NFS Luna / Duo Follow up

[theophile]

Some good news to share....

I have made arrangements to have the original Luna tested in a true anechoic chamber. This will, once and for all, give me the answers I seek and provide some closure...

Great Dave, very interesting! To collaborate the two testing scenarios and their similarities will be positive confirmation...keep us informed!!

Ted

[davef]

Great Dave, very interesting! To collaborate the two testing scenarios and their similarities will be positive confirmation...keep us informed!!

Ted

Yes, I am excited about this. To be honest, I hope the chamber measurements perfectly match our NFS measurements in that port resonance range. Things will be a bit "messy" if they do not and I will then have to get Klippel involved to determine what is going on...

[Pogre]

Some good news to share....

I have made arrangements to have the original Luna tested in a true anechoic chamber. This will, once and for all, give me the answers I seek and provide some closure.

I will have to ship the speaker to Norway (SEAS), but our friends at SEAS are happy to run the measurements I have requested. SEAS also uses Klippel measurement gear (not the NFS though since they have a chamber), but all Klippel gear is based off the same software and same hardware analyzer.

I'm really curious to see how close everything matches too. This will be interesting to follow. Very cool you have a relationship with SEAS and they're gonna run that speaker through the anechoic gauntlet for you. This should definitively let you know how accurate the NFS is compared to the real deal.

You're a real dog on this one man. Git 'em! Lol

[davef]

Huge thanks to our good friends at SEAS. I shipped them the Luna that was tested by Amir (and by us) to verify the accuracy of the Klippel NFS measurements, especially in the area of the port resonance.

SEAS measured this for me in their anechoic chamber. They also use Klippel test gear for their measurements, but they don't need or use the NFS since they have a dedicated true anechoic chamber.

These test results speak for themselves, an exceptionally close match with our Klippel NFS measurements. This fully confirms that our NFS measurements are dead-on accurate, even in the area of the port resonance. These results also confirm that gated measurements (what nearly every speaker designer / speaker company uses) are not accurate enough to truly capture a high Q port resonance. This also explains why so many speakers tested by Amir show similar port resonance issues, it isn't that the NFS is improperly calculating this, it is that nearly all other measurement systems (aside from the NFS or a having a true anechoic chamber) are simply not capable enough to meet more stringent standards.

I am most pleased with this outcome, it fully puts to rest this bothersome and somewhat obsessive issue for me.

Measurement of the OG Luna taken by SEAS in their chamber is in green. Our NFS measurement of the exact same speaker in Red. I offset the curves to makes it easier to visualize. There are some slight differences, mostly in the low end and this would be due to SEAS's chamber being limited to about 80Hz. No anechoic chamber is accurate down to 20Hz, the wavelengths are just far to long to absorb. In this regard, the NFS is more accurate than any chamber.

OG Luna SEAS (green) & OG Luna Ascend (red).jpg



In the below 2nd measurement, also taken by SEAS, the slot port as been sealed off. You will note that this measurement tracks our published measurement for the Luna. This indicates that our gated quasi-anechoic measurements are accurate, but were just not capable of accurately picking up that front slot port resonance under typical conditions.


OG Luna SEAS sealed port.jpg