Hydrogenaudio Forums

Hydrogenaudio Forum => General Audio => Topic started by: BearcatSandor on 2017-05-14 01:57:53

Title: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: BearcatSandor on 2017-05-14 01:57:53
I'm looking at subwoofers these days.   Many of the 'high end' subs are rated (on paper) to go down to levels like 10 Hz at 126dB.

When playing music that was recorded live, like jazz in a church does a sub that goes down that low give any benefit at all since we can't hear it? I've read that the room acoustics of a recording can be recreated with subsonic subwoofers, but is that true?

Even if it helps on movies (does it?) what does it do for well recorded music?

Thanks.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Arnold B. Krueger on 2017-05-14 03:01:15
I'm looking at subwoofers these days.  Many of the 'high end' subs are rated (on paper) to go down to levels like 10 Hz at 126dB.

When playing music that was recorded live, like jazz in a church does a sub that goes down that low give any benefit at all since we can't hear it? I've read that the room acoustics of a recording can be recreated with subsonic subwoofers, but is that true?

Even if it helps on movies (does it?) what does it do for well recorded music?

There is no doubt that sounds < 10 Hz are reliably perceived. Whether it is exactly the same as hearing sounds > 30 Hz may be disputed, but it is reliably perceived if it is loud enough.

This is a link to some provisional information about the threshold of hearing at very low frequencies: Provisional information about the threshold of hearing at very low frequencies (https://www.facebook.com/photo.php?fbid=10155320278760859&set=a.10150618475980859.410282.533050858&type=3)

One fairly common source of such information is things like musicians tapping their feet while playing.


Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: BearcatSandor on 2017-05-14 04:03:11
I'm not sure i'm interpreting that graph correctly,  but it seems to be saying that 10 hz is audable at around 98dB.  That all well and good, but i certainly don't play anything that loud :")  I tend to play music around moderate listening levels.  It is percievable even at lower levels? That is to say if i'm playing a recording of a concert grand piano in a hall at a moderage level, is a subwoofer that has that much extension going to make any difference? 
Note, that i'm not restricting this to "hearing" per se.  Would i feel anything different even if i can't conciously hear it and it's at a moderate level?  This is starting to sound like the folks who claim that 'super tweeters make a difference, but i'm assuming that deep sound wave work differently.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Arnold B. Krueger on 2017-05-14 14:32:40
I'm not sure i'm interpreting that graph correctly,  but it seems to be saying that 10 hz is audable at around 98dB.  That all well and good, but i certainly don't play anything that loud :")

I can see two approaches to this question.

One is that not that many people have audio systems that are capable of 98 dB SPL at 10 Hz.   For example, check out this compilation of technical tests on commercial subwoofers: Data-Bass subwoofer system tests (http://www.data-bass.com/systems)  Only a very few of many are even capable of 98 dB @ 10 Hz., particularly over the long term.

The other is that if you accept that 98 dB SPL at 10 Hz is barely audible, it is not all that surprising that you don't perceive it as being all that loud if you hear it. I've experienced this sort of thing many times, and its an odd experience. The sound is on the one hand very soft, but on the other hand there is a strong perception of something rather large going on in and around you.

Quote
I tend to play music around moderate listening levels

98 dB SPL  is excruciatingly loud at 2-4 KHz, and it is still pretty loud at 100 Hz. But at 5 Hz, you may not be able to hear it at all.

Quote
It is percievable even at lower levels? That is to say if i'm playing a recording of a concert grand piano in a hall at a moderage level, is a subwoofer that has that much extension going to make any difference?

It is not going to make that much difference to the music from the piano strings, because in fact their response is dropping off pretty fast well above 100 Hz, even for bassy pianos like a Bosendorfer grand.  However the sound of the musician operating the pedals and tapping his foot might be audible at frequencies well below that.

Quote
 
Note, that i'm not restricting this to "hearing" per se.  Would i feel anything different even if i can't conciously hear it and it's at a moderate level? 

I can't underemphasize how problematical clean reproduction at very low frequencies is in terms of rattling things that aren't well padded or tied down, and the possibility that the paneling on room walls or even the floors are flexing in a nonlinear fashion.

