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Ricci

Sundown Zv4 18d2 Sealed Tests discussion

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Discussions of or questions about the Sundown Zv4 and its measurements should go here.

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that's the beefiest 8" driver I've ever seen!  :)

 

Capture_zpsa6dc20fa.jpg

 

On a serious note, this performs almost identically to the HST-18.  

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Just wondering, what is causing a 7dB drop in output between 25Hz to 20Hz, and another 7dB drop between 20Hz to 16Hz? Most drivers only drop 3-4dB, and that's probably because of excursion limitations. Looking at maximum SPL with no THD limits, it doesn't suggest that the Zv4 is having output drops because of distortion limitations.

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It is because of inductance effects and distortion. This is fairly common behavior with a lot of heavy subwoofers. The response shape becomes humped in the middle and the driver has its best performance near the system resonance. Away from there the distortion rises and sensitivity falls off. Around the impedance maximum the driver receives minimal power and remains the most linear. The absolute maximum output recorded with no THD is stopped when the driver makes obvious signs of being "close". In the case of this driver despite the distortion being relatively low 25-40Hz the testing had to be stopped at those points because the driver made some very unpleasant noises which indicated damage may be a possibility if it was pushed further. This doesn't always coincide with excursion maximums either which would be roughly 4dB increase per 1/3rd octave up in frequency for a sealed system.

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