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Thread: Natural Sound Pressure Level

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    Senior Member Jan Daugaard's Avatar
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    Natural Sound Pressure Level

    I have frequently wondered what the natural sound pressure level is at symphonic concerts, so I brought my sound level meter with me when I attended a concert in the Tivoli Gardens in Copenhagen yesterday. I sat in the middle of the concert hall, about 20 meters from the orchestra. All measurements are C weighted, i.e. made with a nearly linear frequency response.

    The first item on the programme was Mozart's Symphony No. 17. The average sound pressure level during the 1st movement of this symphony was less than 70 dB, and the peak level was 85 dB.

    The 2nd item on the programme was Prokofiev's 1st violin concerto. The peak level during this concerto was 90 dB.

    The 3rd item on the programme was excerpts from Prokofiev's 3 suites based on his own ballet music "Cinderalla". The peak level was here 98 dB, reached during the "Midnight" section. The brass was responsible for this -- they played much louder than other instruments.

    High SPLs and excessive treble -- which are tempting remedies with speakers lacking transparency -- aren't called for with proper speakers.

    PS1. I enjoyed the concert in the intervals between SPL readings.

    PS2. At the recent Roskilde Festival -- see http://www.roskilde-festival.dk/ --, sound pressure levels in excess of 130 dB were measured in the Techno Music tent.
    Last edited by Jan Daugaard; 07-08-2003 at 08:47 AM.

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    Cool

    Obviously it is going to depend on which hall and WHERE you sit not to mention the type of music played. In Indianapolis (Circle Theatre), the best sound is near the back of the hall, upper mezzanine, where it is extremely balanced and refined but not very loud at all on an absolute level.

    Now IN THE ORCHESTRA, the sound levels are very loud and in pops concerts, I am constantly reaching for ear plugs. We're playing a concert in the park tonight, so with this question in mind, I'll take my sound meter. As with all outdoor concerts, it is amplified. No, they don't use JBL's. hmmm.

    Monte

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    O.K. I realize that you had in mind sound pressure in the audience. But, I just had to say:

    So, last night the Indianapolis Symphony was playing in a park under a "band shell"--really it's just one huge horn. I had my sound pressure level meter on in the oboe section. I got 104 dB just warming up! Yes, it is due to the brass. I was all ready to measure the major increase from there due to the brass when we get to John Williams' "Star Wars." Unfortunately, a very dark cloud rolled up. The concert was cancelled. A tornado had been spotted elsewhere in the city.

    Monte

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    Senior Member Jan Daugaard's Avatar
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    Record Company Info about SPL

    The record company Telarc provides elaborate instructions on loudspeaker set-up in the booklets supplied with their SACDs, and they even suggest the use of a sound level meter to adjust the speakers.

    The next logical step would be to inform the record buyers about the sound pressure level during the recording so we can get a natural reproduction in that regard, too. I made this suggestion some time ago in an e-mail to comments@telarc.com, but never received an answer.

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    Your Memory Lives On RIP Tom Loizeaux's Avatar
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    My view on playback volume is to consider what the music was like"live". A piano, singer, or acoustic music isn't too hard. The question is only "How far away should I be from the musicians?" Listening to how it was mixed and listening for the proximity (nearness to the musicians) the final mix intended, tells you a good deal about how it should be presented in your listening environment. What would a live Jazz group sound like in your living room? That should get you started in judging appropriate sound levels.
    Amplified music, studio sessions (especially with overdubs and systhesized instruments) gets a little more difficult to judge in terms of "correct volume".
    You can always turn the level down and say that you've "moved away" from the musicans, but why would you want to make a habit of that?
    As you get louder playback you'll need more power and better and bigger speakers so the distortion from pushing your playback system remains inaudable...not a small task!

    Tom

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    Administrator Robh3606's Avatar
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    Depends on the music. Went to see a band in the middle 70's just when the max. SPL laws came into effect. Brought my trust Radio Shack SPL metter. Had it set for 110db figuring I would just bring it down. Max was 116db. The band opened and we all literally ran for cover. We were in the 10th row and went all the way to the back. The meter pegged and never moved again!!! God knows how loud it was. I used toilet tissue stuffed in my ears to try to give some protection. The funny part is they were thrown off the tour for excessive SPL level. I never went to another show without some kind of ear plugs after that. On the other end used to go to small jazz club. Ever have a sax 10ft away WOW talk about dynamics! Just a wonderful experience with the sax. He had to be getting very high peak levels. You could feel them!

    Rob

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    Senior Member Jan Daugaard's Avatar
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    SPL laws

    There is to my knowledge no SPL law in Denmark, but certain concert arrangers stipulate a max. SPL in contracts with the performing bands. The Ringe Festival thus specifies a max. average SPL of 102 dB in their contracts.

    Is there a federal SPL law in the USA? Or is it different from state to state?

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    Dis Member mikebake's Avatar
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    Quote Originally Posted by Monte
    O.K. I realize that you had in mind sound pressure in the audience. But, I just had to say:

    So, last night the Indianapolis Symphony was playing in a park under a "band shell"--really it's just one huge horn. I had my sound pressure level meter on in the oboe section. I got 104 dB just warming up! Yes, it is due to the brass. I was all ready to measure the major increase from there due to the brass when we get to John Williams' "Star Wars." Unfortunately, a very dark cloud rolled up. The concert was cancelled. A tornado had been spotted elsewhere in the city.

