Why aren't cinemas targeting sub 20hz response?

[stevenswall]

Have you ever been to a high end movie theater?

Powerful, deep, impactful bass is hard. There is nothing wrong with sacrificing a little extension to achieve more impact, especially when you know bass peaks are being compressed otherwise.

What qualifies as high end? I thought IMAX theaters sound the same, but maybe the spec is useless.

Bad studio engineers made bad decisions. That's my subjective opinion when it comes to many movies and a lot of music. Not saying they are violent or evil (beyond some live sound ones purposefully, methodically, consciously destroying people's hearing)... Just disgustingly horrible at their jobs, destroying art.

....Which is what I think most cinemas do as well, though to a lesser extent, when it comes to the audio, by aiming for SPL, and bass impact that to me doesn't sound deep or immersive, just impactful and loud like a wall of cheap subs.

If you know of a high end theater in Utah or an adjacent state I'd like to know. Maybe one of the laser IMAX theaters will come here soon and have equally good improved sound, in addition to the I proved projector.

Could also be that I just like what a quiet studio sounds like with primarily direct sound and a great soundstage, and that makes theaters sound terrible to me. I've never turned my head towards a voice that I thought was from real life in a theater, or mistaken singing or humming as coming from someone near me. That's happened in studios though.

 

[3ll3d00d]

some sciency stuff you're misunderstanding here

You can do your own research to learn more about that science stuff

https://en.m.wikipedia.org/wiki/Sound_intensity

The threads on the subject on avs were long and died years ago so you can read them at your leisure if you like.

 

[sigbergaudio]

You can do your own research to learn more about that science stuff

https://en.m.wikipedia.org/wiki/Sound_intensity

The threads on the subject on avs were long and died years ago so you can read them at your leisure if you like.

Thanks, I'm not interested enough in the subject right now to spend hours on that. I haven't read anything yet disproving my assumption. Moved to the extreme: A wrongly designed ported subwoofer will give audible chuffing, which I hope you agree is a distortion of the sound. If it's this acceleration through the port we think changes particle velocity (thus increasing intensity) and as a consequence make us "feel" a ported subwoofer more than a sealed subwoofer, then it's also affecting the sound. Depending how extreme the effect, it may or may not be audible.

 

[3ll3d00d]

The suggested mechanism is quite simple

Human auditory system is sensitive to pressure
Sound intensity is product of pressure and velocity (both vectors)
Human non auditory senses are sensitive to intensity
Thus changing the particle velocity for a given spl can feel different yet have no audible impact when compared to a similarly linear sealed sub.

I don't recall ever seeing a paper demonstrating the sensitivity of humans senses to sound intensity but I may misremember.

Audible chuffing is a result of compression driven by turbulence as a result of particle velocity being too high. Similar effect to driving a sealed sub towards and beyond xmax with different bad noises. Better to focus on subs operating within their linear range though comparing sealed and ported is quite hard in that case (as they fail in different ways).

 

[Chromatischism]

So at least to me it seems pretty logical that if the tactile sensation is different from two different subwoofers, the sound is necessarily different too. And that means one of them must have higher distortion than the other, if we agree that distortion is deviation from the original sound (source). If neither had any distortion, the sound would be exactly the same, and so would any induced vibrations.

No, no, and no.

The subwoofer itself does not produce a different sound, or more distortion, just because it's producing more TR. However, tactile sensations can alter our perception of sound.

 

[Mnyb]

Can it depend of distance to the source , I sure get the tactile feel from a ported system if I'm close to the ports while playing loud
But in a big enogh room given that the sub is not in distress in any way does it really matters ?

 

[Chromatischism]

Can it depend of distance to the source , I sure get the tactile feel from a ported system if I'm close to the ports while playing loud
But in a big enogh room given that the sub is not in distress in any way does it really matters ?

The further away the sub is, the less vibration will reach you.

 

[Andysu]

cinemas can't target 20Hz at present .. there all closed down.

 

[echopraxia]

cinemas can't target 20Hz at present .. there all closed down.

I suppose one could say they reached 0 Hz ...

 

[stevenswall]

Why target 20hz when you could just make everything louder?

Why target perfect blacks and better colors when you could just make everything bigger?

