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I don't fully understand Waveguides.

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  • I don't fully understand Waveguides.

    I need a good explanation of how Waveguides work, nothing overly complicated, just the basics, something concise. I don't quite understand how or why they do what they do, or if we even need to use them. Thank you

  • #2
    I’m no expert, but my take is they do 2 things:

    1.) Mildly horn-load a tweeter for greater low-end response with less harmonic distortion, all else being equal.
    2.) Control the dispersion pattern of the tweeter for greater directivity matching through the crossover region. For instance, a 1” dome tweeter acts as a point source fairly low, close to a standard crossover point. Cross that to a 12” woofer at 1.5kHz to 2kHz and the woofer is beaming more at these frequencies (acting less as a point source). The waveguide on the tweeter causes the tweeter to beam as well for greater directivity matching.

    I believe the mechanics behind the how are horn theory, which is beyond me.

    Cheers,

    Comment


    • #3
      Simple explanation, it takes energy that would otherwise go off the side side towards 90 degrees along the baffle surface and focuses it to be more forward facing.
      I'm not deaf, I'm just not listening!

      Comment


      • #4
        Adding a 3rd to Greg's list: the WG moves the tweeter back which can better align the acoustic center of the tweeter with that of the woofer.


        Augerpro has a long thread with lots of experiments with 3D printed waveguides. Doesn't go into a lot of the reasons WGs can be good, but lots of graphs of drivers with and without various WGs. https://techtalk.parts-express.com/f...es#post1398387

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        • #5
          Wave guides work the same way that horns do, because they are horns. What's different about them is that they have throat diameters which are as large or larger than the driver diaphragm. That results in them working as direct radiators above the frequency where the throat diameter is a wavelength or larger. That's true of all horns, but most horns have the throat as small as possible, to load the driver to as high a frequency as possible. Also note that the majority of wave guides use the term for purely marketing purposes. Those unfamiliar with how horns work often associated the term 'horn' with harsh sound, so they avoid them. Using the term 'wave guide' for the exact same product removes that objection.
          www.billfitzmaurice.com
          www.billfitzmaurice.info/forum

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          • #6
            https://www.diyaudio.com/community/t...a-horn.163581/

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            • #7
              Originally posted by dcibel View Post
              Simple explanation, it takes energy that would otherwise go off the side side towards 90 degrees along the baffle surface and focuses it to be more forward facing.
              Well, isn't that what a horn does? All horns are waveguides, but not all waveguides are horns!

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              • #8
                Originally posted by AEIOU View Post

                Well, isn't that what a horn does? All horns are waveguides, but not all waveguides are horns!
                At some high frequency even waveguides offer horn loading. My own definition is a horn offers horn loading to well below the crossover frequency, whereas a waveguide only loads at or above the crossover. YMMV
                Francis

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                • billfitzmaurice
                  billfitzmaurice commented
                  Editing a comment
                  As I already noted one of the requirements for gain, ie., horn loading, is for the throat to be a wavelength or less in dimension. The crossover frequency has nothing to do with it, although the path length and mouth area do. The usual reason to use a wave guide/large throat horn is to realize gain at the lower end of the intended pass band, or to extend the pass band lower than the driver can handle when direct radiating, while having minimal effect above where the throat is a wavelength in dimension. This is all easily modeled using HornResp, as is directivity.

                • fpitas
                  fpitas commented
                  Editing a comment
                  99% of the waveguides I've seen offer little horn loading at the crossover point, just directivity. That's not how I would use a real horn, since part of the point is to reduce diaphragm excursion.

              • #9
                Originally posted by billfitzmaurice View Post
                Wave guides work the same way that horns do, because they are horns. What's different about them is that they have throat diameters which are as large or larger than the driver diaphragm. That results in them working as direct radiators above the frequency where the throat diameter is a wavelength or larger. That's true of all horns, but most horns have the throat as small as possible, to load the driver to as high a frequency as possible. Also note that the majority of wave guides use the term for purely marketing purposes. Those unfamiliar with how horns work often associated the term 'horn' with harsh sound, so they avoid them. Using the term 'wave guide' for the exact same product removes that objection.
                Thank you for your input, but my current understanding is, that all horns are waveguides, but not all waveguides are horns. How much loading is achieved, Is there a major increase in the output/spl as compared to the raw tweeter?

                Comment


                • #10
                  Originally posted by a4eaudio View Post
                  Adding a 3rd to Greg's list: the WG moves the tweeter back which can better align the acoustic center of the tweeter with that of the woofer.


                  Augerpro has a long thread with lots of experiments with 3D printed waveguides. Doesn't go into a lot of the reasons WGs can be good, but lots of graphs of drivers with and without various WGs. https://techtalk.parts-express.com/f...es#post1398387
                  I definitely like time aligned drivers, but that can be achieved via a variety of techniques.

                  Comment


                  • #11
                    Originally posted by dcibel View Post
                    Simple explanation, it takes energy that would otherwise go off the side side towards 90 degrees along the baffle surface and focuses it to be more forward facing.
                    That's too simple of an explanation, not thorough enough.

                    Comment


                    • #12
                      I have my curiosities about waveguides myself. That is why I am using one in my "Misguided" speakers. I am getting a 6db boost at my crossover frequency, which is allowing me to cross lower. I am curious how it helps with directivity. I have heard the claims, but have not experienced them for myself. I do know that unlike traditional horns, adding the waveguide did not affect the impedance of the driver.

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                      • #13
                        Originally posted by johnny5jz View Post
                        I am curious how it helps with directivity...
                        I like this post because it offers nice pictures that I could actually understand.
                        https://www.harmanluxuryaudionews.co...er-waveguides/

                        Comment


                        • #14
                          Originally posted by AEIOU View Post

                          That's too simple of an explanation, not thorough enough.
                          That was a good precise answer to what the wave-guide does. The decision to use one, and how to make it useful to the design vary with the overall goals of the speaker designer. That could take a bit of typing to explain, and every designers goals are not necessarily the same for every speaker.

                          Comment


                          • #15
                            Originally posted by johnny5jz View Post
                            I have my curiosities about waveguides myself. That is why I am using one in my "Misguided" speakers. I am getting a 6db boost at my crossover frequency, which is allowing me to cross lower. I am curious how it helps with directivity. I have heard the claims, but have not experienced them for myself. I do know that unlike traditional horns, adding the waveguide did not affect the impedance of the driver.
                            The 6dB boost on axis comes with a reduction in off axis output, so the tweeter off axis response is weakened at your x-over frequency. You have to decide if that's a good thing, or not. When your x-over flattens the tweeter response, it does not have to play as loud as it would without the wave-guide. That reduces the distortion in the range where there was significant boost. At the x-over point, the woofer is providing half the sound output. Hopefully, it has low distortion in that range, or it could negate the advantage of the lower tweeter distortion.,

                            Comment


                            • Billet
                              Billet commented
                              Editing a comment
                              The reduction in off axis output of the tweeter at the crossover point can be an advantage if designed properly. A low freq driver is typically narrowing at it's high end and a high freq driver usually has its widest dispersion at the low end. This can cause a rapid dispersion change at the crossover point which can cause response irregularities. A properly designed waveguide can minimize this issue and create a smoother transition.
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