Differing vertical plots from Erin and Amir

[Another Bob]

Curious to be sure, and worthy of investigation. But let's keep things in perspective. For most listeners, with most music, those differences above 10k will have minimal audible impact. Throughout the range where it really matters, the two measurements are in very good agreement. Hardly a situation that would render speaker measurements meaningless. Furthermore, since other speakers reviewed by both Erin and ASR don't exhibit this kind of difference, it appears to be an anomaly with this particular speaker (as already mentioned) or possibly this particular test run.

 

[NTK]

Seemingly minor differences in mic positioning and configurations can have significant effects on the measurement results at the higher frequencies. For example, here are the differences between having the Klippel supplied mic-collision-protection-cage installed or not, and adding an extension boom. Changing the mic position relative to the speaker will have a larger effect.

Erin's Audio Corner gets a Klippel NFS!

The biggest concern I had once I set up the NFS was the microphone boom as well as the cage. The cage is a safety feature. It isn't intended to be used on the microphone at all times (not my opinion; Christian Bellman verified this when I had as Skype session with him and asked about it...

www.audiosciencereview.com

 

[NTK]

@NTK So if somebody asks you what the vertical directivity of the Wharfedale 12.1 speaker is what would you say? I don't know how to interpret Erin's conclusion that the vertical directivity is ±5 when it contrasts with Amir saying that it's >30.

I'd judge directivity based on the normalized plots. When normalized, the deviations are calculated by comparing to the on-axis/listening window response. So it is not conflated with the dips or peaks in the on-axis/listening window response.

Also, the vertical directivity mismatch is usually confined to a fairly narrow frequency range (higher order cross-overs will have an advantage here), and thus audibility is often not high.

 

[ctrl]

A ~10db swing, 10db! Not 1, not 2, not 3, not 4, not 5, not 6, not 7, not 8. . .10 mother effing db!
Respectfully, I don't buy it. Either way, if that is enough to create a 10 db swing, then speaker measurements are meaningless which is even harder to believe.

A few things you can easily check yourself. Exemplary for the Wharedale 12.1 which is the subject of this thread.

Compare the vertical FR +-10° over 15kHz. In this frequency range, the edge diffraction hardly plays a role anymore, because of the narrow radiation of the tweeter.
If the center of the tweeter is taken as reference axis, the ver +10° and -10° FR of Amir's and Erin's NFS measurements should be nearly congruent.

In the vertical direction, both NFS measurement series show that the center of the tweeter was very well targeted.
Amir's measurements only contain more reflections due to the NFS device setup in the range 1000-10000Hz (sound reflecting surfaces that were not damped with damping material or something like this).

Since the loudspeaker is horizontally symmetrical, we can, for example, compare the +-20° measurements to see if the reference axis was optimally aligned here.

For Erin's +-20° measurements, the congruence of the measurements is perfect; for Amir, there are significant discrepancies above 10kHz (3dB diff @15Khz).

The deviations in Amir's measurements can have different causes, on the one hand the horizontal reference axis could not have been aligned exactly with the tweeter or the measured loudspeaker itself was no longer perfectly symmetrical due to manufacturing tolerances or transport damage.

Now we compare how much the horizontal 40° FR measurements of Erin and Amir differ from each other - differences by the measurement mics are eliminated because of normalization.
To do this, we superimpose the measurements of the two normalized to the on-axis FR, because we likely know that Amirs speaker is slightly asymmetrical, we use his +-40° measurement - cyan Amir -40° (light green +40°), dark green Erin +40°:

Up to 14kHz the match of Erin's +40° and Amir's -40° is perfect.
Only above 17kHz the deviation becomes larger than 2dB.

The reasons for the deviation above 17kHz can be different and a mixture of different things.
It can be differences in the settings of the NFS measurements (some kind of none FR linear behavior) and very likely deviations due to manufacturer tolerances (different reflections by the tweeter WG).

 

[CleanSound]

The reasons for the deviation above 17kHz can be different and a mixture of different things.
It can be differences in the settings of the NFS measurements (some kind of none FR linear behavior) and very likely deviations due to manufacturer tolerances (different reflections by the tweeter WG).

Klippel NFS setting and configuration is the most reasonable, manufacturer tolerances is not for this example. Because it's opposite swings and the difference is close to 10db.

 

[beagleman]

Both Amir and Erin have submitted their raw spinorama data to Pierre (at spinorama.org). Both of their data shows the exact same vertical direcivity for Wharfedale 12.1


I don’t know where you got the +-5 deg from, but that sounds like an eye-ball approximation, rather than a calculated value.

I trust spinorama, since it’s always calculated and easily compared between speakers. There’s no ambiguity.

I think Erin actually mentions this on his YouTube review of the 12.1

He says something about it being only 5 degrees and tweeter height being important and so on.
I own the 12.1 and do find the vertical dispersion to be fairly small, but not sure it is only 5 degrees either.....

 

[Curvature]

Research from Vanderkooy shows that vertical crossover dips are hard to hear even at -12dB.

Personally I find narrow regions like these to be inaudible. What's more audible is speakers with AMTs or ribbons where a large chunk of the FR changes.