Here's more:
Quote: One acoustic watt is equivalent to 107.5 dBSPL at around a meter from an omnidirectional source.
Taken from here:
http://www.kemt.fei.tuke.sk/Predmety/KEMT320_EA/_web/Online_Course_on_Acoustics/hearing.html
Quote: One acoustic watt is equivalent to 107.5 dBSPL at around a meter from an omnidirectional source.
Taken from here:
http://www.kemt.fei.tuke.sk/Predmety/KEMT320_EA/_web/Online_Course_on_Acoustics/hearing.html
sreten said:Hi,
Well a genuine* 92dB/W/1m is very good for a hi-fi speaker, = 1%.
/sreten.
(*Many speakers with this sort of sensitivity are 4 ohm)
If by this you are implying that their ratings are higher because the lower impedance alows more current input, then you are missing a key concept. Efficiency is defined as (power out) / (power in). Many manufacturers post 2.83V sensitivity for 4 ohm units and that is not 1w sensitivity! You cannot use that number for efficiency because the nominal power in is 2w. If your 4 ohm nomimal speaker has a 92 dB 2.83V 1m sensitivity, then your nominal 1w 1m sensitivity is 89 dB.
If I've misunderstood you and you didn't mean this I'm sorry.
sreten said:Hmmm........
Wouldn't a theoretically perfect massless diaphragm constant charge (how does that work with a massless
diaphragm) push-pull electrostatic with super conductive transformers with super magnetic cores hit 100% ?
That is act as a perfect capacitor except for the losses, which are all acoustic ?
Actually it does not need to be massless. The mass will only consume reactive power, which is typically not considered when it comes to calculating effeciency. If mass was considered, there would be a "problem", since the air also has a mass.
Actually, I think an ordinary driver with a superconductive voice coil and lossless suspension would yield 100% efficiency too. The load becomes almost purely reactive though, which means that a very small portion of the total power is active.
Like this:
An externally hosted image should be here but it was not working when we last tested it.
109dB is what I always heard for 1 acoustic watt into 4pi space. Seems to be what is stated here.
The most efficient speaker I ever heard was said to be almost 50% efficient and had an SPL of 115dB/W into its angle of coverage. That was the Western Electric 15A horn driven by a Westrex driver. Quite amazing. For the most part you would want to attenutate the output voltage of a CD player for a horn like that.
Cal should be getting up there in the high % with those new 1803 and 288s, eh Cal?
The most efficient speaker I ever heard was said to be almost 50% efficient and had an SPL of 115dB/W into its angle of coverage. That was the Western Electric 15A horn driven by a Westrex driver. Quite amazing. For the most part you would want to attenutate the output voltage of a CD player for a horn like that.
Cal should be getting up there in the high % with those new 1803 and 288s, eh Cal?
would that be the cinema speaker located behind the screen?panomaniac said:109dB is what I always heard for 1 acoustic watt into 4pi space. Seems to be what is stated here.
The most efficient speaker I ever heard was said to be almost 50% efficient and had an SPL of 115dB/W into its angle of coverage. That was the Western Electric 15A horn driven by a Westrex driver. Quite amazing. For the most part you would want to attenutate the output voltage of a CD player for a horn like that.
Cal should be getting up there in the high % with those new 1803 and 288s, eh Cal?
Do they still do that in cinemas? or have they gone to ported for the bass to save some (a lot of) space?
AndrewT said:
The WE 15A horn was from the early days of sound, circa early 30s. Could light up a whole movie palace with a few watts, "full range." I also got to play with a pair of Vitaphone 11 foot horns, the little brothers of the 15A.
The Westrex driver was a 50s vintage. The U.K. version of the Altec 288 driver, like the ones Cal has.
There are not many horn loaded bass bins going into cinmas these days, more likely coming out.
The tops are all horns, though. Cinema sound ain't what it used to be.
poptart said:
Yes, isn't that a stimulating thought?
I mean as an ultimate idealised model, in the dull real life it is obviously not possible.
PS Actually, I think also that speaker would stop, ultimately. The oscillation would generate a voltage across the speaker terminals. This voltage, in turn, would generate a weak electromagnetic wave that would transport energy away from the system...
Rybaudio said:
Hi,
My point here is that its not easy to state the efficiency of a loudspeaker
but it is easy to state the sensitivity. Sensitivity is measured / illustrated.
For example what is the efficiency of a typical 2-way speaker at
the top of the mid-band impedance peak ? Any use to you ?
/sreten.
Svante said:
Well...
That is true if and only if "around a meter" equals 1.19 meters.
I'll bet I know what that is about.
In the early days of audio, some people measured SPL using feet instead of meters.
1.22 meters equals four feet. Rounding off the decimal of the SPL accounts for the difference from 1.19 meters.
Whoever made the Java applet got the formulas from an old book which used feet instead of meters, hence "around a meter".
kelticwizard said:
I'll bet I know what that is about.
In the early days of audio, some people measured SPL using feet instead of meters.
1.22 meters equals four feet. Rounding off the decimal of the SPL accounts for the difference from 1.19 meters.
Whoever made the Java applet got the formulas from an old book which used feet instead of meters, hence "around a meter".
Ah, clever! Didn't see that.
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