about 1,600Hz to about 3,200Hz, the amplitude of the diffracted audio gets softer from the rounding over of the edge until it completely goes away above 3,200Hz and the response is smooth. This demonstrates how the edge diffraction changes the comb-filtering frequencies as the mic moves off center.īelow about 1,600Hz the diffraction is at it's maximum as the rounding over has no impact on the diffraction. As the mic moves to the side, the distance from one side edge gets shorter and the distance from the other side edge gets farther away. I normalized all of the responses to the directly forward, 0 degree, on axis measurement so each subsequent measurement shows how the response changes from the direct response. All of those charts are shown below from 500Hz to 20,000Hz. I took a frequency response measurement about 19" from the speaker directly on axis then at 7.5 degree off axis until I reached 90 degrees, or directly to the side. Using real world measurements, I am able to show the impact of this effect in real life. Still, below a certain frequency there will be edge diffraction as any sound which travels along the face of the baffle (90 degree, or perpendicular, to the driver) will be create diffraction with it encounters the edge. The edges of the baffle are rounded over with a 1/4" router bit to give the look a softer edge and to reduce the impact of edge diffraction. There is also a small flare on the tweeter which extends from the edge of the dome's voice coil by about 1/4" all around. Here's a photo of the face of the baffle with dimensions written over it:Īs you can see, the driver is positioned on the center width, but offset on the height dimension. They sound pretty good, but while making gated measurements (pseudo-anechoic) I couldn't help but notice some prominent comb filtering caused by baffle edge diffraction and more. I recently completed a set of Lil Joker satellite speakers which are based around a Dayton Audio Coaxial speaker.
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