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post #2011 of 4913 Old 02-06-2017, 02:39 PM
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Originally Posted by m. zillch View Post
Filtering out the very deep bass is exceeding common, especially for Rock music made prior to digital [because it is hard for cartridges to tack at high levels].

Turn on your subs, or use good headphones, and listen at a good level to the nice swirling around the room of the descending bass note in Heart's classic, "Magic Man", for an example. [Jump to 4m in and listen to the deep note at least until 4m17s]:
https://www.youtube.com/watch?v=3vlAdMeZSfw

Pretty pleasing and deep, right? Well interestingly it actually has gone through a steep filter and there's pretty much no serious content below 50Hz!
You call that deep bass? I don't. Perhaps if all the music you listen to is no more extended than this track, then you can justify weak sub capability, but that would exclude most modern music and film sound. Certainly I listen to stuff on an almost daily basis with clear extension to 30 Hz and often below.

I currently have 15 Hz capability and am in the process of upgrading to single digits capability soon. I would say that in the majority of cases, the additional content down to that frequency adds more than takes away. Yes, I do encounter examples in which there is unwanted noise / slop down low, but these are relatively rare and reflect QC issues that probably unaddressed because of insufficiency in the monitoring system. Indeed, some of the more offensive examples are remastered where subharmonic synthesis is used to try to "improve" the bass but is often used excessively.

At the same time, steep low-end filters contribute their own negative consequences. The frequencies just above the drop tend to be excessively emphasized due to the increased group delay, very similar to the sound of a poorly designed ported box subwoofer. This is apparent on a lot of movie soundtracks where 30 Hz is emphasized ahead of a steep roll-off to get a loud sound on typical movie theater subs, but sounds very stereotypically one-noteish on my home system.

Really, I think anyone arguing against bass extension down to at least 20 Hz and ideally more hasn't heard good quality sound tracks on a capable system. IMO, there's no comparison at all. It's not even close.
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post #2012 of 4913 Old 02-06-2017, 03:02 PM
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I bet fewer than .1% of commercial US cinemas can reproduce full level content cleanly below 20 Hz or so, in fact Dolby Labs doesn't even care if their commercial Atmos theaters can do full level below 31.5 Hz, their F3 point.
https://www.dolby.com/us/en/technolo...ifications.pdf

There's not a single wide release movie ever made, in the entire history of cinema, with loud, sustained content below ~20Hz [that's intentional] that didn't simultaneously also have loud content in the octave band above that point and it is this content which people are actually being impressed by . . . but their eyes see their measurement gear registering 10Hz, etc., and expectation bias, aka the placebo effect, does the rest.

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post #2013 of 4913 Old 02-06-2017, 05:36 PM
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@beastaudio , I get what you are saying, but I also agree with @m. zillch that less than .1% of commercial cinemas or mix stages can even reproduce anything that low (not to mention home theaters).

It's simply the needs of the many outweighing the needs of the few

I would be willing to bet that the mix engineer who created the soundtracks with below 20 hz content never even heard it when they created it - it's most likely created by some of the bass-max type plugins they put in the signal chain. Movies are mixed on a variety of different brands of speakers (JBL being the most common), but other brands are used as well. That's why I pointed out the Genelec, which goes down to 25 hz max.

RE: placebo effect. This does not sound unlikely. We'd have to set up a double blind system where the same track is played with and without a sharp filter below 20 hz, and see what happens

Remember too, that we only have so much dynamic range to play with in a movie soundtrack, and putting a lot of effort into sub-20hz information will limit what can be put elsewhere.
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post #2014 of 4913 Old 02-06-2017, 06:42 PM
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While smaller studios might be able to reach into the teens for bass it is not seen in the dubbing stages where typically the final mix is recorded for movies. There are companies that make models that can go into the teens like Genelec,, JBL and others depending on model which will be fine in smaller spaces. The dubbing stage and cinemas are much larger spaces and would need a LOTS of BIG subwoofers to get into the teens and single digits. The subs for Cinemas tend to focus on 30hz and up at greater output than trying to go lower with more limited output. JBL does make a model that is-3db at ~25hz but would require multiples to fill the average cinema with 25hz output.

