This looks better. Time window set to 3,60ms, are Tukey 25% L and R standard REW window settings anyone?
Bad news: you will hardly be able to design a low to mid crossover with such a time window, resolution dwon in the 100s of Hz is too low.
The low mid thing is why my gate settings were what they are. Thanks for taking the time to check the data out.
I have a long drive way to do ground plane but it's a gravel driveway :/
I have a long drive way to do ground plane but it's a gravel driveway :/
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Yoi can approximate errors: if gravel is reasonably flat, objects smaller than say 10cm, measurements have relatively low effect on 1m wavelength and longer. Another, if mic is right on the ground perhaps 3m away, speaker on its side say 30cm wide so that driver center is 15cm above ground, first reflection (from the ground) comes perhaps 5cm later pf dorect sound (questimating), so interference di pwoukd be at 10cm wavelength and shorter, so good data up to about few kilohertz.
Levelwise, you could get it in the ballpark with close range measurements and correction for baffle step plus relative levels (using the cone area for correction, just as with merging nearfield with farfield measurements).
Another issue is that the DC139 has a little bit of a nasty breakup at 3kHz. It showed up at the burst decay plot too. I’d cross it fairly low, under 2kHz.
Another issue is that the DC139 has a little bit of a nasty breakup at 3kHz. It showed up at the burst decay plot too. I’d cross it fairly low, under 2kHz.
Perhaps that's why I prefered the d27 in many cases with a lower xover freq than the nd25fw.
Ah that's where I messing up, I wasn't putting in baffle step correction.
This is what I have to work with
I'm trying to wrap my head around the merging of files and baffle step stuff, here's the woofer data if anyone wants to help out with that. I applied offset to match far field, perhaps I shouldn't have done that yet.
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For bafle step... you have possibility to implement an high shelf eq before audio leave your computer yes?
In your daw as an insert on mix bus ( or control room section) insert a plug and set Q to have 4 octave wide high shelving action, fc determined following formula given there :
https://trueaudio.com/st_diff1.htm
Then adjust ( by cutting high end, not boosting low end, its better for headroom imo) to taste. I usually use headphone i know well as reference of untreated track to find ballpark attenuation value.
In your daw as an insert on mix bus ( or control room section) insert a plug and set Q to have 4 octave wide high shelving action, fc determined following formula given there :
https://trueaudio.com/st_diff1.htm
Then adjust ( by cutting high end, not boosting low end, its better for headroom imo) to taste. I usually use headphone i know well as reference of untreated track to find ballpark attenuation value.
The gravel / grass surface is not a problem from 20 Hz up to about 1k... in fact it may not be a problem even above 1k, it all depends. It is only when you need to do ground plane measurements all the way into the trebel that you need a really smooth surface. You need about 18 ft of distance to the nearest wall to get measurements down to 32 Hz. In other words, about 36 inches between the speaker and the mic, and then 18 ft from the mic to the nearest wall, and 18 ft from the speaker to the nearest wall.
There is an established process to stitch together the near field driver response with the gated far field response, even if the near field gate is as small as 4 ms. It is a multi-step process where you (1) simulate the effect of baffle step (2) measure the near field response (3) adjust the near field response using the baffle step simulation (4) measure the far field response using a reflection free gate (5) merge the adjusted near field response into the gated far field response. The final result is (in theory) a full range anechoic equivalent response.
I have done this technique many times, and I have compared the results with a ground plane measurement. With good lab technique, the nearfield-farfield merge is within 1 dB of the ground plane response.
There is an established process to stitch together the near field driver response with the gated far field response, even if the near field gate is as small as 4 ms. It is a multi-step process where you (1) simulate the effect of baffle step (2) measure the near field response (3) adjust the near field response using the baffle step simulation (4) measure the far field response using a reflection free gate (5) merge the adjusted near field response into the gated far field response. The final result is (in theory) a full range anechoic equivalent response.
I have done this technique many times, and I have compared the results with a ground plane measurement. With good lab technique, the nearfield-farfield merge is within 1 dB of the ground plane response.
I'm not having good luck with the baffle sim, trying to use Jeff's tools and they don't seem to work in my versions of excel I have access to.
result of trying ground plane, looks like butt 🙂 1meter and 2 meter(green) There's a hump around 180hz which is where that resonance is I heard. Doesn't show up in woofer close mic but it does when you back away, so maybe it comes in when the port and woofer combine farther away.
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Port data is on post 88
its with filtering on though, I don't wanna run around in circles again with this problem...
https://www.diyaudio.com/community/threads/help-with-3-way.400834/page-5#post-7399438
its with filtering on though, I don't wanna run around in circles again with this problem...
https://www.diyaudio.com/community/threads/help-with-3-way.400834/page-5#post-7399438
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I have seen tests where the nearfield-farfield method gives result VERY close to ground plane or anechoic.
@wafflesomd - (1) I assume you have a copy of Jeff's white paper on measuring down to 10Hz, (2) just use VituixCAD to merge.
You DO need decent merged low frequency measurements for a three way like you are working on.
While convenient to confirm your box modeling, you do NOT need port measurements since that is well below the crossover frequency.
I understand the steps, but I'm kinda confused when it comes to executing them with the software.
Have you considered using VituixCad? I find the merger feature to be very easy to use. You do not need to master every aspect of VituixCad to start using some of the features.
Have you tried this approach for applying the baffle step response to your nearfield then splicing with the farfield? It uses REW to do the splicing / merging and Edge to do the baffle step and diffraction response generation (that you import into REW):
https://drive.google.com/file/d/1Nb...stdXUrRBhMZqHjS9aVrtTcqE72gY-xawgosp2tSyF5PBA
That way you can avoid Excel related issues.
If you want me to use Jeff's FRC tools - post your files here and I'll run them so you can compare.
https://drive.google.com/file/d/1Nb...stdXUrRBhMZqHjS9aVrtTcqE72gY-xawgosp2tSyF5PBA
That way you can avoid Excel related issues.
If you want me to use Jeff's FRC tools - post your files here and I'll run them so you can compare.
Basta just crashes on my computer.
I'm confused, how does one export baffle step and no baffle step?
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@DcibeL wrote a nice PDF guide for this, I think. Can't remember the link.
Here it is: https://www.diyaudio.com/community/threads/vituixcad-for-newbies.391824/post-7163363
You could just attach your measurement files and let Dave do it. 🙂
Here it is: https://www.diyaudio.com/community/threads/vituixcad-for-newbies.391824/post-7163363
You could just attach your measurement files and let Dave do it. 🙂
