new to ht, can someone explain speaker specs

Discussion in 'Archived Threads 2001-2004' started by Jared_C, Dec 7, 2002.

  1. Jared_C

    Jared_C Stunt Coordinator

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    i don't know partically that much about speakers, and want to learn more. for example when i see this,

    - Impedance: 8 ohms
    - Max. Input power: 200Watts
    - Sensitivity: 87dB (characteristic of glass fiber cones).
    - Frequency response: 50-25,000 Hz

    i understand only the wattage and the ohms, not the sensitivity or frequency. can someone please explain what they mean or link me to somewhere that explains it. forgive me if it is already posted somewhere
     
  2. Pete Mazz

    Pete Mazz Supporting Actor

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    Sensitivity is usually given as 1 Watt/1 Meter. That means that when fed 1 watt of power these speakers will produce 87 dB at 1 meter distance. Now, you have to double input power to increase output by 3 dB. So 2 watts at 1 meter = 90 dB. To determine how much power it takes to reach a certain level at a certain distance you need to also factor in the decay rate of 6 dB per doubling of distance. So 2 watts at 2 meters = 84 dB.

    Freq response is the range of freqs that the speakers faithfully reproduce. Human hearing ranges from 20 Hz to 20,000 Hz (20 KHz). Most music doesn't go too much lower than 30-40 Hz at the low end which is where most speakers have trouble. If these go to 50, I would consider a sub to help out in the lower octaves. It eases the work the speakers have to do trying to reproduce those lower freqs.

    Pete
     
  3. Kevin T

    Kevin T Screenwriter

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    well, i'm not really techinically knowledgeable but i'll give you what i understand those numbers to mean. sensitivity is how loud the speaker will play compared to another given a specified amount of power. usually, the measurement is dB/watt/meter. that is to say that the above speaker will put out 87dB at 1 meter when driven by 1 watt of power. the speaker you're referring to has a relatively low sensitivity but the impedance appears rather benign. most speakers with sensitivity in the 80's tend to be 4 ohm loads from my experience. the frequency response is how deep and how high the speaker will play. since it only goes down to 50 Hz, you'll probably need a sub as that's not incredibly deep. 25,000 is way out of your hearing range. most adults have a range that peaks at around 16,000 hz (16 kHz). hope this helped. i'm sure someone will come along shortly to impart any more wisdom that i couldn't.

    kevin t
     
  4. Jared_C

    Jared_C Stunt Coordinator

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    thanks for the responses. i am still confused, if the speaker has a sensitivity of 87db, like the example i posted, does this mean these speakers require a greater amount of wattage than most to drive them. what are the benefits/down sides to the sensitivity rating. i am confused
     
  5. Kevin T

    Kevin T Screenwriter

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    yes...that speaker will require more power to be as loud as a higher sensitivity speaker is with less power. other than the need for more power, there's really no benefit or down side to the sensitivity rating as long as you don't intend to use a shoddy amplifier / receiver. most mass market gear will be able to play those speakers louder than you'd want to listen.

    kevin t
     
  6. Jared_C

    Jared_C Stunt Coordinator

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    thanks for the reply kevin
     
  7. GeorgeTW

    GeorgeTW Stunt Coordinator

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    sensitivity is not a measure of quality.

    Cerwin Vega has a reputation for playing loud (not always accurately).

    Infinity speakers are less sensitive, but are highly accurate in their reproduction.

    Manufacturers market their product to their best feature, which may mean you need to 'listen' to the spec less-hyped, to get a real feel.
     
  8. Dustin B

    Dustin B Producer

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    If you haven't found this, the HTF Primer is a great resource to answer most beginners questions.
    http://www.hometheaterforum.com/htfo...threadid=55635
    I wrote something for it that specifically addresses one of you questions (just more elborate on what Pete has said):
    http://www.hometheaterforum.com/htfo...124#post517124
    The only thing I'll add about freq resp is that manufactures specs on it are pretty much always over optimistic. Sure it may have that extension at 80dB, but on a 100dB plus peak not a chance.
     

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