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<blockquote data-quote="bigbassman" data-source="post: 101834" data-attributes="member: 542419">back emf does a good bit to sealed box woofers.. but nothing to damage an amp.. lets jump into it a lil //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gifwell as you know, sealed woofer systems have a huge impedence peak at resonance..&nbsp; yet their actual response maintains a rather flat signature..&nbsp; here&#039;s why...Now you understand that a subwoofer motor is a generator, meaning it has a conducting voice coil moving in magnetic field which generates voltage. This voltage is in series with amplifier voltage but the polarity does not have to be the same. In fact whenever the speaker cone is moving in the same direction in which the amp is forcing it to move the voltages are of opposite polarities and try to cancel out each other. This is the case at resonance.&nbsp; but at resonance the amount of cone motion is also very high, this means that voltage produced by amp and that produced by speaker motor (generator) almost totally cancel each other out. The result of diminished voltage is a small current...Since impedance is just voltage divided by current, you have a large voltage divided by small current = very high impedance as &quot;seen&quot; by the amp. This impedance peak in a sealed system would exactly counteract the efficiency peak produced by resonance.So back EMF is a major player in a sealed box.. but it&#039;s not abusive to the amplifier...&nbsp; Most amplifiers with a decent damping factor are perfectly adept at controling whatever the sub sends back to it..&nbsp; &nbsp;&nbsp; Well.. except for vacuum tube amps.. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gifnow Im gonna go relax my fingers.. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gifLoyd L.</blockquote>

[QUOTE="bigbassman, post: 101834, member: 542419"] back emf does a good bit to sealed box woofers.. but nothing to damage an amp.. lets jump into it a lil [IMG]//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif[/IMG] well as you know, sealed woofer systems have a huge impedence peak at resonance.. yet their actual response maintains a rather flat signature.. here's why... Now you understand that a subwoofer motor is a generator, meaning it has a conducting voice coil moving in magnetic field which generates voltage. This voltage is in series with amplifier voltage but the [B]polarity[/B] does not have to be the same. In fact whenever the speaker cone is moving in the same direction in which the amp is forcing it to move the voltages are of opposite polarities and try to cancel out each other. This is the case at resonance. but at resonance the amount of cone motion is also very high, this means that voltage produced by amp and that produced by speaker motor (generator) almost totally cancel each other out. The result of diminished voltage is a small current... Since impedance is just voltage divided by current, you have a large voltage divided by small current = very high impedance as "seen" by the amp. This impedance peak in a sealed system would exactly counteract the efficiency peak produced by resonance. So back EMF is a major player in a sealed box.. but it's not abusive to the amplifier... Most amplifiers with a decent damping factor are perfectly adept at controling whatever the sub sends back to it.. Well.. except for vacuum tube amps.. [IMG]//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif[/IMG] now Im gonna go relax my fingers.. [IMG]//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif[/IMG] Loyd L. [/QUOTE]

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