Klaus,
Main Steps:
> Set REW 'loopback timing'/'Acoustic timing' depending on XLR/USB mic.
> Measure MR driver and TW driver
> Select the TW measurement/impulse chart
> Open the 'controls' panel
> Select 'Estimate IR Delay' Record the delay that is offered (ms).
> Select 'Shift IR' [The TW impulse will shift that amount back to near 0 ms]
> Select the MR measurement/impulse chart. In the 'controls' panel and enter the recorded offset value used for the TW IR into the 't=0 offset(ms):' entry box and select 'Apply'
[The MR IR will shift the same amount as the TW. The relative timing will be unchanged as they were both shifted the same distance.]
REW settings for phase analysis:
> Open the 'overlay/phase' graph panel.
> Set 1/48 octave filtering for both measurements.
> Activate the 'IR Windows' popup.
- Enter 0.00 into the 'Window Reference Time' box
- Check 'Add Frequency Dependent Window'
- Enter '5' into 'Width in cycles' [A greater number often works fine. Using a lower number will start to distort the trace tails.]
- Select 'Apply Windows to All'
The phase overlay graph now displays the correct relative phase between the MR and TW and should be easily read. If it is not clear then there was an error in this process.
If you shift the MR impulse location to find the offset need for proper phase tracking then it is necessary to again enter 0.00 into the 'Window Reference Time' box and select 'Apply'. Any IR shift requires resetting the 'window reference time' to 0.00 to assure the phase relationship will be correct.
