Post by Ex_Vintage on Apr 14, 2021 13:26:47 GMT -5
An anechoic chamber is by definition "standardized" (since it is, by definition, "a room with absolutely no acoustic reflections").
The problem is that this is like saying "pure water"...
We have a few really expensive rooms that come really really close...
And a lot that don't come quite so close...
HOWEVER, you can in fact come pretty close without too much work.
Dig a big hole in your back yard...
Mount your speaker in a big plate, making sure the front of the speaker is dead flush with the plate, and the plate is dead solid...
Now sit the plate in the hole, flush with the ground, with the speaker facing up...
Now, if you hang the microphone above the speaker, from a really narrow beam, you have no reflections in front of the speaker...
(You get bass reinforcement at low frequencies because the speaker is "radiating into a half space"... but that can be calculated.)You can also just sit the speaker, facing sideways, in a big flat empty field, and have a relatively predictable "quarter space".
(Actually at very low frequencies, it's also a half space... but the math can be worked out.)
(This works pretty well for measuring subwoofers... as long as you take the geometry into consideration.)
However, since none of these in any way approximates a real room, the measurements you get are of limited value anyway.
Remember that different speakers that measure identically in an anechoic chamber will sound VERY different in an actual room.
The anechoic chamber eliminates both room acoustics and directional acoustics.
(But, because of that, the response will be very different than it will be in any real room... because NOBODY builds an anechoic home theater.)
You can take accurate measurements at multiple angles... which will give you the speaker's directional characteristics.
But that won't tell you what it will all sound like when they all add together in a real room.
(So, while these measurements are all very useful to a speaker designer, they don't really help a consumer know what a speaker will sound like.)
HOWEVER, the bottom line here is that a 3 dB difference between efficiencies due to different measurement techniques is pretty much meaningless.
You're going to see much greater variations due to things like room acoustics and the directionality of the speakers anyway.
And you're going to have to use the trim adjustments to eliminate those other variations anyway.
Apr 13, 2021 16:15:03 GMT -5 @deleted said:
Well, you could always buy only 8 ohm speakers with ratings at 2.83 volts. There should be no variation then at 1 watt. Problem solved. That is, unless the room they are tested in varies. Is there a standardized type of anechoic chamber across the industry? And exactly as you stated, what if a manufacturer rates their speakers in actual room and not an anechoic chamber?
In all seriousness, there is no standardized sensitivity rating. Either verify the process used by the company in their manufacturer's rating [call them and find out how they came to that spec] or deviate from it.
Other than that one could appeal to some government office to involve themselves in governing the audio industry. That's worked out well in every case!
