AndreNewman
Prominent Member
It's here:Attachment missing?
It's here:Attachment missing?
Thanks, I renamed to .mdat.txt but both times the attachment never appeared, strange it's worked before.Either zip them, or rename them to TXT files, both work for attachments.
The filter is a combination of the woofer correction, filters 4,5,&6 and tweeter 1,2&3. The 24dBLR crossover was done in the Crown XLS1502 power amp so after the processors PEQ. I then added filter 7 an additional correction from the measurements I got from the combined filers and crossover.just looking at the correction filter, you showed
View attachment 1762052
and (I think) said the W correction was based on NF which looks like a fairly typical rolloff
View attachment 1762053
I don't see how you get from one to the other
Sorry, I thought I'd picked out the relevant measurements so you could see what I started with and the progression as the crossover and each PEQ was added.fwiw the mdat is v hard to follow because it contains a mix of measurements + intermediate stuff
Is there some canonical guide to this?what you might say is a traditional approach does work well... take measurements (not just on axis) and as quasi anechoic as you can,
Listening window is about dispersion, angles from the axis of the driver?decide how to combine them to design purposes (listening window, power response, some combination or whatever)
In your opinion is 15 degrees enough for a coaxial or should I ignore on axis and average 15 and 30 degrees, to avoid over correcting the on axis response?The five frequency response measurements that are averaged for the Listening Window are: on-axis, 15 degrees left and right off-axis, 15 degrees up and down off-axis.
That's what my measurements were, I thought...and then design filters against that, listen, repeat to fade.
not really, https://kimmosaunisto.net/Software/VituixCAD/VituixCAD_Measurement_REW.pdf gives a good view on how to measure but leaves you to your own devices on how to design the XO. You just have to read a bunch of threads basically and look at other designs.Is there some canonical guide to this?
perhaps a picture helps, this is my CD 0-45 degrees at ~7.5 degree steps. The highlighted line is a vector average of those (a quick example of what you might use as a listening window measurement). Power response takes that further and is basically the total power radiated by the speakerListening window is about dispersion, angles from the axis of the driver?
it's the naming of the measurements that is a bit confusing along with the not so obvious EQ referencesSorry, I thought I'd picked out the relevant measurements so you could see what I started with and the progression as the crossover and each PEQ was added.
The cyan one looks different too as far as I can seeThe only real discrepancy is the eBay driver I haven't done anything with yet, it's the green one in both graphs.
The massive mic holder looks bad for this purpose, the ideal is a really long pole exactly the diameter of the mic housing (never worked out how to make such a thing myself)I posted a pic of the setup I used for measuring here.
Yeah, I ran several sweeps on each driver and there seemed to be small variations each time so hopefully it's not too significant.The cyan one looks different too as far as I can see
Ah, thanks, that I can change easily.The massive mic holder looks bad for this purpose, the ideal is a really long pole exactly the diameter of the mic housing (never worked out how to make such a thing myself)
I'll double check the wiring, I just checked and the amp I'm using doesn't inherently invert so I don't know why it would be inverted.to highlight a couple of points about the 1m measurement
firstly, it seems inverted
There are thick three layered curtains on the back and side walls, ceiling is bare though.secondly, once the speaker itself dies down then you can see a lot still going on such that there is no obvious first reflection. This is good in some respects (something must be damping down the first reflection)
There is a bookcase near the back wall, maybe there's enough diffraction from that to create the mess?but not in others (there's too much signal bouncing around making some degree of mess
so your freq resp is noisy
View attachment 1763693
for comparison, taken roughly in my yard (which isn't massive and has big hard brick walls nearby but no ceiling cos it's outside and the speaker was a reasonable distance from the floor)
Very diplomatic, thank you.I think this driver is inherently difficult to measure mind you, bound to get a load of diffraction mess given it's built into the design
Seems not is, i.e. it looks like it might be. I don't recall seeing such behaviour (extremely strong extremely early reflection) before, depending on your appetite for risk/tweaking you might try reseating the diaphragm on the CD to see if it changes. This could also be worth trying on the driver that behaves differently to the others on the impedance sweep.first peak is an upswing, so why do you say it's inverted?
I haven't seen much of anything before and it looks pretty wonky to me too.Seems not is, i.e. it looks like it might be. I don't recall seeing such behaviour (extremely strong extremely early reflection) before,
No problem, I've done a lot of miniature camera work, microscopic electronics and lens rebuilding, I have suitable tools, I'm happy to have a go.depending on your appetite for risk/tweaking you might try reseating the diaphragm on the CD to see if it changes.
I'm going to try a few of the other drivers in the box too, that should tell me if it's the box or the drivers it seems it's not the environment.This could also be worth trying on the driver that behaves differently to the others on the impedance sweep.