Speaker input sensitivity.

[jm55]

I recently read the following speaker specification.


Input sensitivity for a2.83V input (= 1W @ 8 ohms or 2W at 4 ohms) is 91dB.

What does this mean? I would be grateful if someone could explain what speaker input sensitivity means, and or how to interpret the values. Thanks.

 

[Oerets]

I think what they are trying to say is the SPL - Sound Pressure Level is 91dB
That is a measurement taken by a 1W input @ speakers with a microphone 1 meter away and the dB reading (how loud) at that point.


Barney

 

[jm55]

Can any generalities be made regarding this value, e.g., a speaker with a higher dB rating (input sensitivity) will sound _______________________ compared to a speaker with a lower rating. In other words, what qualitative information does this value provide about a given speaker?

 

[karlo]

iec standard is for a 2.83v input. i believe it was intended to standardize efficiency/
sensitivity ratings ,and assumed to be used comparing 8 ohm speakers with 1 watt
of input.

at lower impedances , this results in more power
than 1w@8ohms . so , a 4 ohm speaker draws 2 watts of power when given 2.83v.
a 2 ohm, 4w , a 1 ohm, 8 w ... a 16 ohm, .5w .

so , sensitivity ratings can be misleading /confusing , when comparing speakers of
diff/unknown impedance.

 

[karlo]

speakers with very low sensitivity may have very steep crossovers , highly damped
drivers or drivers with limited bandwidth,sealed cabinets.

highly sensitive speakers often use reflex or horn loaded bass drivers , horn -loaded/compression mids and/or/tweeters , crossovers with moderate slope .

there are poor and excellent designs of either type, with mid-road 90-91db also
being equally ambiguous !

 

[Zilch]

Can any generalities be made regarding this value, e.g., a speaker with a higher dB rating (input sensitivity) will sound _______________________ compared to a speaker with a lower rating. In other words, what qualitative information does this value provide about a given speaker?

Yes. For a given input wattage, the higher sensitivity speaker will be louder, by the number of dBs specified.

There are also design parameter differences associated with building speakers with higher vs. lower sensitivities. It's not apples and apples.

 

[wineslob]

Can any generalities be made regarding this value, e.g., a speaker with a higher dB rating (input sensitivity) will sound _______________________ compared to a speaker with a lower rating. In other words, what qualitative information does this value provide about a given speaker?

What Zilch said, plus not all speakers are the same. My Aps (see avatar) are rated at 86 db at 3 meters, not 1.
One other thing, don't assume that a higher db rating infers quality, it does not.

 

[lab]

If your Apogees are 86 dB at 3 meters, wouldn't that make them somewhere around 94 dB at 1 meter? I thought Duetta's are in the low 80's efficiency wise. Or am I getting senile again? (I'm assuming you're talking at 2.83 volts)

How is the bass on them, by the way? I've ony heard Maggies and Acoustats.

 

[wineslob]

If your Apogees are 86 dB at 3 meters, wouldn't that make them somewhere around 94 dB at 1 meter? I thought Duetta's are in the low 80's efficiency wise. Or am I getting senile again? (I'm assuming you're talking at 2.83 volts)

How is the bass on them, by the way? I've ony heard Maggies and Acoustats.

I pulled the specs from the Ap owners site. In reality I think they measured 82 db, quite low (@ 1 meter). What's "odd" is how the speakers seem louder at 12-14 feet or so (listening position). At that distance the imaging is errie, sounds seem to come from beyond walls, and I hear things that you don't hear at closer sitting positions. The first time I found the "sweet spot" I kept hearing "noises" from my garage (it's on the other side of the right wall in the room) and I actually got up to check the garage to see what was messing around in there! I repeated the tracks again and the same noises showed up, mystery solved. The noises, I think, were people moving around the recording studio.
The bass is some of the best I've heard. Extension is about 27 hz in my room with no bloom or boom. It's detailed and very fast. When I first aquired them and set them up, I had to get "used" to the bass, because of how free from coloration it is.

 

[Odd I/O]

Most often, sensitivity is rated via SPL at one meter. Since the SPL scale multiplies exponentially, a speaker rated at 91 db sensitivity will be much louder than one rated at 89. The small difference in numbers often misleads people into thinking that there is not a difference between, for example, 89 and 91. There is, in fact, a substantial difference.

 

[SpruceMoose]

a difference of 2 db is not much. 1 db is barely noticeable, 3 db is quite obvious (and requires a doubling of power to achieve). 10 db is perceived as twice as loud, and takes 10 times the power.

 

[RayW]

I pulled the specs from the Ap owners site. In reality I think they measured 82 db, quite low (@ 1 meter). What's "odd" is how the speakers seem louder at 12-14 feet or so (listening position).

Those big critters behave differently than cone-n-domes. Because you effectively have a big panel it's throwing a plane wave instead of a spherical wave like a cone/dome. IOW, it's not approximating a point source like most cone/dome speakers until you get something like 40 or 50' away. It will decay much more slowly with distance than a spherical wave (the typical 6dB/doubling of distance). I think maybe they seem louder because you expect them to drop off with distance but they don't. Then again, 1m may still be in the very near field for a driver that size so there's all kinds of nonlinearities going on to mess with an effective measurement.

Ray

 

[wineslob]

Those big critters behave differently than cone-n-domes. Because you effectively have a big panel it's throwing a plane wave instead of a spherical wave like a cone/dome. IOW, it's not approximating a point source like most cone/dome speakers until you get something like 40 or 50' away. It will decay much more slowly with distance than a spherical wave (the typical 6dB/doubling of distance). I think maybe they seem louder because you expect them to drop off with distance but they don't. Then again, 1m may still be in the very near field for a driver that size so there's all kinds of nonlinearities going on to mess with an effective measurement.

Ray

I don't know if it's an expectation or not. Could be.
I believe you are correct about the size of the panel effecting the dispersion pattern and making the speaker sound louder.
It is odd when you get the positioning right on these things, and they project an image like mad. Quite often singers will seem to be standing at a mid-way point between me and the speakers. I feel like I have to look up slightly because they are standing right in front of me at full height.