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Driver geometry questions

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  • Driver geometry questions

    I'm learning how to use Jeff's 'Passive Crossover Designer'. I have watched all the Tube videos on this program but I'm still confusf on how to set up the Driver Geometry (circled in the pic). I know how to convert inches to meters. For example purposes, how would i set up driver geometry in a 2-way design using a Dayton Classic 5-1/4" round woofer and the round Dayton Classic 1-1/8" silky tweeter? Do I leave the Woofer "Y" value 0.000 and make the Tweeter "Y" value -0.??? (? = the distance the tweeter centnr would be when placed above the woofer). Also, do I need to worry about the Woofer "Z" value? If I do, would that value need to be a negative (-0.???) value? Say a -1/2" to -3/4" since its such a small woofer. Thanks for any help.

    Thanks for whoever suggested changing the settings in Windows to make things on the screemm super huge so I can see better.

  • #2
    If you hover over the boxes with red triangles in the upper right corner, they will pop up with tips that explain each setting. Typically, you use the tweeter as a reference, so it will be at position 0,0,0 (x,y,z). In your example, let's assume you have a 2-way TM with the woofer directly below the tweeter on the baffle. The woofer X position would stay zero since there is no offset. If there is an offset, a negative value is to the left of the tweeter and a positive is to the right. They Y position of the woofer would be meters (center to center distance on the baffle) since it's below the tweeter. A positive value would be above the tweeter. The Z value is the acoustic offset. This is arguably the most critical value (depending on crossover frequency) because a very small difference will result in a large change in the acoustic phase relationship between the drivers. This needs to be measured acoustically. There are lots of references on the forum as to how to do that. A negative Z value is typical for a woofer as that puts the acoustic center of the woofer further from the microphone than the tweeter.


    • #3
      If the tweeter is directly above the woofer center and not offset to one side the horizontal offset is 0. The vertical offset is a physical measurement from tweeter center to woofer center up and down ( same as it would be side to side if there was a horizontal offset left or right), so since tweeter is usually always the zero point, if the woofer center was say 125mm below tweeter center your vertical offset would be tweeter 0, woofer -0.125m. If you can’t measure the z axis due to no measuring equipment, you will need to make an educated guess. With your drivers I would guess at (tweeter 0) woofer -20mm, or -0.020m.

      From what I have read, been told, and found, a typical 6.5 woofer is about -25mm from a typical dome. So for your 5.25 I just am guessing a little less. Could be off.
      Last edited by dynamo; 04-22-2018, 09:06 AM. Reason: Added a little more info

      Breezy Monitors:
      Vintage Style 2-way:


      • #4
        I think I have j pretty good grasp on how to set things up now. Not knowing what driver to use as a starting point confused me the most but now I know. Thanks for both responses, they helped.