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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
ellajeanelle's avatar
ellajeanelle
386 posts
 

Could impedance and sensitivity be getting mixed up somewhere?

ditusa's avatar
ditusa
1,887 posts
 

@immatthewj Wrote:

 

Basic question about sensitivity

See article below:

Mike

 

ghdprentice
7,051 posts
 

I think, in general, the way you are looking at things with more sensitivity requiring more power is correct. I think Harbeth are somewhat of an anomaly.

Like all things audio, it depends. Recommended wpc amplification is a very open and unscientific… well recommendation. It can be as much marketing as a real requirment.

 

The nominal impedance of the Harbeth P3ESR XD is 6 ohms. Which they advertise as “easy to drive”, since many speakers with a sensitivity of 83 are very hard to drive, requiring a lot of power and having impedances dipping down to 2 ohms or lower. The impedance is a measure of easily electrons flow through… and at 2 ohms they flow easily, and if the amp can’t produce tremendous current then it runs out of power.

Also speakers are rated at nominal impedance… because they vary across the audio spectrum. So, some speakers dip to 1 ohm, then go to 8 or more ohms… the nominal impedance could be almost any thing. The electrical characteristics are so much more complicated that these two parameters show, they tell very little with certainty.

A better measure of amps is current… and for speakers the lower the impedance the more current they need to perform properly.

I never look at the power requirements and when purchasing solid state amps I have generally purchased amps of far more than the recommended power rating because they tend to sound better. Tube amps are not nearly as likely to show that they are running low on power.

I choose amps for their character and make sure they have lots of power… regardless of speaker. If you choose Harbeth, you are choosing a specialty speaker and should research amplification carefully.

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