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rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
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Old 24th April 2017, 08:01 PM   #2001
SwissBear is offline SwissBear  Switzerland
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Quote:
Originally Posted by ppmmcc View Post
pos,

I assume I need to click the 'Average The Responses' button under the 'All SPL' section. While the response-averaged measurement doesn't have phase information anymore, is it ok for me to import the response-averaged measurement to rePhase? Or do I miss any important step(s)
If you want to average 2 measurements in REW and keep the phase information, you need:
- to align the impulses of both measurements in the time domain (Impulse -> Controls -> Estimate IR delay)
- use the (A+B)/2 function of impulses algebra in REW and not the "Average the responses" (All SPL -> Controls -> Trace Arithmetic)

Last edited by SwissBear; 24th April 2017 at 08:04 PM.
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Old 24th April 2017, 08:36 PM   #2002
ppmmcc is offline ppmmcc  United States
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Originally Posted by pos View Post
Hello ppmmcc

Thank you for your kind words.
Averaged measurements are one tool you can use, among others (or combined with others).
If phase info is missing then you have to concentrate on minimum-phase magnitude EQs only, and then possibly use another (close range and/or gated) measurement for phase linearization.
Sure. You do deserve that.

Yes, I did another measurement and used rePhase to linearizing the later measurement and minimum-phase EQs. Now each channel has two filter .wav files. Works great. Will keep on working at it when new multi-channel DAC arriving.

Thanks again!
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Old 24th April 2017, 08:44 PM   #2003
ppmmcc is offline ppmmcc  United States
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Quote:
Originally Posted by SwissBear View Post
If you want to average 2 measurements in REW and keep the phase information, you need:
- to align the impulses of both measurements in the time domain (Impulse -> Controls -> Estimate IR delay)
- use the (A+B)/2 function of impulses algebra in REW and not the "Average the responses" (All SPL -> Controls -> Trace Arithmetic)
Thank you SwissBear!

Got it. Now I can combine two measurements together still keeping the phase information.
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Old 25th April 2017, 08:09 AM   #2004
pos is offline pos  Europe
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Quote:
Originally Posted by ppmmcc View Post
Yes, I did another measurement and used rePhase to linearizing the later measurement and minimum-phase EQs. Now each channel has two filter .wav files.
You should not need to separate FIRs per channel: you could simply drag and drop each measurement on the same rephase instance and adjust settings accordingly, focusing on a different aspect in turn (eg magnitude with a spatially averaged measurement and phase with a single gated measurement)
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2019-01-16: rePhase 1.4.3
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Old 25th April 2017, 01:56 PM   #2005
ppmmcc is offline ppmmcc  United States
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Quote:
Originally Posted by pos View Post
You should not need to separate FIRs per channel: you could simply drag and drop each measurement on the same rephase instance and adjust settings accordingly, focusing on a different aspect in turn (eg magnitude with a spatially averaged measurement and phase with a single gated measurement)
Thanks again pos!

The second FIR was actually created based on the second measurement; while the second measurement was done with the first FIR applied on the signal path already. I did the second measurement because I found it is hard for me to get the equlizing results as good as REW estimates in the EQ section.

In this case, should I directly put both measurements on the same rePhase instance? Or maybe on rePhase,I can modify the first-measurement EQ based on the result of second measurement; then create single FIR. I will try the gated measurement later as well.
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Old 25th April 2017, 03:38 PM   #2006
BYRTT is offline BYRTT  Denmark
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rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
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Originally Posted by ppmmcc View Post
.....because I found it is hard for me to get the equlizing results as good as REW estimates in the EQ section.....
If not mistaken this sounds as gating is needed to filter out enviroment reflections because if measurement data is true to reality REW estimate will work precise.

About REW before command export measurement as text to use in Rephase have IR aligned either manual or use "Estimate IR Delay" to have phase curve right and set some kind or gating. As a start proposal for all right universal gating (near-far field) to filter out most environment could be frq dependant window 1/6 as seen below and is probably also good setting before use of REW EQ menu.
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Old 25th April 2017, 04:08 PM   #2007
ppmmcc is offline ppmmcc  United States
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Quote:
Originally Posted by BYRTT View Post
If not mistaken this sounds as gating is needed to filter out enviroment reflections because if measurement data is true to reality REW estimate will work precise.

