Loudspeaker & Room correction

As input data we need 6 to 9 room transfer function measurements (RTF) for each channel. One measurement position should correspond to the sweet spot. The other ones can be spread randomly around the sweet spot in order to spatially cover your usual listening area (typical distance between sweet spot & other measurements = 30 to 100 cm)

 

To perform those measurement you need a microphone (Dayton UMM-6 or UMIK-1 for instance) and a specific software.

 

You can use our own solution by downloading the following package (inc. instructions) Measurement tool  

 

The other alternative we recommend is REW. Here are some guidelines for performing the measurements when using REW:

  • Use a mic stand for the microphone and stay away from loudspeakers/mic during the measurement
  • If you have the appropriate calibration file (90° for UMIK) point the mic to the ceiling otherwise point it to the midpoint b/w loudspeakers
  • Set the output level as if you were listening to music
  • Position the mic at your usual listening position (sweet spot)
  • Measure left channel and set L1 name in the text box as explained on attached picture (sweep measurement and not RTA)
  • Measure right channel and set R1 name
  • Move the mic to next position and repeat the above procedure
  • When you have performed all measurements save them in a .mdat file and transfer them using a service like GoogleDrive / Onedrive / Dropbox / Wetransfer / etc...
  • Make sure you don't change the output level during all measurements

Crosstalk reduction

We offer 3 different options for crosstalk reduction.

 

The required input data for each level are:

  • "Generic model" : we need the D & L geometrical data defining the listening configuration as described on the drawing
  • "Head model" : D & L data must be complemented with your head dimensions (Width between ears entrance, Height, Depth) One practical way to get these data is to take a picture while holding a ruler as reference
  • "HRTF" : you need to measure your own transfer functions by using the measuring package available here: HRTF measurement tool. Measurement requires a in-ear binaural microphones that can be used for room measurements as long as you can find a way to hold it with a stand mic

When using crosstalk reduction it is recommended to lower the span angle between loudspeakers compared to the traditional stereo configuration. This helps keep a stable image despite head movements. If your room configuration allows it you can go down to 20 degrees angle.


Filters implementation

Our correction method requires a specific filters topology putting a specific demand on the convolution capacity of the audio player.

 

Here is a list of players compatible with our technology: Roon, HQplayer, JRiver, Foobar (together with the VSTconvolver plugin) and any other player with VST plug-in format compatibility or using Brutefir convolution engine (like Volumio). Filters can be implemented in Audirvana using a "true stereo" convolution plugin in AU format like Reveberate Core from LiquidSonics

 

With the filters we deliver an installation instruction for your audio player.

 

For audio players having only a classic stereo convolution we can generate "downgraded" versions of the correction (no cross talk for instance) Such filters can also be used with hardware solutions like the ones from miniDSP.