Theaters are for quantity rather than quality I think, though sometimes large quantity is a quality I want.

 

[Andysu]

Why target 20hz when you could just make everything louder?

Why target perfect blacks and better colors when you could just make everything bigger?

Theaters are for quantity rather than quality I think, though sometimes large quantity is a quality I want.

cinemas are 4k digital rubbish trash now. Glad they finally coming close to bust I won't miss a single pixel of a frame.

 

[luft262]

You can get 119 dB @ 20 Hz from 3x FV18 for $5k.

However, I would contend that theatre reference level is almost never used at home. I would subtract 10 dB for a more realistic level. In that case, 2x FV15HP are perfect for the task and will only set you back half that. Therefore, I suggest:

System C: LCR mains capable of 95db from 100hz to 20khz, and sub(s) capable of 105
db down to 10hz.

That is what you get when listening at -10, a common home movie level.

With that said, some prefer to equalize and boost the bass region, so they may want more. Also, there's nothing wrong with having main speakers capable of more than 95 dB, in fact it's preferred, but I just wanted to illustrate that the SPL requirements need not be so high.

-10dB makes a lot more sense. In all honesty, 90% of the time, even if we have friends or family over for "movie night" we're probably listening at more like -15 to -20dB from reference. For me reference level is only attempted for "academic" purposes or to re-watch a scene when my wife isn't around. I'd like to maintain my hearing thank you very much!

 

[Daka]

-10dB makes a lot more sense. In all honesty, 90% of the time, even if we have friends or family over for "movie night" we're probably listening at more like -15 to -20dB from reference. For me reference level is only attempted for "academic" purposes or to re-watch a scene when my wife isn't around. I'd like to maintain my hearing thank you very much!

I agree -20db is loud and still listening over longer periods would damage your hearing. My partner even complains at -20db being too loud so sometimes I need to go -25db. In cinema I often measure sound level and usually movies are around 90DBs, there was one or two in past 3 years which exceeded 90DBs with peaks around 100DBs and it was immensely painful.

 

[Chromatischism]

90 dB peaks are nice because the dialogue is still easily heard (75-85 dB) and the exciting parts are just enough. Note that the bass peaks will be over 100 dB - as they should be!

 

[Vacceo]

Our hearing stops at 20 hz. Seems enough if subs do the same. I seem to remember one reason is with hearing below 20 hz we'd hear our joints creaking.

Plus there is the chance to make people sick, queasy or see illusions at high levels below 20 hz.

But we do feel infrasonics. They are an old trick for horror films to increase disconfort and suspense.

 

[sigbergaudio]

I agree -20db is loud and still listening over longer periods would damage your hearing. My partner even complains at -20db being too loud so sometimes I need to go -25db. In cinema I often measure sound level and usually movies are around 90DBs, there was one or two in past 3 years which exceeded 90DBs with peaks around 100DBs and it was immensely painful.

Sounds strange, 100dB isn't immensely painful on a reasonably balanced system that isn't distorting heavily, peaks of 110dB or more is pretty normal at concerts.

 

[Joe Smith]

And, of course, there was this equipment effort back in the day...

https://en.wikipedia.org/wiki/Sensurround

 

[Hayabusa]

Sounds strange, 100dB isn't immensely painful on a reasonably balanced system that isn't distorting heavily, peaks of 110dB or more is pretty normal at concerts.

It all depends on the frequencies played at 100/110 dB.
A 32Hz 110dB is doable but a 110dB 8KHz will make you instantly want to cover your ears.

 

[sigbergaudio]

It all depends on the frequencies played at 100/110 dB.
A 32Hz 110dB is doable but a 110dB 8KHz will make you instantly want to cover your ears.

Sure, luckily most material have way less high frequency content.

 

[Ra1zel]

Sounds strange, 100dB isn't immensely painful on a reasonably balanced system that isn't distorting heavily, peaks of 110dB or more is pretty normal at concerts.

I'm starting to think this whole "pain" situation is actually just discomfort from speakers that exhibit too much distortion/resonances/breakups. I'm very sensitive to resonances, once I hear them my day is ruined, that's why I'm drawn to overkill box designs.