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I could really use some help designing 3 way Crossovers

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  • #46
    Originally posted by rpb View Post

    Since it's your design, I'll offer a suggestion. Try a smaller coil on the tweeter filter, and see how things look. If nothing else, it should protect the tweeter from damage. It will probably change the impedance at high frequency a little, so there's a trade-off. Might be minor though.

    If you can add resistance of the coils in your sim, I'd ballpark them at .3 ohms. Don't worry about being exact. If it's a big coil, the values may be more important. The cheaper coils sometimes are higher resistance. That might be an advantage, or not. Depends on multiple factors.
    Thanks rbp. Let me try tweaking it a bit before I order anything.

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    • #47
      Originally posted by Chris Roemer View Post
      Clang - there IS a problem.
      You absolutely can NOT rely on an "out-of-phase" condition to achieve a "flat" FR curve.
      That's exactly what your mid is up to. You (EYE) can SEE it right on your plots! Your mid (yellow) is higher than your summed response (the black line). This is BAD. I can only explain it to you, I can't understand it for you.

      SOMEbody else please back me up here? ??
      Yep. I understand. I'm just choosing to ignore you.

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      • #48
        Here's what my sim shows for 20 degrees upwards. Big dip at the tweeter xo, but the mid to woofer looks fine.

        Click image for larger version  Name:	20 degrees vertical.jpg Views:	0 Size:	251.5 KB ID:	1450488

        Below, I changed the xo for the intention of listening 20 degrees above axis. I added an order on the tweeter filter. The tweeter would have better power handling due to the steeper slope.

        Click image for larger version  Name:	20 degrees vertical by design.jpg Views:	0 Size:	245.7 KB ID:	1450489

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        • #49
          Originally posted by rpb View Post
          Here's what my sim shows for 20 degrees upwards. Big dip at the tweeter xo, but the mid to woofer looks fine.

          Click image for larger version Name:	20 degrees vertical.jpg Views:	0 Size:	251.5 KB ID:	1450488

          Below, I changed the xo for the intention of listening 20 degrees above axis. I added an order on the tweeter filter. The tweeter would have better power handling due to the steeper slope.

          Click image for larger version Name:	20 degrees vertical by design.jpg Views:	0 Size:	245.7 KB ID:	1450489
          Definitely looks like an improvement. When you look at off axis performance, is it standard to evaluate 20 degrees upwards? I can understand why you don't do downwards, but how about left/right? I'm just curious since this is new to me.

          For the record - I'm probably going to tilt them upward. I'm staining and varnishing a couple of dowels that I can roll under the front of the speakers to tilt the angle upwards. If that doesn't work out, I can always put them on stands, even if only milk crates.

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          • #50
            I think your attachment is missing. Let's see that center channel speaker.

            What changes did you do on my model?

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            • #51
              Originally posted by clang View Post
              I think your attachment is missing. Let's see that center channel speaker.

              What changes did you do on my model?


              On your speaker, I had a 2nd order filter in my sim. I changed it to a 3rd order. Does your software let you change the axis angle?
              Last edited by rpb; 09-08-2020, 09:01 PM.

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              • #52
                I'm using XSim and really just learning by trial and error. Are you posting attachments? I don't see anything. Post #48 is the last place I see pics.

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                • #53
                  Originally posted by clang View Post
                  I'm using XSim and really just learning by trial and error. Are you posting attachments? I don't see anything. Post #48 is the last place I see pics.
                  strange. They show when I open this thread. I'll delete them anyway.

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                  • #54
                    OK, so I reworked my sim with a 3rd order on the tweeter:

                    Click image for larger version

Name:	my 5th xover design 3rd order tweeter.jpg
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                    Decent freq response and no cancellation:
                    Click image for larger version

Name:	my 5th xover design 3rd order tweeter fr.jpg
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ID:	1450639

                    Impedance on the tweeter goes down, but hopefully not too far:
                    Click image for larger version

Name:	my 5th xover design 3rd order tweeter im.jpg
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                    • #55
                      That looks pretty good. I think that maybe you could pad the mid and tweeter slightly, and bring the impedance up. (If you wanted.) Some of the cap and coil values might need to be tweaked if you do, but it should be minor. I'm thinking 1.5 ohms or less on each section, before the x-over.