Quote
This is starting to sound like the folks who claim that 'super tweeters make a difference, but i'm assuming that deep sound wave work differently.

If nothing else really intense low bass at the right frequencies can literally rattle your guts. For example based on personal experience I dispute the relevance of the "Brown Note" tests by the Mythbusters. Their tests were done with SR speakers and in that realm it is not unusual for so-called subwoofers to start rolling off starting at 30-40 Hz. The tests I recall were done out-of-doors and that eliminates reinforcement from nearby walls and the floor which can be very significant.  People who put several long-stroke woofers into a small vehicle and apply kilowatts of power are doing it right if deep clean bass is the goal.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: BearcatSandor on 2017-05-14 22:50:02
Thank you Arnold. That answers a lot of questions.  I'm still wondering though about accoustics. I've read (probably in a stereofool magazine) that having a subwoofer that can reproduce <20hz frequencies can help reproduce the sound of the room that the performance was recorded in.  That is to say that i would sense the boundies of the chuch, jazz hall etc., because (according to the article) the accoustical cues are all relegated to deep bass frequencies, especially in naturally recorded surround material, such as used in Ambisonic recordings.

This is all assuming that the engineer didn't filter that out, but is there any truth to the idea that deep bass improves sound staging and presence?  (frankly, i'd bet you'd get a lot of mic noise in badly done recordings as well sometimes)
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: RonaldDumsfeld on 2017-05-14 23:05:10
Quote
Many of the 'high end' subs are rated (on paper) to go down to levels like 10 Hz at 126dB.

Is that really true? It is not what I recall.
Out of interest I just checked some well known manufacturers models in the $5000+ range. These are their top of the range models.

Neumann KH870 claims 18-300Hz (+/- 3dB) max 118.7dB
Genelec  7271 claims 19-100Hz (+/- 3dB) max 118dB
ADAM Sub2100  claims 18-150Hz (+/- 3dB) max 128dB

I mean this is genuine pro quality studio gear. If the guys who make the recordings cannot hear it themselves what's the point?

Not to cause a row or anything please.
If this stuff exists who is selling it and why?
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Porcus on 2017-05-15 09:41:06
This is a link to some provisional information about the threshold of hearing at very low frequencies: Provisional information about the threshold of hearing at very low frequencies (https://www.facebook.com/photo.php?fbid=10155320278760859&set=a.10150618475980859.410282.533050858&type=3)

https://hydrogenaud.io/index.php/topic,105844.0.html . In particular, xnor's graph in #2. Myself I got to 11 Hz with earbuds.

Wasn't "buttshaking movie chairs" a thing a few years ago?
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: drewfx on 2017-05-15 18:05:54
I mean this is genuine pro quality studio gear. If the guys who make the recordings cannot hear it themselves what's the point?

Not to cause a row or anything please.
If this stuff exists who is selling it and why?

Think video games and movies (typically with the sub set way too loud!).
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: PoisonDan on 2017-05-16 14:04:24
Wasn't "buttshaking movie chairs" a thing a few years ago?
If not, there's always this:
http://subpac.com/
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: RonaldDumsfeld on 2017-05-17 23:08:24
Anyone able to identify any of the claimed to be many
Quote
'high end' subs are rated (on paper) to go down to levels like 10 Hz at 126dB
.

Do they exist? OP?
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: KozmoNaut on 2017-05-18 08:40:28
Anyone able to identify any of the claimed to be many
Quote
'high end' subs are rated (on paper) to go down to levels like 10 Hz at 126dB
.

Do they exist? OP?

I know of one subwoofer (10" driver, sealed cabinet, 300W amp) where the manufacturer claimed frequency response down to 16Hz. The manufacturer was approached on their official forum to explain how this was possible, with measurements to back it up, showing a -3dB point around 35Hz. Surprise surprise, we got banned, after being told that the manufacturer "relies on in-room listening tests, not measurements".
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: milkshake on 2017-05-18 11:08:32
Anyone able to identify any of the claimed to be many
Quote
'high end' subs are rated (on paper) to go down to levels like 10 Hz at 126dB
.

