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Impedance Measurement / Computer Problem

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  • jmb
    Re: Impedance Measurement / Computer Problem

    Here are the LIMP files, as promised. Any suggestions would be welcomed. I have been doing measurements for a long time and this is the first time I have run into this...of course, it is not a computer that I used in the past but it seems like since LIMP does fine, so should Soundeasy, if it is a hardware issue. So this leads me to believe it is some sort of software conflict but I don't know where to look.

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  • jmb
    started a topic Impedance Measurement / Computer Problem

    Impedance Measurement / Computer Problem

    I have posted this at DIYaudio and at the Soundeasy Board also but there seem to be several sharp minds here that I don't see there so I apologize to those who see both posts.
    I have two set ups with which I measure loudspeakers with computer and software, one at home and one at my office. Both have dedicated Windows XP SP3 computers that run SoundEasy v19 without a problem. I have the ARTA software on both, as well. Both use the same jig. I have 3 different amplifiers. Same soundcard on each (Creative XFi Xtreme Gamer).

    The problem is in testing a resistor (metal film - 20 ohm) I am getting a strange high pass effect on the office computer. This shows in doing a frequency response on the calibration setting, as well. Neither shows on the home computer. I switched out the jigs and amps and it is clearly an effect of the office computer. It does not show up when running LIMP in Pink Noise or using a Sine Wave Test. So it is isolated to the SE program only on my office computer.

    My office has fluorescent lighting so I tested that computer at home (incandescent) and the problem followed the computer. I only switched out the computer and explored distances from the monitor thinking that perhaps this impacted things but it had no impact.
    I switched out the leads, as well. At home, no problems regardless of which leads were used; in the office, all produced similar issues with a high pass function.

    The settings are the same for SE on both computers. When I ran a direct loop from the output to the input using RMAA, it does not show up so the soundcard appears to be doing just fine. The only thing that I can think of from a hardware perspective is perhaps the output caps on the soundcard are having problems under load, but this is unlikely given the expected results obtained with Sine and Pink Noise tests.

    I unloaded the virus program and still no change.

    The computer is already streamlined with recommendations made by George Soong.

    I would welcome any guidance for further investigation. I uploaded the Soundeasy Screenshots. Will do the LIMP shots in another entry.

    Thnx, Jay

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