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  • Chamfer vs. Roundover?

    I know roundovers are said to be better than chamfers but just how bad would a 3/4" chamfer sound vs. a 3/4" RO? Would is completely change the sound or is it something only a very trained ear would hear? What would the difference be anyway?

    In case you haven't figure it out I want to chamfer the current build I'm working on.

    Thanks for any input!

  • #2
    Re: Chamfer vs. Roundover?

    There are some great speaker on the market with a simple champher. But I would have to think the roundover would still be the best.
    Mark


    http://www.diy-ny.com

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    • #3
      Re: Chamfer vs. Roundover?

      I believe if you model it, the differences are minimal, and size for size, the nod can actually go to the chamfer in some instances.

      Try it using the BDS software over at the FRD Consortium...

      C
      Curt's Speaker Design Works

      "It is the mark of an educated mind to be able to entertain a thought without accepting it."
      - Aristotle

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      • #4
        Re: Chamfer vs. Roundover?

        Sorry Curt, that's a little over my head right now...

        I'm building Zaph's WgTMM's. Here's an excerpt from his write-up.

        There are quite a few other benefits to waveguides. The low end of the tweeter's output has a change in directivity that more closely matches the woofer's directivity. The result is very smooth horizontal off axis response, and a power response that does not have the same deep null that a standard speaker would have. Related to the directivity benefit is the fact that a waveguide is not affected by the baffle it's on. Baffle diffraction is a non-issue compared to a standard dome mounted in an enclosure. In a waveguide system, you will not see the lower treble "ripple response" present in typical box systems.

        Maybe I'm reading it too literally or just not seeing the whole picture but to me that sounds like the baffle edge treatment will have no effect on the tweeter. Even if that is the case I don't know what impact it would have on the woofer.

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        • #5
          Re: Chamfer vs. Roundover?

          Yeah I'm working on a pair of WG TMMs too and was wondering the same thing. If I can just leave the front corners hard. If so I could build out of birch ply, miter the corners and then just finish the outside with no plys showing where the corners got rounded over.

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          • #6
            Re: Chamfer vs. Roundover?

            While I haven't worked with the MCM waveguide, I have worked with dome tweeters in custom CNC'd waveguides and can say that there was NO baffle edge diffraction. I have a 1.5" roundover bit, and compared the waveguide on a square edge baffle vs. on a 1.5" roundover baffle and there was no sign of diffraction effects.

            That said, not all waveguides work the same of course. The MCM might not have the same amount of control that my custom guide does, and might show some diffraction ripple. My guess though is that if it doesn't totally negate diffraction effect, it probably comes pretty close.
            Vapor Audio

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            • #7
              Re: Chamfer vs. Roundover?

              Well Zaph says the MCM Wg/27tdfc combo does and your experiences matches that with Wg's so that's 2-for-2. What about the woofer? ... I don't know what frequencies are involved in baffle diffraction...

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              • #8
                Re: Chamfer vs. Roundover?

                Originally posted by Ryan_M View Post
                Well Zaph says the MCM Wg/27tdfc combo does and your experiences matches that with Wg's so that's 2-for-2. What about the woofer? ... I don't know what frequencies are involved in baffle diffraction...
                You will still have baffle step to deal with.
                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
                Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

                95% of Climate Models Agree: The Observations Must be Wrong
                "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

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                • #9
                  Re: Chamfer vs. Roundover?

                  Originally posted by Ryan_M View Post
                  Well Zaph says the MCM Wg/27tdfc combo does and your experiences matches that with Wg's so that's 2-for-2. What about the woofer? ... I don't know what frequencies are involved in baffle diffraction...
                  I had my xo at 875hz, so not a problem at those low freqs. And with the Zaph around 2khz xo, the woofer starts to become directional below that point, so I wouldn't think it would be radiating 180 degrees ... thus no interraction with the baffle edge, and no diffraction.
                  Vapor Audio

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                  • #10
                    Re: Chamfer vs. Roundover?

                    Thanks!

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                    • #11
                      Re: Chamfer vs. Roundover?

                      Originally posted by curt_c View Post
                      I believe if you model it, the differences are minimal, and size for size, the nod can actually go to the chamfer in some instances.

                      Try it using the BDS software over at the FRD Consortium...

                      C
                      +1. A radius of less than 2" tends to have minimal effect, if any, so in this case whether its chamfered or rounded is mainly a cosmetic issue.
                      www.billfitzmaurice.com
                      www.billfitzmaurice.info/forum

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                      • #12
                        Re: Chamfer vs. Roundover?

                        Originally posted by curt_c View Post
                        I believe if you model it, the differences are minimal, and size for size, the nod can actually go to the chamfer in some instances.

                        Try it using the BDS software over at the FRD Consortium...

                        C
                        Or, if you don't have Excel, the program called the Edge... (at least I think it's a standalone program)

                        I'm trying to remember who did some modeling, Dennis Murphy or on RJBAudio... there was a study and a .75" roundover had a fairly measurable effect. In BDS, you can see a fair amount of reduction at that size. I haven't done any real world measuring though.

                        On the waveguide thing, since most of the baffle diffraction ripple effects are up above 1kHz, (ignoring that first big hump) its mostly a tweeter level issue... You're helped by the waveguide's directiveity "hiding" the baffle edge in a case like that, and it matters less what the edges of the baffle are like.

                        With a regular surface mounted tweeter, you would have more effect from the edges, so how they are will be more influential.

                        So in a way I'm both disagreeing and agreeing with Bill... ;) in that I think a relatively small roundover or chamfer will help you (at higher freq's) while down lower at the top of the woofer range, it will take a larger roundover to do much to that first hump. (usually just lived with or adjusted for in the crossover)

                        Play with some of the edge simulators, that's probably the easiest way to understand the effects.

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                        • #13
                          Re: Chamfer vs. Roundover?

                          Originally posted by billfitzmaurice View Post
                          +1. A radius of less than 2" tends to have minimal effect, if any, so in this case whether its chamfered or rounded is mainly a cosmetic issue.
                          A radius as small as .75" has a significant effect on ripple at frequencies above 2500Hz for flush mounted dome tweeters. So there is benefit, even if less than 2" for such mountings. For mids, the larger the radius/chamfer the better as it will smooth the step/peak transition and reduce the overall size of the response change.
                          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
                          Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

                          95% of Climate Models Agree: The Observations Must be Wrong
                          "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

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                          • #14
                            http://techtalk.parts-express.com/sh...d.php?t=214805

                            I'll add the Zaph evidence to the larger argument there.

                            [Don't get stuck in a loop, tho.... :D ]

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                            • #15
                              Re: Chamfer vs. Roundover?

                              A radius as small as .75" has a significant effect on ripple at frequencies above 2500Hz for flush mounted dome tweeters.
                              Put a ring of rock wool around it. No diffraction, no diffraction ripple.
                              "It suggests that there is something that is happening in the real system that is not quite captured in the models."

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