Originally Posted by John Schuermann
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.
Originally Posted by Ellebob
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.
Originally Posted by fatsow
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.
Originally Posted by Ted C
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".