Question About NFS and Theile-Small Box Alignments

[Ascend0577]

Has the Klippel NFS confirmed or differed any expectations of a theoretical design Q for a woofer/enclosure/port/rolloff combination based on Theile-Small parameters with any of the latest Ascend speakers?

If there are differences, how do they affect the Q values (lower/higher), F3/F10, dB rolloff/ octave, etc. and/or what has had to be adjusted to meet a target? Dave, I have enjoyed and appreciated all the knowledge you have shared over the years!

Thank you for being a pioneer establishing an audio company that gave consumers objective data way back with the CBM-170! I remember the Soundstage! review and NRC measurements, along with yours, and being so impressed. Witnessing the journey to the NFS has been amazing, with a newly optimized version of nearly the entire product portfolio.

[davef]

Has the Klippel NFS confirmed or differed any expectations of a theoretical design Q for a woofer/enclosure/port/rolloff combination based on Theile-Small parameters with any of the latest Ascend speakers?

Thanks so much for your nice comments!

No, Klippel NFS is for frequency response measurements. While the KA3 (Klippel analyzer) can measure T/S parameters, they would not be any more or less accurate than the other systems we use for taking T/S parameters, including the T/S params we specify to our driver manufacturers or what they measure. If anything, our NFS measurements fully confirm the accuracy of said measurements as bass response and Q are what we expect.

[Ascend0577]

Dave,

Thank you for the reply. I was likely unclear in that I did not think the NFS would measure different T/S parameters. It was more whether the theory for Q/box alignments/associated frequency response still held true with the resolution of the NFS. I'm glad that the NFS has confirmed that alignments based on T/S parameters are accurate.

[davef]

Dave,

Thank you for the reply. I was likely unclear in that I did not think the NFS would measure different T/S parameters. It was more whether the theory for Q/box alignments/associated frequency response still held true with the resolution of the NFS. I'm glad that the NFS has confirmed that alignments based on T/S parameters are accurate.

The Klippel NFS uses the Klippel KA3 analyzer, which by itself is a powerful R&D / measurement platform. It has the capability to take T/S params either by added mass method, or by laser displacement (most accurate method). We did not purchase the laser sensor so we have not used this feature, perhaps sometime in the future.

We use MLSSA for T/S params and we almost always confirm these with the driver manufacturer. SEAS uses the Klippel KA3 for T/S params.

That stated, yes - our NFS full range bass measurements correlate quite well with our theoretical models that are based on the T/S params. Variations can often be traced to environmental changes (temperature, humidity) or just unit to unit variations, but overall - the consistency between our modeling and actual measurements is even better than I anticipated. If you notice with our NFS measurements, bass response is accurate with no low-Q bumps or any odd behaviors.