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Well I picked up a Markaudio Alpair 6P Gen 2 (6.2 or whatever :D) for testing, thinking I'll use that in a 3-way with shallow slope crossovers. Right now I'm envisioning an OX20 for the top end, and then some nice pair of 8" or a 10" for the bottom. Here is the first measurement. I did no break in, besides listen to some music. Its on a test baffle (flush and rears routed out for breathing room) 12" wide and 4.25" from the top, like so:
What you can't see behind that is a poorly (but effectively) mated .25 cubic foot PE box providing what could pass as a rear enclosure. I took these measurements with my ECM8000 at 6.5" from the cone (somewhat nearfield) on 0, 30, and 60 degrees. The voltage was calibrated by meter to 2.8V. The off-axis plots are scaled at -5 and -10 db for visibility.
Well alright, so there is an impressive dip from 1000 to 2000 hz with a deep base, -5 db at its worst. Also, some kind of 1200hz 2 order harmonic distortion hiccup. Both of these issues begin to fade when you move off-axis however. So I wonder what the cause is, perhaps cone geometry?
Its interesting that I could not detect the dip or 2nd order peak in my listening, but I didn't do anything extended. I just crossed it over at 150 hz to my subwoofer and gave it a quick listen on acoustic stuff I know well. It sounded nice and balanced, with too much top end sizzle (I could hear the peak above 10k).
More tests to come.
What you can't see behind that is a poorly (but effectively) mated .25 cubic foot PE box providing what could pass as a rear enclosure. I took these measurements with my ECM8000 at 6.5" from the cone (somewhat nearfield) on 0, 30, and 60 degrees. The voltage was calibrated by meter to 2.8V. The off-axis plots are scaled at -5 and -10 db for visibility.
Well alright, so there is an impressive dip from 1000 to 2000 hz with a deep base, -5 db at its worst. Also, some kind of 1200hz 2 order harmonic distortion hiccup. Both of these issues begin to fade when you move off-axis however. So I wonder what the cause is, perhaps cone geometry?
Its interesting that I could not detect the dip or 2nd order peak in my listening, but I didn't do anything extended. I just crossed it over at 150 hz to my subwoofer and gave it a quick listen on acoustic stuff I know well. It sounded nice and balanced, with too much top end sizzle (I could hear the peak above 10k).
More tests to come.
I just figured I'd try the smaller, most cost-effective model.
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