Some sub 20hz content can certainly be recorded but unlikely to be heard in the dubbing stage, maybe in a smaller studio when being transferred to disc for the home. I doubt most mixers focus much on content that low. If you get it and have the subwoofers to enjoy it, consider it a bonus.
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post #2015 of 4913 Old 02-06-2017, 07:00 PM
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So what's going on in Live Die Repeat. That almost took my house down.
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post #2016 of 4913 Old 02-06-2017, 10:05 PM
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The dominate frequencies you're hearing/feeling are very likely above the aforementioned.
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post #2017 of 4913 Old 02-07-2017, 02:04 AM
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Originally Posted by John Schuermann View Post
[...]

I would be willing to bet that the mix engineer who created the soundtracks with below 20 hz content never even heard it when they created it - it's most likely created by some of the bass-max type plugins they put in the signal chain. Movies are mixed on a variety of different brands of speakers (JBL being the most common), but other brands are used as well. That's why I pointed out the Genelec, which goes down to 25 hz max.

RE: placebo effect. This does not sound unlikely. We'd have to set up a double blind system where the same track is played with and without a sharp filter below 20 hz, and see what happens

Remember too, that we only have so much dynamic range to play with in a movie soundtrack, and putting a lot of effort into sub-20hz information will limit what can be put elsewhere.
Just because the mix engineer didn't hear it doesn't mean that it doesn't improve the experience. To spin this argument the other way: What's the big deal about the M2s and their ability to reveal more detail than other speakers if most existing music was mixed on lesser speakers? There's no need to answer.

As for the question of placebo effect, this has been tested in various ways, though not necessarily double blind. OTOH, I'm of the opinion that double blind testing is only really necessary for subtle changes. I can assure you that with the right soundtrack and reference playback level, filtering of content below 20 Hz is not subtle.

There is debate, however, as to how much more sub extension is worthwhile for movie tracks. From the data I've seen, the *audibile* extension of of bass in some tracks goes down to about 10 Hz or so. This is based on experiments involving listeners sitting on concrete slab floors, which don't tend to be easily excited by the high SPL sound field. For those with suspended floors and/or risers, the interaction of the sound field with the surface can induce mechanical vibration that may be readily perceived down to 3 Hz or lower, again depending on the content. Alternatively, tactile transducers may be used to reproduce vibrations down into the single digits.

This last point may be much more relevant because tactile transducers are becoming more common in both home theaters and cinemas. The Crownson brand is known to reproduce single digits frequencies very well. I can't speak for the other brands, which may not have as much output down there, but most should be able to extend a lot lower than a typical theater sub system is capable of. So here's another argument for monitoring content below 20 Hz, even if using tactile transducers instead of subs for that purpose.

As for dynamic range, you have quite a lot to work with (127 dB RMS 7.1) if bass management if involved. Quite a number of BD mixes exceed 120 dB at reference level after bass management. Of course, if the particular scene calls for 125 dB, mostly centered @ 30 Hz as appears in the infamously loud film "The Dark Knight Rises", then there won't be any room left over for lower stuff.

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Originally Posted by Ellebob View Post
While smaller studios might be able to reach into the teens for bass it is not seen in the dubbing stages where typically the final mix is recorded for movies. There are companies that make models that can go into the teens like Genelec,, JBL and others depending on model which will be fine in smaller spaces. The dubbing stage and cinemas are much larger spaces and would need a LOTS of BIG subwoofers to get into the teens and single digits. The subs for Cinemas tend to focus on 30hz and up at greater output than trying to go lower with more limited output. JBL does make a model that is-3db at ~25hz but would require multiples to fill the average cinema with 25hz output.

Some sub 20hz content can certainly be recorded but unlikely to be heard in the dubbing stage, maybe in a smaller studio when being transferred to disc for the home. I doubt most mixers focus much on content that low. If you get it and have the subwoofers to enjoy it, consider it a bonus.
A couple of large 15 Hz ported boxes and/or horns, each with dual 21"s ought to do the trick for 10 Hz and up in most cinemas. There may be other practical issues like ensuring the structure is up to the task. Subwoofer structural damage becomes a real thing in larger rooms.

The Genelec sub may be anechoic flat to 25 Hz but some room gain is to be expected, even in larger rooms, potentially allowing usable extension to 20 Hz or a bit lower. If the sub has a slow, sealed sub roll-off, the room gain in a smaller room could enable even more extension.

