- Oct 17, 2018
Does anyone have data they can share showing measurements in an anechoic chamber compared with those coming from models? I would like to see the degree of correlation.
Hi! Welcome to the forum. Are you Alan Shaw?
In many reviews here I often try to correlate the data from the Klippel NFS and quasi-anechoic measurements with known anechoic measurements, and in some cases it's apparent the Klippel NFS is as accurate as anechoic responses, or more so. Off the top of my head...
Neumann KH80 measured by Neumann using an anechoic chamber+groundplane compared to the klippel NFS(note the vertical scale is just 20dB and in this case the klippel NFS used an uncalibrated mic, hence the difference above 10kHz):
Here is the JBL HDI-3600 as measured in Harman's anechoic chamber(blue, heavily smoothed) vs the klippel NFS (red, from here):
Here's the Revel M106 as measured by ASR vs harman (I'm not sure if Amir was using the mic calibration at this point, which might explain the difference in treble):
While there are some differences, I'm not sure if the differences are due to the different units/microphone calibrations/positionoing as opposed to anything inherently wrong with the Klippel NFS as a system. It's apparent that the anechoic chambers available to companies usually aren't large enough to be perfectly anechoic at the lowest frequencies, so here the NFS actually has an advantage.
Klippel NFS aside, In terms of my own nearfield + gated splice, we see good correlation here with the JBL L82 (my measurements were taken before seeing harman data):
I do correct my nearfield response for baffle step, so we don't see the exagerrated bass response as in Stereophiles; the above is just what the speaker is like.
Here's the JBL HDI-1600 (note harman's is heavily smoothed):
In this case I had already seen Harman's measurements beforehand, so I did know what to expect, but I certainly didn't try to purposefully align the measurements.
Certainly there are flaws to different measurement methods, but I think when considering the effect of the room on these frequencies we can see one can achieve rather good enough results in matching measurements from different methods to an anechoic chamber. It does seem like, barring a humongous anechoic chamber or lifting a speaker dozens of feet off the ground, the Klippel NFS is the best we have.