Announcement

Collapse
No announcement yet.

Best Volume for an Open Midwoofer in a 3-Way

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Best Volume for an Open Midwoofer in a 3-Way

    I'm considering designing a 3-way using an open midwoofer - I've always used closed mids in the past, so this would be my first design using this type of driver - and my question has to do with how to determine the optimum volume for this driver. Would the enclosure size affect how the mid sounds? What are your design mantras in regards to open midwoofers. Thank you.

    Hong
    Some people are addicted to Vicodin. I'm addicted to speaker building.

    The Chorales - Usher 8945A/Vifa XT25TG Build
    ESP Project 101 Lateral MOSFET Amplifier
    LM4780 Parallel Chipamp
    Sonata Soundbar Project
    The Renditions - Active/Passive Towers

  • #2
    For an open back mid you do not want an enclosure. Any enclosure will create a resonance you will have to deal with in the crossover. An enclosure tube or box can help to extend the low end response of a woofer but that's not usually required for a mid.

    Thing 2 would be to design the mid to reach the tweeter with constant directivity. This is often ignored, but off axis drop outs where the rear wave is out of phase with the front wave can be avoided by crossing the tweeter below the first dipole null of the mid.
    John H

    Synergy Horn, SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

    Comment


    • #3
      I'm confused. Are we talking about an open baffle design for the mid or the mid having its own box (sub-enclosure) within the enclosure? If it's not OB, shouldn't there be a sub-enclosure for the mid so it is less impacted by the back wave of the woofer? I always assumed that the enclosure was typically about the size needed for a sealed design for the mid with appropriate damping material included.

      Comment


      • #4
        No, it's not an open baffle design Paul. Just a regular 3-way vented system using an open back mid. John, I'm slightly confused over your explanation above. Care to expand on that? Thanks.
        Some people are addicted to Vicodin. I'm addicted to speaker building.

        The Chorales - Usher 8945A/Vifa XT25TG Build
        ESP Project 101 Lateral MOSFET Amplifier
        LM4780 Parallel Chipamp
        Sonata Soundbar Project
        The Renditions - Active/Passive Towers

        Comment


        • #5
          Hong, not trying to change your mind, but one of my favorite open back mid designs is the Nola concept. You might take a look. I think Dan N did a design like you are talking about, and maybe Paul K.
          craigk

          " Voicing is often the term used for band aids to cover for initial design/planning errors " - Pallas

          Comment


          • #6
            Craig, do you have a link? Thanks man.
            Some people are addicted to Vicodin. I'm addicted to speaker building.

            The Chorales - Usher 8945A/Vifa XT25TG Build
            ESP Project 101 Lateral MOSFET Amplifier
            LM4780 Parallel Chipamp
            Sonata Soundbar Project
            The Renditions - Active/Passive Towers

            Comment


            • #7
              Originally posted by hongrn View Post
              Craig, do you have a link? Thanks man.
              Will send you one this evening
              craigk

              " Voicing is often the term used for band aids to cover for initial design/planning errors " - Pallas

              Comment


              • #8

                Comment


                • #9
                  I was confused, my comments were for a open baffle mid. For a open framed driver in the mid range position, I like sealed with a Qtc of .55 where the driver Qts is low. I also like the variable stuffing density practice to control reflections.
                  John H

                  Synergy Horn, SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

                  Comment


                  • #10
                    https://en.wikipedia.org/wiki/Standing_wave

                    Comment


                    • #11
                      Quick question about open baffle mids- if back of enclosure is open and x/o point is quite high, say 4khz, does this cause more of an issue? Sent from my SM-G950F using Tapatalk

                      Comment


                      • #12
                        Originally posted by jhollander View Post
                        I was confused, my comments were for a open baffle mid. For a open framed driver in the mid range position, I like sealed with a Qtc of .55 where the driver Qts is low. I also like the variable stuffing density practice to control reflections.
                        Can you elaborate on the variable stuffing density approach? Is it just what it sounds like, and how is that better than a fixed stuffing density throughout? Thanks in advance...

                        Francis
                        Francis

                        Comment


                        • #13
                          Originally posted by bill poster View Post
                          Quick question about open baffle mids- if back of enclosure is open and x/o point is quite high, say 4khz, does this cause more of an issue? Sent from my SM-G950F using Tapatalk
                          Hi Bill,

                          All of the Statements are crossed around 3.7K. How that interacts with the cabinet depth is a Curt question. He doesn't frequent any of the forums these days so an email from his website would probably be the best way to contact him.

                          Jim

                          Comment


                          • #14
                            Paul, jclin4 and Jim, thank you for your replies. My first instinct was to use the sealed/stuffed enclosure that Paul suggested, but I'm intrigued about Curt's write up. Jim, do you happen to have a pic of the mid enclosure anywhere? Thanks.

                            Craig, good talking to you. Can't wait to see your project. Thanks.
                            Some people are addicted to Vicodin. I'm addicted to speaker building.

                            The Chorales - Usher 8945A/Vifa XT25TG Build
                            ESP Project 101 Lateral MOSFET Amplifier
                            LM4780 Parallel Chipamp
                            Sonata Soundbar Project
                            The Renditions - Active/Passive Towers

                            Comment


                            • #15
                              Originally posted by hongrn View Post
                              Paul, jclin4 and Jim, thank you for your replies. My first instinct was to use the sealed/stuffed enclosure that Paul suggested, but I'm intrigued about Curt's write up. Jim, do you happen to have a pic of the mid enclosure anywhere? Thanks.

                              Craig, good talking to you. Can't wait to see your project. Thanks.
                              Hi Hong,

                              Here's a link to Curt's website where many of our projects are fully documented; http://www.speakerdesignworks.com/Anthology_1.html

                              I built the mid tunnels in the Statements series rather than use PVC only because I couldn't find 5" PVC at a reasonable price. I needed 5" because the mids are considered 4" in the Statements. The Anthology's use 5 1/4" mids so 6" PVC was perfect. Either way works fine.

                              Also, due to the open back design, 12" - 36" from the wall behind is required for them to sound as designed.

                              HTH

                              Jim

                              Comment

                              Working...
                              X