If you get REW running down the road is it okay ask if you would share a REW mdat-file that includes your HATS calibration file and a HD650 sweep, would love have that fine reference data to comparison my own chain of HD650/miniDSP EARS
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@Mad_Economist,
@DualTriode,
@JohnYang1997
About precision to measure excess phase i get from some paper that the more bandwidth the better and therefor down the road i think of mod my miniDSP EARS to analog if its possible so that the ADI Pro unit i saved up for last year can run head phone measurements up a 384 or 192kHz rate.
Below is how REW look at a synthetic impulse for a 20Hz-20kHz bandpass with 2nd order BW stopbands created in Rephase for 44,1/48/88,2/96/176,4/192/352,8/384kHz rates using relative huge FFT lenght that doubles with rates and a rectangular window, dotted black is the minimum phase textbook reference for that passband ..
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Animation below includes amplitude, else its same as above inluding the colour scheme..
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Left one below is the above one that use a rectangular window plus relative huge FFT lenght that doubles with rates, right one use HANN window and locked FFT lenght of 262144 samples, at low end and probably especial below REW's lowest reach of 2Hz curves amplitude gets out of tune to textbook minimum phase ones..
View attachment 82328
Another technical thing that mayby can represent some of the relative small number of excess phase in measurements, blue trace is not directly important to graph and represent phase of my HD650 impedance measured with a DATS unit and should be familiar to most, the interesting phase distortion or excess phase is that tranducer itself is a current device and phase for current in transducer device is the green graph (reverse of impedance), phase for voltage in transducer device is the red graph and pure flat and not the same as for current or vice versa..
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