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So what's going on in Live Die Repeat. That almost took my house down.
That is a good question. Were the strong, low fundamentals (up to 120 dB @ 10 Hz) put there intentionally? Probably not, at least not specifically. So is this a QC issue then? The mixers who didn't catch how absurdly high in level those fundamentals were might think so. Likewise anyone running subs without sufficient protection may think so after they get blown up. But those strong fundamentals *were* part of the synthesized effect.

Another example comes to mind is the fundamental frequency of rotating helicopter blades. Helicopter sounds appear in all kinds of movies, but only some are filtered. Those with the extension find the unfiltered helicopter sounds to be more satisfying because they are more realistic. But in one example, "Lone Survivor" IIRC, the fundamental was so strong and the sound effect was sustained for so long that a lot of people have cooked their subs. Perhaps if they mixers had known about it, they could have toned down the fundamental frequency a bit while leaving enough there for those with the capability to reproduce it cleanly, but chances are, they had no idea it was there.

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The dominate frequencies your hearing/feeling are very likely above the aforementioned.
I would say this is true below 20 Hz or so, even though the stuff below 20 Hz definitely does contribute. For bass heavy movies that don't filter it out, however, I'd argue that the 20-30 Hz range has the most to give in terms of what sounds/feels "impressive".
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post #2018 of 4913 Old 02-07-2017, 04:55 AM
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You don't get room gain in large acoustical spaces like theaters because the room's longest dimension is greater than the 1/2 wavelength of the frequency you are trying to achieve. In a SMALL 200 seat theater that is maybe 30,000 cubic feet you will not get below 20hz at any appreciable volume from 2 - dual 21" subs. Tactile transducers under each seat or in a raised floor would be a much more practical solution if you want to add more feel for large spaces.

I am not saying there is not below 20hz material recorded but it is probably not heard in the dubbing stage which is the size of a small theater and where all the recordings of music, effects, foley, dialogue, etc. get put into the final mix. In a smaller room like one where it is re-mastered for disc and home playback it is possible. Whether it is or not would vary between studios if they have equipment capable of it. Some I think might.
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post #2019 of 4913 Old 02-07-2017, 08:59 AM
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Quote:
Originally Posted by m. zillch View Post
There's not a single wide release movie ever made, in the entire history of cinema, with loud, sustained content below ~20Hz that didn't simultaneously also have loud content in the octave band above that point and it is this content which people are actually being impressed by . . . but their eyes see their measurement gear registering 10Hz, etc., and expectation bias, aka the placebo effect, does the rest.
Wha? @awediophile pointed you out to two excellent examples of which I think there are two different actual reasons for the content. IIRC the opener for Edge of Tomorrow is a 25/20/15/10 hz sustained 2-3 second note that progresses down finishing at that 10hz fundamental. There is NO other content above, and if you see it, it's distortion otherwise. Yes it is a short portion of the movie and the rest of the soundtrack has nothing close to that, but it's there nonetheless.

Lone Survivor is a different animal and IMO this 6.5hz sustained effect for close to 2:30 was put in their either unintentionally, or as has been said, the mixer had no idea it was there... We would only get a good answer by asking the man himself. Regardless, there is definitely other content above the 6.5hz drone, but none of that content is sustained like it is, nor is it anywhere close to at the same level. My room CRIES when running this scene at reference, and yes, in testing out different woofer's capability, we have released the magic smoke on more than one occasion attempting to find the limits.

There are many other excellent examples of movies with full BW soundtracks that you can clearly tell have an advantage to the presentation by being so, especially in a room with a suspended floor. Im surprised we are talking about 20hz here in general and not 10hz. 10hz I can understand and would be willing to give up below (I am on slab however) that, but 20hz? Not even close. I could spend an entire day presenting movies and music to you with <20hz content in it that I would certainly HOPE you would find the benefit of their reproduction. The added weight to a movie's sound track is easily noticeable. From subtle effects in horror movies where you just "Feel" a presence type of effect in the room to massive effects like the scene in the movie "Pulse" where she is in the server room, which is from 17-21hz sustained sweep. Yes with a 20hz ported sub you'll get some effect, but not like you would with a system that extends past this area and isn't beginning its filter rolloff at say 25hz. You won't sell me placebo effect at all in these certain cases.