About REW before command export measurement as text to use in Rephase have IR aligned either manual or use "Estimate IR Delay" to have phase curve right and set some kind or gating. As a start proposal for all right universal gating (near-far field) to filter out most environment could be frq dependant window 1/6 as seen below and is probably also good setting before use of REW EQ menu.

Thank you BYRTT! I will try it. One of my speaker is only two inches away from the side wall and is too heavy to be moved. Will it affect the gating?
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Old 25th April 2017, 05:25 PM   #2008
BYRTT is offline BYRTT  Denmark
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rePhase, a loudspeaker phase linearization, EQ and FIR filtering tool
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Originally Posted by ppmmcc View Post
Thank you BYRTT! I will try it. One of my speaker is only two inches away from the side wall and is too heavy to be moved. Will it affect the gating?
If you fresh at it we could try a little study to investigate your environment influence and compare it to mine "Overlays" below which was microphone at about 0,9 meter having side wall 1,5 meter away. In REW open one of your previous sessions and highlight one measurement and then "File" "Save measurement", close REW and open it again to have a clean new session, open the saved measurement 5x times and with button "IR Windows" command first to be raw then FDW 1/15-1/10-1/6-1/3 as seen below and maybe save session "File" "Save all measurement". Think exercise will show that if yours in "Overlays" window vary more than below from filtered to non filtered then that sidewall reflect heavy and maybe it will make clues to where in frq its worst and what is best settings to FDW.
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File Type: png 200.PNG (157.9 KB, 206 views)
File Type: png 201.png (134.9 KB, 203 views)
File Type: png 202.PNG (40.5 KB, 200 views)
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Old 25th April 2017, 06:00 PM   #2009
torgeirs is offline torgeirs  Norway
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A method for checking reflections from nearby wall, celling or floor is to use the energy time curve, ETC
Add a window to the measurement to try to window out the direct sound. Picture 1.
It can only be used for frequencies higher then 1/T where T is the with of the window.

Then you might see the frequency content of the reflection. (picture 2)
Do a real world check with a measurement and try to see if the first reflection can be right. The reflection travels 34cm/ms. So 5 ms is about 170 cm. Use a flexible measureband to check.

The shifted window (remember to press "Apply windows") SPL measurement gives you an idea of the frequencies reflected the most. (inside the window)

I would be careful to correct those frequencies to much.
And you might have a suckout at half the main frequency
Picture 3 is 20 ms window starting at 0.
A suckout around 150 hz, maybe because of first reflection, can be seen.
Attached Images
File Type: jpg Window.JPG (321.3 KB, 194 views)
File Type: jpg SPL 3 ms shifted.JPG (196.0 KB, 51 views)
File Type: jpg SPL 20ms window.JPG (201.3 KB, 46 views)

Last edited by torgeirs; 25th April 2017 at 06:13 PM.
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Old 25th April 2017, 06:12 PM   #2010
ppmmcc is offline ppmmcc  United States
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Quote:
Originally Posted by BYRTT View Post
If you fresh at it we could try a little study to investigate your environment influence and compare it to mine "Overlays" below which was microphone at about 0,9 meter having side wall 1,5 meter away. In REW open one of your previous sessions and highlight one measurement and then "File" "Save measurement", close REW and open it again to have a clean new session, open the saved measurement 5x times and with button "IR Windows" command first to be raw then FDW 1/15-1/10-1/6-1/3 as seen below and maybe save session "File" "Save all measurement". Think exercise will show that if yours in "Overlays" window vary more than below from filtered to non filtered then that sidewall reflect heavy and maybe it will make clues to where in frq its worst and what is best settings to FDW.
Thanks again. Will try. Before doing that, need to improve my limited REW knowledge and experience first
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