Originally Posted by jlpowell84
2. Anyone can chime in hear and please do so. Have you noticed over time the BMS4593 compression driver becoming better/sweeter/more refined over time and break in?
Your set of 215RT's already had at least 30 hrs on them prior to shipping since they were played at AXPONA. Any break-in is typically for the woofers which will change as the spider is softened. Dan Wiggins (founder of Adire Audio and inventor of XBL2 motor) said this about their woofers:
The biggest reason there is a break-in period for drivers is the spider. The spider - for those who don't know - is a piece of cloth, permanent pressed, and dipped in epoxy. When you break in a driver, you introduce micro-cracks throughout the epoxy, which will make the spider softer.
ALL mechanical systems will wear and all mechanical springs will get softer; in this case, it's by design. You break/crack a lot of the epoxy bonds (phenolics are used as well) that permeate the spider, and thus it becomes softer.
We often see a 20% drop in Fs over a lengthy break-in, and we quote numbers for drivers broken in. Out of the box all our drivers measure high; beat on them for 40-50 hours, though, and they will be permanently lowered (Fs, that is).
One thing to note is that it would be expected Fs would drop, Qes and Qts would drop, and Vas would increase; all these are exactly what happens when you raise Cms, which is the same thing as making the spider softer.
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