EQ of the X curve

[Tomlinson Holman]

The X curve is a target response for EQing of the room reponse in cinemas and mixing theaters. This means that it has no direct effect on the spectrum of the mix, but an indirect.
Everything is already explained in the things I have written or linked. If you are really interested in this, please read my link.

Regarding the indirect effect, I want to give an example.
You are mixing music on a system which has a lack of bass. When you do the mix you will put a lot of bass into your mix untill it sounds good.
When you now play your mix on a speaker system with a flat response, you will have too much bass.
You see that the setup of the speaker response will have an influence on how the mix will be done and how it sounds.

Cinema mixes are done on a system with a falling curve toward higher frequencies and are designed to sound perfect on such a system.
When you play thoose back on a system with a flat response it will sound different.

Regarding to this topic you can do 3 things.

- Trust me with what I have written.

- Trust the guys from THX that this compensation for home is an interessting topic because they implented exactly such an inverse eq of the X curve into their algorithms.

- Just look at my result. If there is no difference between theater and BD mix in terms of spectrum it does not matter for what you are doing here anyway.

As requested you find an example attached which is a small piece of the comparisions I am doing. Shown are the average responses of two channels for the whole movie. No X curve correction has been applied, but the center channel level has been increased by 1 dB.
So far I checked two studios, both have not compensated the X curve.

[Jetrell Fo]

I know DTS had a calibration disc for theater sound as I have one. So are you just trying to determine which studios actually implement the x-curve and which ones don't? Home calibration would have to be done on a case by case basis due to the variations in size of apartments vs. homes and their styles. I don't know that a blanket x-curve could be calculated that would be a universal fix for such things.

[Tomlinson Holman]

I know DTS had a calibration disc for theater sound as I have one.  So are you just trying to determine which studios actually implement the x-curve and which ones don't?  Home calibration would have to be done on a case by case basis due to the variations in size of apartments vs. homes and their styles.  I don't know that a blanket x-curve could be calculated that would be a universal fix for such things.

The average home frequency response and the average studio (non cinema sound mixing) frequency response is a flat one, as written in this (very good) book: https://www.amazon.com/Sound-Reproductio...0240520092

The average cinema response curve is different, it is a X curve, as you can see here: https://www.smpte.org/sites/default/file...202014.pdf

I am trying to find out if the studios are therefore trying to compensate the spectrum for home usage, as the THX processing is doing.

[Jetrell Fo]

I know DTS had a calibration disc for theater sound as I have one.  So are you just trying to determine which studios actually implement the x-curve and which ones don't?  Home calibration would have to be done on a case by case basis due to the variations in size of apartments vs. homes and their styles.  I don't know that a blanket x-curve could be calculated that would be a universal fix for such things.

The average home frequency response and the average studio (non cinema sound mixing) frequency response is a flat one, as written in this (very good) book: https://www.amazon.com/Sound-Reproductio...0240520092

The average cinema response curve is different, it is a X curve, as you can see here: https://www.smpte.org/sites/default/file...202014.pdf

I am trying to find out if the studios are therefore trying to compensate the spectrum for home usage, as the THX processing is doing.

I don't imagine they would be since most homes/studios aren't going to be the size of a theater and it seems the x-curve is designed specifically for them. I always thought that THX was designed more for consumer use originally to try and simulate a simple form of an "x-curve" to make the home viewing experience more dynamic.

[spoRv]

If we apply a "reverted" X curve - from something like /-\ to \-/, wouldn't we get a --- flat curve (pun intended)?

[Tomlinson Holman]

I don't imagine they would be since most homes/studios aren't going to be the size of a theater and it seems the x-curve is designed specifically for them.

Please read very carefully what I have written before. Cinema soundtrack were done on a system with a falling curve towards higher frequencies and optimised for this.
Just taking the mix and listen to it on a flat system will create a different experience, see example with the lack of bass system.

I always thought that THX was designed more for consumer use originally to try and simulate a simple form of an "x-curve" to make the home viewing experience more dynamic.

The X curve and the compensation of it, are static EQs and therefore they do not change the dynamic.

[zoidberg]

You are mixing music on a system which has a lack of bass. When you do the mix you will put a lot of bass into your mix untill it sounds good.
When you now play your mix on a speaker system with a flat response, you will have too much bass.
You see that the setup of the speaker response will have an influence on how the mix will be done and how it sounds.

Why are you mixing in a studio with a lack of bass? The setup of the speaker response will have an influence on it's calibration/equalisation, that's all.
Movie studios released films (on celluloid) with analogue or digital soundtracks. Can you imagine if they had to produce different mixes to account for big/small theatres, perforated/non-perforated screens, horns/speakers? It would be a mess.

Please read very carefully what I have written before. Cinema soundtrack were done on a system with a falling curve towards higher frequencies and optimised for this.
Just taking the mix and listen to it on a flat system will create a different experience, see example with the lack of bass system.

Cinema soundtracks are PLAYED BACK on a system with a falling curve towards higher frequencies (or not). The playback system is calibrated to deliver the same audio response as the mixing studio (which in turn is calibrated, frequently). It's no different to calibrating your TV/display using standardised video test patterns, some displays need more adjustment than others.

The THX Theatre Alignment Program (TAP) came into being because George Lucas went to various screenings of his Star Wars films and found the sound was terrible, sounding nothing like the original mixes. Cinemas were re-equipped to replicate the sound of the original mix, because of that we have the lovely cinema experience that we have today.

[Tomlinson Holman]

Do we agree on the point that the same soundtrack played back in a cinema with a falling curve will sound different then played back at home with a flat response?

How do you explain that the guys from THX you are refering to have added the X curve correction into their equipment?

[Jetrell Fo]

Tomlinson,

I am unsure as to why you're suggesting I have not read what you've posted. I have. I also remember mentioning to you to check out hairy_hen and capablemetal's posts on OT. Those two were instrumental in helping us understand how to best work with the cinema DTS audio for projects with regards to translating the cinema effect to home use. There has not been any complaints that I'm aware of that those here that have done the editing/syncing that points to them not listening to that information.

The DTS system had it's own "sweetener" in their hardware to compensate which was why DTS had calibration discs to go with their machines so they would do what they were designed for with regards to the x-curve. So I guess I'm just trying to understand. It seems that maybe whatever you feel is wrong with the audio is a personal issue with the studios that did the audio. If that is the case then this might be the wrong venue for you to take that up.

If that is not the case then I'm totally confused about this entire thread's purpose.

[Jetrell Fo]

Do we agree on the point that the same soundtrack played back in a cinema with a falling curve will sound different then played back at home with a flat response?

Now you're just being insulting. Why would that not be the case? The cinema and the home are 2 different places, of course they would sound different, their size, equipment, and person capacity alone make that a 100% no-brainer

I'm beginning to tire of whatever it is you're saying about our members here.