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It's simply the needs of the many outweighing the needs of the few
This is the most unfortunate part, but when those new movies with full bandwidth ST's come out, it is still a wonderful breath of fresh air! Tom Cruise seems to almost have a say in the audio sountracks of his movies, as even 10+ years since the infamous "Pod Emerges" extreme bass scene that is only one of two I know of that can power cycle my amps, his movies still come the closest in most cases to very well executed full bandwidth bass.

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The dominate frequencies your hearing/feeling are very likely above the aforementioned.
Not on that particular one. Each effect is a standalone tone that has no harmonic presence anywhere close to the same level.

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Just because the mix engineer didn't hear it doesn't mean that it doesn't improve the experience.
I will argue that point to the end with you. It definitely adds to the experience, and I'd be willing to test that theory with anyone and everyone that would want to come by and do it with me. Once again, I can see a great argument for <10hz content, but in the 10-20hz range and losing it too? I will never again own a system that doesn't get me this area to reference plus. Even if every movie from here on out is filtered all to heck, I will still want my system capable well below 20hz.

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post #2020 of 4913 Old 02-07-2017, 10:41 AM
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I bet fewer than .1% of commercial US cinemas can reproduce full level content cleanly below 20 Hz or so,
Does anyone here dispute this?

Is the argument now that the audio engineers making movies are intentionally catering to the .1% that will faithfully reproduce this infrasonic content signal even though it is detrimental to the other 99.9% of movie theaters in that it saps amplifier power, saps reserve peak power, saps maximum woofer cone excursion before the onset of tremendous harmonic distortion, saps dynamic headroom, and limits the maximum SPL for the truly audible ~20Hz and above content which does matter?
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post #2021 of 4913 Old 02-07-2017, 01:55 PM
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Originally Posted by Ellebob View Post
You don't get room gain in large acoustical spaces like theaters because the room's longest dimension is greater than the 1/2 wavelength of the frequency you are trying to achieve. In a SMALL 200 seat theater that is maybe 30,000 cubic feet you will not get below 20hz at any appreciable volume from 2 - dual 21" subs. Tactile transducers under each seat or in a raised floor would be a much more practical solution if you want to add more feel for large spaces.

I am not saying there is not below 20hz material recorded but it is probably not heard in the dubbing stage which is the size of a small theater and where all the recordings of music, effects, foley, dialogue, etc. get put into the final mix. In a smaller room like one where it is re-mastered for disc and home playback it is possible. Whether it is or not would vary between studios if they have equipment capable of it. Some I think might.

You don't need the longest room dimension to be below the 1/2 wavelength for room gain to apply. Any time you have boundaries, you have room gain. The answer to the question of how much at what frequency is all in the details.

I'm fairly certain that two large cabs with 2 high-output 21s could get close, especially if the walls and floor are sufficiently rigid. The M.A.U.L., which uses 4 Rockford Fosgate TS3-19 drivers, can burst 126 dB at 16 Hz at 2 meter ground plane. Put one of those into a corner and assume 5 dB gain for each additional boundary: 126 dB + 10 dB (addl. boundaries) - 17.5 (extrapolate from 2 m to 15 m) = 118.5 dB. (Sadly, that's probably more output than many cinema systems can do at 40 Hz much less lower.) The M.A.U.L. is constrained by the "small" port at that frequency, so if the design is split into two cabinets, each with volume somewhat more than half of the original, more output is possible. And if that's not enough, two more can be placed in the rear, which provides an option for surround bass management as well. These figures don't include the effect of the ceiling, which is likely constructive as well.

Would this be expensive? On their own, yeah. But compared to the cost cinema projectors these days, not so much. As I already stated, my bigger concern is structural. The walls and ceiling need to be very rigid and robust for this so that the high SPL bass doesn't literally bring down the ceiling. For this reason, tactile tranducers in seats may still be the best solution for cinemas, and indeed, many cinemas are already doing this.

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Originally Posted by m. zillch View Post
Does anyone here dispute this?

