Reference vs. Preference
Here is a trick question: “What if I correct the acoustical problems in my room, but I don’t like the resulting sound?” If you find yourself asking this question you have stumbled on the line between Reference and Preference.
Let’s look at what room correction aims to do. You start with a good (or not so good) set of speakers, you place them in a room and what you have is problems: acoustical problems. Sound from the speakers comes to you from many different directions. Some of it directly, but most of it after interacting with the floor, ceiling, walls, and furniture. Because each of these elements is at different distances from where you sit, the combined sounds arrive at slightly different times and what you hear is a form of distortion. Voices can sound unnatural, the low frequencies are muddy or boomy, and the high frequencies lack air and sparkle (yes, these are all technical terms).
A well-designed room correction system captures information throughout the listening area and analyzes it in the time domain. It then creates an equalization solution for each speaker and applies it so that the response matches a certain target sound. And here is where we first catch a glimpse of the Reference vs Preference line: What should this target sound be?
The answer lies earlier in the chain, where the content is made. The film industry adheres to a set of strict standards that are used in the creation of the content and in the reproduction of the content in movie theaters. These standards define the location, level, and frequency response (target sound) of the speakers in the audio system. They are in place so that content created in one location can translate perfectly to thousands of movie theaters. The same translation should apply when the content is played back in a home theater.
So, calibrating your home theater system “to reference” means that: (i) the levels of each speaker and subwoofer are matched to each other; (ii) the playback level of the system reaches a certain sound pressure level when the volume control on your AVR is set to “0”; (iii) the time delays for each speaker and subwoofer are adjusted so that sound from all of them arrives at the same time to the central point of the listening area; and (iv) the frequency response of each speaker and subwoofer is such that the perceived octave-to-octave balance is the same at home as it is in the dubbing stage or the movie theater.
Reference is a good thing because it gives us a way to reproduce the art the way it was made. But, you might say: “I like more (or less) bass.” OK, I’ve never heard anyone ask for “less bass,” but I suppose it’s possible. As soon as the word “like” is uttered we have crossed into the uncharted waters of the Preference abyss. It can be a fun place to be and there is nothing wrong with applying personal touches to your sound, especially if you are the one enjoying it. But know this: It’s not the job of a room correction system to determine your preference. That is entirely up to you. What room correction gives you when it delivers reference is a known baseline and the ability to apply preference consistently. Without it, boosting the bass for some content would not sound the way you want it for other content because you are not starting from a known condition. If you want to apply your preference, I have some words of advice: “Start with reference.”
May 13th, 2009 at 11:20 pm
Chris,
Starting with “reference” for movies is clear enough. But, what about music? You’ve mentioned the lack of standards in the music industry in forums. I haven’t found any need to make changes to accommodate personal preferences when I listen to music. However, is starting with the default “reference” designed for movies about as good as it’s going to get if one’s most critical listening is music? Is there, for instance, a better frequency response curve or a better volume adjustment (the per-source volume adjustment that affects the frequency response versus amplitude correction) that would be a better default for music? I listen to a wide variety of music genres, all in two channels, and at wife-limited amplitudes.
Harrison
May 14th, 2009 at 9:59 am
Harrison,
Yes, part of the music industry is… “reference challenged”. But, the issue is not so much the frequency response calibration of the monitors used. It is a safe assumption that a flat response will match the mixing conditions reasonably well. We could argue about the high frequency roll off above 10 kHz, but that is a rather fine detail.
The bigger issue with the lack of standardization in music mixing is the mix listening level and the amount of dynamic range compression used in the creation of the content. That is what varies dramatically from film mixing, particularly for some genres of music (e.g., pop).
Not knowing the exact monitoring mix level (as we do for film) makes it more difficult to compensate when you listen at lower volumes. Dynamic EQ was designed to compensate for the changes that occur in our hearing at lower listening levels, but it really needs to know the starting reference point. In the new products coming out with Dynamic EQ this year, we are introducing an “offset” adjustment that allows you to better tailor Dynamic EQ to varying music mix levels. Not as good as having the entire industry standardize, but a useful step nonetheless.
May 14th, 2009 at 9:21 pm
Thanks. Ah yes, dynamic range compression. I’ve learned to recognize it immediately … and despise it. With a good quality sound system and MultEQ XT and Dynamic EQ it’s all the more irritating. I’ve given up country music because a lot of it has gone this route. Much of what I listen to is older and doesn’t have this problem.
Thanks, Harrison
May 19th, 2009 at 8:24 am
“Start with reference.”
How? Audyssey is either on or off. It would be nice to have the tools at the retail level to see what Audyssey is doing and make adjustments to suite taste. I know Audyssey has lots of knobs to turn, and simplifying it down to something a consumer can adjust is difficult, but it is what I crave.
May 20th, 2009 at 1:21 pm
Hi Ryan,
When Audyssey is “on” then you are at reference. The tools for making changes based on individual preference are available today through the Audyssey Pro software. They can be used to tailor the target curve in products that are Audyssey Pro enabled. We are also looking at ways to create a simple interface that will give some more control to the built-in version of MultEQ.