Do they exist? OP?

Danley Soundlabs make decent subs.
The TH221 has a claimed max output of 144dB with a frequency range of 22 Hz - 180 Hz - 3 dB and 18.5 Hz - 200 Hz -10dB. So that one doesn't cut it. Its their biggest commercial sub.
http://www.danleysoundlabs.com/products/subwoofers/tapped-horns/th-221/

But they also made a military grade sub called The Matterhorn that needed to produce a 15Hz-20Hz sine of 94dB at 250 meter. This should do it. Not for your average home theatre.
http://www.danleysoundlabs.com/the-matterhorn/
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Arnold B. Krueger on 2017-05-18 11:27:58
Anyone able to identify any of the claimed to be many
Quote
'high end' subs are rated (on paper) to go down to levels like 10 Hz at 126dB
.

Do they exist? OP?

The deepest loudest test results for an actual commercial product that I know of:

data-bass.com - ZOD Audio M.A.U.L. installed subwoofer (http://www.data-bass.com/data?page=system&id=131&mset=143)

"During the loudest 185 volt nominal measurement the M.A.U.L. cabinet was audibly rattling the building behind me and producing in excess of 120dB at 14Hz, 125dB at 22Hz, greater than 130dB by 38Hz and 135db or greater from 68-99Hz."
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Porcus on 2017-05-18 11:50:26
OK ... 1.2 m tall & wide and 250 kg. Not for everyone even if the price tag had its decimal point bumped one position to the left.

Of course there are stories like this good'old one: http://gizmodo.com/5025867/horn-subwoofer-takes-up-crazy-mans-entire-basement
I wonder, why not make it a bit bigger, put a mattress in, and you have a bedroom? No window though.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Arnold B. Krueger on 2017-05-18 14:40:33
OK ... 1.2 m tall & wide and 250 kg. Not for everyone even if the price tag had its decimal point bumped one position to the left.

Of course there are stories like this good'old one: http://gizmodo.com/5025867/horn-subwoofer-takes-up-crazy-mans-entire-basement
I wonder, why not make it a bit bigger, put a mattress in, and you have a bedroom? No window though.

The point is that if you *really* want deep clean bass, you will probably have to incorporate it into the structure of your listening room, and not rely on regular  commercial products. I've seen and heard this done several times, and it even can be fairly economical.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: old tech on 2017-05-23 01:34:35
Whether or not sub sonic frequencies can be perceived, it is more likely to be so than weak, directional +20khz frequencies which vinyl fanbois bang on about.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Arnold B. Krueger on 2017-05-24 11:15:12
Whether or not sub sonic frequencies can be perceived, it is more likely to be so than weak, directional +20khz frequencies which vinyl fanbois bang on about.

Not to mention that there is no way that response at 20 Hz and below can be accurately reproduced by a LP.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Porcus on 2017-05-24 16:31:40
Not to mention that there is no way that response at 20 Hz and below can be accurately reproduced by a LP.
But maybe by an EP played back at 16 2/3. A switch every kid who had access to it just had to try, right?

IIRC there were some turntables where you had to remove the platter and gear the belt manually between 45 and 33 1/3. Certainly there must have been a demand among parents.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Arnold B. Krueger on 2017-05-24 18:54:29
Not to mention that there is no way that response at 20 Hz and below can be accurately reproduced by a LP.
But maybe by an EP played back at 16 2/3. A switch every kid who had access to it just had to try, right?

IIRC there were some turntables where you had to remove the platter and gear the belt manually between 45 and 33 1/3. Certainly there must have been a demand among parents.

Its not the turntable speed that is the key factor here. It is the tone arm resonance which is the same no matter what the rotational speed is.  The tone arm and cartridge compliance forms a modestly damped high pass filter.  The damping is enough so that the resonance is pretty broad and covers the first few octaves of the audible range. By convention, the corner (peaking) frequency is around 12 Hz or so. So, it has quite a bit of positive resonance at 20 Hz and the  next octave up.  The lightly damped curve then goes into its dip and is probably still has measurable effects up to around 100 Hz.  This would be for an optimal cartridge for that particular tone arm. 

