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How much SPL do you really need?

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  • Pallas
    replied
    Re: How much SPL do you really need?

    Originally posted by spasticteapot View Post
    I'm going to make a few assertions and see what people make of them. ***
    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.
    My experience differs on this point.

    I don't know what the Khanspires are, but I recently had a chance to hear a design called the Statements, which use two 8" Dayton woofers, two 4" (I think) TangBand midranges, and a ribbon tweeter. I was very surprised that, despite the large cone area and volume displacement - both in excess of what my "reference" mains offer - the Statements indeed "sounded loud" as levels increased.

    That there was plenty of power on tap (enough to get them, on paper, to ~111dB, assuming ~88dB/W/m sensitivity, which is well in excess of listening levels used) and we're not talking about huge differences in listening space volume or listening distance.

    Originally posted by spasticteapot View Post
    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?
    Audax's old HM130Z0 is a really good one, and they sometimes come up on eBay. And there's always, for a price, the Century 500 neo-magnet mid JBL uses on their LSR32/LSR6332, which seems to be a development of their old 500GTi car midwoofer. (There has always been a lot of overlap between JBL's flagship car stuff, and their smaller high-end Pro stuff.) You can order it direct from JBL Pro parts. NOT cheap, though. But it's a fair bet that it's better than the ScanSpeak Disco. Still, the 15M/4624G is an interesting driver on paper, one that looks pretty easy to work with and makes smarter compromises than other currently-available 5" drivers. It might be worth a gamble at its current price. I don't know what tweeter one would match with it, though. Perhaps one of the 6" JBL waveguides Zilch used in his smaller speakers? It is better, IMO, to pad down a tweeter than waste midband efficiency. And always better to match the directivity at the top of the midrange with the directivity at the bottom of the tweeter.

    Leave a comment:


  • Brent_S
    replied
    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.
    It sounds like you may have a receiver that overrides/ignores the master volume setting when you do your channel calibration. Some units lock the MV at 0dB for test tone calibration and some use the current MV setting when you activate the test tones. Without knowing your unit's operation method and signal level, you can't really assume 75dB on your SPL meter is Reference.

    Strictly speaking, Reference level is the master volume setting where each channel produces 75dB from a -30dBFS signal or 85dB from a -20dBFS signal...IOW, a 0dBFS signal should produce 105dB at the seats if the system is capable. I prefer to use a 3rd party signal source to verify since some units internal test tones have been found to vary wildly from the -20/-30 de facto standards. Naturally, movies will be mixed with different average levels, but all mixing stages should be using the same -20/-30 produces 85/75 for Reference level.

    In my home theater room, movies are always watched at -15dB below Reference (occasionally a few dB louder when I'm alone), which produces peak dBs in the low-mid 90s on bombastic scenes. Even on something like LOTR, with extreme dynamic range and lots of whispered dialog, I don't recall needing to adjust the volume to understand the dialog. Broadcast TV, with its (typically) much narrower dynamic range, calls for a much lower MV setting in the same room...probably -27dB to -30dB.

    Music recording doesn't use a standard for mixing and a lot of current commercial material has an average level in the -3dBFS to -6dBFS range (see "loudness wars); IOW, on my system, the average playback of a CD at -15dB below Reference would still produce an average SPL around 90dB. I'd personally find that way too loud for an extended listening session. For comparison, the 15hp Kohler on my zero turn measures about 93dB at 1' and its annoyingly loud even with hearing protection.

    As always, YMMV and season to taste. ;)

    -Brent

    Leave a comment:


  • Sydney
    replied
    Re: How much SPL do you really need?

    1. More SPL is required in low-bass frequencies than any other.
    Yes

    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.
    My (2) 15's are higher sensitivity than average: under typical listening the cone excursion is very low. To get a lower F3 as well I had to use large cabs.

    Leave a comment:


  • spasticteapot
    replied
    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?

    Leave a comment:


  • bkeane1259
    replied
    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

    Leave a comment:


  • czag
    replied
    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

    Leave a comment:


  • Deward Hastings
    replied
    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.

    Leave a comment:


  • czag
    replied
    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

    Leave a comment:


  • czag
    replied
    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

    Leave a comment:


  • fbov
    replied
    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

    Leave a comment:


  • Deward Hastings
    replied
    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 . . .

    Leave a comment:


  • Pallas
    replied
    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...

    Leave a comment:


  • badman
    replied
    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.

    Leave a comment:


  • generic
    replied
    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.

    Leave a comment:


  • Andrew P
    replied
    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.

    Leave a comment:

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