speaker sensitivity

[matengawhat]

i always get confused with speakers - whats easier for an amp to drive a speaker at 87db at 8 ohms or a speaker at 91.5db at 8 ohms?

 

[Anonymous]

[quote user="matengawhat"]i always get confused with speakers - whats easyier for an amp to drive a speaker at 87db at 8 ohms or a speaker at 91.5db at 8 ohms?[/quote]The latter... I think you meant 87dB at 8ohms or 91.5dB at 4ohms

 

[matengawhat]

def meant at 8 ohms for both comparing two speakers - anyone know of an easy article to follow

 

[Anonymous]

[quote user="matengawhat"]i always get confused with speakers - whats easyier for an amp to drive a speaker at 87db at 8 ohms or a speaker at 91.5db at 8 ohms?[/quote]

Hi matengawhat.

A speaker, 91.5db @ 8ohms will produce more sound than the 87db @ 8ohms for a given output.

Sensitivity ratings are given in decibels per watt at one meter, or db/Wm. So, with an input of one watt (usually white noise), a speaker with a sensitivity of 90 db/Wm will produce 90 decibels of sound at a distance of one meter. A sensitivity of 90 is considered average, with ratings of 87 and below considered low sensitivity and above 93 considered high sensitivity. To increase the volume by 3 db, you must double the power. So, using the example above, to make 93 db you would need two watts, and to make 96 decibels, four watts.

 

[matengawhat]

so the larger the sensitivity the louder it will go? but what about ease to drive or is that an ohm issue? so based on the above if i had a speaker of 87db it would require .5 watts for the same volume so easiers to drive?

 

[Craig M.]

i would guess that the amp is doing the same work in your example, but one set of speakers will be much louder. the higher the sensitivity the more efficient the speaker. i think a lower ohm figure draws more current from the amp.

 

[Anonymous]

Craigs got it. If you ABC tested speakers with 85, 95, and 105db efficiencies at 9 o'clock they would exert the same amount of effort for the amp, but be quiet, normal, and haneously loud respectively. the keyword is efficiency. 1watt at one metre.