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I am updating the look (new socks/stained rails)and crossovers of my SMBb's. Does anyone know the crossover frequency? Mine have a 27ufd. series tweeter cap and a combo 25ufd. cap parallel acorss the woofer with a series, rather physically large, inductor (unknown value). Also, my SMGb's are bent slightly in an arc. Can these be straghtened or should I leave them alone? Magnepan says they bent do to the tensioning durng manufacturing. Attaching taller aftermarket frames would be a challenge. Phil
Follow Ups:
Sorry, I got the capacitors reversed. The 25ufd. is in series with the tweeter and the combo 27ufd.(10+17) is in parallel with the woofer. Phil
Using the same analysis, the inductor calculates to 1.73 mH with a resulting -6db point at 735 Hz for the low pass and a -3db at 1590 for the hi-pass. The resulting xo point is 810 Hz down about 7db. The curve is not quite as flat, but not bad.Personally I would try using a 1.6 mH coil with a 25 mfd cap for the low pass and a 27 mfd cap for the high pass as the curve is almost flat and has a xo at 810 - almost identical to the SMGa which Peter Gunn has singlehandedly rescued from oblivion.
I may be an egoist but at least I don't talk about other people.
If you set the Q of the 2nd order low pass filter to 0.5 (L-R configuration) then the inductor value calculates to 1.56 mH with a -6db corner of about 530. The 1st order hi-pass has a -3db corner of 1475 Hz. The crossover point then works out to 830 Hz (down 6db) with a fairly flat output curve(assuming the drivers are "phased-aligned"). The SMGa crosses at ~800 Hz so I think the 830 estimate is probably correct. The only way to know for sure is to measure the inductance of the coil.
I may be an egoist but at least I don't talk about other people.
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