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  • How to import FRD files into XSim to get relative acoustic offset...

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    The title kind of says it. I can't seem to load more than one FRD file into XSim's frequency response graph at a time. I have graphs for tweeter, mid, woofer, and all to get the relative acoustic offset, but I can't seem to get them to load up. Am I doing something wrong or is this not possible in XSim? I thought it was for some reason...



    This is a pic of the tweeter response, but when I try to click on "Curves" to get another file to add, there is no option to do so.
    Can you use XSim to get the relative acoustic offset?

    Thanks

    TomZ
    Zarbo Audio Projects Youtube Channel: https://www.youtube.com/channel/UCEZ...aFQSTl6NdOwgxQ * 320-641 Amp Review Youtube: https://youtu.be/ugjfcI5p6m0 *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
    *Part 2 *Gluing multiple curved laminations of HDF

  • #2
    Re: How to import FRD files into XSim to get relative acoustic offset...

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    • #3
      Re: How to import FRD files into XSim to get relative acoustic offset...

      I'm not sure what happened, I think it's there now.

      TomZ
      Zarbo Audio Projects Youtube Channel: https://www.youtube.com/channel/UCEZ...aFQSTl6NdOwgxQ * 320-641 Amp Review Youtube: https://youtu.be/ugjfcI5p6m0 *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
      *Part 2 *Gluing multiple curved laminations of HDF

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      • #4
        Re: How to import FRD files into XSim to get relative acoustic offset...

        right-click on the driver symbol. It's Tune window has a place to load the FRD, the ZMA, and even another "tweak/cheat" curve.
        Free & Free-form simulator/designer for Passive Crossovers
        SynergyCalc 5: design spreadsheet for Wooden horns and DIY Synergy Waveguides
        Super easy and cheap to make high performance sound diffusers

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        • #5
          Re: How to import FRD files into XSim to get relative acoustic offset...

          I'm not sure what happened, I think it's there now.

          TomZ
          Zarbo Audio Projects Youtube Channel: https://www.youtube.com/channel/UCEZ...aFQSTl6NdOwgxQ * 320-641 Amp Review Youtube: https://youtu.be/ugjfcI5p6m0 *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
          *Part 2 *Gluing multiple curved laminations of HDF

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          • #6
            Re: How to import FRD files into XSim to get relative acoustic offset...

            Originally posted by bwaslo View Post
            right-click on the driver symbol. It's Tune window has a place to load the FRD, the ZMA, and even another "tweak/cheat" curve.
            Thanks, Bill.

            I'm assuming that I only need FRD files for tweeter, mid, woofer, and then all together to do this. When I change the 'mod delay' in the 'Tune' section after right clicking on the woofer for instance, the response in the graph for that driver isn't moving at all no matter what numbers I put in pos or neg.
            Zarbo Audio Projects Youtube Channel: https://www.youtube.com/channel/UCEZ...aFQSTl6NdOwgxQ * 320-641 Amp Review Youtube: https://youtu.be/ugjfcI5p6m0 *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
            *Part 2 *Gluing multiple curved laminations of HDF

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            • #7
              Re: How to import FRD files into XSim to get relative acoustic offset...

              Tom,

              David Ralphs has pretty good instructions in WinPCD for finding the acoustic offset. His latest version has an entire tab dedicated for this process. Like you, I couldn't make sense of XSim at all.
              Some people are addicted to Vicodin. I'm addicted to speaker building.

              The Chorales - Usher 8945A/Vifa XT25TG Build
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              • #8
                Re: How to import FRD files into XSim to get relative acoustic offset...

                Tom,

                It is possible to do this in XSim, but the results are not the same as what you'd find in PCD. I'll explain in a minute. First, how to use XSim to find the "offset":

                For a 2-way, put 3 drivers in your schematic: One for your HF, one for LF, and one for the combined HF+LF response. Double-click on each driver and load the appropriate FRD file. Wire only the HF+LF speaker to the power amp and you should see your combined response on the FR graph.

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                Click on the "hold" button to keep that response as an overlay.

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                Delete the wires from the amp to the HF+LF speaker and wire up the HF speaker to the amplifier as well as the LF speaker to the amplifier.

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                You will now see the response of your HF and LF drivers as if there were no offset between them.

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                Go back to either your HF or LF driver and apply a "mod delay" until your responses align with each other (positive number in XSim means farther from the mic).

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                In my case, I have a horn loaded compression driver that sits significantly farther back than my LF woofer. Once I had the correct offset entered, the plots lined up quite nicely.

                Now, if you're going to use Xsim for your crossover design, then there's no need to do anything further, but your response will only be accurate for that one distance. If you want to use this "offset" and use something like PCD or WinPCD, then you'll have to do a little more work. This value you have found in XSim is the total acoustic offset between the drivers in a "polar" distance to the microphone. Depending on how far away you measured from, and the distance between the drivers, this can differ from the actual Z-offset that you would use in something like PCD.

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                • #9
                  Re: How to import FRD files into XSim to get relative acoustic offset...

                  I could only put 5 pictures in a post, so here's the response after adjusting the offset of the HF driver:

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                  • #10
                    Re: How to import FRD files into XSim to get relative acoustic offset...

