Some guides to REW and acoustic measurement

Todd Anderson

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Parag Ingle

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Hi


I want to know How REW(Room Equalization Wizard) works.can you please share the block diagram of how the received(Log Sweep) audio processed and converted to IR(Impulse Respose).this is only for my educational curiosity.
 
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John Mulcahy

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See Swen Müller, Paulo Massarani, "Transfer Function Measurement Using Sweeps", JAES Volume 49 Issue 6 pp. 443-471, June 2001. An extended version of the paper is available at CiteSeerX.
 

Parag Ingle

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Hi

I have read the document it is showing many of the measurement method(as below)
and its comparison.which one of these REW uses

1)Time Delay Spectrometry

2)Dual Channel FFT Analysis

3)Stepped Sine

4)Maximum length sequences (MLS)

5)Periodic Signals of length 2^N

6)Non periodic sweeps
 

John Mulcahy

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Stepped sine isn't a sweep. Log sweep is an example of a non-periodic sweep.
 

mikewellington

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Hi - I am pretty sure I have everything connected okay. I am using the UMK-1 and a USB audio interface that is connected to my speakers. I have the UMIK-1 set as the input device loaded with its calibration file. I have the audio interface outputting a decent level to the speakers but I keep receiving the message "The soundcard did not provide any input data, please check that it is connected." Not sure why this is happening...... I am running Windows 10.
 

John Mulcahy

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The cable in the back of the UMIK needs a very firm push to seat properly, that can cause problems sometimes. Beyond that probably best posting a screenshot of your REW soundcard preferences.
 

mikewellington

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The cable in the back of the UMIK needs a very firm push to seat properly, that can cause problems sometimes. Beyond that probably best posting a screenshot of your REW soundcard preferences.
Thanks John. I had tried that and also a reboot. Seems to have done the trick. It's been a while since I used REW and my UMIK-1. Just moved into a new studio so trying to get my head back into the software again. Is there a link on tis website to the basic read out settings - I remember being advised before but have forgotten.... Thanks again for your help.
 

mikewellington

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Thanks John. I had tried that and also a reboot. Seems to have done the trick. It's been a while since I used REW and my UMIK-1. Just moved into a new studio so trying to get my head back into the software again. Is there a link on tis website to the basic read out settings - I remember being advised before but have forgotten.... Thanks again for your help.
It's all coming back to me now. Made a couple of measurements 45 Hz-20,000 Hz with 1/6 smoothing. Looking good. Is there a place to post measurements on here to get feedback?
 

Sal Caralucci

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This is my first post and I am probably putting it in the wrong place. I have used REW for about a year and a half but, not since I updated my Mac to Mojove in October 2017. I am not getting audio in. When I do a loop back to calibrate my Focusrite Scarlett 2i4, I get output level and set the trim to be just under distortion on the Focusrite but, am not getting level in the input in REW. I have both Input and Output settings set for the Focusrite. I am running REW 5.20 Beta 4 and Mac OS 10.14.2. I have installed REW 5.20 Beta 4 on Windows 10 which I run thru Parallels on the same Mac. Everything works perfectly. It appears that REW on the Mac does not receive audio in on any input. I have tested the onboard sound and a second Focusrite RED 4 Pre on the Mac and can not get anything. I have clicked on Levels and talked thru a microphone and see no levels. I have tested the Mac with other audio software like Sound Studio and have no problems getting sound in. I have uninstalled and deleted all prefs for REW and reinstalled and still no audio in.

Ideas???
 

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John Mulcahy

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This is my first post and I am probably putting it in the wrong place. I have used REW for about a year and a half but, not since I updated my Mac to Mojove in October 2017. I am not getting audio in.
Aside from the privacy setting/clicking OK when the OS asks if REW can access the mic, choose actual inputs and outputs from the lists in the REW soundcard preferences rather than leaving them set as Default output and Default input.
 

