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dB meter

Discussion in 'Sound, Music, and Intercom' started by erosing, Jan 24, 2008.

  1. erosing

    erosing The Royal Renaissance Man

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    Hey guys, I was wondering if anyone had any recommendations on a dB meter, something not overly expensive but reliable would be best, and any thoughts as to digital vs. analog?
     
  2. museav

    museav CBMod CB Mods Departed Member

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    What is the use and what information are you trying to get? There's a wide range of capabilities, accuracy and cost and what may work fine for just getting a quick idea of levels is quite different from what a professional audio designer/installer may use which could be different from what an acoustician may use. Without getting detailed, you can get into factors like accuracy or Type ratings, ability to store/recall data, frequency based analysis, time based analysis and many others.

    For basic "how loud is it?" type measurements, the Radio Shack meters are hard to beat for value. They are very careful to say that these have no specific accuracy rating and are not for professional use, but people find that they are usually fairly accurate for non-critical uses. They have both analog and digital versions, there is no specific 'better' choice. The digital meter may be easier to read as far as getting a specific number, but I personally find that an analog meter can sometimes give some additional information simply in more visually indicating how the levels are changing. Galaxy Audio offers the Checkmate series of meters that come in sort of entry level/good/better/best versions that give some options. If you want to get into looking at some frequency based analysis, the Phonic PAA3 is hardly an instrumentation quality meter, but gives a lot of bang for the buck.

    If the application is for performance verification or compliance measurements (or if it is something that may end up as part of a legal proceeding), then you may need to look at measurement systems with Type 2 or even Type 1 ratings. In these cases you need to consider the mic as well as the meter and often also need to include a calibrator that allows you to verify the meter readings before and after measurements. Obviously, the price for these systems also goes up significantly, a Type 1 measurement system might typically starts at $2,000 to $3,000 and can easily get to several times that cost. I doubt that's what you're looking for, so I won't go into more details, but let us know if it is.
     
  3. Hughesie

    Hughesie Well-Known Member

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    i read about a diy one in a audio mag recently i will try and track it down for you
     
  4. Chris15

    Chris15 CBMod CB Mods Premium Member

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    Now to be picky, we should be calling it an SPL meter... to have a dB meter, you would need two inputs, be it one of those might be a reference. This is because dB is a ratio, a logarithmic one, but a ratio none the less and it has no units. I'm not aware of a way to measure something that has no units...
     
  5. mixmaster

    mixmaster Active Member

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    Things to looks for:

    weighting- a reasonable db (spl) meter should allow you to chose A or C weighted measurements. For quick checks to find out how loud the show is, weighting is less important. If you are doing specific work like designs, or trying to match specs on an install or rider, or make reference measurements, your measurement qualifications need to match.

    Speed- good digital meters will let you chose the speed that they function at. Fast speeds catch the individual peaks better, slow speeds will result in a better "average" reading.

    Back light/display- most of the time I find myself using mine in places with less than adequate lighting. A big display is easier to read, and back light is a nice (but more expensive) option. I wish mine had a better display.
     
  6. erosing

    erosing The Royal Renaissance Man

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    True, I am looking for an SBL meter, bad habbits say write it other ways. As far as it's uses I mainly just need to make sure I'm not going to blow out anyone's ear drums at the moment. So a quick and dirty meter would work as long as its reliable.




    If you could that would be awesome, the diy route is always more fun when its safe.
     
  7. museav

    museav CBMod CB Mods Departed Member

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    I guess that technically the correct termionology might be dBSPL meter as it isn't actually reporting the SPL, which would be the actual pressure, but rather the pressure level in dB re: an established reference level. dB levels are measured all the time, for example audio and video levels are often measured in dBu or dBm or dBV and many meters read those directly. And digital signal will often be reported as dBFS. A dB level does require a reference, however in most cases that reference is a defined standard level and that reference is identified in the suffix (SPL, PWL, V, m, u, etc.). All that being said, SLM or Sound Level Meter is probably the most accepted term for what is being discussed.

    There might be a DIY meter but I would think that would need something to calibrate it, so it may require having a calibrator or reference meter for comparison.

