# Create FRD file with minimum phase applied



## chChrLam (May 6, 2013)

I am making gated measurements of individual drivers mounted in the loudspeaker enclosure at a distance of 1 meter.
I am using a UMIK-1 with its calibration file and also a seperate tweeter as an acoustic timing reference.

My goal is to export SPL and MINIMUM PHASE measurements of individual drivers - make FRD files containing the minimum phase.

My Method as per John here http://www.hometheatershack.com/forums/rew-forum/57874-can-rew-create-min-phase-frd-files.html
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1. Click Generate Minimum Phase in the SPL and Phase window
2. File > Export Impulse Response as WAV > X Export Min Phase version of IR
3. File > Import Impulse Response
4. Change Cal... select my calibration file for UMIK-1(which only has Freq SPL and no phase in it)

The frequency response is identical but the phase looks nothing like the minimum phase in step 1.

What did I do wrong?:dontknow:


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## JohnM (Apr 11, 2006)

When you re-import the min phase IR t=0 will be placed at the peak by default. Use 'Estimate IR delay' to remove the time delay from the imported IR, it will then have the same phase as the min phase version of the measurement.


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## chChrLam (May 6, 2013)

Thank you very much John - That works fantastic.

My final solution: *How to export minimum phase frd files with REW*

1. Click Generate Minimum Phase in the SPL and Phase window
2. File > Export Impulse Response as WAV > 32 Bit [X] Export Min Phase version of IR
3. File > Import Impulse Response
4. Change Cal... select calibration file for the mike
5. Impulse window > Controls > Estimate IR Delay > Apply
6. File > Export > Measurements as text

Note: Exporting at 16 bit produced sub optimal results with the estimated IR delay at 0.06 ms. 32 bit estimated at 0.063 ms

@JohnM - The Mesurement Info window (Big blue ! button) shows the Peak X.XXXXXXXXX at 0.YY ms
It might be an idea to increase the precision of YY to three decimal places


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