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Coil rub cause amp to blow?
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<blockquote data-quote="Doxquzme" data-source="post: 8854892" data-attributes="member: 689267"><p>Usually, it’s not the amp that gets burned; it’s an overdriven, clipping amp that burns the woofer. That said an amp that is being driven to clipping for long periods of time it can be ruined and conversely, the driver too. In my experience I have seen far more woofers or large diaphragm, low freq. drivers ruined than high freq. speakers like tweeters from under-powering. That’s because they have crossovers (usually utilizing 250v caps or better where the subs, not so much). In the case of under-powering, the driver is blown because the amplifier is driven to the point that it can no longer amplify the signal. The amp tries to generate the amplified version of the input waveform, but runs out of "headroom" before the full wave is generated. The result is a square wave. The sinusoidal version of the waveform is only partially generated and the result is a square wave with a "plateau" on the top. The "plateau" is pretty much a DC current at that point. DC in large enough amounts is what burns up speakers. The driver is only driven part of the way in or out, but it is held in a suspended position at the top of the square wave the amp is generating. The result is the speaker is in a near DC state and the constant voltage without any corresponding movement causes the windings of the voice coil to heat up.</p><p></p><p>Eventually the heat is too great for the windings and they burn up. In practice, the motion of the speaker also pulls in cooler air and forces out the heated air around the voice coil. With the speaker mostly in the motionless state, but with voltage being applied there is no cooling from the speaker moving in and out. In the case of too much power, the amplifier is sending more power than the voice coil windings can stand and they burn up, or...</p><p></p><p>In the case of woofers, the voice coil is bottomed-out against the magnet. ( could be the rubbing you're talking about) This causes a distortion in the shape of the voice coil. Once the voice coil is distorted in shape the windings rub against the sides of the gap (more likley the rubbing you're aling about). They either wear though or are so thin that power surge burns them out at the weak point caused by wear.</p><p></p><p>Honestly though, I would suppose that trying to make a blown woofer do its thing could cause overheating issues with the amp. If you have a blown amp, it’s likely the reason that you have a blown driver.</p><p></p><p>**** NOTE, there is no such thing as an “off balance” VC, if it’s rubbing, dinging or clacking, there is something wrong, mechanically.</p><p></p><p><img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite2" alt=";)" title="Wink ;)" loading="lazy" data-shortname=";)" /></p></blockquote><p></p>
[QUOTE="Doxquzme, post: 8854892, member: 689267"] Usually, it’s not the amp that gets burned; it’s an overdriven, clipping amp that burns the woofer. That said an amp that is being driven to clipping for long periods of time it can be ruined and conversely, the driver too. In my experience I have seen far more woofers or large diaphragm, low freq. drivers ruined than high freq. speakers like tweeters from under-powering. That’s because they have crossovers (usually utilizing 250v caps or better where the subs, not so much). In the case of under-powering, the driver is blown because the amplifier is driven to the point that it can no longer amplify the signal. The amp tries to generate the amplified version of the input waveform, but runs out of "headroom" before the full wave is generated. The result is a square wave. The sinusoidal version of the waveform is only partially generated and the result is a square wave with a "plateau" on the top. The "plateau" is pretty much a DC current at that point. DC in large enough amounts is what burns up speakers. The driver is only driven part of the way in or out, but it is held in a suspended position at the top of the square wave the amp is generating. The result is the speaker is in a near DC state and the constant voltage without any corresponding movement causes the windings of the voice coil to heat up. Eventually the heat is too great for the windings and they burn up. In practice, the motion of the speaker also pulls in cooler air and forces out the heated air around the voice coil. With the speaker mostly in the motionless state, but with voltage being applied there is no cooling from the speaker moving in and out. In the case of too much power, the amplifier is sending more power than the voice coil windings can stand and they burn up, or... In the case of woofers, the voice coil is bottomed-out against the magnet. ( could be the rubbing you're talking about) This causes a distortion in the shape of the voice coil. Once the voice coil is distorted in shape the windings rub against the sides of the gap (more likley the rubbing you're aling about). They either wear though or are so thin that power surge burns them out at the weak point caused by wear. Honestly though, I would suppose that trying to make a blown woofer do its thing could cause overheating issues with the amp. If you have a blown amp, it’s likely the reason that you have a blown driver. **** NOTE, there is no such thing as an “off balance” VC, if it’s rubbing, dinging or clacking, there is something wrong, mechanically. ;) [/QUOTE]
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