Everything was the same between both FR measurements except for the port and the volume it displaced from the box volume. The slight level mismatch is from the change in level setting on my mic mixer. The box had the same 1" foam lining on 4 of the interior sides. I think for purposes of of the crossover design you could get by with the sealed box measurements.There's really note much difference between the two from 400 up.
The ported woofer measurement was extremely flat until I added the box diffraction and looking at the current crossover sim I felt that I'd like to try to improve the woofer crossover. I have been able to flatten it out with the addition of a traditional BSC circuit (a coil in parallel with resistor) and by moving the crossover point down to 800. The next step is to see how well I can get that to mate with the mid-range. I'll look into moving the port tuning up after I measure with the actual crossover. I wish every driver sim I did looked as good as this one.
Hi Ron, when you measure the drivers in box, wouldn't hte baffle / box diffraction already be in the measurements?
I am confused by when you said, "until I added the box diffraction" - Is this a simulation of the baffle response or actual measurement?
It's a simulation of the box diffraction. With gated measurements you can only trust the far field measurement down to the frequency set by the earliest room reflections. In SoundEasy you measure the far field. Then you measure near field and sum that with the port response. Then you add the diffraction to the near field + port FR. After that you splice the far field with the near field with box diffraction measurements. If you look at some of the woofer FR plots you can pick out the splice around 400 Hz. This is the what the baffle step sim looks like and you can see it echoed in the far field measurements above 400Hz in the FR measurements posted earlier.
Comments
The ported woofer measurement was extremely flat until I added the box diffraction and looking at the current crossover sim I felt that I'd like to try to improve the woofer crossover. I have been able to flatten it out with the addition of a traditional BSC circuit (a coil in parallel with resistor) and by moving the crossover point down to 800. The next step is to see how well I can get that to mate with the mid-range. I'll look into moving the port tuning up after I measure with the actual crossover. I wish every driver sim I did looked as good as this one.
Ron
I am confused by when you said, "until I added the box diffraction" - Is this a simulation of the baffle response or actual measurement?
It's a simulation of the box diffraction. With gated measurements you can only trust the far field measurement down to the frequency set by the earliest room reflections. In SoundEasy you measure the far field. Then you measure near field and sum that with the port response. Then you add the diffraction to the near field + port FR. After that you splice the far field with the near field with box diffraction measurements. If you look at some of the woofer FR plots you can pick out the splice around 400 Hz. This is the what the baffle step sim looks like and you can see it echoed in the far field measurements above 400Hz in the FR measurements posted earlier.
Ron