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Multi-Way Conventional loudspeakers with crossovers

rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
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Old 25th November 2019, 01:19 AM   #2871
BYRTT is offline BYRTT  Denmark
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rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
Quote:
Originally Posted by Oabeieo View Post

...My question is, if the box , the cabinet causes a natural roll off at 45hz but the room boosts below it and you say it acts as a Linkwitz Transform, that would mean it’s minimum phase and doesn't need any farther work done from Rephase

I was wondering I guess if room gain is minimum phase now that I think about it...
First will say remember room is global so don't count its corrections dedicated for the lowest pass bands but as global for the summed system passband, and yes room gain is of minimum phase except the reflections that arrive late at listening position, one can repair late reflections but think forget about it because correction only works at that particular spot in space where microphone was positioned. Reflection free is no room but we can get superior sound with a perfect dialed in speaker system corrected for room gain and a house curve that is tweaked to suit the speaker/room profile.


Below is sim model your system HP stopband with the red curve, you can see the numbers in first row, next i set the program WinSpeakerz model for auto cabin response with the numbers in second row. Now look the blue curve it is hot and worthless in you get a flat boost all the way down to DC, this will sound bloated with DC thumbs and mud sound signature way up into higher frq.

rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool-o_1-png


Cure for that if WinSpeakerz model is spot on is a linkwitz transform as the first two rows below, first it linearize your HP stopband to flat in row 1 then in row 2 the new 66Hz HP stopband is set, now we are flat down to DC because remember your system is at 2nd order 66Hz corner and auto cabin response boost a 2nd order 66Hz flat down to DC, therefor set some HP filter in area 15-20Hz (15Hz 2nd order used below). Overall correction is the blue curve and red curve is your new speaker plus room HP response, hope it makes sense ...

rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool-o_2-png
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Old 25th November 2019, 02:35 AM   #2872
Oabeieo is offline Oabeieo  United States
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Quote:
Originally Posted by fluid View Post
That was pretty much the discussion that was had above. If you linearize the sealed box you will change the phase away from minimum and end up with a phase that does not follow the amplitude response.

Measure the result you have and use REW with a FDW to clean up the phase, generate a minimum phase version in REW and compare to what you have. If there's excess phase you can export that and use rephase to try and correct for it and see if you like that any better.
Perfect answer thank you!

I love getting steps to follow. That helps so much.


So one thing I learned big time from the conversation is that the crossover shifts more than just the spin. This is invaluable to me. It seems as if a low pass moves everything below it back a little bit.


So my next step beyond making linearized crossovers is trying to attempt a room correction. I wanted to get the crossovers done right and I’m think I’m there for the most part. I’m sure there’s some that could be better, but it’s fairly good I think. This conversation definitely helps me know what’s going on.

I have run countless sims with rephase to study what the phase does when I apply all kinds of situations with no measurement imported just to see what it looks like and that too has taught me a lot but I can say I’ve never noticed how the phase gets moved back all the way into the lows from the highs. So this is great.

But this brings up another question now.


So I’ve been running more sims just now noticing this effect an it makes me wonder how using peq on each channel/speaker output and not gloabal eq isn’t detrimental.

In my case I have 12ch of dsp (I’m only using 10) I have front door midbass , kickpanel midrange , Horns , subs, rear door midbass. If I do close mic measurements and make all of them flat prior to any global eq for listening position measurements and eq would not the phase be scattered all over the place?

Earlier you said time align the drivers. Which I’ve done using tape measure distance, wouldn’t the peq change the time at some frequencies and not others?

If this effect happens wouldn’t the driver peq be detrimental to the timing of everything? If a lot of eq is required couldn’t it be as bad as randomly putting on an APF in places it doesn’t belong?

Seems to me now gloabal eq is the only acceptable eq to use if this is what happens.

As an experiment I just tried turning off all my other eq and tried using only gloabal eq (it was quick n dirty but just to see) and it definitely seems better in some ways. But I can’t say for sure

What do you think, how does that part function?


Quote:
Originally Posted by BYRTT View Post
First will say remember room is global so don't count its corrections dedicated for the lowest pass bands but as global for the summed system passband, and yes room gain is of minimum phase except the reflections that arrive late at listening position, one can repair late reflections but think forget about it because correction only works at that particular spot in space where microphone was positioned. Reflection free is no room but we can get superior sound with a perfect dialed in speaker system corrected for room gain and a house curve that is tweaked to suit the speaker/room profile.


Below is sim model your system HP stopband with the red curve, you can see the numbers in first row, next i set the program WinSpeakerz model for auto cabin response with the numbers in second row. Now look the blue curve it is hot and worthless in you get a flat boost all the way down to DC, this will sound bloated with DC thumbs and mud sound signature way up into higher frq.

Click the image to open in full size.


Cure for that if WinSpeakerz model is spot on is a linkwitz transform as the first two rows below, first it linearize your HP stopband to flat in row 1 then in row 2 the new 66Hz HP stopband is set, now we are flat down to DC because remember your system is at 2nd order 66Hz corner and auto cabin response boost a 2nd order 66Hz flat down to DC, therefor set some HP filter in area 15-20Hz (15Hz 2nd order used below). Overall correction is the blue curve and red curve is your new speaker plus room HP response, hope it makes sense ...

Click the image to open in full size.



Would it help to post room responses for sub?