    $50-$60 will get you a basic Radio Shack or Galaxy Audio CM-130 meter, nothing fancy but usually good enough for simple uses and not something you'll lose sleep over if it is lost or damaged (like when one of my co-workers 'misplaced' one half of a matched pair of B&K instrumentation mic capsules). You might be surprised by how many audio professionals use a Radio Shack SLM for quick checks in the field.
     
  8. BNBSound

    BNBSound Active Member

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    If all you're trying to do is keep from deafening people, a meter is a really great tool. But keep in mind that it should be just that, don't rely on it. Sure you may need to explain yourself to some angry dude at a show and it's great to have numbers to back you up, "See? It's just under 120, we're fine!"

    The point should be to train your ear though. I found that after about a year of glancing over at my trusty Radio Shack SPL meter I had actually developed some pretty good calibration in my head, at least between 80 and 105 or so. I can usually listen to a show and compare my guess figure to the meter and be within a point or two.

    So even if you don't get a meter right away, DO start listening critically and make adjustments accordingly. With a little practice you should be able to mix without ever hearing from people complaining that it's too loud just by using your ears.
     
  9. museav

    museav CBMod CB Mods Departed Member

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    You can also have fun with weighting and response. If someone complains that it isn't loud enough, show them the C-weighted (or even better, flat) fast response reading. If another person complains that it is too loud, show them the A-weighted slow response reading. Depending on the source material you'll often see a significant difference between those two readings.

    Also keep in mind that if it is hearing damage that is the concern, that is very much a matter of exposure and not just peak level. So it's not just that it is 120dB, it is how long people are exposed to it, how much of that time it is at or near the peak levels and what happens during the other times. That is one of the concerns with modern, heavily compressed music as the compression often causes the average levels to be much higher so the risk of hearing damage is actually greater than with a performance with the exact same peak levels but with greater dynamics and thus a lower average level.
     
  10. musictom

    musictom Member

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    Another vote for the Rat Shack meters.
     
  11. DaveySimps

    DaveySimps CBMod CB Mods Premium Member

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    I too am a fan of the digital Radio Shack SPL meters. I have had one for several years, and it continues to serve me well. I have even compared it side by side to more sophisticated systems, and it produces the same numbers (give or take a very small decimal). Afterall, they are just for reference.
     
  12. mixmaster

    mixmaster Active Member

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    For rough measurements:

    at 60db, granny gives the sound guy a dirty look

    at 70db, granny turns off the hearing aid

    at 80db, granny leaves

    at 90db, parents people start thinking "it plenty loud", kids start having fun

    at 100db, parents are at the back of the house, kids are down front rockin' out

    at 110db, you've hit full rock concert level, start to risk long term damage to your ears, kids are having fun, parents have left, and I tell visiting engineers in my venue "no louder or I pull the plug"

    Seriously, learn to watch your audiance's reactions, it will be obvious when most of them think it's too loud. Also consider your program material, and enviorment. 95-100 db is fine for a medium energy concert, but I always get comments at anything above 80 for our praise band in church.
    I remember one gig, the promoter asked my boss (system provider) to turn things down. Per the rider, my boss directed the promoter to the BE mixing the show first. Conversation went something like this:
    Promoter: It's too loud
    BE: No its not
    Promoter: You're over 110 db (actually about 125 db A at 50 feet in front of the SL stack)
    BE: Sooo?
    Promoter: People are leaving!
    BE: Sooo? If they don't like it, let'em leave.
    Promoter: Turn it down or shut it down.
    My boss finally turned down the the DSPs and we locked them. We finished the show at a nice 110. Haven't worked with the band again. Promoter is still a good customer
    Moral of the story....Having a meter is important, but don't rely on it too tell you when things are too loud.
     
  13. avkid

    avkid Not a New User Fight Leukemia

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    Unless granny is hard of hearing that is.
     
  14. Eboy87

    Eboy87 Well-Known Member

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    Huh? What? Speak up sonney!

    Going back to meters, I've got a few gigs coming up in outdoor Chicago, and I'm probably gonna pick up the RatShack digital meter. Since I seem to have lost the search function over at PSW, can someone here tell me what I need to do for caliberating it? First off, does it come calibrated? (I'd be a little leary trusting it straight from the factory) How do I go about calibrating it?

