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:sos: How would you measure this?
I have a unique 3way that I need to take design measurements for. This is my first 3way and only my second complete design. My application is unique in that it is omnidirectional and all the drivers are firing up or down, so the listening axis is what would normally be considered 90º off axis.
There are two RS225’s firing at each other, centered about 15-3/8” above the floor. They are 4-1/4” apart and have a diffuser separating them. There is a single RS52 mid that sits in a cut down 8” PE waveguide that fires up into an 8" concave cone shaped diffuser. That diffuser holds a Dayton ND20FB in a 6.5” MCM waveguide firing up into a 7.5” concave cone diffuser. There is about 19-7/8” from the center of the woofers to the mid’s WG/baffle and 3-3/16” from the mid to tweeter WG/baffle. Attached is a pdf of the plans.
Since all drivers are omnidirectional throughout their range and are playing in 4pi space throughout their range, it is my understanding that I do not need to worry about making any baffle step adjustments. Also of interest is that the drivers have their VC’s and acoustic centers time aligned to the listening axis at 37” and 12’ away.
So, the question is what is the best ways to take design measurement for these? For a typical two-way, one might simply do gated farfield measurements at one mic position, say 38” high and 1m away for both the woofer and tweeter, and then splice in a nearfield on the woofer to better represent the bottom end. For these, I could see where one mic position, centered between the mid and tweeter might work for those two drivers, but the distances would be off for the woofers, not to mention serious floor bounce issues with them only 15” or so above the floor, requiring the gated window width to be be very short. Also, since the drivers are time aligned at 37”/12’ they will not be time aligned with the mic at any position closer than that, which will ness with the phase accuracy. Of course, I will need to do a nearfield on the woofers, perhaps at the front edge of the speakers, but that won’t help me determine the spl level match with the mids and tweeter. I need something that I can merge the nearfield into that represents the spl level and phase that is comparable to the mids and tweeters.
My initial thought is to set the mic level at the tweeter baffle height, about 38.5” and 1m away. Measure the tweeter output. Elevate the box about 3” and measure the mid. Then elevate the box another 20” and measure the woofers. This way, I can remove the floor bounce cancellation from the woofers and by raising the box, all the speakers are measured at the same distance, so there should not be any phase related issues. I’m thinking I can use the same gated window for all these measurements and that they can be done inside. I would also merge a nearfield on the woofers to better represent the bottom end below 400-500hz or so. Another approach might be to do a ground plan farfield on the woofers, with the distance adjusted so it matches that used for the mid and tweeter
BTW, my projected crossovers are expected to be around 600hz and 4200hz or so. Also, according to BoxyCad2, for a at 37” listening height and 12’ listening distance, the midrange floor bounce null at 396hz and woofers are at 890hz, with a recommended optimum crossover point of 594hz.
Does this seem like a valid approach?
Does anyone have any other approaches I should consider?
I’m very concerned that I’m overlooking something. BTW, I’m using SoundEasy.
Thanks for any comments!
I have a unique 3way that I need to take design measurements for. This is my first 3way and only my second complete design. My application is unique in that it is omnidirectional and all the drivers are firing up or down, so the listening axis is what would normally be considered 90º off axis.
There are two RS225’s firing at each other, centered about 15-3/8” above the floor. They are 4-1/4” apart and have a diffuser separating them. There is a single RS52 mid that sits in a cut down 8” PE waveguide that fires up into an 8" concave cone shaped diffuser. That diffuser holds a Dayton ND20FB in a 6.5” MCM waveguide firing up into a 7.5” concave cone diffuser. There is about 19-7/8” from the center of the woofers to the mid’s WG/baffle and 3-3/16” from the mid to tweeter WG/baffle. Attached is a pdf of the plans.
Since all drivers are omnidirectional throughout their range and are playing in 4pi space throughout their range, it is my understanding that I do not need to worry about making any baffle step adjustments. Also of interest is that the drivers have their VC’s and acoustic centers time aligned to the listening axis at 37” and 12’ away.
So, the question is what is the best ways to take design measurement for these? For a typical two-way, one might simply do gated farfield measurements at one mic position, say 38” high and 1m away for both the woofer and tweeter, and then splice in a nearfield on the woofer to better represent the bottom end. For these, I could see where one mic position, centered between the mid and tweeter might work for those two drivers, but the distances would be off for the woofers, not to mention serious floor bounce issues with them only 15” or so above the floor, requiring the gated window width to be be very short. Also, since the drivers are time aligned at 37”/12’ they will not be time aligned with the mic at any position closer than that, which will ness with the phase accuracy. Of course, I will need to do a nearfield on the woofers, perhaps at the front edge of the speakers, but that won’t help me determine the spl level match with the mids and tweeter. I need something that I can merge the nearfield into that represents the spl level and phase that is comparable to the mids and tweeters.
My initial thought is to set the mic level at the tweeter baffle height, about 38.5” and 1m away. Measure the tweeter output. Elevate the box about 3” and measure the mid. Then elevate the box another 20” and measure the woofers. This way, I can remove the floor bounce cancellation from the woofers and by raising the box, all the speakers are measured at the same distance, so there should not be any phase related issues. I’m thinking I can use the same gated window for all these measurements and that they can be done inside. I would also merge a nearfield on the woofers to better represent the bottom end below 400-500hz or so. Another approach might be to do a ground plan farfield on the woofers, with the distance adjusted so it matches that used for the mid and tweeter
BTW, my projected crossovers are expected to be around 600hz and 4200hz or so. Also, according to BoxyCad2, for a at 37” listening height and 12’ listening distance, the midrange floor bounce null at 396hz and woofers are at 890hz, with a recommended optimum crossover point of 594hz.
Does this seem like a valid approach?
Does anyone have any other approaches I should consider?
I’m very concerned that I’m overlooking something. BTW, I’m using SoundEasy.
Thanks for any comments!
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