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  • #46
    Re: How much SPL do you really need?

    Originally posted by generic View Post
    but if I stick in a movie or CD, at the same volume level, it may or may not be loud enough to play at the same level.
    or do they just stick it in, and play back at the level they want?
    Yes, because of what you just said before :D
    "Not a Speaker Designer - Not even on the Internet"
    “Pride is your greatest enemy, humility is your greatest friend.”
    "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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    • #47
      Re: How much SPL do you really need?

      Originally posted by JRT View Post
      For most speakers, 1_kHz is radiating mostly into 2pi from the face of the baffle, so the room isn't going to provide much help at the recommended 1_kHz used in setting levels, can be lumped into the headroom IMO.

      Going with the high side of that...
      83_dB at 1_kHz at -20_dBFS at 4 meters distance from one loudspeaker is
      83+20+12 = 115_dB at 1_kHz at 0_dBFS at 1 meter distance.
      3_dB of headroom gets you to 118_dB at 1_kHz at one meter, separately from each of a stereo pair, operating within linear range (Xmax? Xlinear?), at half power for the amplifier headroom.
      .
      Bob Katz, and film mixing calibration both use pink noise, with 85dbC being the standard for film on a mixing stage and the Katz scale with maximum dynamic range for music (leaving 20dB of headroom, think classical). So lots of low frequency energy, and definitely interacting with the room.

      Having said that, when mixing or listening to films in smaller rooms like a living room something like 79dBC standard makes a bit more sense. Rooms smaller than a theater sound louder, and theater reference levels sound too loud in a living room.

      So add in the room, knock 6dB off the calculations, and you are probably in the ballpark.

      Really two things are getting confused now, what the system can reproduce cleanly, and how loud something needs to be. For music all bets are off because there is still no standard, despite's Katz's ideas. 105dbC is probably a good number to shoot for at home for peak levels to be on the very very safe side, based on my ears and nothing else. 100dB would make me happy, and cost a lot less. FWIW my speakers generally can do 110dBC at 1m, and my listening distance brings that down to 100-102dBC depending on where you are in the room. Meanwhile, in the real world, my "very loud" peaks are closer to 90-95dBC for music, tops.

      Erring on the side of caution is never a bad thing however. This came up in an amp thread not long ago, and I was arguing the opposite side. More power for the amp. But thats because power scales up so quickly when you need a little more headroom. At short listening distances especially, 3dB can be a matter of where you sit in a room.

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      • #48
        Re: How much SPL do you really need?

        Originally posted by JRT View Post
        Those sources have recommended a mastering level for high quality audio that falls between 85_dB to 86_dB at -20_dBFS signal level at 1_kHz, summed with uncorrelated phase at the listening position. That is 82_dB to 83_dB at 1_kHz at -20_dBFS separately from each of a stereo pair at the listening position.

        . . .

        But again, most people are not willing to dedicate the resources needed for that extreme for the purposes of high quality home audio. As I recall, I think the Linkwitz Orion can provide ~105_dB of SPL at one meter, which is 13_db below the figures detailed above, and the Orion enjoys a reputation for prodiving good quality home audio on a wide spectrum of recorded material.
        Most people don't need those "extreme" levels in a home environment. Listening is commonly done at considerably less than 4 meters distance from the speakers, and in both a relatively small and a relatively "live" environment that adds considerably to the average sound field. And almost any commercially available music program material (and any film soundtracks that conform to THX) will have "peaks" limited to no more than 20dB above average signal level (or above "reference" for film), which as a practical matter eliminates the need for both the 3dB speaker and 3dB amplifier "headroom" in the home environment. So where one might want 115dB peak capability for distant listening to uncompressed (studio) material in a sound-deadened control room you will get essentially the same listening level in a home environment with 10-12dB less capability . . . with no added "compression" or loss of quality to be concerned about.

        You're comments about "equal loudness" are also spot on . . . to reproduce acoustic sources with the same perceived tonal balance as one might have heard the original the reproduction must be at the same level. This may cause concern if you are after the sound level you'd get standing on stage directly in front of a guitar cab . . . it will not be an issue if you want the sound levels that are reached in the audience at a symphony performance, which rarely exceed 100dB on even the highest peaks. And for movies, where the "peak" sound levels always come with explosions and other "synthetic" sounds, it's hard to sustain an argument that "quality" or "fidelity" much matters . . . (and at 105dB it's too loud anyway . . .).
        "It suggests that there is something that is happening in the real system that is not quite captured in the models."

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        • #49
          Re: How much SPL do you really need?

          Originally posted by generic View Post
          I hope I don't open up a bad can of worms, but... How do you guys who want to watch a movie at 75db, find 75db? All my source material sounds different and levels are all over the place.

          I can use pink noise to match the main speakers to a sub from a listening position and set the sound to 75db, but if I stick in a movie or CD, at the same volume level, it may or may not be loud enough to play at the same level.

          Do people really try and find the reference level when they watch a movie, or do they just stick it in, and play back at the level they want? Like me, and everyone else I know would do.
          Just turn it up. DVDs are not particularly reliable. I've tried to find -the- reference level at home, it just wasn't possible. The differences are dramatic.