    Monte
    When the massive F4-5 tornado destroyed the Van Wert Ohio cinema (google) and much else in the city, I visited the site the next day and found a busted up Radio Shack SPL meter, flung from the theater. I wonder what the SPL in an F-5 tornado is................and also what happened to the house sound system, which I believe was JBL.

    Update; I found this link; those are JBL, are they not??
    http://www.crh.noaa.gov/iwx/climate/...t/VW23.JPG.JPG

    Complete and amazing photos of the cinema and elsewhere here
    http://www.crh.noaa.gov/iwx/climate/...rt/index.shtml

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    Senior Member pelly3s's Avatar
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    I bet you that shifted a couple maginets in that whole mess.

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    Senior Member Steve Schell's Avatar
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    Peter Walker, inventor of the Quad ELS loudspeaker, once said something to the effect that in his opinion the correct playback level was determined by a particular recording, the goal being to produce a listening level similar to what the microphone heard.

    This may serve as a rough guide for simply miced recordings, but what about modern pop stuff? Levels at live performances are almost always much louder than what I want to hear at home. Also, some events are so loud when recorded (Sheffield Drum Record, horn bands) that I wouldn't want to be present for either original performance or realistic playback without ear plugs.

    Many folks feel that horn systems are used to perrmit playback at very high levels without strain. They will do this of course, but another virtue is their extremely low distortion and natural presentation of fine details at lower listening levels. We hornies want, and can have, it all.

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    Senior Member edgewound's Avatar
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    Inverse Square Law

    The Inverse Square Law says that with every doubling of distance there will be a 6dB drop in SPL....boundary dependent of course.

    I was recently at an Alternative Rock showcase courtesy of one of my 20-something customer's band at The Troubador in Los Angeles. The SPL was PAINFULLY ridiculous...I'd venture to say that it was approaching 130db!!!! in a relatively small room. Luckily we had earplugs...stayed to support the band...but it was the most unpleasant sound experience I'd EVER had....the sound guy at The Troubador should have been shot...it just beat the living hell out of us...never again.
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

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    Dis Member mikebake's Avatar
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    I have used this for one room in particular that we use periodically;

    Special information for bands playing in Memorial Hall. Memorial Hall is under a mandated "speed limit" for maximum SPL. The following notice is given to all bands playing in Memorial Hall.


    ATTENTION BANDS: PLEASE READ BEFORE SETUP. Welcome to Memorial Hall. Help us maintain the crowd and the sound of your band by being professional in following our volume policies.
    This is a ((((LOUD)))) room. As a result, MINIMUM STAGE VOLUME IS REQUIRED at all times during the duration of your engagement. All amplifiers must be placed at a very close distance to the player, and at a height /angle in which the players can hear with minimal sound spillover off the stage. Players are expected to control their instruments with minimal peaks in level. Drummers are expected to comply with a controlled attack. Stage monitor levels will be adjusted for minimum spillover by the tech also.
    Following these rules will help you hear your monitors, and keep the vocals present in the live mix. The Sound tech WILL NOT adjust vocal levels above set db level to overcome stage volume, either in the stage monitors, or house mix. We provide the means to mic/line each instrument into the House PA system, as well as a sound technician who is required to maintain a LEGAL room volume of 96 db.average. Help him do his job please! If this level is surpassed because of stage volume, performance shall be interrupted.
    Memorial Hall has hosted MANY big name professional acts on this very stage, who have understood and complied fully with our stage volume policies. All bands will please do the same. Thank you.

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    Senior Member Steve Schell's Avatar
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    I attend the NAMM music trade show every January in Anaheim, CA. My friend Alan and I like to make the rounds and try out guitars. One year Alan picked up some free tickets to a NAMM sponsored evening event in a nearby hotel ballroom. It was called "The Acoustic Cafe", and was to feature several acoustic guitar performers.

    We arrived to find large banks of speakers on either side of the stage. When the music started it was too loud, and the SPLs rose steadily all evening. By the time we left it was insane- a tap on a guitar sounded like an explosion, and the vocals would part your hair. It was too loud for me even with 25dB of attenuation from foam earplugs. Acoustic Cafe, my dimpled a**. I'll bet Hendrix performed with more restraint on volume.

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    Senior Member edgewound's Avatar
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    That's great Mike...but in this case it wasn't the band's stage volume, although I know that can be a big problem....it was the sound guy's need to exploit HIS horsepower...I'm a musician that gigs for both fun, sanity, and a little walking around money. Unfortunately, we've discovered there is less fun to be had when the sound guy is both a dictator and incompetent...and has never played or sang a note onstage. I agree with your principles though...the high power PA wars that go on sometimes defeat the purpose of having plenty of headroom required for good sound.

    Oh...and please don't think I'm inferring you're either a dictator or incompetent...just our local experience .
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

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    Dis Member mikebake's Avatar
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    I am the promoter/stage manager, so I have final say-so on SPL. (it is harder to get stage level down than mains, for me) I fight this battle BEFORE the gig so there isn't one DURING. Recently I hired a touring-level rig for a small-mid size festival venue.
    The rig owner is fine at the helm, but a couple of the various FOH guys with the bands rode the shit out of the rig like it was a concert. Even George Thorogood didn't hammer the same rig as badly a few weeks later. The same bands repeated at another outdoor venue, with the same rig. A little convsersation on the phone prior to the second gig solved that issue.

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