May 23rd, 2009 at 12:21 am
If I were a sound engineer paid based on how good my product sounds on normal equipment, and I had to choose between making my mix sound good on non-reference systems (which are the vast majority of end user systems) or on reference systems which end users rarely hear, I’d tweak it for the normal non-reference systems. Just on a practical level, you want to please as many people as possible if your goal is to make money.
So while I agree that the world would be a better place if engineers actually did mix for reference, I suspect that they mix for end users instead.
May 23rd, 2009 at 7:28 am
It’s important to understand that engineers don’t mix *for* reference. They mix *to* reference. Sounds like semantics, but it’s not. “To reference” means that when they walk in the dubbing stage it has been calibrated to meet the required reference conditions of frequency response, speaker placement, etc. Then they sit down and start doing exactly what you say. Always. Every mix is intended to deliver the message of the director and that message is both based on art and the desire (as you say) to please as many people as possible.
They make adjustments to the frequency response of every element in the mix, boost bass, apply effects, etc.
The point of calibrating to reference at home is to make sure that the desires of the content creators are perfectly translated. They chose to put a certain amount of bass in a scene. If your subwoofer is not calibrated at the same level as what theirs was then what you hear will have more or less bass. That may be your preference, but in effect you are remixing the film.
So, reference is a just a tool that lets you peek into the dubbing stage and hear what they heard.
June 1st, 2009 at 6:31 am
Chris, I would add a caveat to this statement: “When Audyssey is “on” then you are at reference.”
The caveat is assuming the measurement process was executed correctly. As we have seen with the development of the Audyssey Setup Guide, there are a few steps to ensure a good measurement run.
Mark
August 17th, 2009 at 4:16 pm
thanks for this very engaging discussion. I am wading through many, many web sites after re-calibrating my 7.1 system using the MultEQ XT Auto Setup in my Denon 2808CI. I must admit I was really confused by just how different my system sounded after the Audyssey adjustments–and, to be honest, I am not sure if it is better or worse or just…different. (I measured 6 positions, 3 on the sofa, 3 off.)
(I am using Axiom Audio M60v2s for my mains, anAxiom Audio VP100v2 for my center, 4 Cambridge Soundworks surround speakers (legacy, I will get rid of them eventually) and an SVS 10″ sub, the PB-10NSD.)
The biggest differences:
- what seemed like an expanded soundstage in the front (good)
- a significant dropping of bass in the center channel. Like, it just sounded like it got chopped off at the knees. When I turn off the Audyssey EQ and go to my calibrated Manual settings (using a sound pressure meter, etc), there is a lot more warmth to the front speakers, especially the center channel.
Now, of course, after reading this, I wonder, if after setting my M60s to small (when I get home tonight), if there will be a change, but I just have to wonder: the difference between Audyssey being on and off is so dramatic, that I have to wonder if I have done something wrong.
It’s just so incredibly confusing. I wanted to use the Audyssey MultEQ XT to make everything sound better, as the feature advertises, but when I use it, it just sounds so different–worse, really. I just don’t know if the difference is just something I will adjust to or not.
anyway, I dunno where to go with my comment, I am just trying to figure out why it sounds so different.
thanks for this great blog.
-mike
August 18th, 2009 at 12:01 am
hey hey–
After much tweaking (and 8 mic positions), followed by 3 hours of Mad Men, I must admit–I am turning a corner on the Audyssey setup. It really does seem to expand the stage and now when I listen to the content with out it, the front sound stage sounds more boomy and thick. I am still trying to figure out what’s what, like what IS the reference, but I am beginning to think that this does sound better.
I will keep working on it.
thanks,
mike
August 20th, 2009 at 9:59 am
Chris,
Is the Audyssey “reference curve” a flat response or does it emulate the “X curve” used in the film industry?
I have read some confusing articles that state that a subjective “house curve” that boosts low frequencies (in smaller rooms) is preferred to a measured flat response.
August 20th, 2009 at 4:09 pm
It is neither. This curve was derived from multiple factors. One is to account for the differences in the listening conditions. Content is created in rooms where the listening is more direct sound and less reverberant sound. But, at home the opposite occurs and so a translation needs to happen to make sure that content mixed to the X-curve is properly experienced at home.
September 29th, 2009 at 11:33 am
Hi chris
i have the Denon AVR-4310 and i have both plasma tv and a projector in my home theatre , some times i use my plasma tv for watching moveis and other time i use the projector , the thing is that i have notes with the projector screen pulled down , i get more sound reflection in the room ,and when it,s pulled up again i get less reflection from the room , my question is that should i run audyssey calibration setup with the projector screen pulled down or up ? or do i have to sacrifice one for the another? as i have mentioned i tend to use both the projector and the plasma tv sometimes. Thank you!
October 22nd, 2009 at 2:47 pm
Hi Marco,
Unfortunately the current AVRs don’t provide enough memory to store multiple calibrations so you will have to chose one.
January 28th, 2010 at 12:17 pm
Hi Chris
I have just listened the “THIS IS IT” bluray mastered in DTS HD MA . Since this was mixed for film I figure it was mixed in the “standard” films mixing practices ….and this sound mix shines when played with Audyssey processing.
I don’t understand why all bluray concerts don’t stick with the film mixing practises
thanks for this magnificient technology!