Apple iBall
Steve Sedmak's experience with the iBall I spent some time playing with the iMac speakers (Harmon Odyssey 1" drivers) and measured them with CLIO. Free Air resonance of ~300Hz. They are not at all suitable as full-range speakers. Initial listening experiments showed that they could not image at all when used as full ranges, and they just plain sounded wierd. Measurements with CLIO showed that their THD was wholly unacceptable under 1KHz, which explains the full-range imaging problems.
Fig 1: FR in stock enclosure <clik image for larger picture>	Their stock response was a ragged +-5dB from 1.5KHz to ~18KHz and a fairly smooth (though highly distorted) response from 300Hz-1KHz. Being an inverted 1" metal dome, it had a large, sharp peak at 20KHz. I tried plugging the vent and that didn't do much to the response in practical terms.
Fig 2: FR in free air <clik image for larger picture>	I removed the driver from its housing and measured the raw driver in free space. Much better. The response was very smooth from 4KHz to 18KHz, but quite ragged outside those extremes.
Fig 3: FR in modified enclosure <clik image for larger picture>	I hack-sawed off the non-flat front of the enclosure so that so that the enclosure more closely approximated a sphere. Then I lined the interior of the enclosure with modeling clay and stuffed it with wool. I reinserted the driver and measured again. Presto! The response is now about +-1.5dB from 2KHz to 18KHz UNSMOOTHED and it has a relatively clean waterfall plot to boot, though there seems to be some sort of resonance around 2KHz that appears in all the frequency and impedence response measurements I did, as well as the waterfall. There's a 7dB notch around 1.5KHz and it rolls off below 1KHz. Based on the THD I wouldn't use it below 2KHz anyway. The pesky peak at 20KHz seems an inherent part of this little driver.
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