# NOOB---Reference level?



## memarcus (Jan 28, 2010)

So I've been lurking a while and see many references to the term "reference level." What is the definition of this? I know its a very basic thing and from inference can tell its a very loud level but how is it determined? Is it based on the point at which speakers begin to bottom or is it related to an absolute measure of volume, such as 120dB. Most posters mention they "don't listen at reference levels" or something similar but I have looked for a definition of what this means and haven't been able to figure it out precisely.

In the upcoming months I have been given the approval by my "domestic manager" to build a theatre room while finishing the basement and am trying to set design goals for now and this was one thing I was hoping to nail down an understanding for. 

Hope this isn't too stupid a question and thanks in advance.


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## Home Theater Guy (Jul 18, 2009)

Listening at reference level simply means listening to a soundtrack at the same volume level as the filmmakers did when they produced the soundtrack. In a properly calibrated home theater with a referenced volume control, this would be the "0dB" setting.


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## Zeitgeist (Apr 4, 2009)

This page has a pretty good explanation too:
http://www.hometheaterhifi.com/volume_13_1/feature-article-thx-1-2006-part-1.html

From link:
"Reference level is by any definition, objective or subjective, quite loud. It basically mirrors the dynamic range of the studio system, which in the case of all movie sound tracks, is 105 dB. Any single channel of the system is calibrated to play 0 dB FSD (the loudest sound the sound track can contain) at 105 dB (115 dB for the LFE channel). While that is really, REALLY loud, its important to remember that there is 105 dB of dynamic range and the artist can put a sound at any level they want. So while a system's volume may be set to reference level, dialogue within the sound track can, and most often is, at a normal, natural level. Reference level, with the dynamic range available, permits a movie to have that normal, natural dialogue, and then suddenly a spectacular, loud car chase without anyone touching the volume control. Every element in the sound track comes out as it should.

Now, having said all that, watching a movie at reference level in a home theater is almost never done. It can be extremely loud to begin with, but the close spaces typical of home theaters make it perceptibly even more so."


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## jeremy7 (Feb 7, 2008)

Great explanations, I never knew that. Thanks


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## fitzwaddle (Aug 25, 2010)

Zeitgeist said:


> Now, having said all that, watching a movie at reference level in a home theater is almost never done. It can be extremely loud to begin with, but the close spaces typical of home theaters make it perceptibly even more so."


Yes, but a must for demos.

For movies, I like to listen around -5 to -10 db. :hsd: Keep in mind that that doesn't mean the soundtrack is that loud for the entire movie, just transients give you a nice kick in the pants.


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## Zeitgeist (Apr 4, 2009)

In another thread about surrounds... playing reference or close to it - seems to be a big factor in getting better results from surrounds..

Some people feel that the surrounds are too dead - but others (like myself) hear a lot more from surrounds when the overall level is higher.

Just food for thought.


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## GranteedEV (Aug 8, 2010)

With respect to speakers it means being able to do 105db at the seating position without any hint of distortion/compression. 

Depending on the distance of the seating position to the front speakers, this can mean being able to do 110db to 120db @ 1m !

Something like a Revel Salon might be able to do an honest 112db, but you would need to get into compression drivers, pro audio woofers, horns, or line arrays to start getting true reference levels at big distances.


With respect to subwoofers it means being able to do 115db at the seating position. Three 18" ported subs is probably your best bet


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## grn1969c10 (Sep 18, 2008)

Is there an accepted method to calibrate the receiver to reference level? Since pairing speakers with different efficiencies to a given receiver and placing them in different sized rooms will all affect the sound level at a particular listening position, how would the receiver know how loud "0" really is? Can audyssey or MCACC measure and calibrate actual sound level during setup? I had previously assumed "0" represented a particular voltage range for the receivers output signal and the actual volume depended on the external system variables.