Is the argument now that the audio engineers making movies are intentionally catering to the .1% that will faithfully reproduce this infrasonic content signal even though it is detrimental to the other 99.9% of movie theaters in that it saps amplifier power, saps reserve peak power, saps maximum woofer cone excursion before the onset of tremendous harmonic distortion, saps dynamic headroom, and limits the maximum SPL for the truly audible ~20Hz and above content which does matter?
Well, a recent SMPTE publication documents in-room LFE channel response for two dub stages, a reference theater, and three commercial cinemas. One of the dub stages and one of the commercial cinemas shows flatish response down to 22 Hz. Because the measurements don't go any lower than that, it's anyone's guess as to whether they extend more than that, but it's certainly possible.

And anyway, as discussed already, many cinemas (surely more than 0.1%) install tactile transducers in the seats that are likely capable of a lot more extension than the sub system is.

Such content should not be detrimental to the "others", provided they use filtering upstream of their amps to remove it. They should be doing this anyway to avoid blowing up their equipment with "Lone Survivor" / "Edge of Tomorrow" examples that escape notice in the mixing process.
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post #2022 of 4913 Old 02-07-2017, 02:35 PM
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Originally Posted by awediophile View Post
Well, a recent SMPTE publication documents in-room LFE channel response for two dub stages, a reference theater, and three commercial cinemas. One of the dub stages and one of the commercial cinemas shows flatish response down to 22 Hz. Because the measurements don't go any lower than that, it's anyone's guess as to whether they extend more than that, but it's certainly possible
They didn't think to use measurement gear which goes even lower than 20/22Hz? That's odd, considering we all know the notion that humans only hear from 20-20kHz, roughly, is just an old wives tale invented by "the man". [sarcasm]

This "SMPTE" group you mention must not be very knowledgeable about motion picture and television engineering.
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Originally Posted by awediophile View Post
And anyway, as discussed already, many cinemas (surely more than 0.1%) install tactile transducers in the seats that are likely capable of a lot more extension than the sub system is.
These devices are silly toys analogous to a flashing LED which goes off whenever there is deep bass. I guess when humans can't hear the deep bass translating it into another sense that they do detect makes sense to some people.

[Yes, I've experienced them, in fact I was once a dealer of them. They are a gimmick, a novelty, or an "amusement ride" IMHO.]
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Originally Posted by fatsow View Post
So what's going on in Live Die Repeat. That almost took my house down.
When there is super loud 10Hz content in a movie or song it can:

- rattle objects, such as a vase on a glass shelf, and these rattling sounds are at high, easy to hear frequencies.
- rattle the subwoofers' AC cord and signal wire [this clues people into the direction the sound comes from which dupes them into thinking stereophonic sub bass is important but perceptually they will swear they only hear the deep bass part]
- make your amps clip on peaks, which is audible
- increases woofer distortion, which is audible
- smack your woofers' voice coil/bobbins against the end stops because they reach the limits of the safe excursions [my friends call this "stamping"]
- causes port noise or chuffing, also a directional cue people don't realize they are keying on.

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^ Also, although nobody here reading this has any harmonic or intermodulation distortion in their deep bass reproduction [], we have to be cognizant of the fact that many people do and again these act as "tells" or giveaways as to when the infrasonic content arrives in the soundtrack making homestyle A/B testing of this very difficult/impossible, not to mention double blind protocols and level matching are almost never done in most home settings we read about in the forum.

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Originally Posted by m. zillch View Post
They didn't think to use measurement gear which goes even lower than 20/22Hz? That's odd, considering we all know the notion that humans only hear from 20-20kHz, roughly, is just an old wives tale invented by "the man". [sarcasm]

This "SMPTE" group you mention must not be very knowledgeable about motion picture and television engineering.
"Despite the general understanding that infrasound is inaudible, humans can perceive sound also below 20 Hz. This applies to all humans with a normal hearing organ, and not just to a few persons." (http://www.noiseandhealth.org/articl...age=57;aulast=)

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These devices are silly toys analogous to a flashing LED which goes off whenever there is deep bass. I guess when humans can't hear the deep bass translating it into another sense that they do detect makes sense to some people.

