Can you explain the speaker spec: "89db" to me?

Discussion in 'Speakers' started by RobertMc, Nov 4, 2004.

  1. RobertMc

    RobertMc Agent

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    Hi

    Sorry if this has been covered before (probably has but I can't find it specifically on a search that I did), but I am wondering if you good people can explain a spec to me.

    On speaker specs that I have seen, there is sometimes / usually a nominated "db" rating. For instance, I believe that my speakers have an "89db" rating. I think I know that it has nothing to do with how loud the speakers is - possibly to do with sound quality...??

    What does this refer to?

    Sorry if this is a lame question, but thanks for any help.

    Rob.
     
  2. MikeDuke

    MikeDuke Stunt Coordinator

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    If you goto http://www.audiovideo101.com
    and look for the definition of sensitivity you will get a decent explanation. Basically it means how loud a speaker can play given a certain amount of power. Typically you might see
    88 dB SPL, with 2.83 V rms at 1 m. That equals what the speaker can produce with one watt at one meter. There is no direct correlation with sensitivity and sound quality. It just means that a lower number needs more power so the speaker will preform the way it should. This is important so you can make sure that you do not over drive the amp. That is the way I look at it.
    Mike D
     
  3. WayneLVS

    WayneLVS Extra

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    Good explanation......it does effect sound quality to a certain extent.........if you have a spkr that has a sensitivity of 50db, and another one rated at 100db being driven off the same amp, the 100db spkr will sound better because it's not working the amp as much to produce the same levels. The more power a amp puts out, the more distortion it puts out. So ultimatly you want a set of speakers that will operate as efficently as possible (ie, larger db rating

    If you are using a large powered amp, you probably won't be able to tell the difference, but if you have a small weak amp, the speaker sensitivity will have more of an effect on final sound quality.
     
  4. MikeDuke

    MikeDuke Stunt Coordinator

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    Agreed. That was in my head but it had no way to get out.
    Mike D
     
  5. WayneLVS

    WayneLVS Extra

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    hehe..........i know exactly how that goes.............
     
  6. John Garcia

    John Garcia Executive Producer

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    It has everything to do with how loud the speaker is, since it is the measure of how efficiently a speaker converts engergy to sound.

    Sound QUALITY is not affected by sensitivity, though as Wayne notes, it may make a particular speaker sound better than another using the same amp in the same room.
     
  7. Yung

    Yung Stunt Coordinator

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    Which sensitivity rating do most speaker manufacturers provide. Paradigm provides both Room and Anechoic. A lot of manufactures only provide one number, but which is it, Room or Anechoic?

    Which one should I look at when comparing Paradigms to specs provided by another manufacturer?

    I would think Anechoic would be a more apples to apples comparison between speakers.
     
  8. RobertMc

    RobertMc Agent

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    Thanks for those replies & the link Mike - that was a good article.

    In short, I am now 'enlightened' and I have got my head around the concept of db ratings.

    Perhaps another small question, the article at audiovideo101 hinted that most speakers are rated 89-90 db, is this actually the case? Would it be fair to say that if this is the case, then amplifier manufacturers would tend to build units with this 'average' in mind?

    Also, can anyone give examples of manufactured speakers that have quite low db ratings? - and would this be intentional?

    Rob.
     
  9. JamesCB

    JamesCB Second Unit

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    Most ratings are measurements taken in anechoic chambers. IMO, a room rating means very little as rooms vary quite a bit.

    James
     
  10. MikeDuke

    MikeDuke Stunt Coordinator

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    Revel audio has speakers that range from 86-88db. There are some Theil speakers that go down to 86db. I know that some of Klipsch go the other way on the scale 99db and above. My speakers are 90db. As far as being intentional I do not know. It just may be a by product of the components that they use in the speaker. Again this does not mean that they are bad. Just that they need work to get them going. Dynaudio is another company that has speakers that range from 86db up to maybe about 90db. I am sure there are plenty more. But I can not think of any right now.
     
  11. WayneLVS

    WayneLVS Extra

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    Also, i think the higher the sensitivity is, the more "crisp" it sounds at low to medium level. Since the voice coil (or whatever component) reacts earlier to input.

    Most commercial grade speakers are 95+, but they sometimes have to run 24/7 without clipping the amp.

    .02c
     
  12. John Garcia

    John Garcia Executive Producer

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    I would not say a low sensitivity is intentional, but rather a function of the drivers selected and the crossover used. To me, it generally just means you need a larger amp to run these particular speakers, and that's not always a bad thing [​IMG]

    2.83 V = 1 watt, so this translates into the more common: 1w @ 1m.
     
  13. RobertMc

    RobertMc Agent

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    Do the individual drivers of speakers have individual sensitivity ratings? If so, are subwoofers likely to have a lower sensitivity than say a mid-range driver?

    In saying that a speaker with 3 drivers (woofer, mid & tweeter for arguments sake) has a 90db sensitivity, am I correct in thinking that this is the sound level @ 1 metre for the entire frequency range across all 3 speakers? If that is the case, would this figure be made up with perhaps a high sensitivity tweeter averaged down by a less sensitive woofer, or vice versa.

    Not that any of this is particuarly affecting me or my system, just trying to increase my knowledge base here - thanks for being patient[​IMG]
     
  14. John Garcia

    John Garcia Executive Producer

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    Yes, each driver has a sensitivity, and the combination of those drivers, as well as how they are crossed over in the speaker, determine the overall sensitivity. The number of drivers will also affect the sensitivity, with more drivers playing the same frequencies yeilding higher sensitivity.

    I forget exactly what frequency range is used to take the measurement, but I have a book at home that I believe has the info. I'll get back to you.

    Driver sensitivity can be all over the place due to a large number of design factors, so it is really hard to classify a sub driver as always less efficient than a midrange or tweeter, though tweeters will typically have a fairly high sensitivity.
     
  15. MikeDuke

    MikeDuke Stunt Coordinator

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    Another factor that should be thought about is impedance. Again you can goto that above web site and get a definition. I would very much suggest that you go to that website and look it up. Also on the bottom of the page it says for more info check out these items. The are helpful. Basically it means how much resistance there is. The lower the number the greater the resistance. Typically it will vary depending on the frequency. The lower the impedance the more difficult it may be to drive the speaker. That would also dictate the need for more power to them. For example the Dynaudio Contour S5.4 has a nominal impedance of 4ohms. Basically this means that it takes some power to run these speakers.

    This is from their website
    Recommended Amp. Power:
    Small size rooms: -- watts
    Medium size rooms: >50 watts
    Large size rooms: >100 watts
    IEC Long Term Power Handling:
     
  16. Dean Arizona

    Dean Arizona Agent

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    Hi MikeDuke,

    You said, "The lower the (impedance) number the greater the resistance." Don't you mean the opposite? Speakers with lower ohm values have less resistance, and therefore have the capacity to draw more power which inturn requires greater amplification....Are we in agreement?[​IMG]
     
  17. MikeDuke

    MikeDuke Stunt Coordinator

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    You are correct Dean [​IMG]. I was thinking of it in the wrong way. A lower value would mean less resistance and would have the ability to draw more power. I was thinking that the impedance restricted the flow, hence the need for more power. Sorry for any mix up.
    Mike D

    Here is a good analogy from
    http://www.audiovideo101.com

     

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