(under construction)
I looked everywhere but could not find a tutorial or helpfile which describes how to use REW with Convolver. Hence I thought I will start a thread.
First: What is convolver?
Convolver is an Windows application which can be used for Digital Room Correction. It can be used as a plugin for Windows Media player (and other apps).
Full details are
here.
A long convolver thread is
here.
Second: Where does REW fit into the picture?
REW measures the room's impulse response. That is how it produces the frequency response plots. Then you can (automatically or manuall) setup the filters. After this you can export the impulse responses of filter setups
Step by step guide:
- Install convolver.
It is available for download here: http://convolver.sourceforge.net/download.html
Full instructions are here: http://convolver.sourceforge.net/usage.html
- Use REW to generate the Filter Impulse Response file
(This assumes that you already know how to use REW)
- Measure your room’s response
Use the Generic setting for the equalizers. That has the widest range of filter types and the best filter resolutions.
- Create / Adjust filters
You can automatically adjust the filters following the usual REW sequence. REW only auto adjusts filters upto 500hz. If you need to correct room response beyong 500 Hz. you will need to add/ edit the filters manually.
Why does REW not aetup filters automatically all over the 20-20k Hz range? Well, here is what one post says: http://www.avsforum.com/avs-vb/showt...&&#post6966447
Quote:
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The peak search function is restricted to lower frequencies as it is looking for modal resonances. Above a few hundred Hz the resonances overlap to such an extent that it si no longer useful to try and correct individual resonances, but you can of course apply broader filters to even out the response. Future versions of the Wizard will address other parts of the range, but that is quite a way off as there is much yet to do for the low frequency range. It is worth bearing in mind that room treatments work very well in these ranges.
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- Export the Channel Filter Impulse Response as WAV file
The File -> Export -> Channel Filter Impulse Response as WAV option generates the impulse response of the filters for the current channel in WAV format, written as 16-bit mono PCM signed data, with the impulse peak normalized to digital full scale.
- Use this file in convolver
Basically, you have to point the convolver to the file you just exported above.
Full details here : http://convolver.sourceforge.net/usage.html
That is it !
Until here the setup is simple. But for best sound quality you have use multiple files for multiple channels.
I will quote jrpavel’s post on AVSForum here:
http://www.avsforum.com/avs-vb/showt...&&#post6939704 Quote:
Others with more experience of room correction may want to chip in, but there are several approaches of increasing complexity.
Assume that you are using stereo, then:
You can measure the impulse response of your left and right speakers separately, and apply the results to the respective channels. The first example on http://convolver.sourceforge.net/configegs.html shows the convolver config file that allows you to do that. Alternatively, you can combine the mono impulse responses into a single stereo WAV file and load that directly instead of using a config file.
That is not, however, the theoretically best way of correcting your system, although it may give good results in practice and has the merit of simplicity. (At least not if you don't listen with a board in front of you that prevents the left channel sound from reaching your right ear ...)
The more correct way, apparently, is to take 4 impulse response measurements (left speaker to left ear, left to right, right to right and right to left) and then apply them using the head-related transfer function (HRTF) network example on http://convolver.sourceforge.net/configegs.html as a model.
I'll leave it to others to comment on / correct this advice, but the long and the short of it is that with convolver you can mix input channels, filter the result, mix/sum the results of different filter paths, and direct them to specified output channels in a completely configurable way. (In fact, I am trying to decide how best to reduce the flexibility, as it makes convolver more complex to set up than is probably strictly necessary.) So, if you want to do other things like split a channel into different frequency ranges and send the results to different output channels, you can do it.
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By this time you can also do this with REW:
It will allow a pair of responses to be exported as a stereo WAV. This can be used on convolver for 2 channel audio (stereo)
I will add More later...
Others, please correct me if I am wrong and add tips and questions in this thread.
Here are some more links for further info on this topic:
HTPC and Digital Room Correction :
http://archive2.avsforum.com/avs-vb/...d.php?t=445559
Step by Step guide for using DRC:
http://www.duffroomcorrection.com/im...Guide_v1.0.pdf
In the search for the best parametric eq software for the HTPC...
http://archive2.avsforum.com/avs-vb/...d.php?t=283878