, unless the sub requires a steep high pass filter to prevent damage.

If the sub is standard ported then it will roll off 24 db per octave. In theory a sealed design will roll off 12 db per octave, but a cone alone is not going to effective at these frequencies.

My TLS roll off 12 db per octave. Driven from a signal generator I know there is content below hearing by the physical effects on the room.

That brings me to the last point. If you can reproduce those frequencies you seem to be obsessed with, the limitation will not likely be the speaker, but the physical construction of the room. When an organist does use the 32 ft stop at power, the problem is not from my TLs but the physical properties of the room, making the pictures shake and the windows rattle. I can assure you it does not have to be loud to do that.

So the bottom line is you don't hear it, and if you do produce it, the room will react in a way that is a distraction. So if you want it you will have to start with a room that is not stick construction with standard windows.

There is a house going up next door to me that will be all concrete. With special attention to windows that just might fit your requirements.

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.

 

[TLS Guy]

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.

Well I have done a literature review. It is accepted among most hearing experts that most people can not hear below 20 Hz. Some can hear between 15 and 16. There is no 8th cranial nerve response below 15 Hz, and even those are far and few between. So below 20 Hz it is really feeling and comes from internal organ resonance, bone conduction and issue like that.

There is absolutely no point in designing for an F3 below 20 Hz. That is low enough to catch those who can hear to 16 Hz.

So for music what I have posted is correct. If it is explosive effect you want to reproduce that is not an auditory issue, and distortion is not a sensible thing to be concerned about.

 

[panteragstk]

Now you might feel it. I have no idea what level of distortion the bones of your ass can detect, nor do I care.

Quote of the day.

 

[panteragstk]

The Stereo Integrity HST18 mk II will reach nearly 10Hz at 100dB in an 8ft³ box tuned to the driver's Fs of 15.6 Hz, driven with 1000W of power. To achieve that tuning, you'd need to fold a slot port 3" x 20" to a length of over 76" to keep the vent velocity under 20m/s.

OOOOOH I've been looking for an alternative to the TC Sounds drivers and for some reason those never came up in my search.

Someday I'd love to get a few of those and built a monster sub. For now my 4x infinity 12" in each corner will have to do.

 

[lovinthehd]

OOOOOH I've been looking for an alternative to the TC Sounds drivers and for some reason those never came up in my search.

Someday I'd love to get a few of those and built a monster sub. For now my 4x infinity 12" in each corner will have to do.

Just get the 24" http://stereointegrity.com/product/hs24-24-subwoofer/

 

[panteragstk]

Just get the 24" http://stereointegrity.com/product/hs24-24-subwoofer/

Yeah, I was more referring to a company that makes high xmax drivers in general. I'd love to build something with ANY of their drivers.

Two of those 24" would be silly in any room. Glad I have dual dedicated 20 amp circuits for just this reason.

I could even make an IB sub with those. Always wanted to try one of those.

 

[ATLAudio]

@TLS Guy @shadyJ

Benefits aside the cost difference between demanding clean reproduction from 20hz, down to 16hz, is very linear, if it’s visible at all in most cases. Most ported systems which can handle 20hz, will very likely handle 16hz just as well, especially in-room.

That said, if someone prefers, and demands clean THX reference capability down to 5HZ, let’s not beat them up with text books and white papers; just let folks enjoy things. That’s what life’s all about.

 

[shadyJ]

Well I have done a literature review. It is accepted among most hearing experts that most people can not hear below 20 Hz. Some can hear between 15 and 16. There is no 8th cranial nerve response below 15 Hz, and even those are far and few between. So below 20 Hz it is really feeling and comes from internal organ resonance, bone conduction and issue like that.

There is absolutely no point in designing for an F3 below 20 Hz. That is low enough to catch those who can hear to 16 Hz.

So for music what I have posted is correct. If it is explosive effect you want to reproduce that is not an auditory issue, and distortion is not a sensible thing to be concerned about.

Here is a survey of research regarding 'infrasonic' hearing (not really infrasonic if it can be heard).

 

[TLS Guy]

Here is a survey of research regarding 'infrasonic' hearing (not really infrasonic if it can be heard).

Well I look more closely later.

But you have to define "heard". The acid test is a response in the eighth cranial nerve. If there is no response then it was not heard, but received via some other mechanism. 15 Hz was the lowest response I could see referenced. That was only a few people. I think the musicians have long been right. Human hearing to all intense and purposes is 20 Hz to 20 KHz if you are lucky. The audio enthusiast and audio engineer need not concern him or herself outside of those parameters. Outside those limits we are technically and in fact outside the boundaries of audio reproduction from the ear. To claim otherwise is mental masturbation.

 

[yepimonfire]

This is simply just a thought experiment. Obviously there are diminishing returns to going below 20hz. I do know that studies have shown that humans can hear down to 8hz with a high enough SPL, and I also know that ultrasonic frequencies, while not audible, have been shown to impart emotional responses to music.

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[TLS Guy]

This is simply just a thought experiment. Obviously there are diminishing returns to going below 20hz. I do know that studies have shown that humans can hear down to 8hz with a high enough SPL, and I also know that ultrasonic frequencies, while not audible, have been shown to impart emotional responses to music.

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I don't think good studies. To prove hearing you need to show that the stimulus can cause a signal from the eight cranial nerve. I can not find that anyone has shown that. Down to 20 Hz yes, but not reliably below that and certainly not below 15 Hz. So yes people can detect it, but through which sense it comes is the question. Almost certainly t does not come through the auditory apparatus.

 

[yepimonfire]

I don't think good studies. To prove hearing you need to show that the stimulus can cause a signal from the eight cranial nerve. I can not find that anyone has shown that. Down to 20 Hz yes, but not reliably below that and certainly not below 15 Hz. So yes people can detect it, but through which sense it comes is the question. Almost certainly t does not come through the auditory apparatus.

This one has found that at high enough levels humans do indeed perceive infrasound via outer hair cells of the ear, in fact, the response curve flattens below 10hz. Ultrasound has been shown to contribute emotional responses to music.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2923251/

Either way, one is missing out on the raw visceral experience of a 32' organ stop without being able to reproduce a 16hz fundamental. Feeling is just as important as hearing. Have you ever felt a system reproduce the same body shaking feeling of a real life helicopter? I haven't, even with high volumes, that feeling is missing.

Obviously, its extremely rare for content to contain infrasound at any noticeable level, which is why I say this is more a thought experiment, rather than practical.

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[lsiberian]

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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