Loudspeaker Frequency Response: Stereophile vs true Anechoic

[Vladimir Filevski]

I then hopped on the internet, found stereophile's review/measurements...
There is a 10db hole near 700hz....
"It was never audible" they said.....

nteresting commentary:
Although this dip does exist, it probably does so only at the 45" measurement distance. Getting farther away from the loudspeaker will likely result in better integration of the individual drivers' outputs, making the suckout disappear.
Why didn't they move further away and measured again to verify this theory?

Vertical distance between midrange and woofer is very big (that flat membrane between is passive radiator), so certainly the short 45" measuring distance is the culprit of that 700 Hz hole on measured frequency response.
Here is the proof - vertical response (normalized), from the same review:

from 15 to 45 degrees below the reference measuring axis (tweeter) that 700Hz hole is nicely filled up.

 

[Vladimir Filevski]

I stopped caring about anything stereophile put out after reading their comments on the grimm ls1 previews, and then seeing the data that completely contradicts what they said.

??? Subjective review was extremely positive ("I'd hold on to these exceptional monitors and enjoy the hell out of them for the rest of my days. They're that good."), and Atkinson concluded the objective review with the words "it is the best-measuring loudspeaker I have encountered!"
Where is the contradiction?

 

[Vladimir Filevski]

--The impedance graph is poorly scaled for the phase. There is no need to have the chart go from +180 degrees to -180 degrees. It should be +90 to -90. As it is, it's hard to discern anything useful from the phase plot.

--The impulse response graph is improperly scaled and impossible to interpret as provided. It goes from -1ms to +10ms, but in the text above they state that the first reflection off of the floor occurs at 5ms. So why show the plot all the way to 10mS? And if the first reflection occurs at 5ms, where is it in the plot? A better range for this plot would be -1ms to 5ms, or even to 3ms.

--The horizontal polar response should be provided taller, and the color mapping used needs improvement. Also, it apparently goes all the way to 45kHz, which is entirely too high and unnecessary, thus reducing amount of info that can be gleaned from the more important audible range.

I concur.

--The frequency response at 1m is ranged from 20Hz to 40kHz. I see no need to go so high. 30kHz is plenty high enough, and it could be argued that even 20kHz is sufficient (the only reason to go above that being to see a tweeter's ultrasonic resonance). Having this scale also blurs information in the more relevant/audible frequency ranges.

Ratio of the picture nicely accommodate extended range to 40 kHz. Always is nice to see how big ultrasonic resonances are.

--I like that they still include individual driver responses, but the scale going to 40kHz is still unnecessary. The woofer nearfield response doesn't show the dip that occurs due to the port. Why not? And where is the port output? It almost looks like it's actually not a nearfield response of just the woofer but instead a response of the woofer and port together at farfield.

Obviously, measured low-frequency response of this bookshelf is combined cone+vent nearfield output. It would be nice to see separate port and cone output, especially when there are pronounced resonances from the port output.

--The waterfall/CSD plot is shown at a weird angle.

It seems fine to me.

 

[SigbergAudio]

Vertical distance between midrange and woofer is very big (that flat membrane between is passive radiator), so certainly the short 45" measuring distance is the culprit of that 700 Hz hole on measured frequency response.
Here is the proof - vertical response (normalized), from the same review:

View attachment 554407
from 15 to 45 degrees below the reference measuring axis (tweeter) that 700Hz hole is nicely filled up.

Yes, I didn't necessarily doubt that was the case, just strange that they didn't share an on-axis measurement further away to prove it.

 

[Beave]

Vertical distance between midrange and woofer is very big (that flat membrane between is passive radiator), so certainly the short 45" measuring distance is the culprit of that 700 Hz hole on measured frequency response.
Here is the proof - vertical response (normalized), from the same review:

View attachment 554407
from 15 to 45 degrees below the reference measuring axis (tweeter) that 700Hz hole is nicely filled up.

True, the 700Hz hole fills in at those angles, but then another hole develops in the region of the mid-to-tweeter crossover. First order crossovers.

 

[Beave]

I concur.


Ratio of the picture nicely accommodate extended range to 40 kHz. Always is nice to see how big ultrasonic resonances are.

I too find it interesting to see behavior from 20kHz to 40kHz, but it's not really relevant in terms of audibility, and in my opinion it should only be shown if it does not impact the presentation of the data below 20kHz. Unfortunately, in the case of these measurements, it does impact the presentation of the data below 20kHz.

Obviously, measured low-frequency response of this bookshelf is combined cone+vent nearfield output. It would be nice to see separate port and cone output, especially when there are pronounced resonances from the port output.

Yes, I agree.

It seems fine to me.

I suppose this one is purely down to personal preference.

 

[Vladimir Filevski]

True, the 700Hz hole fills in at those angles, but then another hole develops in the region of the mid-to-tweeter crossover. First order crossovers.

You are looking at he "wrong" side of the vertical response - curves behind the 0 degrees normalized flat line. You should look the curves in front of the 0 degrees normalized flat line (below the tweeter axis) - there is no hole at all.

 

[Beave]

You're right. My mistake.

It's hard to tell which direction is for angles *above* the on-axis reference and which direction is for angles *below*.

In any case, moving one direction fills in the 700Hz hole, while keeping the rest flat. Moving the other direction almost seems to *over*fill the 700Hz hole while also creating a new hole.

Edit: I'm guessing the front-most curves are for angles below on-axis, and the rear-most curves are for angles above.

 

[LiveTek]

??? Subjective review was extremely positive ("I'd hold on to these exceptional monitors and enjoy the hell out of them for the rest of my days. They're that good."), and Atkinson concluded the objective review with the words "it is the best-measuring loudspeaker I have encountered!"
Where is the contradiction?

I said preview, not review. They made comments about the rear panel being close to the driver would cause issues, and that some people might not care for the narrow dispersion. Two things that are not found in the ls1, and they made these comments before measuring them. I mean my god who cares if I don't want to read their stuff.