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Listening
While the woofer was being exercised, a quick perusal of the EFX C124D鈥檚 owner鈥檚 manual indicated that the woofer is intended for either sealed or vented applications, but after checking over the published Thiele-Small parameters, it was quite evident the sealed system would be a much better choice. (A combination of low Fs and high Qes always indicates a preference for a sealed box) The EFX C124D has a recommended sealed enclosure volume of 1 cubic foot, (resulting in Qtc of about 1.4) but some quick math told me that 1.25 cubic feet would be better for critical listening.
So, I grabbed my trusty Makita and installed the woofer in a 1.25 cu.ft. sealed enclosure, with the 4 ohm coils wired in parallel for a 2 ohm load. I selected a second order crossover, with a low pass frequency of 100Hz.
My listening began with some basic performance tracks I always use just to see what鈥檚 what. Immediately, I noticed the exceptional output from the C124D. Even at low input power, the woofer sounded strong, and as I increased the juice, it just got progressively louder without complaint. The bass was very good sounding, with reasonably good articulation and without excessive boominess or ringing. In my enclosure, the bass was deep and sounded strong, maybe not quite as 鈥渢ight鈥� as some other woofers I have tested, but the output level was probably 3dB higher or more, so for the vast majority of folks the tradeoff is a no-brainer.
I played a widely varied mix of music, and from rap to rock or country to classical the C124D handled them all in stride, even when I occasionally pushed the 300 watt limit.
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Measured Performance
After my listening had been completed, I allowed the woofer to cool and normalize overnight, and then I measured it鈥檚 parameters. I鈥檓 happy to report the published specs are quite accurate, and well within the normal tolerances found in a subwoofer. Also, my measurements tracked almost perfectly with my previous math calculations, so building custom enclosures for this woofer should result in very predictable results, which is not always the case.
Conclusion
If you are looking for a moderately priced 12-inch subwoofer that has gobs of output, decent power handling, and you are a bit short on enclosure space, the EFX C124D may be just what you need. Plus you will not need a huge (read expensive) amplifier to drive them. A modest 500 watt amp on a pair of these babies in a two and a half cubic foot sealed box will rock anyone鈥檚 world!
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