          And even theater mixes are a casualty of the loudness wars. Dynamic range is disappearing, and theaters are turning down more and more from reference levels. So yeah. Use the clicker.

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          • #50
            Re: How much SPL do you really need?

            Originally posted by Andrew P View Post
            Just turn it up. DVDs are not particularly reliable. I've tried to find -the- reference level at home, it just wasn't possible. The differences are dramatic.

            And even theater mixes are a casualty of the loudness wars. Dynamic range is disappearing, and theaters are turning down more and more from reference levels. So yeah. Use the clicker.
            That's what I thought. I was just confused because some of the post were talking about 75db reference levels and then how loud it can go above that. Me personally, I just turn it up loud enough to hear what everyone is saying at a decent level. I wouldn't be surprised if peaks during normal play back don't exceed 88-92db, and that is enough to shake the sofa. It's enough for me.

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            • #51
              Re: How much SPL do you really need?

              <snip>

              nominal listening level at home would have to be similar to that used in mastering, would have to be similar to that experienced listening to the symphony orchestra live, else there a nonlinear distortion in loudness perception imposed across the frequency range, illustrated clearly in the ISO:226 equal loudness contours.


              <Endsnip>

              Yup! And it's one reason why "boom and tizz" sound in small speakers gives people the impression of a louder sounding loudspeaker. I'd rather just go close to the 'right' spl, but that's me.

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              • #52
                Re: How much SPL do you really need?

                Originally posted by generic View Post
                I hope I don't open up a bad can of worms, but... How do you guys who want to watch a movie at 75db, find 75db? All my source material sounds different and levels are all over the place.
                One way to find reference level is simply to use a modern receiver with Audyssey's top processing suite. Part of the autocal routine is to calibrate the volume dial such that "0dB" is cinema reference level at the primary listening position.

                I can't say I've ever watched a movie or TV show at "reference." Generally speaking, I like to watch TV and movies at a level that allows me and everyone in the room to clearly understand the dialogue, and no louder. That often means -40dB on the volume dial, or quieter. Maybe -20dB when my mother is visiting; her hearing has suffered from enjoying live music (The Who playing at her high school, Woodstock, various concerts at the Fillmore East, etc.) at a time before knowledge about long term exposure to continuous SPL was widely circulated.

                I don't know if that actually means -40dB below reference (Denon AVR) or not. I've never measured.

                With some music, I'll creep down to 0dB, or even in the positive range...
                --
                "Based on my library and laboratory research, I have concluded, as have others, that the best measures of speaker quality are frequency response and dispersion pattern. I have not found any credible research showing that most of the differences we hear among loudspeakers cannot be explained by examining these two variables." -Alvin Foster, 22 BAS Speaker 2 (May, 1999)

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                • #53
                  Re: How much SPL do you really need?

                  Originally posted by generic View Post
                  I just turn it up loud enough to hear what everyone is saying at a decent level. I wouldn't be surprised if peaks during normal play back don't exceed 88-92db, and that is enough to shake the sofa. It's enough for me.
                  Another voice of reason . . .

                  If normal dialog is at the same level as would be normal conversation in your listening room you will never come close to straining a system that can deliver 105dB peaks. Except for the sub-woofer you'd be unlikely to get over 95. Unless, of course, you're one of those "here comes an explosion, turn it up" people . . .
                  "It suggests that there is something that is happening in the real system that is not quite captured in the models."

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                  • #54
                    Re: How much SPL do you really need?

                    Originally posted by generic View Post
                    I hope I don't open up a bad can of worms, but... How do you guys who want to watch a movie at 75db, find 75db? ...
                    I let my wife set the volume.

                    If I set the volume where I'm happy, it's more like 85dB. Slow and C-weighted. It's at the point where conversation becomes difficult, but it still doesn't sound "loud."

                    And a speaker producing 118dB@1m is far louder indoors than outside, where the majority of you do your calculations that require this level of speaker output. You guys doing the decibel exercises need a reality check. Predictions of speaker performance can be accurate, but without detailed characterization of the listening room being considered, the predictions must make assumptions. Few rooms in actual homes fit the assumptions being made in these exercises.

                    Invalid assumptions yield invalid predictions, even if theory is correct and properly applied.

                    Have fun,
                    Frank

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                    • #55
                      Re: How much SPL do you really need?

                      Originally posted by Deward Hastings View Post
                      Most people don't need those "extreme" levels in a home environment. Listening is commonly done at considerably less than 4 meters distance from the speakers, and in both a relatively small and a relatively "live" environment that adds considerably to the average sound field.
                      Where did you get the idea that listening is commonly done at that distance? In my circle of friends and close relatives, there is only one household where the main audio/ht system has a listening distance of less than 12 feet(4m). That is my brother who just moved into an apartment. I think that we sometimes forget that all parts of the country are not the same. In the areas of the country that have reasonable housing cost(suburbs of a lot of major cities), it is quite common to have large living rooms with 4-5 meter listening distances. However, if you live inside the loop here in Houston(which I do not) or anywhere in California, where housing cost are high, it would probably be more common to have living rooms with less than a 4 meter listening distance. Just from the pics that I've seen here of speakers that also show the living room, it seems that listening distances vary wildly from 2-3 meters to 4-5 meters. You are basing your argument on your living room, so it does not apply to many people here.


