record the output of a soundbox look strange in excessphase and rt60.

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user44455555

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• Dec 23, 2024

• #1

Hello

I think there is no feedback, because distortion is very low and FR is very linear. I choose estimate IR and create minimum phase. attach is the mdat file too . maybe a setting is not good or REW problem ?

 

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John Mulcahy

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• Dec 24, 2024

• #2

The RT60 curve is from the octave band filter delay, there are options to reduce it - see the RT60 graph help.

 

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• Dec 28, 2024

• #3

John Mulcahy said:

The RT60 curve is from the octave band filter delay, there are options to reduce it - see the RT60 graph help.

Click to expand...

I choose third octave this give more delay in low. I choose time reversed filtering it reduce to 200 ms at 50 hz and then filter order 6 then i get 120 ms. have the time reversed filtering any disadvantages ?. At least good to see that it is not only my room that increased that so much.
is it possible to add for settings a compensation. measure a theoretic perfect signal as reference example displayValue50hz=result50hz - reference50hz. displayValue60hz=result60hz -reference60hz ?.

same maybe work for the phase ?.

 

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• Friday at 9:37 AM

• #4

or a better idea . is it possible when do a calibrate soundcard that this is the reference and the result of the soundbox loopback is subtract from the measurement automatic ?.

 

John Mulcahy

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• Friday at 11:27 AM

• #5

user44455555 said:

is it possible to add for settings a compensation

Click to expand...

No, the effect of the filters depends on the signal.

user44455555 said:

same maybe work for the phase ?

Click to expand...

No, phase is affected by the position of t=0. Adjust the t=0 position or try estimate IR delay to alter it. Minimum phase generation needs to use suitable low and high frequency tails for best accuracy, but note that DAC reconstruction and anti-alias filters are usually not minimum phase.