    And I've been reading up on the different ratings. But one last question on that. I've got a pretty good grasp on what each of the ratings is for, but which do you normally use in a concert-environment? I've heard of engineers using both C weighted (which makes sense, since it's more for loud music*), but I've also heard of people using A weighted measurements. Which would be beneficial for a concert downtown outdoors?

    * broad generalized statement. Too tired to get complex.
     
  15. museav

    museav CBMod CB Mods Departed Member

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    You don't, in fact the Owner's Manual states that the calibration adjustment is for service techs only. You could probably do it yourself, but you'd need to buy a calibrator that costs probably close to 10 times what the meter does and then find an appropriate adapter to fit the Radio Shack's mic. If you need calibrated readings then you probably should actually look for a calibrator and better meter. FYI, if the events are soon, make sure that the meter has a chance to acclimate before making measurements, taking the meter right out of a warm storage area or car to make measurements in the cold will result in errors.

    It depends, at concert levels C-weighting should be a better representation of the perceived level for the audience. However, the vast majority of hearing loss and community noise codes are written around A-weighting and it appears that Chicago's noise ordinances do use A-weighting. So it then probably becomes a matter of whether you're measuring for the bands and your use or for community noise or public safety compliance purposes.
     
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  16. Eboy87

    Eboy87 Well-Known Member

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    Thanks Muse, that was exactly what I was looking for. I had heard somewhere something about calibration, but couldn't remember the details. The gigs aren't until April/May, which is soon in the grand view of things, but I'll make sure to let it adjust to air temp.
     
  17. seanandkate

    seanandkate Well-Known Member Fight Leukemia

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    OK, so I just picked up a Radio Shack, or "The Source" up here in the Great White North, SPL meter. Scosche was the make--I hope that was the one people were talking about! Now the follow-up question: What is a reasonable SPL for an event in a public high school. Last staff meeting, I was involved in a classic "It was too loud" / "It was was fine" conversation, so I decided it's just easier to have a meter on hand. So, are there any guidelines or even mandates regarding event levels? And as always, something that's in print will probably trump best practices, but I trust the collective wisdom of you folks.
     
    Last edited: Oct 5, 2009
  18. museav

    museav CBMod CB Mods Departed Member

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    The Radio Shack SLMs that I have seen are Radio Shack brand, Digital-Display Sound-Level Meter - RadioShack.com. If this is what you are referencing, Car Audio Accessories Tools Scosche SPL Meter 135db max, then all I know about it is that WalMart has it on sale for $15, marked down from the regular $20 price. I'm unable to find any manual for or literature on that model and between that, the price and a couple of reviews I did find noting significant differences between the measurements made with two units or compared to other meters, I'd be a bit wary.

    Unless you are addressing occupational hearing loss guidelines, noise ordinances or cinema applications, none of which is probably relevant to an indoor event, then at least in the US there are no definitive references. Any criteria are usually subjective with many factors that can contribute to both the perceived loudness, the level of 'acceptability' and the associated measurements. Some of those factors are empirical and some are subjective, for example the coverage a system provides could affect both the peak levels required for the same perceived general loudness and the levels measured, at the same time the type of music could affect what might be an acceptable or desired level. In most cases it becomes more a subjective issue, finding what is acceptable and then using the levels and measurement process established for subsequent comparative levels.

    You may find some guidelines that other venues use and that can be very useful information, just be aware that those criteria are probably subjective and based on their system, room, application, etc., which may differ from yours.
     
  19. seanandkate

    seanandkate Well-Known Member Fight Leukemia

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    Yup, that's the Scosche all right. Back she goes . . . Looks like I get my brother in Florida to send the Radio Shack one to Canada for me. And I figured that the "guidelines" might be all over the map. I guess I'm looking for a mean, not necessarily an "After 120 dB people's heads start to implode" kinda thing. I think most people just have a sense of what's too loud. I'm just running into several different senses of that sense. If that makes sense. :p
     
    Last edited: Oct 6, 2009
  20. jkowtko

    jkowtko Active Member

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    +1 for the Radio Shack digital meter.

    I've used it primarily to make RELATIVE measurements ... figure out what "decibel" level is comfortable to you and the staff or management of the specific production, then monitor levels throughout the performance to make sure it doesn't exceed that level on the meter.
     
    Last edited: Oct 6, 2009

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