Will someone please explain "phase angle"?
How to read speaker sensitivity rating?
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When reading the sensitivity rating on speaker specs, does a lower number mean the speaker is easier to drive than a speaker with a higher number? Such as a speaker rated 78 db would be easier to drive than a speaker rated 102 db?
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When reading the sensitivity rating on speaker specs, does a lower number mean the speaker is easier to drive than a speaker with a higher number? Such as a speaker rated 78 db would be easier to drive than a speaker rated 102 db?
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- 26 posts total
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FWIW, when a speaker's specs include both its sensitivity and its power handling capability, it allows the user with a similarly capable amp to estimate how loud the speaker will play safely and continuously. For example, ratings of 87dB and 150 Watts translate to a maximum volume of just over 108 dB, earth shaking but not shattering. |
Will someone please explain "phase angle"?It refers to the phase relation between voltage and current, at a given frequency. Speaker impedance, or any impedance, will be some combination of resistance, inductance, and capacitance. For a pure resistance, voltage and current are in phase with each other at all frequencies. In the case of a pure inductance, voltage leads current by 90 degrees (1/4 cycle of the signal frequency, denoted as +90 degrees). In the case of a pure capacitance, voltage lags current by 90 degrees (denoted as -90 degrees). Pure resistances, pure inductances, and pure capacitances only exist in theory, although depending on the device, the application, and the frequency it is often reasonable to neglect two of the three terms as insignificant. That is not generally true for speakers, though. Derivation of the net phase angle corresponding to a given combination of resistance, inductance, and capacitance, at a given frequency, involves some mathematical complexity, and is described in my post here in a thread on the difference between resistance and impedance. Phase angles that are significantly capacitive, say -40 degrees, more or less depending on impedance magnitude, make life more difficult for the amplifier because they increase current draw. If significantly capacitive phase angles coincide with frequencies at which impedance magnitude is low, current requirements are increased further. The speaker reviews in Stereophile generally include a plot and a discussion of impedance magnitude and phase angle, in John Atkinson's measurements which usually appear at the end of the review. Regards, -- Al |
- 26 posts total