Can someone please help me understand Sensitivity - AVS Forum
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post #1 of 4 Old 08-27-2012, 01:57 PM - Thread Starter
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My naïve understanding of sensitivity was that it's a measure of how much sound a speaker can output per unit volume of electrical input (a crude measure of efficiency and loudness?). Clearly I must be wrong because my outgoing Polk R150 has a sensitivity of 89 dB while the new B&W CM5 has a sensitivity of 88 dB. At the same volume level on my receiver, the CM5 produces way more sound.

Thanks in advance.
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post #2 of 4 Old 08-27-2012, 03:08 PM
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Unless accompanied by a measured SPL chart sensitivity claims should be taken with a truckload of salt.

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post #3 of 4 Old 08-27-2012, 03:12 PM
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Quote:
Originally Posted by index2020X View Post

Clearly I must be wrong because my outgoing Polk R150 has a sensitivity of 89 dB while the new B&W CM5 has a sensitivity of 88 dB. At the same volume level on my receiver, the CM5 produces way more sound.

After you've swallowed your truckload of salt, consider that the actual difference between 88dB and 89dB is quite small.
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post #4 of 4 Old 08-27-2012, 03:23 PM
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You understand it right. What you discovered is that manufacturers don't always report sensitivity accurately, or they use different methodologies.

The ohm rating of a speaker is listed as a single number, but in reality sometimes fluctuates dramatically in actual usage. A 8 ohm speaker can dip below 4 ohms at certain frequencies. Every speaker varies differently and the actual ohm of the speaker can significantly impact the sensitivity measurement.

For example, the standard methodology to measure sensitivity is a 1watt(or 2.83v) signal measured at 1 meter. Using this method, a speaker that dips to 4 ohms at the frequencies measured would have a 3 dB higher sensitivity than a speaker that was 8 ohms at that frequency.

Also, sensitivities are reported by some manufacturers as in-room and others anechoic. The in-room sensitivity will be higher due to room gain, and that could be 3+ dB. Many don't tell you which method they use.

So using the industry "standard" to measure sensitivity can lead to very different results.






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