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Offsets, Asymmetrical Slopes, and Mysticism - revisited *PICS*

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  • #76
    Originally posted by xmax View Post
    I'm only speaking of the phase (relationship between 2 or more drivers) and how it is affected by the
    electrical filter slope. I don't mean to insult any of you but please stop being A holes.

    Mr XMAX - these are basically the nicest people you will ever meet on the internet.

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    • #77
      Originally posted by donradick View Post


      Mr XMAX - these are basically the nicest people you will ever meet on the internet.

      +1.

      I personally cannot thank Pete, Jeff, Dlr (and others) for sharing their knowledge with the DIY community. I'm always humbled when they take the time to answer even the most elementary questions.

      In my short experience here, I noticed the members that are the most knowledgeable about the subject keep their calm and are ALWAYS cordial/respectful when challenging other members' posted comments.

      I really respect them for that. I'm sure deep down they must be fuming when they read inaccurate information being posted :-), but they always seem to do a good jobs keeping calm and will often simply ask the opposing side to elaborate on their claim.




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      • #78
        Of course it matters what filter order you're using to combine two (or more) drivers. That's why when you have a system using LR2 slopes (acoustic slopes, not electrical) you reverse the polarity of one of the drivers in order to get proper summation at the crossover point. Similarly, when you have LR4 slopes (acoustic slopes, not electrical) you connect both drivers in the same polarity due to the extra phase shift.

        But when there is phase shift due to time of flight (acoustic offset problems) you can use slightly different transfer functions in the hope of making up some of that extra phase shift over a narrow range of frequencies in order to get better summation in the design axis at the crossover region. It's easier to accomplish with higher order filters.
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        • #79
          Of course it matters what filter order you're using to combine two (or more) drivers. That's why when you have a system using LR2 slopes (acoustic slopes, not electrical) you reverse the polarity of one of the drivers in order to get proper summation at the crossover point. Similarly, when you have LR4 slopes (acoustic slopes, not electrical) you connect both drivers in the same polarity due to the extra phase shift.

          But when there is phase shift due to time of flight (acoustic offset problems) you can use slightly different transfer functions in the hope of making up some of that extra phase shift over a narrow range of frequencies in order to get better summation in the design axis at the crossover region. It's easier to accomplish with higher order filters.
          I was just never convinced that he agreed that a second order filter, when used with a tweeter with a second order roll-off could produce a textbook 4th order Linkwitz-Riley response in both amplitude and phase. And this point is important to going any further with crossover design.
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          • #80
            If I was wanting to learn about designing/building my own crossovers, what sites//books would be most helpful?
            http://techtalk.parts-express.com/fo...khanspires-but
            http://techtalk.parts-express.com/fo...pico-neo-build
            http://techtalk.parts-express.com/fo...ensation-build

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            • #81
              Originally posted by Kornbread View Post
              If I was wanting to learn about designing/building my own crossovers, what sites//books would be most helpful?
              Well, right here of course. For books, Speaker Builder 201 and Loudspeaker Design Cookbook vol7. For measurements, Mr Appolitos book,
              https://www.facebook.com/Mosaic-Audi...7373763888294/

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              • #82
                Originally posted by donradick View Post


                Mr XMAX - these are basically the nicest people you will ever meet on the internet.
                +1.

                Originally posted by Kornbread View Post
                If I was wanting to learn about designing/building my own crossovers, what sites//books would be most helpful?
                This is a tough question. I don't feel that the commonly suggested route of reading the standard Speaker Builder 201 or Loudspeaker Design Cookbook is a good suggestion. Personally I found them to be excellent theoretical resources, but they're lacking in practical applications, and a very poor choice for beginners. For example, I don't think either book explained very basic concepts what acoustical vs electrical slopes are, or the fact that a 3 way speaker needs a midrange chamber.

                Unfortunately there is no singular source I've found that will teach the basics to the advanced concepts in a clear manner. I feel that the best source is to ask someone to be your mentor. There is a lot of snippets of information scattered online, and it is difficult and time consuming to piece them together and properly understand them. This is why I feel there is so much misinformation for audio. Everyone is trying to piece scattering information together to make sense of them, but a lot of people piece them together wrongly, and end up misunderstanding the concepts. If not corrected early on, it will linger in the mind and become very difficult to change. Case in point, there are a lot of "great" debates in speaker design that does not need a debate at all as they have a very clear answer if one truly understands the concepts. All the debate is with people who don't actually understand the theory, or did things improperly, and reached the wrong practical conclusion and then blamed it on the concept.

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                • #83
                  Of course it matters what filter order you're using to combine two (or more) drivers. That's why when you have a system using LR2 slopes (acoustic slopes, not electrical) you reverse the polarity of one of the drivers in order to get proper summation at the crossover point. Similarly, when you have LR4 slopes (acoustic slopes, not electrical) you connect both drivers in the same polarity due to the extra phase shift.

                  But when there is phase shift due to time of flight (acoustic offset problems) you can use slightly different transfer functions in the hope of making up some of that extra phase shift over a narrow range of frequencies in order to get better summation in the design axis at the crossover region. It's easier to accomplish with higher order filters.
                  ^This is exactly what I am saying and I'm saying it for people who would like to understand it more than we do. Of course you can flip the polarity on the
                  tweeter and get the phase CLOSE to the same at the corner frequency (2nd compared to a 4th order) However impulse response will suffer (some agree more than others)

                  The main point I am expressing is, regardless of acoustical roll off, the phase will be changed between 2 drivers as you change the order of the electrical
                  filter at the crossover frequency (one or both slopes) and as the post originally states we can use this to our advantage when we are dealing with offsets.
                  Guess xmax's age.

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

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