Super Xmax Technology A speaker designer must optimize all parameters in balance with the woofers. One of most important factor is the linear excursion, or the Xmax parameter. This is commonly expressed in millimeters (mm) of excursion, representing a driver‘s allowable piston travel distance to the cone before it gets into non-linear operation. This figure also directly reflects the maximum undistorted SPL output to a woofer.
Many woofers are described as “long-throw” without specifying Xmax to the audiophile. It can only reflect one fact, this being that the cone has a longer travel range with a better suspension system and may sometime incorporate with higher handling power capacity. This does not mean that this driver has maintained low distortion during large cone movements. While dynamic current forces the cone piston to exceed its linear range into non-linearity the SPL output can no longer respond in proportion, resulting in severe, unbearable audio distortion.
Although every manufacturer wishes to make woofers with high output, low distortion characteristics; it is rather difficult to further increase the gain of the Xmax through conventional designing. There is not only the cost concern for using larger magnets but one must also consider the many trade-offs affecting other parameters of performance at the same time. The alternative is to employ more woofers in parallel to get higher SPL output just like many floor-standing systems do today. Yet, unless the speaker enclosure is enormously large, this solution will sacrifice the deep low-end bass for a higher F3.
M&D®‘s patented SX technology has wisely reversed the traditional relationship of the (shorter) magnetic field vs. (longer) voice-coil. With the most powerful NdFeB magnets, it is able to create an enormously long and even magnetic field over the relatively shorter voice-coil, incorporating a long-throw suspension system, resulting in a very high Xmax that guarantees an undistorted operation to the cone piston under much higher SPL output. 
The only trade-off to SX solution is the high cost on magnetic system, but the rewards are worthwhile:
♥ Compared with similar sized drivers, the SX unit is capable of reproducing deeper, undistorted bass with a much higher SPL and dynamic output.
♥ Under the same SPL requirement, a much smaller enclosure of the SX driver is applicable. For example,at half the cone size, it requires 4 times Xmax, but needs only 1/16 the enclosure volume.
For a conventional woofer to be good quality, it have an Xmax normally within ± 3.0 to 4.5mm for a 5” or 6.5“driver. We can rarely find an 8” or 10“ driver that has an Xmax exceeding ±7.0mm, except for a few expensive drivers specially designed for sub-woofer applications. Modern digitized recording requires an additional 10 to 20dB in music dynamics. This forces the bass driver to exceed its excursion limit more often.
Under sealed enclosure application, a good conventional 5” woofer with ±4.5mm (0.35”) linear excursion is able to reproduce a sound pressure to 99.5dB at 50Hz in theory; but observing our 5” SX driver with a ±10mm (0.8”) Xmax, the undistorted SPL output can reach to 106.5dB under the same circumstances. This is an output of 5 times (7.0dB) more acoustic power than conventional woofer! The SX driver is indeed, the more superior Hi-Fi element in speaker design today.
Our patented SX series woofer has a typical ±10mm (0.8“) linear excursion for the 5.5” and 6.5‘ drivers, and an amazing ±15mm (1.2”) Xmax for 8“ & 10” drivers, at least doubles the excursion ability over most Hi-Fi drivers on the market!
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