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  • WMTMW - crossover time

    Ok guys, I'm working on an WMTMW for a friend of fine. What are some opinions on the best way to input the data into PCD/WinPCD/etc.? Should I take all individual measurements and put them in as woofer 1 & 2 and mid 1 & 2? Should I measure the mids and the woofers together and just input data for one driver each? To me, that seems easier but then I cannot account for the offset of each driver (since the Y axis would be positive for the drivers above the tweeter and negative for the two below). Do I need to even worry about that as long as I have the offsets correct for the 1 (summed) driver?

    Here is a picture of the speaker - yes, I work in my attic. Fortunately, it's not too hot until between 3-7pm.

    People hear with their eyes.

  • #2
    Re: WMTMW - crossover time

    I hope Jeff drops by for this one. will be there soon myself.
    " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

    Quote Originally Posted by hongrn. Oct 2014
    Do you realize that being an American is like winning the biggest jackpot ever??

    http://www.midwestaudioclub.com/spot...owell-simpson/
    http://s413.photobucket.com/albums/pp216/arlis/

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    • #3
      Re: WMTMW - crossover time

      Since you have the capability, and PCD can accept it, if you want to model the off axis behavior, measure each driver independently. Then measure the mids and tweeter together to determine the acoustic offset.

      If you don't care about modeling the off axis performance (since you can actually measure it) then measure the woofers as a unit, the mids as a unit, and the tweeter. Also measure the mids and tweeter together (parallel) to determine acoustic offset.

      Don't worry about mid/woofer acoustic offset. They cross too low for it to really matter.
      R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
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      • #4
        Re: WMTMW - crossover time

        I would probably get the speaker horizontal and off the floor(middle between floor and ceiling) so if you are going to use far field of the woofers response, the gating is a bit wider (read, nearest boundary distance is longer)
        I am not sure how PCD works but you can also measure 2 woofers together and input them as one for the ease of calculations (forgive me but my own computer is so old, it takes minutes to calculate 5 drivers in Sound Easy Cad, so I cheat and present a system like this as 3 driver). Same with the mids.
        I would probably take all measurements at slightly longer then standard 1m distance as well. Say 1.5m or 2m.
        Or you could try ground plane measurements.
        http://www.diy-ny.com/

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        • #5
          Re: WMTMW - crossover time

          Is it possible for you to take the driver measurements at your friend's house with the speakers sitting in their intended positions? If so I would do that and use Pete's suggestion of measuring each of the five drivers individually from one fixed mic position. Then enter them all into PCD. That way the real floor bounce and boundary reflection information will be accurately captured and accounted for in your XO simulations. Probably will save you a lot of time in the post simulation phase. That's what I've done on my last couple of projects and it required far less tweaking by ear after prototyping the sim'd XO.
          Craig

          I drive way too fast to worry about cholesterol.

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          • #6
            Re: WMTMW - crossover time

            I would probably get the speaker horizontal and off the floor
            Hmm. I hadn't thought of that. I wonder if doing that would put the woofers closer to the slanted walls/ceiling and not really gain me anything? I can certainly try it.

            am not sure how PCD works but you can also measure 2 woofers together and input them as one for the ease of calculations
            Yep, I've considered that. My question with that method is whether or not it matters that the y offsets would only apply to one driver of each pair.

            I would probably take all measurements at slightly longer then standard 1m distance as well. Say 1.5m or 2m.
            I have space to do this, but why?

            Is it possible for you to take the driver measurements at your friend's house with the speakers sitting in their intended positions?
            I'm afraid not. I live in MN and right now he's in VA then off to Okinawa in a few months. So, it really won't matter what room they are taken in since the room will be changing.

            That way the real floor bounce and boundary reflection information will be accurately captured and accounted for in your XO simulations.
            Since measuring in the room is not an option, this question is simply for the sake of curiosity: If I were to do as you suggest, wouldn't I actually want to do both speakers and all 10 drivers? Otherwise I'd only have reflection information relavent for the one speaker. And then would I be looking at two very similar (but still different) crossovers?