                      On the other hand, if you were to stretch the range of the mid a little lower, the portion between 1k and 2k may drop a dB or two. The impedance will probably come down in the 300hz range, but it's currently pretty high there. Maybe you could go as low as 400hz. Odds are, C4 could be doubled, and that slight hump at 600hz would come down. It will drop the impedance some though. Adding 1.5 ohms before the tweeter xo should help the impedance at higher frequencies.

                      You're doing good. You just have to keep sneaking up on the ideal response / impedance. Use the xo above if additional changes don't improve things.
                      Last edited by rpb; 09-08-2020, 08:50 PM.

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                      • #56
                        Earlier you asked about off-axis. I don't dwell on it, but I do measure it, and hope for something smooth. The left / right off axis is mostly determined by driver sizes, and the xo point, and slopes. Diffraction comes into play as well. I've made some that measured like a roller-coaster off-axis, but sounded decent. This speaker of mine worked out rather well. This is 45 degrees off axis. Second picture is on axis. One of the tabs is incorrectly marked 45 degrees.
                        Click image for larger version  Name:	new center off axis.JPG Views:	0 Size:	223.6 KB ID:	1450651 Click image for larger version  Name:	version two.JPG Views:	0 Size:	248.4 KB ID:	1450654

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                        • #57
                          Originally posted by clang View Post
                          Yep. I understand. I'm just choosing to ignore you.
                          While some of what Chris Roemer wrote might be harder to listen to (both because some of the blunt tone in one or two posts here and some of the fairly technical language that might be rough for someone still learning a lot of this), his advice is still very much worth considering.

                          Some of these crossover designs being shot down (including the first one by DeZZar, I think) are going to drop that 3way's ohms/impedance far below the 6.6ohms that many 8ohm amps want as a minimum. If your amp isn't rated for 4ohms, this might cause it to overheat or worse depending on how overbuilt and well-protected it is.
                          Sometimes I'm kinda blind, but I didn't see this answered when someone asked earlier what ohm-rating your amp can handle...sorry if I just missed it.
                          Last edited by LOUT; 09-09-2020, 02:14 PM.
                          My first 2way build

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                          • #58
                            Thanks Gents, I'm going to keep tweaking.

                            rpb - for some reason I do not see your design, so I have no idea what it looks like. What program are you using? Maybe I have to download it to see your design.

                            LOUT - 4-16 Ohm speakers for my amp.

                            I welcome anyone who wants to share their Xover design and accompanying graphs on this thread. Constructive feedback that respects other's contributions and efforts is also welcome. There was an old timer that said something about treating other people the way you want to be treated. I'm a big fan of that.

                            Comment


                            • #59
                              Originally posted by clang View Post
                              Thanks Gents, I'm going to keep tweaking.

                              rpb - for some reason I do not see your design, so I have no idea what it looks like. What program are you using? Maybe I have to download it to see your design.

                              LOUT - 4-16 Ohm speakers for my amp.

                              I welcome anyone who wants to share their Xover design and accompanying graphs on this thread. Constructive feedback that respects other's contributions and efforts is also welcome. There was an old timer that said something about treating other people the way you want to be treated. I'm a big fan of that.
                              You don't see the measurements? That's all I attached.

                              Comment


                              • #60
                                Originally posted by LOUT View Post
                                While some of what Chris Roemer wrote might be harder to listen to (both because some of the blunt tone in one or two posts here and some of the fairly technical language that might be rough for someone still learning a lot of this), his advice is still very much worth considering.

                                Some of these crossover designs being shot down (including the first one by DeZZar, I think) are going to drop that 3way's ohms/impedance far below the 6.6ohms that many 8ohm amps want as a minimum. If your amp isn't rated for 4ohms, this might cause it to overheat or worse depending on how overbuilt and well-protected it is.
                                Sometimes I'm kinda blind, but I didn't see this answered when someone asked earlier what ohm-rating your amp can handle...sorry if I just missed it.
                                We are trying to keep impedance above 6 ohms, which is a challenge. Clangs xo in post #54 is pretty much there.

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