REW fails to output sound on Linux

keantoken

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I am running Debian Sid. I've tried REW both in WINE and with the Linux installer but the issue is the same. I know the problem is not with Linux because I can play music at the same time REW is attemping to check levels but failing. If I turn up REW to max in the software mixer I hear a bit of noise during the level check, but it's nowhere near as loud as it should be.

I had REW working previously on this machine, so I know it can work.

Just to check if what I want is possible with REW: Is it possible to find frequency/phase response, then do a single tone THD measurement, which is then normalized to the freq/phase response, and then export the result as a .wav file? Is it also possible to normalize it to the loopback audio signal rather than the REW output?
 

John Mulcahy

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Which REW version are you running? If 5.20 beta 2 open the REW signal generator before trying a level check.

I'm afraid I don't understand what you are asking for regarding the THD measurement.
 

keantoken

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Sometimes it mentions trouble writing the fade out block. The closest I get to sound output is choosing the Pulseaudio mixer for output. Whenever I end the tone I get one startling burst of sound for a split second. The same thing occurs for both 5.1 and 5.2.

What I want to do:

1: Generate frequency response and phase based on loopback from the amp output.
2: Measure THD at a constant frequency
3: Apply magnitude and phase response to the THD spectrum to remove phase shift and response variations.
4: Export the result as a .wav file.
 

keantoken

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If I do a level check on the Settings page it hangs with most of the boxes greyed out, and I have to restart REW to reset it. I can instead do it on the Measurements page, going back and forth between Measurements and Settings to change the sound devices. But no luck so far.
 

John Mulcahy

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Perhaps a Linux user will comment on the audio setup, not something I can help with, sorry. For level check on settings open the REW signal generator first.

Measuring responses is REW's main role, a loopback connection can be used as a timing reference. Sweep measurements also include distortion measurement and the harmonics can be normalised to the level of the response at the harmonic frequency, there is an option in the distortion graph controls for that.

REW doesn't really have a way to capture a tone and alter it. It is possible to import recorded audio data as long as the segment isn't too long (less than a minute or so) and the trace arithmetic features of the All SPL graph would allow an A/B operation between that audio sample and the system's impulse response, the result of that could be exported as a WAV though I'm not certain it would achieve what you want.
 

keantoken

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Well I figured out that REW works in WINE. Apparently the level check sound is just a noise blip played in loop!? I just assumed it was a bug.

Problem is the Linux version still doesn't work and the Windows version is limited to 48KHz.
 
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