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Erin's Audio Corner gets a Klippel NFS!

Not sure if you guys saw this post I made but in case you missed it...
https://www.audiosciencereview.com/...ion-with-christian-bellmann-of-klippel.20970/

As you all know, I now use the Klippel Near-Field Scanner (NFS) for my measurements. I planned to create a video discussing the NFS and how it is used before I begin publishing data captured with it. However, rather than me attempting to explain the science behind it, Christian Bellmann - one of the brilliant minds behind the NFS - joins me to provide insight in to the design and workings of the NFS.

Join us live Friday, March 5th at 9am Central for discussion and feel free to ask questions if you'd like (not sure if we will have time to get to them or not). Already happened.

Background: Christian was born in Freiberg, Germany, in 1987. He studied mechatronics in Dresden University of Technology with the focus on control engineering, power electronics and electrical drives. In 2013 he received a Diploma degree for his thesis “Separation of direct sound and room reflections using holographic methods” which was supervised by Dresden Technical University and the Klippel GmbH in Dresden. After his graduation, he joined the Klippel GmbH where he is currently engaged in the research and development of loudspeaker measurement systems with focus on acoustical holography.



 
Some updates.

Kef R3 testing is 100% complete. I shipped the data off to Klippel who ran the Field ID module for me (since the new beta software is not licensed to work with anyone’s hardware yet). They sent it back to me yesterday. I changed some of their scripts to change the colors up a bit on the horizontal and vertical FR plots (per a previous request) and they closely match @MZKM data now. I hope to have the data and YT reviews up this weekend. Also, they updated the ER/ERDI calculations and sent that template to me so the new data will have all the corrected curves.


I also began testing the JBL HDI speakers. First up was the HDI-3800.
1E03EE98-618A-4B57-8BF7-A9DE0AD0C767.jpeg



The 3800 is a tower speaker that is about 44 inches tall. Too tall to be measured – upright – on the NFS platform without the z-axis extension (which Amir has). At most, I think I can measure a 38-40 inch speaker. After talking with Klippel it was verified that I can easily test the speaker on its side; the only thing I needed to do was to change the orientation vector. I also had to add the R-Axis extension which gave me an extra 18 inches of measurement *radius* and I can probably push that to about 20 inches if needed. Took about 10 minutes to do that. And I was good to go.

9F3BDF68-65F4-4EFF-9060-F493AD7B4D09.jpeg



Then I built an adapter to lay the speaker on the test stand so it would remain balanced. I had my awesome wife help me lift the speaker on to the stand and then I ran the test. First time with the microphone cage on, just to be safe. 1500 points. The results resembled the spin data Harman published (though, there's appears quite smoothed) but the fitting error in my data was a bit high in the midrange which I determined to be a culprit of the complex sound field. So I adjusted the number of measurements points to 2500 and I took the mic cage off for my final run. I then sent that data off to Klippel to verify that my setup made sense. They replied back to me this morning with the signed data and verification that I did things correctly. So, now I’ve got the data for that. Haven’t looked at it yet. At work. But, the good news is that I am able to test floorstanding speakers. At least up to 44 inches tall. I think I can stretch this to right at 4 foot but I would have to verify that by testing a speaker this size first. I think it is doable, though.


EA59A782-65A6-4392-910B-401ED0A0A171.jpeg


E24A42A2-982D-4B4D-9DAC-C13D8C079EF6.jpeg
 
Last edited:
hardisj said:
Some updates.

Kef R3 testing is 100% complete. I shipped the data off to Klippel who ran the Field ID module for me (since the new beta software is not licensed to work with anyone’s hardware yet). They sent it back to me yesterday. I changed some of their scripts to change the colors up a bit on the horizontal and vertical FR plots (per a previous request) and they closely match @MZKM data now. I hope to have the data and YT reviews up this weekend. Also, they updated the ER/ERDI calculations and sent that template to me so the new data will have all the corrected curves.


