sensativity -+2db what does this mean?

Discussion in 'Speakers' started by Markdf, Nov 25, 2003.

  1. Markdf

    Markdf Auditioning

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    I dont understand what that means after the db rating. Is it good or bad? Thanks,Mark
     
  2. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    Sensitivity is how loud the speaker will play given a certain amount of power. I wouldn't pay much attention to +/- 2db, because all speakers should have some margin of error for their posted specs. 1-2db is hardly noticeable anyways.

    Lets say a speaker plays a high frequency such as 10khz, and a low frequency at 90hz. If the speaker plays the 10khz 2db too loud, and the 90hz 2db too soft, then that means the speaker can have +/-2db for those frequencies. (Its the margin of error)
     
  3. JamesCB

    JamesCB Second Unit

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    Sensitivity is used to tell how efficient a speaker is. Such as:

    98 db @ 1000 hz, 1 watt/1 meter

    Which means:
    The speaker is fed a 1000 hz signal with 1 watt of power (or sometimes refered to 2.83 volts, same thing) and a level meter is placed 1 meter in front of the speaker. The resulting db measurement is the rated sensitivity.

    It is kind of a standard to comare speakers by, but measurements at frequencies other than 1000 hz will usually give different readings. That's where the +- comes in. It is usually used for overall frequecy response.
    Such as:

    40hz - 20Khz +-3db

    A +- in the sesitivity rating is incorrect. It is a defined number.
     
  4. John Kotches

    John Kotches Cinematographer

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    2.83v isn't the same thing, as it depends on the impedance of the speaker.

    2.83v @ 8 ohms is 1 watt.
    2.83v @ 4 ohms is 2 watts

    Cheers,
     
  5. Phil Iturralde

    Phil Iturralde Screenwriter

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    FYI: sensitivity : (1) The minimum required signal at the input of an audio device in order to produce the rated output is generally called the sensitivity of the device. The higher the sensitivity, the lower the signal required at the input. A device with high sensitivity can process very small signals, but may be distorted by large ones, whereas one with low sensitivity can process large signals without distortion, but may add an unacceptable level of noise to a small signal. (2) In general, all information about a transducer’s response characteristics to incoming sound waves. With respect to microphones, a standard performance specification that indicates the output voltage generated when a sound of known SPL and frequency arrives at the diaphragm. Given in mV by most manufacturers, and generally specified for broadband response to pink noise. See efficiency

    efficiency : A measure, usually applied to loudspeakers**, of how much of the input electrical energy is converted to sound energy, expressed in percent. The remaining energy is converted into heat.

    **loudspeaker : A transducer which converts electrical energy into acoustical energy. The most common type of loudspeaker today is the dynamic loudspeaker which has a resonant frequency, the frequency at which it will vibrate naturally if perturbed. The resonant frequency, also called the natural frequency, will be near the lowest frequency that the speaker will reproduce well, and is that frequency at which it is easiest to move the cone (the output from the speaker will be at a maximum). Damping must be added to a speaker system in order to reduce this peak in response.

    Phil
     
  6. John Garcia

    John Garcia Executive Producer

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    +/- spec is how well this speaker maintains it's respnose across the range specified, ie; tighter spec generally means a more accurate speaker. Large peaks or dips in response will give you poor performance becuse the sound is "colored" or inaccurate. If you look at professional monitors, you will often see a very tight spec given, in the +/- 2 to 1.5dB. This is intended to give you an idea of the frequency range in which a given speaker will perform it's best - it will also have a +/-3dB spec with a different range.

    The most commonly given spec is +/-3dB, as this will include the -3dB point of the upper and lower limits of the speaker where response begins to audibly fall off.
     
  7. Iver

    Iver Second Unit

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  8. ChrisWiggles

    ChrisWiggles Producer

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    Nerd! [​IMG] [​IMG]
     

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