How many cartridges and arms are actually optimal combinations in the field?  Given that typically only geometric measurements are done (which are irrelevant to this issue) are used during setup, probably not a heck of a lot. 
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Porcus on 2017-05-25 10:31:40
Not to mention that there is no way that response at 20 Hz and below can be accurately reproduced by a LP.
But maybe by an EP played back at 16 2/3. A switch every kid who had access to it just had to try, right?

IIRC there were some turntables where you had to remove the platter and gear the belt manually between 45 and 33 1/3. Certainly there must have been a demand among parents.

Its not the turntable speed that is the key factor here. It is the tone arm resonance

Right. So it does not (only) matter what can be reproduced to the LP format, but what a turntable setup can get out of the groove.
To balance out their desire for supersonic hiss they cannot hear and which is only noise anyway, audiophiles must certainly equip themselves with a laser turntable in order to listen to those subsonic signals that never were intended to make it to the medium.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Arnold B. Krueger on 2017-05-26 08:04:18
[Right. So it does not (only) matter what can be reproduced to the LP format, but what a turntable setup can get out of the groove.

Correct
.
Quote
To balance out their desire for supersonic hiss they cannot hear and which is only noise anyway, audiophiles must certainly equip themselves with a laser turntable in order to listen to those subsonic signals that never were intended to make it to the medium.

Laser turntable doesn't help because the laser  system ends up containing an analogous mechanical system for tracking the disk.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: BearcatSandor on 2017-06-10 20:32:32
Anyone able to identify any of the claimed to be many
Quote
'high end' subs are rated (on paper) to go down to levels like 10 Hz at 126dB
.

Do they exist? OP?

My apologies for being tardy in coming back to this thread. Life interferes.

I had misread the one i'm considering. It goes to 10hz at 126dB and 7hz at 112db.  https://www.paradigm.com/products-current/type=subwoofer/model=sub-2/page=overview

Way more than i'll ever need, but nice to know that it's there?
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Pusherman on 2017-06-11 11:02:32
Manufacturers marketing specs could be highly exaggerated.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Atmasphere on 2017-07-19 19:50:59
Anyone able to identify any of the claimed to be many
Quote
'high end' subs are rated (on paper) to go down to levels like 10 Hz at 126dB
.

Do they exist? OP?

The deepest loudest test results for an actual commercial product that I know of:

data-bass.com - ZOD Audio M.A.U.L. installed subwoofer (http://www.data-bass.com/data?page=system&id=131&mset=143)

"During the loudest 185 volt nominal measurement the M.A.U.L. cabinet was audibly rattling the building behind me and producing in excess of 120dB at 14Hz, 125dB at 22Hz, greater than 130dB by 38Hz and 135db or greater from 68-99Hz."

One of the more interesting subs I've seen has bandwidth to DC. Really. Its a servo-controlled fan.

This sub is made by Eminent Technology.
http://www.eminent-tech.com/rwbrochure.htm

Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: pdq on 2017-07-19 20:02:41
One of the more interesting subs I've seen has bandwidth to DC. Really. Its a servo-controlled fan.
That's ridiculous. To have DC response it would have to be able to raise or lower the pressure in the room.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: splice on 2017-07-20 08:06:46
That's ridiculous. To have DC response it would have to be able to raise or lower the pressure in the room.

It can do that.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: pdq on 2017-07-20 11:49:29
That's ridiculous. To have DC response it would have to be able to raise or lower the pressure in the room.

It can do that.
Point the fan at a barometer, then lower its speed to zero, and tell me what you see.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Arnold B. Krueger on 2017-07-20 12:18:44
That's ridiculous. To have DC response it would have to be able to raise or lower the pressure in the room.

It can do that.
Point the fan at a barometer, then lower its speed to zero, and tell me what you see.

Obviously, no change because you aren't bringing any new air into the room or even sequestering air in a reservoir , just stirring up the air that is there.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: KozmoNaut on 2017-07-20 13:17:50
Point the fan at a barometer, then lower its speed to zero, and tell me what you see.