                      Chris
                      Chris

                      Goofing around since 2000.

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                      • #56
                        Re: How much SPL do you really need?

                        Originally posted by fbov View Post
                        I let my wife set the volume.

                        If I set the volume where I'm happy, it's more like 85dB. Slow and C-weighted. It's at the point where conversation becomes difficult, but it still doesn't sound "loud."
                        That is how it is at my house. The volume level is dictated by whether or not my wife is home.


                        Originally posted by fbov View Post
                        And a speaker producing 118dB@1m is far louder indoors than outside, where the majority of you do your calculations that require this level of speaker output. You guys doing the decibel exercises need a reality check. Predictions of speaker performance can be accurate, but without detailed characterization of the listening room being considered, the predictions must make assumptions. Few rooms in actual homes fit the assumptions being made in these exercises.
                        I was just wondering about that very idea.

                        Chris
                        Chris

                        Goofing around since 2000.

                        Comment


                        • #57
                          Re: How much SPL do you really need?

                          Originally posted by czag View Post
                          You are basing your argument on your living room
                          Really? You know that how?

                          Actually, my listening/living room is about 16x25, but the "sweet spot" listening position is determined by speaker separation (about 7 ft on center) and optimum distance to the HD display, and would remain pretty much the same regardless of room size (unless I went to a really "big-screen" projection system). In any case once I'm more than about 8 feet from the speakers sound level is pretty uniform throughout the room, being dominated by the reflected sound . . . it does not fall off with distance. That's the nature of sound in enclosed spaces, from living rooms to concert halls, where once you're into the reflected field sound is pretty uniform throughout.
                          "It suggests that there is something that is happening in the real system that is not quite captured in the models."

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                          • #58
                            Re: How much SPL do you really need?

                            Originally posted by Deward Hastings View Post
                            Really? You know that how?

                            Actually, my listening/living room is about 16x25, but the "sweet spot" listening position is determined by speaker separation (about 7 ft on center) and optimum distance to the HD display, and would remain pretty much the same regardless of room size (unless I went to a really "big-screen" projection system). In any case once I'm more than about 8 feet from the speakers sound level is pretty uniform throughout the room, being dominated by the reflected sound . . . it does not fall off with distance. That's the nature of sound in enclosed spaces, from living rooms to concert halls, where once you're into the reflected field sound is pretty uniform throughout.
                            Take it easy, I just meant that your statement of listening distances commonly being less than 4m seems like just a guess on your part and not an actual fact. I would hazard a guess that the majority of people do not follow accepted guidelines of optimal viewing and listening distances or angles. Just think of how many times you have seen speakers placed directly up against a wall or small speakers up near the ceiling in the corner when they clearly were not designed for such placement.

                            I should have said you are basing your argument on your listening distance. But thinking of fbov's and your point of sound level not falling off with distance in an enclosed space, I would have to agree that the extreme sound levels being discussed here are probably more easily reached than one would think in a lot of our living rooms regardless of listening distance.

                            Chris
                            Chris

                            Goofing around since 2000.

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                            • #59
                              Re: How much SPL do you really need?

                              Originally posted by Andrew P View Post
                              Now lets test your 90dbA. Set your meter to A-weighted, slow, and turn it up to 90dB. Now sit in that room for 8 hours, and let me know what you think of OSHA.
                              Very good....very good. :D:D:D
                              Bryan K.

                              Midwest Audio Club

                              Speedster | Sub Attachť | The Wildeman | Sean's NLA Towers | CO‹GAR, COUGAR II and CO‹GAR JR | Triton | Lithium | J-Boom | Trym MLTL | Docere MLTL

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                              • #60
                                Re: How much SPL do you really need?

                                I'm going to make a few assertions and see what people make of them.

                                1. More SPL is required in low-bass frequencies than any other.
                                2. Small speakers with reasonable efficiency - e.g. the Modula MTs - will have trouble keeping up with loud transients due to the significant portion of bandwidth produced by the woofer, especially if baffle step is applied. This is made worse by the requirement for large excursion causing additional distortion to midrange frequencies simultaneously played through the woofer.
                                3. Big speakers with bonkers efficiency (such as the Abbeys) do not have this problem. There's no excursion, and the woofers don't get anywhere near their power handling capabilities, and the high F3 doesn't hurt either.
                                4. Big speakers with low efficiencies (like the Khanspires) deal with this problem by having far more SPL capability from the bass section than the mids and tweeters. By segregating the low frequencies, it's possible to get sufficient SPL from an ~85dB efficient midrange.

                                Of course, I'm just gonna go ahead right now and wonder why the heck we can't get more efficient 5" midranges. ScanSpeak makes one - where's the rest?

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