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Can anyone explain speaker sensitivity to me?

Discussion in 'Amps and Cabs [BG]' started by Johnebass, Dec 22, 2005.


  1. Johnebass

    Johnebass

    Jan 2, 2005
    :help: I am looking to change my SWR speakers to Aguilar and they refer a lot to "speaker sensitivity of 103 dB".

    Can anyone explain this in details please and how it affects the overall sound? :help:


    Ta
     
  2. SuperDuck

    SuperDuck

    Sep 26, 2000
    Wisconsin
    If you have a speaker with a given sensitivity of:

    103 db-SPL @ 1 W @ 1 m, that means that if you pump one watt into that puppy and measure the SPL from one meter away, it will read 103 dB-SPL. (This is usually done with pink noise, yes? Someone will correct me if that's wrong. It might be.)

    Now compare that same speaker to one that is rated:

    94 dB-SPL @ 1 W @ 1 m. Not as loud, not as efficient.

    It's just a way of rating how much energy will come out as compared to how much energy you put in.

    The tricky evil-advertising issues arise when they simply say "Speaker Sensitivity: 103 dB!". That's measured from how far? Six inches? One meter? How much power was put into the speaker? One watt? Ten watts?
     
  3. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    almost right.

    generally speakers are measured for sensitivity @ 1 watt @ 1 meter @ 1KHz.

    Not pink noise, but a frequency of 1K. Not the most useful frequency for bass.

    I've taken speakers that were both rated for the same dB and had one be quite a bit louder than the other one due to the entire frequency response curve (which we generally don't get to see), AKA how the speaker is "voiced".
     
  4. SuperDuck

    SuperDuck

    Sep 26, 2000
    Wisconsin
    See, I knew someone would correct me. :D I couldn't remember for the life of me which of those two it was... guess I should have just Googled it!
     
  5. jsbarber

    jsbarber Supporting Member

    Jun 7, 2005
    San Diego
    There is a related concept called efficiency (which I think is based on an applied voltage rather than 1 watt), but does anyone know the precise definition?

    Jim
     
  6. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    Rating speakers at 1 kHz is not only musically useless for judging bass speakers, but it is also a way to publish an inflated sensitivity rating. Speakers typically have humps and dips in their response curves. If you choose a driver with a response hump at 1 kHz, then you can claim a higher sensitivity rating. Drivers with whizzer cones and tweeters can also have elevated treble response.

    Of much greater importance is how the speaker performs in the crucial region below 250 Hz, and the only way to show the performance of a speaker is with a graph of sensitivity versus frequency. Having a series of graphs for different off-axis angles would be even more useful.

    The speaker makers know all of this, of course.

    While response at 1 kHz is important, you can EQ the higher frequencies without sacrificing overall power, thus it's the low frequencies that really tell you how loud a speaker can get.
     
  7. Passinwind

    Passinwind I Know Nothing Supporting Member

    Huh? Someone still does it that way? Why, the noive...It's a can o' worms though, certainly.

    Here's a little info on how Eminence specs sensitivity: http://www.partsexpress.com/resources/emisens.html
     
  8. etnops

    etnops

    Nov 6, 2005

    efficiency attempts to define the amount converted of electrical energy into acoustic energy by the drive unit. this is usually expressed as a %age. speakers are very in-efficient inherantly. usually around 1-2% efficient or so - meaning, they waste 98-99% of input energy as heat. an electric watt is far different than an acoustic watt. IIRC, an acoustic watt is somewhere in the neighborhood of 108dB or so @ 4' 4PI.

    sensitivity attempts to express an input level (voltage) to an SPL ouptut in regards to frequency.


    hope this helps.


    -SDP
     
  9. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    If only, but that's not always the case either. In theory the SPL rating should reflect an average over the bandwidth of the driver, but more often than not it reflects the highest measured SPL, and that could be at just about any frequency. Bottom line, without a full SPL chart to back it up SPL ratings are about as useful as mammary glands on male bovines.
     
  10. truckin88

    truckin88

    Oct 18, 2001
    Newburgh, NY
    pink noise is used for random reliability tests, I work for a speaker company....that is what we use it for, u are however right about measurements.
     
  11. dave_bass5

    dave_bass5

    May 28, 2004
    London, UK.
    So is the Aguilara GS210 a good 103db or just an average 103db?
    Im planning on getting one in Jan (4 ohms) to be run from my ABM 300evo2 head and i want the full power of the amp into the one cab and i want the cab loud (and i want someone to pay for it but doubt that will happen)

    Dave.
     
  12. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    well, 1st, it's an aguilar (aguilara is a hot chick with a marginal voice) - :p

    2nd, IME, the gs210 is pretty darned loud and voiced rather aggressively. I wouldn't argue with the 103 dB sensitivity, they're top notch cabs.
     
  13. dave_bass5

    dave_bass5

    May 28, 2004
    London, UK.
    Oh yeah but which one is the most musical eh?

    im going to try one out (the GS112) soon but what do you mean by "voiced rather aggressively"

    Thanks

    Dave.
     
  14. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    They don't have any SPL charts so there's no way of knowing. Ask Bruce to add it to his list of cabs to test. But, from the standpoint of what it is possible to achieve from a pair of tens in a cabinet that size, is it 102dB sensitive on average across its advertised 42Hz to 16kHz bandwidth? No.
     
  15. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    well, the gs210 is voiced aggressively. to my ears it has very present almost growly mids. The gs 112 is not voiced aggressively. it is a bit mid shy, but has an excellent low end. different animals alltogether.