Frequency-linear txt export

[Japio]

Hello,

I will first introduce myself: I am Jan Jaap Derksen from the netherlands. As hobby i am building professional audio speaker systems for bands or other events. (when covid 19 is gone....) I am using REW with the umik-1 mic till now just as indication of the frequency responce of the speaker and adapt the EQ manualy in the system.

i am struggeling with a problem in REW..The measurement of the speaker i can import into the DSP of my new amps to use FIR-eq. But the problem is this system can only handle linear line frequency responce.
When i am exporting a measurement as text file i cant find (or is not possibol) to export the frequency lines linear.
Accourding the dsp manual the file should like this:

FFT degree: 14
Sampling rate: 96 kHz
Samples in time domain: 16384
Lines in frequency domain: 8193 (0 Hz … 48kHz)
Line distance: 5,859375 Hz
File entries
Freq[Hz] Real[Pa] Imag[Pa]
0.000000E+00 0.000000E+00 -2.526122E-10
5.859375E+00 0.000000E+00 1.192093E-07
1.171875E+01 6.837189E-03 - 9.961390E-02
…
…
4.798828E+04 -1.115020E+00 -1.757477E+00
4.799414E+04 1.508967E+00 -2.896538E+00
4.800000E+04 -4.855079E+00 2.351044E-10…

Is there a way to get this work? Or is it possibol due to update of the software to get this kind of exports?

Thanks in advance
Jan Jaap Derksen

 

[John Mulcahy]

Which REW version are you using and what REW export options have you set?

 

[Japio]

Which REW version are you using and what REW export options have you set?

5.20 Beta 60
I use export as tekst. I have played with the settings in the field popping up when you export as text. But it always the export is not lineart.
As you can see in the screenshot i have imported the file but checking the frequency it is not linear going up.
Or i am doing somthing very wrong. Till now no succes. I hope you have somthing about this information.

 

[John Mulcahy]

If your measurements are log spaced (they show "96 PPO" next to "resolution of measurement" in the export dialog) you should go to the Analysis preferences, de-select "Allow 96 PPO log spacing", then use the IR windows dialog to re-apply the windows. The export dialog "resolution of measurement" will then show something like "0.366 Hz" (depending on the measurement sample rate), export with "resolution of measurement" selected.

 

[Japio]

thanks for the help. getting closer now. Only new problem showed up unfortunally. Just get a quick try with my laptop speaker and mic. no setup of real system.
do you got an idear about the sample numbers? i played already with custom range. suppose it is somthing like this.

 

[Japio]

after investigation looks like i am getting to many sample points at this moment. The file used as example has a line space of 5,859375 Hz. Now there is 0.366Hz. Is it possibol to modifi this by REW?

 

[John Mulcahy]

No, there isn't an option to alter the spacing. The application looks to be expecting a sample at 0 Hz and at Nyquist (24 kHz I'd guess) so you may need to add 5 entries from 0 Hz to 1.464844 Hz at the start of the file and make sure the last entry is at Nyquist. Total lines would then be 131073. You may be able to generate a subset in a spreadsheet, taking every 16th row to produce a set spaced at 5.86 Hz.

Please note that the file content is not real/imag, it is SPL [dB]/phase [degrees].

 

[Japio]

thanks solved by adding at top and end the numbers manually. Now i have to figure out why the center impulse gives very high number. I get target out of latency in the DSP. I guess i need to ask the supplyer of the DSP about this.