Need help interpreting measurements

[montana1]

Hi Lojzek,
I'm away from my computer today and not able to double check any phase errors that you mentioned. I may be able to shed some light though. All the files that were attached in the above posts were raw measurements that included unwrapped phase in REW without minphase extracted. Now the screenshots of Xsim schematics include files with minphase that has been extracted in Response blender when merging farfield and near fields or RM in the case of the tweeter. Hope that information adds some clarity. Please let me know if there is something I have overlooked.

Tony,
I feel bad this exercise has turned into a headache rather then something fun. Hopefully, as I type this you have the offsets overlayed correctly. Oh, mic distance for the farfield measurements was 27 inches. I'm still confused why in Xsim there would be any issues aligning offsets. I will check back in periodically through the day if you have anymore questions.

Best,
Rich

[mkane77g]

Out golfing are ya

[montana1]

Hi Wish! Boring all day seminar but required to keep my Pesticide license. I'm required by the State of Idaho to have 15 hours continued education every 2 years. So here I am, dreading the start of an incredibly long day. Rather be working on my speaker projects.

Best,
Rich

[wintermute]

Don't feel bad Rich, I assumed that the measurements had already had minimum phase extracted! Now I know why I am having the issue

That's the reason for doing a sanity check, to make sure what I think I'm working with is actually what I'm working with The old addage, never assume, it makes an *** out of u and me!

Tony.

[montana1]

Hi Tony,
That makes me feel a lot better that you are not upset with the whole process. When I'm able to resume working on this tomorrow morning, my first order of business will be to extract minphase from all my farfield measurements. I'm really interested in what settings you arrive at in PCD7 for offsets. Could you post your findings? Even though most of my work will be in Xsim, I will still use PCD7 to see power response as jReave suggested.

Best Regards,
Rich

[wintermute]

Using FRD's with miimum phase works a lot better

I would say that your waveguide combined with this woofer has given you almost perfect time alignment (at least at that measuring mic position).

I didn't have to use any z offset at all. + or - 1mm makes small differences but I think overall it is best left at zero in PCD. See below:

Also works much better in speaker workshop, but not quite as good a match as PCD.

Tony.

[montana1]

Hi Tony,
That is Awesome! I'm glad that the file mystery is solved. I will go through my files tomorrow morning and extract minphase as well. This has been quite the learning experience for me. I'm glad that I sought out second opinion before proceeding with purchase of Xover parts because there probably will need to be changes made to design once correct offsets are included.. While I'm going through my files tomorrow I will look to experiment with smoothing or lack thereof in REW.

Much Thanks!
Rich

[montana1]

Hello Guys,
I'm back once again with another Xover version for consideration. This with corrected phase as pointed out by Lojzek in prior posts. It was an eye opener as how greatly phase effects offsets. I had to remove all mod delay from woofer (.66 inches) and apply 1.22 inches to tweeter in Xsim to get overlays to align. I'm pretty certain things are correct now.

Take note the slight differences in frequency response between Xsim and PCD7. I think the differences could be that in PCD7 I changed the listening distance to 2.00 meters and Xsim it is based on .686 meters (true mic measurement distance). I could have imported a summed response from PCD into Xsim with 2.00 meter distance but have not done that as of yet. I probably will be using PCD7 to make any minor design changes and use Xsim to print a nice schematic to build the Xover. Also, I have attached woofer and tweeter sections from PCD7. Please let me know if it does not match to Xsim schematic in regards to parts layout.

I really appreciate the excellent advice and direction that has been offered in this thread!

Thanks To All,
Rich

[montana1]

And one more Xsim version....

This version has not been changed much from prior post but does reflect an offset adjustment. I took a summed response from PCD7 at 2 meter listening distance and imported it into Xsim. It required reducing tweeter mod delay from 1.22 to .44 inches to align overlays. You can see now that both PCD7 version and Xsim agree. Also, I removed resonant compensation filter from schematic. It probably is not altogether necessary other then to flatten impedance some.

Guys, let me know if I can go to press with this version. I would like to get a Parts Express order together and coming my way.

Best,
Rich

[Lojzek]

Rich, post the XSim dxo file zipped, perhaps the filter can be made simpler.