Impulse correction with rePhase starting from measurements in REW
Pulse correction with rePhase from REW measurements
This tutorial is intended to be used for the implementation of speakers/drivers in the listening area (room) with the Integration of impulse correction and modified filters for your DSP device with or without "room curve". The basis of the "room curve" is the work of Bruel and Kjer in room acoustics, see the following link:
https://www.bksv.com/media/doc/17-197.pdf
The goal is to produce the best possible sound for your room.
Place the microphone at the listening point and point the microphone vertically, and use a 90° calibration file, usually with this mode you will have the best result in the REW software.
Let's start from our REW software by setting the preferences in this way:
1. REW Preferences
Set 1/6 octave smoothing and 15 FDW cycles to generate the correction filter file and avoid "micromanaging" the amplitude and phase corrections.
Timing reference activated.
2. Room curve
The data used to create a "room curve" can be imported into REW as a text file or by using the "target settings" in REW.
“EQ” -> “target settings” -> activate “Add room curve”.
You may need to do the same tuning to achieve the desired result and this task is up to you, it is a subjective setting and depends on taste. The settings in the image below are just a guideline, a starting point.
Assuming you follow this tutorial with the goal of implementing a "room curve" with impulse correction filters for your DSP device.
Then, "Equalizer" choose "repPhase", because we will end up producing FIR filters in the rePhase software for your device.
3. Importing text files into REW software.
This is the diyAudio Forum recommended curve.
0 -90.0
5 -6
6 -3
7.5 -1
10 -0.1
20 0.0
50 0.0
100 -1
200 -2
400 -3.0
800 -4.0
1000 -4.2
2000 -4.7
3200 -5.3
6400 -6.5
12800 -7.5
19200 -8
22050 -10
First you need to create a text file. Copy the above figures and paste them into your text editor and save it as a .txt file with a name of your choice.
Then, “Preferences” ->”House Curve”->”Browser” find your saved file and import it.
How to integrate pulse-corrected filters and "room curve" to your DSP device will be explained in detail in step 7.
<<Every person on this earth is equipped with a unique hearing organ and no one else has the same experience of sound interception.>>
The "room curve" is how most people would like the sound to be in their listening room, it's up to you to use the "room curve" as you see fit.
If you are using it:
The “room curve” must always be activated in the REW software, from the first step of this tutorial until the end.
If you are not using it:
Just don't activate it.
How you will use the tutorial depends on your DSP's hardware/software configuration.
By following to the end of step 7 of the tutorial, we will end up with the information needed for the rePhase software to produce the FIR filter file for your DSP.
Theoretically only one filter would be needed, minimizing the use of PEQ filters.
3. Average measurements
Take several meaningful measurements that represent your listening area. Import them all into REW:
“All SPL” -> “Control” -> “Time Align” -> “Vector average”.
4. Filter generated by PEQ
We have concluded the "vector average" generated in the measurement of REW; the next step is to create a PEQ filter for the "vector average".
At this point it is recommended to save the PEQ filter for use in your DSP or export a PEQ filter as xml for RePhase to create a combined filter - see section 6.
Go back to the main REW window and File->Export->Export filter the impulse response as a wav file and save it.
Import the wav file. From the REW main window “All SPLs”. Controls--> File--> Import --> Import impulse response.
The result should be “Vector Average” and “Vector Average .wav” measurements with the “All SPLs” tab activated in the main REW window.
5. Arithmetic trace
Controls -> Arithmetic Trace -> Choose both measurements in the A and B windows -> Choose A*B -> Generate.
Controls -> Measurement Actions -> A for B -> then enter a negative "SPL offset" to match the "Vector Average" value -> "Add offset to data".
The final level does not matter for this relative level, so use the same amount for each channel. If the level is not reduced the measurement will end up at 150dB or more.
When you press "Excess Phase Version". This will result in the measurement “A times B-EP”.
6. Finalization
From the REW main window: “ All SPL”. File>Export>Export measurement as text.
Import the saved .txt file into rePhase. Then from rePhase generate the *.bin file to use in the FIR filter for MiniDsp.
7. Combined filter
Do everything as in the first part of step 3 “Filter generated by PEQ”.
The next step is to create a PEQ filter for the "vector averaging". Choose “Equalizer Rephase” -Filter Tasks-Save Filter Sets-Files to Store. The filter will be saved as a *.xml file
Open the Rephase import *.txt file created in step 6, then: Paragraphic Gain EQ -> Tools-> Import REW filter settings and import the previously saved *.xml file.
Finally you can generate FIR file in RePhase for your miniDSP device.
