One of the first step to make DRC, is to have a good measurement of caractheristic of your system.
There is several steps to do that :
- playing sweep file or pink noise using Tools in the plugin.
- Recording signal while playing (with REW)
- Modifing the result (with REPHASE) and generating filters.
- Use filter creation in the plugin
- Using this filter in Volumio through the Brutefir plugin.
Tools in Volumio
To help to generate your filter, the plugin can provide some tools.
These wav file contain a 20Hz to 20000kHz signal plus a time reference signal on the right channel.
Pink noise files
Provide pink noise files.
Tools are not installed by default. If you need to install, press install tools in the plugin and wait the windows to be refreshed.
After the page is refreshed, you'll new entries in the page of the plugin.
We will describe a method called MMM - Moving Mic Measurment.
The idea is to make a multi point measurement and use the average of these measures.
MMM (or RTA as called in REW) is reliable up to app 600Hz, and that is anywway the area where most of the problems are.
For the freqs above 600Hz you should use single point (at your listening position) time gated sweep measurement.
Read more about moving microphone method (implemented via RTA in REW) here: : MMM
Measurment points are defined like in above pictures
It avoids to have a single optimized listening point
Let's go !
Now, plug your Microphone on your computer, and place it where you should be to listen music. The placement is important, and you're advised to read some howto...
Launch REW (roomeqwizard)
Before measuring, some adjustement are needed :
- Configure mic calibration as below :
- Then, ajust parameters for input and output :
Now let's use sweep files
- Configure Make a measurement parameters :
- When ready, hit Start measuring a wait for in the message
Waiting for time reference
Now, play the first sweep file for the channel you are measuring (Left or Right)
- Once it is done, in REW, in EQ windows under settings (icon in upper right corner) choose 1/48 smoothing
choose File/Export/Export measurement as text (this file will be imported in rePhase)
- If you want to use automatic filter generation, export the impulse from rew using
- export impulse response as wav with following parameters :
- Repeat the same for the other channel
And then Pink Noise files
In REW, clic on RTA icon. It will open a new windows. Then clic on the gear (right top side corner and set the following parameters
When ready, in the plugin press "play left channel" pink noise. In REW, press the record button (top right)
Move your Mic following the scheme above.
These are measurement points as suggested by DiracLive. You can use them as your MMM points - start from central position, move slowly with constant speed (app 20cm/sec) toward next positions as if you were to draw a line between them. Finish at central position.
When moving mic try to cover area around your head (in all 3 directions) starting at your listening position. Set smoothing to 1/12 and export measurement as text so you can work with it in rePhase.