Members sharnrock Posted February 11, 2007 Members Share Posted February 11, 2007 I hear guys on here talking about running pink noise through their system and checking it with an SPL meter. What is the purpose of doing all of this and what kind of equipment do you use? Link to comment Share on other sites More sharing options...
Members twostone Posted February 11, 2007 Members Share Posted February 11, 2007 SPL=Sound pressure level=loudness Link to comment Share on other sites More sharing options...
Members Al Poulin Posted February 11, 2007 Members Share Posted February 11, 2007 I believe they are often used to measure how loud things are at different points and distances (in the audience) and at the mix position. They are also used to prove that a Bose PAS does not really cover a 1000 seat venue with equally loud SPL levels regardless of listening position. Al Link to comment Share on other sites More sharing options...
Members sharnrock Posted February 11, 2007 Author Members Share Posted February 11, 2007 So, it is just about knowing how loud it is? I thought maybe they were trying to flatten the frequency response or tune to the room or something... Link to comment Share on other sites More sharing options...
Members Al Poulin Posted February 11, 2007 Members Share Posted February 11, 2007 So, it is just about knowing how loud it is? I thought maybe they were trying to flatten the frequency response or tune to the room or something... I'm pretty sure you need something more fancy for that. Some kind of frequency analyzer? Link to comment Share on other sites More sharing options...
Members flanc Posted February 11, 2007 Members Share Posted February 11, 2007 It's for checking "loudness". Some clubs require their engineers to stay within max SPL guidelines. You can get a decent SPL meter at Radio Shack for under $50 http://www.radioshack.com/sm-7-range-analog-display-sound-level-meter--pi-2103668.html Link to comment Share on other sites More sharing options...
Members sharnrock Posted February 11, 2007 Author Members Share Posted February 11, 2007 would 126db be enough? Link to comment Share on other sites More sharing options...
Members prosigna Posted February 11, 2007 Members Share Posted February 11, 2007 would 126db be enough? Yes, more than enough. You would need more to test maximum output of speakers at 1-meter. 110db (full range) is too loud for me. 126 (full range) would have my earplugs in and my hands over my ears. (A or C weighted). Now 126db from a sub is the kind of chest thumpin' stuff I love, but full range would be insane loud. Link to comment Share on other sites More sharing options...
Members Al Poulin Posted February 11, 2007 Members Share Posted February 11, 2007 would 126db be enough? For seriously damaging everybody's ears, yes, a few hours of that would be sufficient. Depending on the type of music and setting, anywhere from 100 - 110 db is what most would consider loud. Rock concerts can reach 120 db and above, which is why they can be so damaging, and why many wear earplugs at these levels... Al Link to comment Share on other sites More sharing options...
Members Al Poulin Posted February 11, 2007 Members Share Posted February 11, 2007 It should be noted that when comparing speakers, the max SPL spec is calaculated at 1 metre from the enclosure. The SPL the audience gets will be much lower, as sound dissapates -3 or 6db everytime you double your distance from the source. So your 126db max SPL speaker is more likely down to 110 DB or less on the dancefloor, again depending on the distance... Al Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 11, 2007 Members Share Posted February 11, 2007 SPL measuring scale is logerithmic, meaning that a doubling of the input does not yield a (linear) doubling of output. It's a way to relate linear to exponential functions. Do not test any speakers at that kind of level unless you REALLY know what you are doing and can control duty cycle. It's a sure way to destroy a set of speakers. Link to comment Share on other sites More sharing options...
Members 6Imzadi Posted February 11, 2007 Members Share Posted February 11, 2007 It should be noted that when comparing speakers, the max SPL spec is calaculated at 1 metre from the enclosure. The SPL the audience gets will be much lower, as sound dissapates -3 or 6db everytime you double your distance from the source. So your 126db max SPL speaker is more likely down to 110 DB or less on the dancefloor, again depending on the distance... Al 126dB @ 1m (3')120dB @ 2m (6')114dB @ 4m (12')108dB @ 8m (24') Link to comment Share on other sites More sharing options...
Members tlbonehead Posted February 11, 2007 Members Share Posted February 11, 2007 So, it is just about knowing how loud it is? I thought maybe they were trying to flatten the frequency response or tune to the room or something...That's what a frequency analyzer is used for. Link to comment Share on other sites More sharing options...
Members Al Poulin Posted February 11, 2007 Members Share Posted February 11, 2007 That's what a frequency analyzer is used for. Good golly miss molly. It is a frequency analyzer. I was just guessing that that's what was used since I have never actually needed to (or have the knowledge to) use one. Some home stereo subwoofers and even complete stereo systems have a similar tool built-in that analyzes the surroundings (the room acoustics as well), does some sound tests and adjust everything for best possible sound. They usually have a built in microphone. Al Link to comment Share on other sites More sharing options...