I think the way the fan works is that it modulates the blade angle, not the speed of the fan.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Arnold B. Krueger on 2017-07-20 13:42:03
Point the fan at a barometer, then lower its speed to zero, and tell me what you see.

I think the way the fan works is that it modulates the blade angle, not the speed of the fan.

That is my Impression as well.  The inherent problem is noise due to  turbulence of the air.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: pdq on 2017-07-20 14:29:03
Nonetheless, having zero amplitude at zero Hz does not constitute bandwidth to DC. Every speaker ever made has zero amplitude at zero Hz.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Arnold B. Krueger on 2017-07-20 14:52:42
Nonetheless, having zero amplitude at zero Hz does not constitute bandwidth to DC. Every speaker ever made has zero amplitude at zero Hz.

Right. At minimum the sound would have to be loud enough to be reliably perceived.

Most of us are familiar with how this works in practice. The most common ways that it is perceived involve displacing our bodies vertically fairly rapidly  by some means of transportation: car, elevator, plane.

I've heard subwoofers that made my ears feel like they wanted to pop, but I think that was actually more like incipient popping, not an actual pop like I have experienced by means of bodily transportation. But, I think it would be reliable, so it probably counts as reliable perception.

A fair number of the local group of ABX-ers also have very substantial subwoofers.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Atmasphere on 2017-07-20 17:14:51
It works by varying the pitch in both directions.

http://www.eminent-tech.com/howitworks.htm

So it can do DC, and that can be measured easily enough. Certain areas of the room would be pressurized and other areas not. If placed in a window, it would pressurize the entire room. Air moving in one direction only would seem to be about the only way to represent DC by motion of air. I think we all agree that motion of air is also how 20Hz is demonstrated.

At any rate, as I understand it this sub started out as a joke. I remember going to CES about 15-20 years ago and hearing weird rumors about a 'DC subwoofer' at the Eminent Technology room. Out of curiosity on my rounds I dropped in, and sure enough there was a one-page brochure that was mostly a photo of a hick sitting beside a large window fan. Bruce Thigpin had produced the brochure as a joke because so many people came in, took literature without reading it (or for that matter listening in the room) and left. He enjoyed the idea that later these people would find the document with no idea where it came from once they got home.

But apparently it got him thinking. If you read the text, the idea has a bit of merit- for example the sub is not limited by the excursion of a woofer, one of the more serious issues limiting all speakers. Of course, there's a limit to how fast he can modulate the vanes, but that's what crossovers are for. It really does work- I've heard them at shows.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: pdq on 2017-07-20 17:34:19
This could also be done in a sealed room with two valves. One connected to a source of compressed air, and the other venting to the outside.
Title: Re: Do we "need" those <20Hz subsonic frequencies for high-fidelity audio?
Post by: Kvalsvoll on 2017-08-02 19:50:43
While waiting for the cpu to render bass-eq on a movie I want to see, it is suitable to use the time to fill in with some comments on low bass.

The important aspects are already covered in the very first posts, so this will not add any new and revolutionary wisdom.

In music there is very little energy below 30hz, but it is there, if it was not filtered in the studio. Transients are short in time, and wide in frequency distribution. Low frequencies can be induced from large surfaces in the recording room, like when musicians move on a stage.

But the level of <20hz content is usually so low that you will only be able to notice it at very loud listening levels.

Some electronic-made music do contain lots of low freq energy.

Impulse response improves when frequency response is extended below "normal" hearing range. But before worrying about that, the range above 20hz is far more important to fix for resonances and timing problems.

On many recordings the full-range reproduction reveals sub-frequency noise - from the recording room, or due to close-mic placements, which can create a boost at very low frequencies. This was not intentional, and it is there because they did not hear it in the studio. Some will find this amusing, some will find it distracting.

But why I am doing the bass-eq on that movie. If the difference is so small, this movie is mostly dialog driven, is it worth the effort?

It is, because movie sound effects are different from music instruments. I could tell right away that this move is filtered - low frequencies are removed - because effects lack natural weight and size. A very steep 25Hz high-pass was applied, and bringing back what was lost will make a huge difference to the experience.
SimplePortal 1.0.0 RC1 © 2008-2018