Yes that is what I meant, no NFs or anechoic at all in
@Nuyes reviews.
As far as I can tell the Klippel unit that Erin is using to take the HD and IMD measurments is Quasi Anechoic. I have always understood that they are not anechoic (or rather calculated anechoic like the NFS) It is 100% possible I do not understand how the ISC unit is aquiring and handing HD data. Erin doesn't seem clear about this aspect in his videos (or on his webapge under 'test methods' which seems very out of date, but does talk about a nearfield measurement for HD IMD)
I don't think he is using the NFS for HD/IMD. But I am just not sure.
@VintageFlanker
here are the details for the ISC
www.klippel.de
&
chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.klippel.de/fileadmin/klippel/Bilder/Our_Products/R-D_System/PDF/S62_In_Situ_Room_Compensation.pdf
This all seems quasi anechoic and windowed to me. But maybe I am off base.
They also have the TRF module which is for HD and the frequency tesing with the KNFS. I can't make sens eof wether the HD is anechoic or not.
TRF module measures two signals simultaneously, and determines the linear transfer function and the harmonic distortion in the output signals.
www.klippel.de
And the MTON for multitone, doesn't seem anechoic either though, but again I am not certain
https://www.klippel.de/products/rd-system/modules/mton-multi-tone-measurement.html
I am not certain, but I wish I knew fo rcertain if he makes anechoic HD/IMD tests. Certainly Erin's measurements are very accurate no matter the case. I just want to know.
The main point I had was that even with REW and UMIK I have almost the same HD results as Amir and Erin using basic near field techniques. I don't think Nuyes HD results will that far off from others though I still agree it best to compare with only like tests by the same person and that modest to even heavy HD is not exactly that important in many cases.
EDIT. I did find this. The ISC is indeed appling quite a bit of very useful and Klippel advanced math filtering to the HD/IMD testing. Very cool!!!! Maybe not quite anechoic but super stuff. Okay so Erin's are def a cleaner HD test.
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