I destroyed my KEF LS50s - how??

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Vladimir

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Dec 26, 2013
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andyjm said:
hg said:
If you put too much power into a driver it tends to melt the voice coil and slam the cone against the stops. Depending on the details of the driver construction the voice coil might pop out of the gap. Depending on the details of the driver the metal cone might get hot during sustained high power use. Wrinkled and split cones are not beyond the realms of possibility but are not what would normally be expected from too much power.

Speakers don't have 'stops'

Overdriving leads to blown or distorted voicecoils. Beer leads to ripped cones.

'Stops' as in the cone/voice coil bobbin hitting the magnet/basket assembly.
 

andyjm

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Vladimir said:
andyjm said:
hg said:
If you put too much power into a driver it tends to melt the voice coil and slam the cone against the stops. Depending on the details of the driver construction the voice coil might pop out of the gap. Depending on the details of the driver the metal cone might get hot during sustained high power use. Wrinkled and split cones are not beyond the realms of possibility but are not what would normally be expected from too much power.

Speakers don't have 'stops'

Overdriving leads to blown or distorted voicecoils. Beer leads to ripped cones.

'Stops' as in the cone/voice coil bobbin hitting the magnet/basket assembly.

Great picture.

Clearly shows the airgap between the magnet's poles and the relative size of the voicecoil. As the voicecoil leaves the high-flux airgap its ability to apply any force to the speaker diminishes rapidly. When none of the coil is left in the gap, it can't apply force. Makes the speaker self limiting in terms of cone excursion. No way the voicecoil in the picture could drive the cone so far back as to hit anything.

There is however an outside chance that if the speaker was in a highly resonant cabinet, and excited at the correct resonant frequency, the air pressure in the cabinet could force the cone backward to impact the back of the magnet - though it seems unlikely to me.

My money still is on beer causing the problem.
 

Vladimir

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I've had multiple speakers hitting the basket/magnet assembly, especially with underpowered amps. I've seen bobbins really smashed on the back side and several rolls of coil coming off due to the disformation.

Not all drivers are made as the one on the photo I guess. The KEF LS50 seems well made for this types of scenarios. The typical 300g ceramic magnet and stamped metal basket woofer, not so much.

IMG_8505.jpg
 

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