Matt


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## Dale Rasco (Apr 11, 2009)

When we are reviewing Bluray's, the team and I generally listen to what we refer to as "reference level". Our general definition is 85db for normal scenes with spikes over 100db. For my system, I will listen at -10db for DTS-HD and -7db for TruHD. In order to get these setting as my reference level, I will go into the receiver settings and adjust each channels volume level to 75db. Then I will watch a scene such as the hotel scene in Hitman with my SPL in hand and see if it is as I expect. If not, I will adjust the volume as necessary to obtain the 85db with spikes over 100db "reference level".


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## Home Theater Guy (Jul 18, 2009)

The standard method for calibrating to reference level is to place a sound level meter at the listening position (make sure it's placed where your ears will be, not held out in front of your seat while sitting down) and set the receiver's test tones so that each channel reads 75dB (slow, C-weighted mode). If you are using a non-THX receiver, this may or may not produce the correct levels. After calibrating in this manner, setting the volume to 0dB will produce the soundtrack at reference level. Automatic room correction systems like Audyssey are designed to calibrate to reference automatically during setup.

After calibration, any volume control adjustment down refers back to this reference level. -10dB, for example, means 10dB below reference. In a home theater, I am usually comfortable listening -6 to -10dB, depending on how hot the soundtrack was recorded.

Listening at these high levels does require that the system be pretty brawny to produce the peaks in the soundtrack without distortion.


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## Dale Rasco (Apr 11, 2009)

Home Theater Guy said:


> The standard method for calibrating to reference level is to place a sound level meter at the listening position (make sure it's placed where your ears will be, not held out in front of your seat while sitting down) and set the receiver's test tones so that each channel reads 75dB (slow, C-weighted mode). If you are using a non-THX receiver, this may or may not produce the correct levels. After calibrating in this manner, setting the volume to 0dB will produce the soundtrack at reference level. Automatic room correction systems like Audyssey are designed to calibrate to reference automatically during setup.
> 
> After calibration, any volume control adjustment down refers back to this reference level. -10dB, for example, means 10dB below reference. In a home theater, I am usually comfortable listening -6 to -10dB, depending on how hot the soundtrack was recorded.
> 
> Listening at these high levels does require that the system be pretty brawny to produce the peaks in the soundtrack without distortion.


Excellent explanation Joe! :T That's what I was trying to get at but failed miserably. Oh well, some days I'm in the game and some days I'm on the bench... :rolleyesno:


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## grn1969c10 (Sep 18, 2008)

> The standard method for calibrating to reference level is to place a sound level meter at the listening position (make sure it's placed where your ears will be, not held out in front of your seat while sitting down) and set the receiver's test tones so that each channel reads 75dB


By "test tones" I assume you mean the white noise used by the receiver to set levels. I will have to check and see where my system is set. I typically listen to movies at -15 on the receiver. It's loud enough to give gunfire and explosions some punch, but the sound is very clean. Much higher than -10 and I'm to worried about how the speakers are handling things to pay attention to whats happening in the movie. (My brother-in-law urges me to turn up the volume every movie night...)

Matt


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## Dale Rasco (Apr 11, 2009)

Correct, the white noise used by the receiver to set levels.


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## Home Theater Guy (Jul 18, 2009)

...narrowband pink noise to be a little more specific.


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## grn1969c10 (Sep 18, 2008)

Home Theater Guy said:


> ...narrowband pink noise to be a little more specific.


Oh, sorry... I figured the subwoofer test tone to be narrowband, but I didn't know that was the case for the mains as well. Hmmm. I wonder if changing speaker setting from small to large changes the test tone used?


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## Dodger66 (Jan 3, 2011)

Wow!
Excellent question!
Excellent responses!

I never knew anything about "reference level".

Thanks for the tutorial guys!:clap:


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## grn1969c10 (Sep 18, 2008)

I definitely learned some things from this thread.

I checked the manual test tones and found the center & mains at 76db and the surrounds & sub at 77db. Close enough to 75 for me. That would suggest that 8 to 9db below reference level is the max volume that I can comfortably run my system. I have seen triple digits on the RS meter during the elephant charge in Tolkiens ROTK. Until I build some DIY "statements" or win the SVSound giveaway, I will have to be happy with what I have.