Members Dogoth Posted February 11, 2007 Members Share Posted February 11, 2007 That's what a frequency analyzer is used for. More precisly a Real Time analyzer or AKA Audio Spectrum analyzer (there are also radio Freq spectrum analyzers which are used to help "tune" out hamonics from a transmitted signal (the FCC has rigid guidlines governing high powered transmitters to keep the harmonics generated from walking on other alotted frequencies)). There are also better units like TEF (time-energy frequency) analyzers which use a combination of pink (weighted) noise and audio sweep tones which will also help locate standing waves and "nodes". Their implimentation is much more involved and the analysis of the data gathered by their use involves a much greater understanding of the science of sound, acoustics and wave physics (at least sometimes much greater than my own:D ). Link to comment Share on other sites More sharing options...
Members guitarharv52 Posted February 12, 2007 Members Share Posted February 12, 2007 This one military base we played at a long time ago would send some sergeant around with a DB meter to see if the bands were too loud.They didn't want anyone over 95db and that is hard to do in a rock band. Link to comment Share on other sites More sharing options...
Members Scodiddly Posted February 12, 2007 Members Share Posted February 12, 2007 Actually 95dB is a pretty good level for rock - you can push the bottom a bit and get it to thump, but you aren't blowing people's ears out. The difficulty is getting the drummer and the guitar(s) to play at a reasonable level. A dB meter is very handy to have, because most people really can't tell how loud something is. A common rookie mistake in live sound is to turn stuff up too much, leading to annoyed patrons and excessive feedback. By the way, here are the OSHA guidlines for sound exposure: TABLE G-16 - PERMISSIBLE NOISE EXPOSURES (1)______________________________________________________________ | Duration per day, hours | Sound level dBA slow response____________________________|_________________________________ |8...........................| 906...........................| 924...........................| 953...........................| 972...........................| 1001 1/2 ......................| 1021...........................| 1051/2 ........................| 1101/4 or less................| 115 Link to comment Share on other sites More sharing options...
Members dboomer Posted February 12, 2007 Members Share Posted February 12, 2007 SPL=Sound pressure level=loudness Actually just to be accurate "intensity" would be correct ... not "loudness" Link to comment Share on other sites More sharing options...
Members BassDemon Posted February 13, 2007 Members Share Posted February 13, 2007 We once played a bar with a 100db limit. They had an SPL meter above the bar. It was the first time the soundguy had been at that venue and he just laughed when the owner said he had to keep it under 100db.I think he was looking at the 9 piece drum kit, two marshall full stacks and a bass rig that stacked was over 8ft tall. Although we were quieter than normal it was still hitting 110 at times on the meter. We're much better behaved now.... Link to comment Share on other sites More sharing options...
Members 6Imzadi Posted February 13, 2007 Members Share Posted February 13, 2007 We once played a bar with a 100db limit I played at a bar outside in a kind of ampetheater setting. The dB limit for this outside venue was 100dB. There was a train track on one edge of the property. When the train went past, it put out 109dB for just the engine, not even counting the horn. I was real upset that the train could be louder than the band, so I finally cranked it to get over the train. I got in trouble for my effort. Link to comment Share on other sites More sharing options...
Members solomaniac17 Posted February 13, 2007 Members Share Posted February 13, 2007 in the studio. we use pink noise to simulate open air.. and then we can monitor it with a spectrum anaylzer. i run pink noise thru reverbs to make then moe sonic, and natural...in the studio enviroment. sumtimes it has a complety reverse effect though.. so ya i agree with Al. u need a spectrumanaylzer to anaylze rooms as well i think. Link to comment Share on other sites More sharing options...
Members solomaniac17 Posted February 13, 2007 Members Share Posted February 13, 2007 Last year I was hired to mix a band in a small nighclub, it was a pretty un organized event, i had no information regard the band or genre. but the company i worked for gave me the dirty work. The SPL was so much that by the end of the night...after i had completly shut the mixer and amps off!!! since the singer decided to look directly into the FOH and point the microphone 6 inches from thedriver...seriously..through the duration of the nigt.. well due to this ridiculous event, I was disoriented, lost my balance, and ended up being sick.. Apperanty and judging by the 6 fullstack triple rectifiers.and bass rig, that the manager of this bar booked a touring band who decided to use all ther gear in this night club only a few hundred sq feet. Im the young guy though so. i always got the ugly stuff.. no matter what i did u cant turn down enough or turn up and EQ enuff to mix a band thats just too beyon too loud, s I just shut everything off. and the bar manager ended up shuting them down. Link to comment Share on other sites More sharing options...
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