[Yes, I've experienced them, in fact I was once a dealer of them. They are a gimmick, a novelty, or an "amusement ride" IMHO.]
Which ones? There are in fact multiple manufacturers of such devices, with varying performance between them. Your argument is equivalent to dismissing these things called "speakers" as gimmicky because you heard (or sold) these things built inside a laptop.
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Originally Posted by m. zillch View Post
I bet fewer than .1% of commercial US cinemas can reproduce full level content cleanly below 20 Hz or so, in fact Dolby Labs doesn't even care if their commercial Atmos theaters can do full level below 31.5 Hz, their F3 point.
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I would be willing to bet that the mix engineer who created the soundtracks with below 20 hz content never even heard it when they created it
Well....yes and no. Content below 20 Hz is there, occasionally. It's just that the cinema playback chain is optimized for output above 30 Hz (more often 40 Hz). When your playback corner frequency is, say, 35 Hz, you can produce much more output for a given amount (weight, size, cost) of gear. Which is what happens in the cinema.

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The dominate frequencies you're hearing/feeling are very likely above the aforementioned.
The amount of output available in large-venue systems optimized for output above 35 Hz is so great that you wouldn't even notice any ~20 Hz material introduced while the main bass system is active.

Quote:
Remember too, that we only have so much dynamic range to play with in a movie soundtrack, and putting a lot of effort into sub-20hz information will limit what can be put elsewhere.
Here we're talking about the ".1" LFE track, which plays apart in its own box.

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Originally Posted by awediophile View Post
Just because the mix engineer didn't hear it doesn't mean that it doesn't improve the experience. To spin this argument the other way: What's the big deal about the M2s and their ability to reveal more detail than other speakers if most existing music was mixed on lesser speakers?
Aside from the pejorative about "lesser speakers," the 2216 woofers in the M2 are rather limited, in AVS DIY terms, in their subwoofing capabilities.

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Another example comes to mind is the fundamental frequency of rotating helicopter blades.
Funny you should mention that. We were outside in the parking lot measuring stuff many years ago when a helicopter flew by. I flipped on our General Radio spectrum chart recorder as it went overhead. As you would expect, there were spectral peaks IIRC corresponding to the rotor speeds, typically around 8-20 Hz.

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Originally Posted by Ellebob View Post
You don't get room gain in large acoustical spaces like theaters because the room's longest dimension is greater than the 1/2 wavelength of the frequency you are trying to achieve.
That's one way to look at it. Another perspective is the simple fact that you can't effectively pressurize a space that large like you can a small, sealed home theater (or an automobile). Which means that it's no longer a pressure vessel -- it becomes quasi-free space.
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post #2028 of 4913 Old 02-07-2017, 03:18 PM
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OK, responses in red:

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Originally Posted by m. zillch View Post
When there is super loud 10Hz content in a movie or song it can:

- rattle objects and these rattling sounds are at high, easy to hear frequencies. Fair enough, yep you can hear sheetrock flexing.
- rattle the subwoofers' AC cord and signal wire [this clues people into the direction the sound comes from which dupes them into thinking stereophonic bass is important and they will swear they only hear the bass part] This is absurd
- make your amps clip, which is audible Sure, if you are underpowered in the first place, which some of us are not...
- increases woofer distortion, which is audible A good point here in most cases
- smack your woofers' voice coil/bobbins against the end stops because they reach the limits of the safe excursions [my friends call this "stamping"] Once again you are assuming an incapable system that doesn't have enough displacement to accomplish 10hz without running hard past the xmax of the drivers.
- causes port noise or chuffing, also a directional cue people don't realize they are keying on.Not gonna get either of those on a sealed design sir.
I see your point coming from a commercial side of things, but as mixers are more often now doing "Home mixes," they could focus on bringing some of that <20hz content into play for home mixes. I agree with you completely that there is absolutely no need for it in a commercial theater but as Bob pointed out, those cinemas should have filtering upstream to cutoff their vented subwoofers, whatever they are and wherever their knee is, to help protect them as this is basically an audio installation 101 base rule.

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post #2029 of 4913 Old 02-07-2017, 03:21 PM
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Originally Posted by awediophile View Post
"Despite the general understanding that infrasound is inaudible, humans can perceive sound also below 20 Hz. This applies to all humans with a normal hearing organ, and not just to a few persons."
Yeah, I guess if I blow a puff of air at a person's face, wait ten seconds and then blow another puff of air, and they can perceive it, it proves humans can hear .1 Hz.

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post #2030 of 4913 Old 02-07-2017, 03:36 PM
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This went from the JBL subs -6 db point being in the audible range to whatever this is lol.