            Thanks for the help so far guys!
            People hear with their eyes.

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            • #7
              Re: WMTMW - crossover time

              Ok, here is what I have so far:

              Click image for larger version

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              Click image for larger version

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              10 parts total - nothing too crazy. Busy day tomorrow so I don't have a fancy schematic to show all the parts. I'll try to get to that tomorrow. You may not be able to tell me if there is an easier way to do it but I know some of you guys are wise enough to look at it and at least tell me if something says "danger, danger!"
              People hear with their eyes.

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              • #8
                Re: WMTMW - crossover time

                Looks good Dan.
                Kenny

                http://www.diy-ny.com/
                DIY NY/NJ 2014 https://www.youtube.com/watch?v=FGwA...ature=youtu.be
                Man does not live by measurements alone, a little music helps.

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                • #9
                  Re: WMTMW - crossover time

                  I like the electrical phase and the impedance, but I'd like to see the FR zoomed in a good bit, and the driver responses, and driver phase. Reverse nulls and power response would be informative, as well.

                  Given the info that's presented, that looks pretty nice, but not really enough there to see the whole picture.


                  Mark
                  You go your way, I'll go mine. I don't care if we get there on time.

                  ~Pink Floyd

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                  • #10
                    Re: WMTMW - crossover time

                    great start Dan. what mark said. especially driver phase and power response.
                    " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

                    Quote Originally Posted by hongrn. Oct 2014
                    Do you realize that being an American is like winning the biggest jackpot ever??

                    http://www.midwestaudioclub.com/spot...owell-simpson/
                    http://s413.photobucket.com/albums/pp216/arlis/

                    Comment


                    • #11
                      Re: WMTMW - crossover time

                      Thanks guys.

                      I can get the other stuff posted but I'm not sure how to show you the driver responses. Isn't that the blue/pink/red lines from graph I already posted?

                      What's the best way to show the driver phase? Each individual or just all of them in the main graph?
                      People hear with their eyes.

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                      • #12
                        Re: WMTMW - crossover time

                        Here is the power response and phase along with driver response from the main graph as pictured previously.

                        Click image for larger version

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                        Here is with the midrange reversed (actually, set back to "normal" polarity). Interesting that the little blip on the FR is mirrored by a blip in the phase. Well, interesting to me since I don't know what causes it. Thoughts?

                        Click image for larger version

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                        People hear with their eyes.

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                        • #13
                          Re: WMTMW - crossover time

                          Ok, something goofy going on there. Did you run your driver files through Response Modeler? Minimum phase needs to be extracted for sure, and your x,y,and z offsets need to be entered. Looks like PCD is seeing all three drivers coming from the same place, there.
                          You go your way, I'll go mine. I don't care if we get there on time.

                          ~Pink Floyd

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                          • #14
                            Re: WMTMW - crossover time

                            Well, I never got an answer to my question on how to add offsets since I'm using two woofers and two mids. I've read on the forum that Jeff Bagby says you don't have to extract minimum phase if using Omnimic for measurements. And someone in chat a few nights ago said to not worry about entering the offsets since the necessary data would be in the phase measurements.

                            I would not be at all surprised if I just misunderstood what they said.

                            Also, Mark, how you can you tell that PCD is seeing all 3 (5?) coming from the same place? I still don't know how to read a lot of this stuff.

                            Thanks!
                            People hear with their eyes.

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                            • #15
                              Re: WMTMW - crossover time

                              Just all the phase lines tracking together the whole way. I forgot those are measured responses. Did you measure with them in the box? If so, then those guys are probably right, and you are probably ok. I could easily be wrong about that, though. I'd still like to see higher resolution than that, as well.
                              You go your way, I'll go mine. I don't care if we get there on time.

                              ~Pink Floyd

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