This thread is to report on an attempt to make develop a waveguide for use with the Neo3pdr and/or Neo3w. DanP and I worked together to come up with the specs for 4 waveguide prototypes, which he then produced and sent to me. I ordered a Neo3pdr and a Neo3w to test in the waveguides. I received the PDR, but the W is on backorder and I should be here next week.
All tests were done using Jeff B’s method of placing the tweeter face up on the floor. These are therefore quasi infinite baffle measurements. I placed a cardboard baffle over a piece of 2x6 with an opening cut in the 2x6 large enough to house the tweeter. All measurements were taken at 69mm from the center of the driver face. A 2.7ms gated window was used to keep out as many reflections as possible. Flat baffle measurements were done by doing a cutout in the cardboard baffle to simulate a flush mount. For measurements with the waveguides, they were placed on top of the tweeter and held only by gravity. Insulation was placed around the WG edges to try and reduce any diffraction from the WG edges, should there be any.
Obviously, these are not high quality measurements or ones that can be used for design purposes. The sole purpose was to do some quick and easy evaluation of these waveguides.
These are the Waveguides used:
1. 132mm H x 165mm W x 39mm D with 90 degree throat termination
2. 132mm H x 165mm W x 39mm D with 61 and 71 degree throat terminations
3. 105mm H x 140mm W x 25mm D with 90 degree throat termination
4. 105mm H x 140mm W x 25mm D with 56 and 71 degree throat terminations
All have 54mm H x 35mm W throat openings and a 13mm lip for mounting
The first measurements were taken on a flat baffle. Shown is 0-15-30-45 horizontal off axis.
I also took measurements at 20mm, 40mm, 69mm and 123mm of the same tweeter and one of the waveguides, to see if the infinite baffle fell apart as you changed distance from the tweeter to the mic. As you can see, all the measurements track very well at all distances, so I stayed with 69mm.
I will post the individual results next. The results for the Neo3w should be completed next weekend and I will post the results here at that time.
All tests were done using Jeff B’s method of placing the tweeter face up on the floor. These are therefore quasi infinite baffle measurements. I placed a cardboard baffle over a piece of 2x6 with an opening cut in the 2x6 large enough to house the tweeter. All measurements were taken at 69mm from the center of the driver face. A 2.7ms gated window was used to keep out as many reflections as possible. Flat baffle measurements were done by doing a cutout in the cardboard baffle to simulate a flush mount. For measurements with the waveguides, they were placed on top of the tweeter and held only by gravity. Insulation was placed around the WG edges to try and reduce any diffraction from the WG edges, should there be any.
Obviously, these are not high quality measurements or ones that can be used for design purposes. The sole purpose was to do some quick and easy evaluation of these waveguides.
These are the Waveguides used:
1. 132mm H x 165mm W x 39mm D with 90 degree throat termination
2. 132mm H x 165mm W x 39mm D with 61 and 71 degree throat terminations
3. 105mm H x 140mm W x 25mm D with 90 degree throat termination
4. 105mm H x 140mm W x 25mm D with 56 and 71 degree throat terminations
All have 54mm H x 35mm W throat openings and a 13mm lip for mounting
The first measurements were taken on a flat baffle. Shown is 0-15-30-45 horizontal off axis.
I also took measurements at 20mm, 40mm, 69mm and 123mm of the same tweeter and one of the waveguides, to see if the infinite baffle fell apart as you changed distance from the tweeter to the mic. As you can see, all the measurements track very well at all distances, so I stayed with 69mm.
I will post the individual results next. The results for the Neo3w should be completed next weekend and I will post the results here at that time.
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