Sal Caralucci

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Thanks, problem resolved. It was setting microphone in the security and privacy setting system prefs that resolved the problem. I did not realize that applied to sound interfaces, I thought it only applied to the microphone on my laptop.
 

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craig lister

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Name is Craig and have been using REW for my home and studio setups for 6 years now and it is the best. Recently purchased the Genelec GLM correction system to go along with some new 8351 monitors and the monitors are superb, the software poor. After trying GLM out thoroughly, will be using REW instead.
Output a REW convolution file into JRiver for all of my popular and classical music. With studio recordings, however, need to find a way to get this REW correction into my DAW (=Samplitude). Samplitude is no longer available for American technical assistance SO I thought I would ask on this site.
Does anyone know how to take the REW convolution file and tailor it so that it can be plugged into a DAW? As near as I can tell, all of the Samplitude plugins are *.dll file types. Is there some way to convert the convolution *.wav file into a version that is plugin compatible?
Am a yearly contributor to REW and it is more than worth the contribution.
 

mikewellington

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Name is Craig and have been using REW for my home and studio setups for 6 years now and it is the best. Recently purchased the Genelec GLM correction system to go along with some new 8351 monitors and the monitors are superb, the software poor. After trying GLM out thoroughly, will be using REW instead.
Output a REW convolution file into JRiver for all of my popular and classical music. With studio recordings, however, need to find a way to get this REW correction into my DAW (=Samplitude). Samplitude is no longer available for American technical assistance SO I thought I would ask on this site.
Does anyone know how to take the REW convolution file and tailor it so that it can be plugged into a DAW? As near as I can tell, all of the Samplitude plugins are *.dll file types. Is there some way to convert the convolution *.wav file into a version that is plugin compatible?
Am a yearly contributor to REW and it is more than worth the contribution.

Hi Craig. Not exactly sure but perhaps you could monitor via a third party VST convolution plugin in Samplitude that would load the wav file and pass your audio via that in real time (if that is possible.....?) I've never used an exported convolution file from REW. Personally I use a hardware parametric/graphic eq to adjust my listening position based on my REW measurements. I think I trust this approach more for studio monitoring/mixing.
 

craig lister

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Thanks Mike. Would like to use the REW Convolution file because it also contains Impulse correction and this is more important than frequency since my studio is nicely treated. Did you have any particular 3rd party convolution plugin in mind?
Again, thanks for the response.
 

John Mulcahy

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Hi Craig, the filter impulse response REW exports as a WAV file is the direct equivalent of applying the same filters via a parametric EQ. The result is the same either way. All filtering affects both time and frequency domains, both impulse response and frequency response. Filters that reduce peaks in the frequency response can also reduce ringing in the impulse response if they are accurately targeted at the resonance responsible for the ringing.
 

craig lister

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Hi Craig, the filter impulse response REW exports as a WAV file is the direct equivalent of applying the same filters via a parametric EQ. The result is the same either way. All filtering affects both time and frequency domains, both impulse response and frequency response. Filters that reduce peaks in the frequency response can also reduce ringing in the impulse response if they are accurately targeted at the resonance responsible for the ringing.
Thanks, John.
Have been using the REW Convolution file in JRiver for all home and some studio locations for over a year now. It cleans the soundstage so that all instruments/voices become crisper against a jet black background. Congrats on all of your superb work -- your application is a sign of your exceptional mind.
Would like to take the convolution file and insert it into my DAW as a plugin. This is easier than having the DAW output to JRiver.
Is there a way to transfer the wave convolution file into a format that a DAW will accept as a plugin? Think that the normal format for plugins is a *.dll file.
Thanks again and keep up the good work.
 

John Mulcahy

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Sorry Craig, I'm not up on the inner workings of DAWs. A dll would usually be software rather than data. Anything that accepts a WAV file for convolution (reverb processors most commonly) should also be able to accept the REW wav file, there is no fundamental difference between the two.
 

night

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