msmith Posted April 21, 2005 Share Posted April 21, 2005 Hi, guys... I promised you some measurements of the OEM head unit's frequency response before and after CleanSweep, so I took some measurements in my LGT wagon... http://img250.echo.cx/img250/5995/volcomparedefeated8et.th.gif The first graph shows the front-channel factory frequency response of the Subaru head unit with its tone controls set flat, and at 3 different volume settings. The Blue curve is the frequency response at volume 10, the Red curve is the frequency response at Volume 25, the green curve is the frequency response at Volume 35. Needless to say, the behavior is non-linear... Subaru employs a typical loudness compensation curve at low volume (not necessarily a terrible thing) and agressive high-pass filtering at high volumes to protect the factory speakers from failure. The Volume 25 curve shows the correction applied by the Subaru engineer's to compensate for their speakers. Upper bass boost, lower bass rolloff and some mild manipulation of the midrange and upper treble. This is actually pretty tame compared to many of the OEM head units I've tested. http://img250.echo.cx/img250/3127/vol25csactivevsdefeated0cb.th.gif The second graph compares the factory frequency response at Volume 25 (Red) to the frequency response after CleanSweep correction (Blue). As you can see, the CleanSweep effectively corrects the response to within plus or minus 1 dB, which is quite comparable to a good quality aftermarket head unit's frequency response. I picked Volume 25 as the calibration point for my CleanSweep. http://img250.echo.cx/img250/448/volcompareactive4rh.th.gif The third graph shows what results if you apply a CleanSweep (calibrated at Vol 25) but decide to use the factory volume control instead of the totally linear CleanSweep volume knob. EDIT: the curves are mislabeled on the first and last graph: Red is actually volume 25, Blue is Vol. 10, Green is volume 35. These should hopefully answer some of the questions about the need for response correction, volume control linearity, etc. Or it might actually prompt new questions... Best regards, Manville Smith JL Audio, Inc. Link to comment Share on other sites More sharing options...
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