Yamaha test tones for getting reference level?

Discussion in 'AV Receivers & Amplifiers' started by cribeiro, Mar 18, 2004.

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  1. cribeiro

    cribeiro
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    Hi!

    Now that I have an SPL meter, I start checking and seeing which are my preferred levels, and so on...
    Yesterday I thought "hey, I wonder since long time ago how loud is reference level, and now I can check it". So I went home and played some music with the SPL monitoring the sound levels. Before, I had searched here for SPL and reference, to know what should I measure, but most reference to test tones in dvd discs like AVIA, and I didn't get one yet. What I know is that I should get 105 dB peaks with a Dolby Digital movie, and yes, that is a lot, compared to what I have measured...
    Anyway, can somebody tell me how are the test tones in the Yamaha rx-v530 implemented, in order to get the reference level? Are they also 20 dB attenuated, like the AVIA disc, or 30 dB attenuated like the DVE? Or something else?

    In short... What should I read in my spl meter when playing Yamaha test tones, to know that I hit reference?

    I don't believe I should read 85 dB (C curve, slow), because that is WAY too loud, even compared to THX cinemas... If so, I would need to push up the level in the amp to read -18 dB on the amp screen (more or less, I don't remember exactly). Apart from the fact that it is more than half way of the knob, so I get more noise than music...
     
  2. davidgriggs

    davidgriggs
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    cribeirio
    My limited knowledge would suggest that the level you refer to is only reference (i.e loud enough for you to take accurate readings to balance all the outputs from the speakers) and then once that is achieved you would listen at normal volumes safe in the knowledge that no matter what volume you listen at you know that the 'reference set up'has not changed.
    David
     
  3. cribeiro

    cribeiro
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    No, reference level is the one that is intended to be played at, like a reference speaker is the one that reproduces the sound in an enough accurate way. At least, that is my understanding of the matter. If wrong, I'd like to learn the right thing.
    Thanks.
     
  4. bobgriffiths

    bobgriffiths
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    cribeiro you are mixing up too different enviroments cinemas are set to a reference level of 85dB (well some are see link) BUT there are still problems and reasons why cinemas turn the volume down again see dolby link
    http://www.dolby.com/tech/toolouds.pdf

    in the home THX suggests setting a reference level at 75dB for initial set up because 85dB is too loud for home users but they wouldnt recoommend blasting it at that level all the time with wide range material. peaks are just that peaks 105dB will damage your hearing if constant
    http://www.thx.com/mod/techlib/volume.html

    LOUDNESS DOES NOT EQUAL QUALITY!

    to access the internal test tones read pages 21 and 22 of your instruction manual see here if you have lost it

    http://www.yamaha-audio.co.uk/pdfs/manuals/RX-V530RDS.pdf

    Here are some tips on using a SPL meter
    http://www.remotecentral.com/cgi-bin/mboard/rc-theater/thread.cgi?2832,1#11
     
  5. nealgs

    nealgs
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    I set all my speakers to 75db using a Yamaha RXV1000RDS reciever and speakers in sig.

    Very rarely use that level though

    Gary
     
  6. cribeiro

    cribeiro
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    I see. So there is a cinema reference, and a home reference...
    Well, I thought there was only one...
    I mean, I quite understand what the reference is (I am a physicist, after all... Should be used to that). But I didn't know they had two different standards.
    Thanks for the links. I have the manual, but the problem is, it doesn't say anything about a reference. They aren't intended to get ref. levels, but to get a balanced sound from all the speakers.
    I had also read already the othe link, about the use of the spl. Thanks again, anyway.
    I think I didn't explain it right (I know, I tend to be messy...). If I leave the amp at a certain loudness, and I play its internal test tones, and then (suposedly, cos I don't have it) I'd play a calibration dvd, would I get the same dB on my spl meter? I doubt it... This is why I was asking the initial question...

    Of course loud doesn't mean quality, that I didn't mean. Actually, I think my receiver would start distorting a lot if I try to reach reference levels. My statement is a different one: the reference level is there because the directors of movies are concerned about their work. Same as you don't hang a Monet upside down (that would only work with Picasso's :) ), the director intend to deliver to you a certain image and sound. Their message includes a certain loudness, like it does with colour tonalities or brightness on the screen. So the audio mixing is done using a certain scale.

    For example, suppose that the screen should be 3 meter wide according to reference (take it as a toy example). When you get your dvd at home, if your equipment is good enough (THX ensures that, but it is not necessary), you need to know what the reference is, and set it at that reference. In the toy example, you need a 3 meter wide screen filled with the image. If you don't have a meter, then you'll get in trouble to know if the size of the image is the right one. Same with the loudness. That's what the reference should give. This is why the thx dvd's have test tones, which are calibrated. If you read 75 dB (or whichever, that is given by the calibration, this is why AVIA and DVE are different), with these test tones, that is the reference.
    Then, if the dvd was mixed using that reference, and you have it at home, you are watching the movie exactly as the director intended. (suppose your system is capable of delivering the quality, etc).

    This doesn't mean the movie is loud... If the director intends it to be quiet, then it will be quiet at reference. So the question is, why do they make it so loud? Maybe they don't have the same reference... I think this could be one reason... Maybe the thx dvd's do share a common reference.

    Last but not least... Of course, keep healthy ears is the first, so if the director intends to make an explosion as if I were next to the bomb, I won't listen at it at reference level...

    Off topic: I went to the cinema this weekend, Europa Kino, in Frankfurt. It is a THX certified one. I am sure they play much lower than reference.
     
  7. avanzato

    avanzato
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    Cribeiro this will probably make more sense to you than me.

    It's from the book '5.1 Surround Sound up and running' by Tomlinson Holman which goes into a whole lot more detail. Might be worth buying if you're interested in how things work.

    One point that I never see mentioned about 'Reference Level' is can your equipent actually get to Reference? My speakers at the moment will only go to 100dB maximum output for instance.
     
  8. cribeiro

    cribeiro
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    Thanks Avanzato.

    Check this out:
    http://www.montagar.com/~patj/db_db.htm
    I wish I could explain it like that :) Although I must also admit that I forgot a lot of my electronics course, and that we didn't deal with such a big amout of different references. I think this explanation is quite clarifying.

    Unfortunately, as you can read there, dBFS is a "Device dependent" unit of measurement (if one may say that dB are "units")... And I don't have a device to produce such a signal. But at least, it helps in the understanding.

    Just one question... What is the difference between "film" and "video"...?

    I hope now it is clear that reference level doesn't necessarily mean "loud", but only "as loud as the director intended"... And that, only in the case he used the same reference...
    I think we need some big congress of all the people involved in this matter, to agree on a common way of measuring and referencing things...
     
  9. avanzato

    avanzato
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    Film = Movies and Video = TV or stuff destined for home viewing.

    THX test tones should all be recorded at the correct level. So your best bet will be to find a DVD with one of their calibration routines on it. 'Finding Nemo' for example.

    I never made it through my Electronics course so that link brought back horrible memories and made my head hurt again. :D
     

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