Matt


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## Home Theater Guy (Jul 18, 2009)

grn1969c10 said:


> Oh, sorry... I figured the subwoofer test tone to be narrowband, but I didn't know that was the case for the mains as well. Hmmm. I wonder if changing speaker setting from small to large changes the test tone used?


I hope you're not thinking of setting your speakers to large?  Just kidding.

Changing the speaker settings from small to large doesn't (shouldn't?) change the bandwidth of the test tones. The reason they are narrowband is so that problems in the low frequencies (caused by standing waves) and high frequencies (caused by the calibration and aiming of the mic) do not affect the overall channel level measurement. By the way, I didn't mention before that the low frequency nature of the subwoofer test tone does require you to take more of an average of the listening area instead of a single seat measurement.


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## memarcus (Jan 28, 2010)

Glad to see the reponse to this question. I had no idea what it meant and thought I might be blasted for asking although that doesn't seem to happen on this site that much......

The reason I asked is becasue I'm on the fence regarding the level of quality components I will need to budget for. What I had in mind was a Klipsch reference system with RF-82's up front and RF-62 center and prolly the 5 1/4 surrounds. I hadn't decided on the sub and am waffling between a pair of LLT's and IB. I'm not set on the Klipsch's for any reason other than their efficiency. I like that they would give me tons of range without having a pro amp on every channel and could be powered to sufficent levels with an AVR. Of course the subs are different story. For the IB setup I was tending toward the typical 4x18" array and for LLT a 2x sonotube setup with good value 18's.

I believe I have fairly good (well sensitive anyway, not necessarily discerning) ears but I'd like to achieve a pretty good setup from the start. I like to build and tweak but like to do that out of desire in the future rather than need from the get go.

Also seems like dealing with the wife on one large expense is easier that a continuing expense for arguable gain. I very rarely listen to anything at high volume. So I was trying to get an idea of what dB levels to shoot for in the preliminary planning.

Thus far the information presented has been great and seems to indicate that my initial thinking is not too far off. thanks to all for their contributions. This forum is fantastic.


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## Home Theater Guy (Jul 18, 2009)

Marcus,

Although it's a good idea to plan for maximum output levels, just make sure you also place as much emphasis on the sound quality of the speakers. In addition to efficiency and power handling, make sure you consider the speaker's frequency response, off-axis response, dispersion, and reliability. It's always a good idea to take a well-balanced approach to system design.

Along the same train of thought, I also recommend using the same model speaker for all three left, center, and right front speakers. Using three identical LCRs makes creating a seamless front soundstage much, much easier.

It looks like you're planning on a couple different subwoofer designs in the same room. It might be a challenge to get good sound with this approach. I would probably stick with the sonotubes only, and maybe add a couple more if you want more drivers. That way you can move them around to find the best balance between smooth bass and maximum output.

Good luck!


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## memarcus (Jan 28, 2010)

I should have worded that a little better. I"m waffling between a pair of LLT's OR an IB setup. IB setup pretty much dictates the layout of the room, where I could move the LLT'sif needed. I'm a little dicey on the IB. Many say they're spectacular and they model well, but I'm concerned about them being statically placed. What if the spot I have for them is awful in terms of FR?

Right now I'm trying to figure what equipment I'll need for budget reasons. Should I plan on 4-18's and a couple EP4000 for power or just a pair of 18" in LLT and a single amp. Seems that good sized and properly designed LLT will probably do everthing I want but it is tempting to chase single digit response with an IB.

I need to post some sketchup models on the design forum to get some feedback there. My room is about 15x22 with a 9 foot ceiling. There is an HVAC soffit that boogers things up a bit though.


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## Home Theater Guy (Jul 18, 2009)

Gotcha. I agree on the IB setup. If it sounds awful, you're pretty much stuck with it. If you use multiple subs you can move around, you can use their placement to deal with the room's modal issues.


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