I've sat in chairs with tactile transducers and it never feels like they match the bass. Maybe it was the set up. Regardless, those are pretty cheesy. I'd rather just feel the real bass and not listen to my chair vibrate.
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post #2031 of 4913 Old 02-07-2017, 03:45 PM
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This went from the JBL subs -6 db point being in the audible range to whatever this is lol.
It was entertaining to read, regardless
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post #2032 of 4913 Old 02-07-2017, 03:46 PM
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Originally Posted by m. zillch View Post
There's not a single wide release movie ever made, in the entire history of cinema, with loud, sustained content below ~20Hz [that's intentional] that didn't simultaneously also have loud content in the octave band above that point and it is this content which people are actually being impressed by . . . but their eyes see their measurement gear registering 10Hz, etc., and expectation bias, aka the placebo effect, does the rest.
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Wha? . . . IIRC the opener for Edge of Tomorrow is a 25/20/15/10 hz sustained 2-3 second note that progresses down finishing at that 10hz fundamental. There is NO other content above, and if you see it, it's distortion otherwise. .
Incorrect, there's lots of deep, subwoofer bass content above the 20Hz point when the 10Hz super deep special effect note appears. Notice the loud note which appears at -6dB on this graph, below, at 30Hz?


That's not an acoustical/subwoofer distortion or amp distortion: I made this measurement in the electrical domain so everyone playing this scene is getting that loud 30Hz signal.
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post #2033 of 4913 Old 02-07-2017, 04:01 PM
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Originally Posted by awediophile View Post
Just because the mix engineer didn't hear it doesn't mean that it doesn't improve the experience. To spin this argument the other way: What's the big deal about the M2s and their ability to reveal more detail than other speakers if most existing music was mixed on lesser speakers? There's no need to answer.
Going to answer, because it just might add something valuable to the conversation

I agree it can, or could, improve the experience. But without a way to monitor it, the mix engineer doesn't know what it actually sounds like, good or bad. The same argument applies for hyper-detailed speakers like the M2 - it can show up warts in the recording, so knowing what's actually going into the recording to begin with is a good thing

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post #2034 of 4913 Old 02-07-2017, 04:26 PM
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Originally Posted by Jsin_N View Post
This went from the JBL subs -6 db point being in the audible range to whatever this is lol.

I've sat in chairs with tactile transducers and it never feels like they match the bass. Maybe it was the set up. Regardless, those are pretty cheesy. I'd rather just feel the real bass and not listen to my chair vibrate.
It's been my experience too - what's happening on screen and in your chair seem wildly disconnected.

It's like you are trying to watch a movie and someone is kicking you in the a$$ at the same time, lol.
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post #2035 of 4913 Old 02-07-2017, 05:26 PM
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Originally Posted by John Schuermann View Post
Going to answer, because it just might add something valuable to the conversation

I agree it can, or could, improve the experience. But without a way to monitor it, the mix engineer doesn't know what it actually sounds like, good or bad. The same argument applies for hyper-detailed speakers like the M2 - it can show up warts in the recording, so knowing what's actually going into the recording to begin with is a good thing
Exactly. I think some others here may have missed my analogy, but you nailed it. And likewise, someone who wants the best possible sound from their audio system might want to look into subs with capability under 20 Hz.

I agree that the content above 20 Hz is a lot more important than the content below 20 Hz, so obviously it comes down to personal priorities. But I would caution those who disbelieve that infrasonic content is irrelevant to reserve judgment until after you've actually experienced it in person.

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It's been my experience too - what's happening on screen and in your chair seem wildly disconnected.

It's like you are trying to watch a movie and someone is kicking you in the a$$ at the same time, lol.
Yeah. A lot of these devices offer very poor fidelity. I forget where, but I've seen measurements of some of these things with huge peaks at 50 Hz and practically nothing anywhere else. I mentioned the Crowson brand because many people on these forums who would agree 100% with your statement with regard to many other products would also say that Crowsons are a "game changer", so to speak. So I guess a lot depends on the quality of the device that get installed as well what kind of gain and equalization is in use on them.
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post #2036 of 4913 Old 02-07-2017, 05:52 PM
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I think there really isn't a "right" answer for this. We can agree that in a commercial cinema, material below 30Hz is filtered for many reasons, most of which were listed in above posts. In a home environment, it's much easier to to be able to reproduce these lower frequency down to 20Hz and below due to the size of the space the subwoofers have to pressurize. We also know that film material that is mixed for a commercial cinema, is redone for playback in the home. It's entirely possible that some mix engineers don't filter out those super low frequencies in the home versions of the mix for the added effect, while some may. The choice is theirs, and like many in here that disagree whether or not it's useful to have those frequencies present or not, the mixing engineers may also disagree with each other about whether or not those frequencies should be there. Those that think they should, leave those frequencies in as we can see in some movie mixes. Those that don't, filter them out.

