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Quad Vertical Array and Baffle Step

JasonPJasonP
in DIY
So I started exploring this idea this morning and figured I'd share it here early on with more data coming as I test it out.

So it struck me that using a set of four drivers is +6db voltage sensitive, the exact amount you lose from full baffle step. Could drivers be arranged on a baffle to compensate for baffle step without much (or any) XO adjustment? Then I fired up WinPCD, loaded in 4 woofers (two as woofers, and two as midrange) and spaced them out vertically. I clicked on the polar plots and here is what I was able to come up with by playing with different spacings:



The red line is the on-axis output of the quad of drivers, and the black line is the averaged hemispherical output. Does that difference look familiar? Sort of the opposite of baffle step.

So the real test will be in the listening, as the first arrival response isn't impacted, just the power response. I'm imagining that ultimately a small slope will still be needed but much less than what you might expect from normal baffle step compensation.

More to come soon!
= Howard Stark: "This is the key to the future. I'm limited by the technology of my time, but one day you'll figure this out."
D1PP1N4thtry

Comments

  • rjj45rjj45
    I built a small (ish) tower as 2.5 way WWWW-MTM - like the Stentorians or Uluwatus.
    Really, really love the bass. My working threory is that the mutlple vertical woofers excite and smooth out room modes. You are right, you don't need as much BSC.
    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • D1PP1ND1PP1N
    Hmmm, interesting, a nice 7-8" driver that digs deep in a small cabinet would be awesome space wise. 
  • ani_101ani_101
    4 vertically soaced woofers would definitely fill in the floor bounce.... But why baffle step, especially if the baffle is not changing shape. The waves still have to wrap around the same....

    Also could you elaborate +6db voltage sensitivity.
  • rjj45rjj45
    ani_101 said:
    4 vertically soaced woofers would definitely fill in the floor bounce.... But why baffle step, especially if the baffle is not changing shape. The waves still have to wrap around the same....

    Also could you elaborate +6db voltage sensitivity.
    Well, you've got 1 woofer very near the floor (3-4 inches) and the woofer above it sort of close to the floor.  The lowest woofer is pretty much in 2Pi space, and the woofer above it contributes a little. In my experience, this contributes 2 - 2.5 dB of total BSC.
    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • JasonPJasonP
    ani_101 said:
    4 vertically soaced woofers would definitely fill in the floor bounce.... But why baffle step, especially if the baffle is not changing shape. The waves still have to wrap around the same....

    Also could you elaborate +6db voltage sensitivity.
    Well we hear both first arrival and power response, so testing would be required in this case. Hence the experiment. Destructive interference changes the power response such that baffle step might need to be reduced, listening tests to confirm.

    +6db voltage sensitivity is from the 4 drivers in parallel/series. Same impedance, but 4x the surface area increases sensitivity. Also an increase in apparent vas is evident.
    = Howard Stark: "This is the key to the future. I'm limited by the technology of my time, but one day you'll figure this out."
  • Nicholas_23Nicholas_23
    Cant wait to see these suckers
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