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Converting measured FRD files with phase into minphase FRDs

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  • Converting measured FRD files with phase into minphase FRDs

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ID:	1406916 I was given FRDs with measured FR/Phase info. I created a crossover sim from the files with great phase tracking. As an experiment I ran the FRDs through the Phase Extractor program to generate minphase FRDs. I notice that the minphase files do not have excellent phase tracking.when substitued into the design file.

    Does it make sense to look at minphase files versus measured phase files? When I substitue the minphase FRDs the phase shift is so much it requires the tweeter to be reversed polarity due to the phase differences. I thought I understood minphase, but clearly I don't understand what is going on here. Is it safe to assume the minphase files are not as "accurate" to use for crossover simulations?

  • #2
    Two ways:
    If YOU measured the FR data (that means neither mic position nor amp voltage were changed between measurement - USUALLY measured on tweeter axis) then you can use it (and its phase data) directly in an XO, but you don't enter any XYZ offsets (0,0,0).
    If you gen "min-phase" files (like, off mfr. charts), then you need to use XYZ offsets to get a valid sim.

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    • #3
      So the graphs attached are measurements without offsets, and minphase conversions with offsets, but phase of summed response is significantly off. I'm trying to figure out if I did something wrong. Sent from my Pixel using Tapatalk

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      • #4
        It's not clear if these are measurements of your system. If they are you can adjust the woofer offset to make it match.

        The woofer offset (delay) would be set using the measured Tweeter plus Woofer FRD file and adjusting until the simulation T+W curve match the measured T+W file. I prefer to adjust both as measured and min ph files with the measured T +W FRD file as T=0 is not constant with single channel measurement systems.
        John H

        Synergy Horn, SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

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        • #5
          I think omnimic would be an exception to measured phase being not needing xyz data as I believe it is kind of minimum phase output and is absent of time of flight info. So it depends on what system/program you use to measure. Definitely could be wrong on this.

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