That's my opinion/guess on the matter.
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post #2037 of 4913 Old 02-07-2017, 07:47 PM
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Originally Posted by awediophile View Post
You don't need the longest room dimension to be below the 1/2 wavelength for room gain to apply. Any time you have boundaries, you have room gain. The answer to the question of how much at what frequency is all in the details.
There is a difference between boundary gain and room gain. Boundary gain happens when the speaker/sub is placed next to a boundary or multiple boundaries like a corner, room gain happens by making the room a pressure vessel and to do that it needs to be less than 1/2 wavelength of the frequency desired. You get that in most HT rooms but lose it in larger spaces. I think you would be surprised how much more subwoofer power is needed in larger spaces to go very low.
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post #2038 of 4913 Old 02-08-2017, 01:28 AM
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There is a difference between boundary gain and room gain. Boundary gain happens when the speaker/sub is placed next to a boundary or multiple boundaries like a corner, room gain happens by making the room a pressure vessel and to do that it needs to be less than 1/2 wavelength of the frequency desired. You get that in most HT rooms but lose it in larger spaces. I think you would be surprised how much more subwoofer power is needed in larger spaces to go very low.
When I say "room gain", I mean the amount the in-room measurement is greater than a ground-plane measurement at the same distance. I am aware that the term "room gain" is also used in the context of the pressure vessel model. The pressure vessel model arises as a limiting case of low frequency in a room with infinitely rigid boundaries. Reality is usually more complicated than that, having lossy boundaries that may exhibit mechanical resonances that couple with the sound. And as wavelengths get longer, reflections between boundaries become gradually more coherent so that gain tends to increase overall with decreasing frequency well above the theoretical pressure vessel transition point.

And no, the amount of extra output needed in larger rooms would not surprise me, and I believe a pair of dual-21" (using the right driver) ported or horn cabinets, with at least 6000W of power ought to do a decent job. Double them to be sure.

Of course, I don't believe subs like this are on the market. So a better option might be something like 4 to 8 JTR 4000ULF. I'd want to ask JTR if they could be built passive with rack amps instead of plate amps, but otherwise, they ought to do the job very nicely while remaining very affordable. With 8 of them installed into corners, and assuming 10 dB of corner gain, they'd be good for at least 119 dB @ 10 Hz at 15 m distance. Not too shabby.

In terms of output requirements, this is totally do-able and with a budget that's relatively small compared to the cost of a high end cinema projector. The issue again comes back to whether the structure can contain the bass enough to achieve that 10 dB+ boundary gain and hold together while doing so.
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post #2039 of 4913 Old 02-08-2017, 03:42 AM
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You are correct that the issue is a lot more complicated in many areas between large and small room acoustics. I work in them all the time, in fact I will be in an auditorium today. You don't deal with room modes in large rooms but you deal with bass decay instead. Many RT60 values only show to 125hz but when you go lower the decay becomes much longer. A recent church I working had decay times of 8 seconds at 50hz causing very bloaty bass hang that they were complaining about. That also has to be dealt with. Working in theses spaces you would be surprised how much drop off you get below 35hz even with multiple large 18" subs. Calculating ground plane, distance and boundary are great in theory but you are losing a lot through walls at that frequency range unless in a bunker of a building and real world experience shows me to go below 20hz in these spaces is not an easy task for multiple reasons.
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post #2040 of 4913 Old 02-08-2017, 03:51 AM
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Though this conversation in the wrong thread, it does at least make me laugh.

So for the 74 people worldwide that can go to 10hz allegedly cleanly, there is a push for the industry to meet their specs?

Sorry, you put your money in a bad spot....
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