                    Ben,

                    First of all, thank you so much for explaining this out so clearly. I would have never been able to figure this out without your explanation. Actually, I tried it this morning, but misunderstood something and will have to retry this when I get home from work. I think I understand it, though.

                    If I could just pick your brain a bit further about my procedures... I placed my Omnimic exactly 30" from the tweeter dome facing directly at it. I used 8 ms gating and 1/48th octave smoothing as Jeff B. suggested this as a decent starting point I believe. I used a cap on the tweeter to protect it, 8 uf I think, and I used the 'bass removed' track to test with.

                    Also, my speaker is a 3 way with two woofers: TMWW style. I brought the level up as high as I thought was safe with the sweep on the tweeter first, it only came to 60 db or so, but it seemed very loud and I was afraid to go louder. I left the level the same and did the same for the mid, then the woofer, then I combined all with the cap on the tweeter and did that sweep... so I have four sweeps, three for the three drivers, and one with all. I don't know if this is the best way to do it, but Jeff B's paper used a two-way, so I just took a shot. The graphs look like they have similarities, so I'm guessing that maybe I can use this data to get pretty close for the offsets. I'll see tonight for sure, though.

                    I do plan on using XSim to do the crossover sim's so I guess I'm good there. One thing though. In your pics, I can see the phase data, but in mine, I can't. Do you know if there is something I need to click on in the Omnimic software to have phase data included in the FRD files I made with Omnimic? BTW, after the sweep ran for several times and the screen looked like it was generating basically the same curve each time, I clicked on the 'pause' button and then went to 'file', and selected 'save curve'. I'm assuming this is the right way to do it, not sure, though.

                    Thanks for your help, Ben I appreciate it a lot.

                    TomZ
                    Zarbo Audio Projects Youtube Channel: https://www.youtube.com/channel/UCEZ...aFQSTl6NdOwgxQ * 320-641 Amp Review Youtube: https://youtu.be/ugjfcI5p6m0 *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
                    *Part 2 *Gluing multiple curved laminations of HDF

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                    • #11
                      Re: How to import FRD files into XSim to get relative acoustic offset...

                      Is there a reason you do not use the “Get File” curve for the combined response (HF plus LF) FRD in the Frequency Response graph?
                      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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                      • #12
                        Re: How to import FRD files into XSim to get relative acoustic offset...

                        Originally posted by jhollander View Post
                        Is there a reason you do not use the “Get File” curve for the combined response (HF plus LF) FRD in the Frequency Response graph?
                        There you go... there's another way to do it

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                        • #13
                          Re: How to import FRD files into XSim to get relative acoustic offset...

                          Tom,

                          First off, I've never used OmniMic and the only time I have ever seen it in action is when Jeff ran it at his "seminar". Since it is a self-contained unit (contains the A/D inside the mic), I assume that OmniMic has been calibrated to be SPL accurate. If you're only measuring 60 dB of signal, then something seems way off and I would be concerned with the accuracy of your results. If the only error in the system is the magnitude offset, then all your measurements will at least correct relative to each other. That aside, let's continue with your process...

                          30" seems like it might be a little close for a TWMM. Jeff's recommendations for distance and timing were based off a 2-way bookshelf TM. What is your baffle width and your C-C spacing of the farthest drivers (T to bottom W)? Also, 8 ms seems very long, even for a TM at 30". If you're measuring from 30" at 48" off the ground, your first reflection will come in just over 5 ms after the direct sound, so I'd cut it down to 5 ms or less. We'll see how far apart your drivers are, but my guess is you'll want to back the mic away a little and cut your gate down to the 4ms range to get an anechoic measurement. You really need to take a look at your impulse response or ETC (energy-time curve) to see where that first reflection comes in, and set your gate to completely exclude it from your measurement.

                          In order to get your offsets for a 3-way TMWW speaker, you'll need 5 measurements: T, M, WW, T+M, T+WW. Using your dome tweeter for a reference point, you want to know how far back the mid-range is from there, and you want to know how far back the woofer is from the tweeter. So, you'll load the T+M curve in the response window and load the T and M curves as speakers in the schematic window to find the T to M offset. Then load the T+WW curve in the response window and the T and WW curves as speakers in the schematic window to find the T to WW offset. Then, when simulating your crossover, your tweeter will have zero "mod delay" while the M and WW sections will each have their mod delay (offset) based on the tweeter reference.

                          Again, I've never used OmniMic, so I don't know what the deal is with your phase data. Hopefully someone else can chime in who has used an OmniMic. Since you're making all your measurements in the same position and using the same setup, I don't think it's anything to worry about when finding the offsets. Keep in mind, when you go to design your crossover, you'll need to extract minimum phase data anyway.

                          I hope that all helps.
                          Ben

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                          • #14
                            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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                            • #15
                              Re: How to import FRD files into XSim to get relative acoustic offset...

                              If your OM is reading levels way low (about 20dB down), then the crystal ball suggests:
                              You are running it with Windows 8, and you aren't using the suggested "WinXP SP3" compatibility mode (see the help files). MS has helpfully thrown away a bunch of the record dynamic range of USB mic inputs in Win8, but fortunately left a way to do it right by the compatibility mode.
                              Free & Free-form simulator/designer for Passive Crossovers
                              SynergyCalc 5: design spreadsheet for Wooden horns and DIY Synergy Waveguides
                              Super easy and cheap to make high performance sound diffusers

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