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<blockquote data-quote="Kyle_Keating" data-source="post: 5989887" data-attributes="member: 582385">i would really encourage you to get an imdpeance meaurment of that box, you might not have a 50Hz tune,a couple theories.60Hz is likely the point at which the driver is going to experience the most displacement in that system (slightly above tuning). if the coil leaves the gap in that case, you get a large drop in back EMF and a surge in current, this is equivlent to loading a port (electrically speaking), expect only in this case, there is nothing to load against so the excursion skyrockets due to the current draw and you&#039;ll see cone&#039;s displacement nearly double with just a few addition volts and the distortion will be very large.second theory, 60Hz could produce a flux modulation in the DC magnetic circuit with a high enough voltage across the coil, flux modulation usually is affected by a very acute frequency (60Hz is common), and if that&#039;s the case, you might be modulating the motor with that voltage level such that the electromagnetic field of the coil offsets itself enough to shoot below the gap and bottom out - clank!&nbsp; A simple shorting ring would solve the problem - it boggles my mind why manufactures do not use shorting rings under gaps - they improve sound quality and can even improve SPL - no reason to omit them really, they cost only a few dollars.</blockquote>

[QUOTE="Kyle_Keating, post: 5989887, member: 582385"] i would really encourage you to get an imdpeance meaurment of that box, you might not have a 50Hz tune, a couple theories. 60Hz is likely the point at which the driver is going to experience the most displacement in that system (slightly above tuning). if the coil leaves the gap in that case, you get a large drop in back EMF and a surge in current, this is equivlent to loading a port (electrically speaking), expect only in this case, there is nothing to load against so the excursion skyrockets due to the current draw and you'll see cone's displacement nearly double with just a few addition volts and the distortion will be very large. second theory, 60Hz could produce a flux modulation in the DC magnetic circuit with a high enough voltage across the coil, flux modulation usually is affected by a very acute frequency (60Hz is common), and if that's the case, you might be modulating the motor with that voltage level such that the electromagnetic field of the coil offsets itself enough to shoot below the gap and bottom out - clank! A simple shorting ring would solve the problem - it boggles my mind why manufactures do not use shorting rings under gaps - they improve sound quality and can even improve SPL - no reason to omit them really, they cost only a few dollars. [/QUOTE]

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