Help With the Final Step of REW measurement averaging + rePhase

[Dan Twomey]

I've been going through SwissBear's REW measurement averaging + RePhase tutorial and I think I need some coaching for the last couple of steps.
So far I'm quite pleased that I time aligned and vector averaged the nine measurements for each channel. I then continued on and used Lavg and Ravg to generate the appropriate EQ filters
for each channel. Guided by the tutorial I was then able to successfully export both the averaged measurement and correction filters into Rephase for viewing and ultimately generating the correction impulse for each channel.

So quoting from the tutorial, here we are
Generate the corresponding correction impulse and import it inside REW and apply the
convolution of this correction to the averaged measurement:

I think the next step is to use "Trace Arithmetic" create A*B?

Which produces the following.

So far so good?

Regards,
Dan

 

[Krunok]

I've been going through SwissBear's REW measurement averaging + RePhase tutorial and I think I need some coaching for the last couple of steps.
So far I'm quite pleased that I time aligned and vector averaged the nine measurements for each channel. I then continued on and used Lavg and Ravg to generate the appropriate EQ filters
for each channel. Guided by the tutorial I was then able to successfully export both the averaged measurement and correction filters into Rephase for viewing and ultimately generating the correction impulse for each channel.

So quoting from the tutorial, here we are
Generate the corresponding correction impulse and import it inside REW and apply the
convolution of this correction to the averaged measurement:

View attachment 29876

I think the next step is to use "Trace Arithmetic" create A*B?
View attachment 29879


Which produces the following.
View attachment 29880

So far so good?

Regards,
Dan

Yes, so far so good - now you have predicted response according to the filter created with rePhase.

What I dont' understand is why that tutorial insists on using the vector averaging which was designed for correcting the phase. For correcting the frequency response you should use "Average The Response" under All SPL tab.

 

[Dan Twomey]

Just quoting from the help file for my own enlightenment.

Average The Responses calculates an average of the dB SPL values of those traces which are selected when the button is pressed. Phase is not taken into account, measurements are treated as incoherent. The frequency range of the averaging result covers the region where the traces used overlap, for example if one trace was measured to 200Hz, another to 500Hz and a third to 1000Hz the average would range to 200Hz(to the lowest end frequency). New measurements (those made after the last average was generated) show new next to the trace value, whilst those included in the last average show avg.

Vector average, which averages the currently selected traces taking into account both magnitude and phase. It can only be applied to measurements that have an impulse response.

Regards,
Dan

 

[Krunok]

Just quoting from the help file for my own enlightenment.

Average The Responses calculates an average of the dB SPL values of those traces which are selected when the button is pressed. Phase is not taken into account, measurements are treated as incoherent. The frequency range of the averaging result covers the region where the traces used overlap, for example if one trace was measured to 200Hz, another to 500Hz and a third to 1000Hz the average would range to 200Hz(to the lowest end frequency). New measurements (those made after the last average was generated) show new next to the trace value, whilst those included in the last average show avg.

Vector average, which averages the currently selected traces taking into account both magnitude and phase. It can only be applied to measurements that have an impulse response.

Regards,
Dan

Try doing pink noise RTA measurement using moving microphone method over some small area (say 0.4m2). Make 4-5 sweeps over the same area. When yuou use Average the responses, as the frequency response has been averaged result will converge toward RTA measurement but you have lost time domain info. Make vector average and you will see that resulting frequency response doesn't converge to RTA as it is the phase response that has been averaged. As phase responses are being averaged with vector average you cannot use it to the responses that don't have time domain info.

So, Average The Responses is a good basis for freqeuncy EQ while Vector average is the good basis for phase EQ and shouldn't be used for freqeuncy response EQ.

Help is vague on this topic but have a look at this post from John Muclahy:

"It doesn't seem to make sense to get annoyed at the feature, that is like being annoyed at a screwdriver for not being a spanner. I don't recall saying that vector average must be used for any particular purpose, it was added at the request of users who wanted a vector average to allow phase correction to be applied to the result. Whether that is a good or bad thing I couldn't really say, it isn't something I have studied. "

 

[Dan Twomey]

Another tutorial from the Rephase website has me scratching my head because it's suggestion of doing A+B produces perfect results for me.

 

[Dan Twomey]

Using A+B as suggested in my previous post seems to produce 'perfect' results?