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Is my Phase too fat?

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  • Is my Phase too fat?

    Been working on my first (well technically second) design. MTM with Eclipse and Satori TW29. I use REW for measurements and primarily WinPCD for the XO work. Since most folks here use PCD I imported into that for the screenshots. I like what I have so far but not sure how this phase looks. Bad? good? Weird? I use the min phase generated in REW.

    Click image for larger version

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  • #2
    While not "perfect" tracking (for LR2/4), it certainly isn't bad between 200Hz and about 4k (before diverging).

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    • #3
      That isn't too shabby. Try adjusting the tweeter values just a bit and they will come right into line.

      What is the lcr for on the woofers?
      https://www.facebook.com/Mosaic-Audi...7373763888294/

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      • #4
        Originally posted by isaeagle4031 View Post

        What is the lcr for on the woofers?
        For the peak as discussed in that previous thread.
        Click image for larger version

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        • #5
          The small cap did not knock that out?
          https://www.facebook.com/Mosaic-Audi...7373763888294/

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          • #6
            Make sure you have entered in the driver sizes, then you can simulate off-axis response and judge for yourself if the phase response is acceptable.

            Basically, if the phase is aligned on-axis, then the response will only drop as you move off-axis. If the phase is not aligned on-axis, then off-axis it will align, and at this angle the output will increase. This is because the alignment axis of the phase is not straight ahead, but at a slight angle, which may be of some benefit if the intended use for the speakers is above or below the listener.
            "I just use off the shelf textbook filters designed for a resistor of 8 ohms with
            exactly a Fc 3K for both drivers, anybody can do it." -Xmax

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            • #7
              Originally posted by isaeagle4031 View Post
              That isn't too shabby. Try adjusting the tweeter values just a bit and they will come right into line.
              So far it seems I would have to go from second order electrical to third on the tweeter to get near-perfect phase tracking. But do I need to? (Guess I will just add that cap and see..)
              Click image for larger version

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              • #8
                Originally posted by isaeagle4031 View Post
                The small cap did not knock that out?

                Yeah, but I have the LCR parts on hand and just kept them there as part of the learning experience.

                @decibel, will do.

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                • #9
                  You have fine frequency response (FR) throughout the crossover region so I wouldn't obsess over the phase. It's easy to caught up in the "I must have a super deep null" train of thought and forget a main reason for phase tracking is to prevent FR irregularities around the crossover region. Good luck with your project!

                  PS - I assume you measured/calculated the acoustic offset and entered that into PCD (as Z offset) along with the Y offset.
                  "Everything is nothing without a high sound quality." (Sure Electronics)

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                  • #10
                    Originally posted by Wushuliu View Post


                    Yeah, but I have the LCR parts on hand and just kept them there as part of the learning experience.

                    @decibel, will do.
                    Understandable. As far as 3rd order, given the somewhat low xover point, I would use that as a minimum anyway
                    https://www.facebook.com/Mosaic-Audi...7373763888294/

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                    • #11
                      Originally posted by isaeagle4031 View Post

                      Understandable. As far as 3rd order, given the somewhat low xover point, I would use that as a minimum anyway

                      Why? To protect the tweeter?

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                      • #12
                        Which version TW29? None of them like to go that low, they have a natural roll off that starts around 4K,
                        but then a large peak at around 1500, even if you get decent measurement it will not sound very good.

                        Also what are you basing your cap/coil ratios on?

                        All the SB stuff can sound fantastic but the tweeters can get naughty below 2K if not very sharply
                        filtered.
                        Guess xmax's age.

                        My guess: 15. His grammar is passable. His trolling is good.

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                        • #13
                          You see even the much cheaper Seas (and the Transducer Labs) has a lot less distortion at 1K.
                          The SB tweeters are some of the best but I would never cross them below 3K at 12 or more dB
                          per octave.
                          Guess xmax's age.

                          My guess: 15. His grammar is passable. His trolling is good.

                          Comment


                          • #14
                            Huh, I thought one of their advantages was that they could be crossed low.

                            Can't cross below 3k?

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                            • #15
                              Here's the TW29 soft dome:
                              http://www.audioxpress.com/article/t...gh-end-tweeter

                              And here's the Be edition:
                              http://www.audioxpress.com/article/t...m-dome-tweeter

                              You have increasing distortion below 2kHz, but it is purely 2nd order. I wouldn't hesitate to use the TW29 with a 2nd order 2kHz crossover, 4th order acoustic rolloff, but no lower.
                              "I just use off the shelf textbook filters designed for a resistor of 8 ohms with
                              exactly a Fc 3K for both drivers, anybody can do it." -Xmax

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