I can do that , if so should I turn off all eq ?

Last edited by Oabeieo; 25th November 2019 at 02:54 AM.
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Old 25th November 2019, 04:11 AM   #2873
Oabeieo is offline Oabeieo  United States
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so here is some measurements of just the sub at listening position, I also took screenshots of the eq pages even tho its not in measurements.

In can post up the actual file or send it if it helps.

I would love to know what to do!

the sub seems like the hardest part to get sounding the best

Super dooper appricated !!!









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Old 25th November 2019, 04:24 AM   #2874
Oabeieo is offline Oabeieo  United States
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sub.zip




here is the mdat



And those measurements do have the linearizations applied and a 80hz crossover applied

There’s a big dip I don’t know what to do with and all that room gain

Last edited by Oabeieo; 25th November 2019 at 04:29 AM.
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Old 25th November 2019, 06:52 AM   #2875
Oabeieo is offline Oabeieo  United States
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so I did this in rephrase, it sounds good..much better with butterworth 6db 20hz hpf

but I don't know what to do with excess phase.....

do I make it flat? look at that around 80hz geesh
this is what I meant by hard to figure out sub measurements...the midbass was much easier


RED is unchanged measurement, blue is the correction ....what am I missing

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Old 25th November 2019, 10:48 AM   #2876
fluid is offline fluid  Australia
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I don't understand what is in the mdat is it a raw driver response or with correction ? And if so what correction.

Attached is a low cycle FDW with generated minimum phase to show what it should look like and another with what is in the mdat. The phase goes the wrong way in yours which makes me think you have processed it.

The phase jump at around 85Hz is a boundary interference null. I think you will probably have to leave that alone unless you can treat it acoustically somehow.
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File Type: jpg FDW MDAT Phase.jpg (83.9 KB, 25 views)
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Old 25th November 2019, 03:22 PM   #2877
Oabeieo is offline Oabeieo  United States
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Quote:
Originally Posted by fluid View Post
I don't understand what is in the mdat is it a raw driver response or with correction ? And if so what correction.

Attached is a low cycle FDW with generated minimum phase to show what it should look like and another with what is in the mdat. The phase goes the wrong way in yours which makes me think you have processed it.

The phase jump at around 85Hz is a boundary interference null. I think you will probably have to leave that alone unless you can treat it acoustically somehow.

Sub only at listening position
No eq just crossover turned on and textbook 80hz linearization


When I took that I just plugged my sound card right into the minidsp that runs sub , so it was missing eq

I was hoping to see what I should do about the excess phase around 70-80 hz

And elsewhere and just post it so it could be seen as what I should actually be doing with the sub.


Aha ! So I won’t mess with that than. Yes a back window is in the way !
I thought weren’t supposed to use FDW on subs. I thought it was all minimum phase and didn’t need it (what I read awhile back) so this is interesting

Last edited by Oabeieo; 25th November 2019 at 03:26 PM.
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Old 25th November 2019, 04:50 PM   #2878
Oabeieo is offline Oabeieo  United States
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FLUID & BYRTT

so I went from mediocre sounding bass that as too fat and deep to
Very nice (very very nice) sounding bass


Guys I can’t say how much I appreciate the help

The 6db subsonic really cleaned things up, and I didn’t know what else to eq because I didn’t know what eq or where to use the eq.

I always did it on the sub output now it’s gloabal , and wow the system sounds so much better now.

The horns sound way more in tune with the bass it’s ridiculous how much better it is.

The 80hz phase issue is what it is. Still sounds way better than before.

I lost a ton of gain but it’s still plenty loud enough for me.

The 12db BW subsonic sounded like too much of the very bottom end was taken out
The 6db BW sounds great, (that was the best improvement)

I think I’m getting there now. It’s way better than I’ve ever had it.
I just took off the cascade and went back to standard linear phase crossovers
I think the subsonic is the timing issue that made things sound weird and off time.
I know it’s rookie but way better than I’ve ever had so thanks so much!
The drive to work was amazing this morning! :-)
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Old 25th November 2019, 11:15 PM   #2879
BYRTT is offline BYRTT  Denmark
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rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
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...The drive to work was amazing this morning! :-)
Nice...
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Old 26th November 2019, 04:55 AM   #2880
fluid is offline fluid  Australia
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Quote:
Originally Posted by Oabeieo View Post
Sub only at listening position
No eq just crossover turned on and textbook 80hz linearization


When I took that I just plugged my sound card right into the minidsp that runs sub , so it was missing eq
It would probably be useful to get a measurement without any processing or EQ, to see what the basic driver response is. With that sort of cabin gain you might be better off eq'ing the slope to what you want rather than flattening and using a textbook crossover. You might get some gain back that way.

Try a close mic measurement as well to see the difference in phase, because something is sending your phase the wrong way.


Quote:
Originally Posted by Oabeieo View Post
Aha ! So I wonít mess with that than. Yes a back window is in the way !
I thought werenít supposed to use FDW on subs. I thought it was all minimum phase and didnít need it (what I read awhile back) so this is interesting
FDW is just different gate lengths at different frequencies and can be helpful to see the direct wavefront before it gets messed up by the room/cabin. In your measurement reflections are happening early due to the small space. I don't understand what a FDW and minimum phase have to do with each other?

Why not use it if it helps you to see what is happening?
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