dank
Seasoned Member
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pair of dual 18 Imperials
Posts: 421
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power = voltage squared divided by impedance. So if the speakers are 8 ohms, 2.83v is 1w. If the speakers are 4 ohms, 2.83v is 2w. Obviously a 91db 4 ohm speaker driven by 2w should be louder than a 91 db 8 ohm speaker driven by 1w.
I really have no idea how the speaker sensitivity number is derived. But I would hope that a number of different frequencies are measured and some sort of average is taken. If I had to guess, being the pessimistic person that I am, I would imagine that the speaker manufacture comes up with a way to measure his speaker that makes it look the best. A few years back a "new" series of raw drivers from Madisound appeared in the marketplace that had sensitivity numbers about 6 db higher than anything else comparable. The one that sticks in my mind was a 15" woofer / subwoofer, 8 ohms, rated at 103 db 1w/1m. Once purchased and installed the they sounded good, but the actual sensitivity was closer to 96. A few years later these drivers from Madisound disappeared from the marketplace. You can find them every once in a blue moon on Ebay.
Dan
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