2. speakers
  3. 187537-171531

Basic question about sensitivity

Obviously I am mistaken, and I am positive that this has been covered before,  but I had thought that the higher the number (sensitivity) the easier the speaker was to drive.  However, when I read a thread in which someone is talking about a speaker they have or are interested in, I frequently do a cursory search and a little bit of reading about it, and, for example, a while ago I read a review & specs on the Monitor Audio Gold 300 5G with a sensitivity rating of either 90 or 91 (which I would have thought at one time meant it was a pretty easy load to drive) but the recommended amp was 100 to 250 wpc.

On the other hand, I just did a search and some reading on the Harbeth P3ESR XD which has a sensitivity rating of 83 (which at one time I would have thought meant it was a tough load to drive) but they are recommending amps "from 15 wpc".

What is the number listed for a speakers sensitivity actually meaning?

 

immatthewj

Showing 3 responses by erik_squires

erik_squires
15,788 posts
 

@yoyoyaya It's a very good point.  The Kef Reference 1 Meta is an excellent example.

I wish someone would loan me one of those, there is some truly wonky stuff going on in their crossover.

erik_squires
15,788 posts
 

@yoyoyaya  It is a good measurement except :

  1. It is not universally available.  We only know about the from what they chose to review
  2. It is not easy to calculate from normally published specifications.

Since manufacturers do not publish EPDR we are stuck trying to identify hard to drive speakers without it.  Often we can't even get minimum impedance values either.

erik_squires
15,788 posts
 

Higher efficiency = easier to drive.

Higher sensitivity = more output at given voltage.

When the speaker is 8 Ohms, efficiency and sensitivity are the same.

 

Here’s a common example: Many mid woofers come in 8 ohm and 4 ohm versions. Nearly identical in all other aspects besides the impedance curves. The 8 Ohm version produces 87 dB at 2.83 V. That is, 87 db @ 1 Watt. The 4 ohm speaker produces 90 dB @ 2.83V, but since it has 2x the current it is 90 dB @ 2 Watts.

Generally speaking though, it’s hard to find high sensitivity speakers ( 97 dB or higher) that are not also benign impedance (8 Ohms or better).

To make it easier on you, keep an eye on "minimum impedance" not "nominal impedance."  Higher minimum is (generally) easier to drive, and the sensitifity/efficiency will tell you how loud it will get with your amp.

More to discover