I also began testing the JBL HDI speakers. First up was the HDI-3800.
View attachment 117845


The 3800 is a tower speaker that is about 44 inches tall. Too tall to be measured – upright – on the NFS platform without the z-axis extension (which Amir has). At most, I think I can measure a 38-40 inch speaker. After talking with Klippel it was verified that I can easily test the speaker on its side; the only thing I needed to do was to change the orientation vector. I also had to add the R-Axis extension which gave me an extra 18 inches of measurement *radius* and I can probably push that to about 20 inches if needed. Took about 10 minutes to do that. And I was good to go.

View attachment 117844


Then I built an adapter to lay the speaker on the test stand so it would remain balanced. I had my awesome wife help me lift the speaker on to the stand and then I ran the test. First time with the microphone cage on, just to be safe. 1500 points. The results resembled the spin data Harman published (though, there's appears quite smoothed) but the fitting error in my data was a bit high in the midrange which I determined to be a culprit of the complex sound field. So I adjusted the number of measurements points to 2500 and I took the mic cage off for my final run. I then sent that data off to Klippel to verify that my setup made sense. They replied back to me this morning with the signed data and verification that I did things correctly. So, now I’ve got the data for that. Haven’t looked at it yet. At work. But, the good news is that I am able to test floorstanding speakers. At least up to 44 inches tall. I think I can stretch this to right at 4 foot but I would have to verify that by testing a speaker this size first. I think it is doable, though.


View attachment 117847

View attachment 117846
Click to expand...
Very nice.
Klippel support is incredible! :D
 
hardisj said:
The 3800 is a tower speaker that is about 44 inches tall. Too tall to be measured – upright – on the NFS platform without the z-axis extension (which Amir has). At most, I think I can measure a 38-40 inch speaker.
Click to expand...

Do you think with the Z-axis extension(or on side) it would be possible to measure the 65" Magnepan 1.7i? I have a pair just sitting around and I've been considering sending them in either of you for testing at some point, but I kinda wanted the excellent multitone testing, because I have never seen any real evaluation of the midbass limitation on Magnepans and I suspect it's one of their biggest problems. I think a lot of people would be interested given how nonexistent real tests of them are(other than Amir's LRS review, and ancient models on stereophile).

It's somewhat complicated in any case as they are expensive to ship and while I don't even want them back, I don't know if you'd want to take responsibility for selling 'em either :P
 
Sancus said:
Do you think with the Z-axis extension(or on side) it would be possible to measure the 65" Magnepan 1.7i?
Click to expand...

(R-axis extension in my case)

No way. I think I'm probably gonna be capped at about 48-50 inches total speaker height. You would have to have Amir test that one, for sure.
 
I've had a few PM me about the JBL HDI speaker review. The JBL HDI-3800 review is coming this week (unless something unexpected happens). I planned to do the review for these and the HDI-4500 center channel in the same video but the center channel data is currently waiting to get "signed" by Klippel for their new beta software. I don't want to pester them so I'll wait on that and go ahead and post the 3800's review within the next couple days.
 
Last edited:
hardisj said:
JBL HDI-3800 review is coming this week (unless something unexpected happens). I planned to do the review for these and the HDI-4500 center channel in the same video but that will depend on timing. Instead of waiting I decided to go ahead and post the 3800's review.
Click to expand...
Broken pictures again - in Chrome on desktop
 
hardisj said:
Is this graphic fairly intuitive (taking the title and the legend in to account)?

(I am purposely not telling you what it is to make sure it's reasonably understood without explanation)
Click to expand...
My interpretation is this is the difference between on axis response at 86dB vs 76dB (and 96dB vs 76dB).

So 86dB linearity graph is freqresp(86dB) - freqresp(76dB) - 10dB

Am I right?
 
Took me a few seconds to understand, so it is fine.
 
hardisj said:
Is this graphic fairly intuitive (taking the title and the legend in to account)?

(I am purposely not telling you what it is to make sure it's reasonably understood without explanation)



View attachment 122489
Click to expand...
I would alter the title to include “compression“ to make it even more easily understood.

I never liked those compression/linearity graphs that showed all the graphs in raw dB, eg:
Namm2020SpeakerCompression_5.png


Having it normalized makes a whole lot more sense.
 
MZKM said:
I would alter the title to include “compression“ to make it even more easily understood.
Click to expand...

Thing is, it isn’t just compression. I plan to add some notes to it like I did my other ones, though.
 
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