Loudspeaker Frequency Response: Stereophile vs true Anechoic

[staticV3]

Though Stereophile provide measurement data for their speaker reviews, it is well known that their method of graphing anechoic response (splicing gated nearfield data), results in some inaccuracies, especially at low frequencies.

To get a feel for how large these inaccuracies are, I looked through their list of speaker reviews, checked for which speakers I could find true anechoic response data, then plotted the difference between them.

Since Stereophile's graphs use a 30° horizontal AVG, I used Listening Window data as reference (not a perfect match, but better than on-axis).

Here are all 45 response errors with the AVG error in red:


Three distinct groups are visible:

• Bass shelf:
  
• Shelf+midrange scoop:
  
  
• Accurate:
  

In hopes of finding trends, each measurement title contains the year in which the speaker was tested by Stereophile, as well as the type (B=Bookshelf, T=Tower).

Unfortunately I did not find any trends related to review date or speaker type.

Though in general, the response starts to deviate below 300Hz.

Attached below is the .MDAT with all individual error curves, as well as a folder containing the raw response curves in .csv, traced from JPGs/PNGs or directly from Amir's Zips.

Enjoy!

Spoiler: Sources

Floor Loudspeaker Reviews | Stereophile.com

stereophile.com

Stand Loudspeaker Reviews | Stereophile.com

stereophile.com

A collection of loudspeakers measurements

www.spinorama.org

 

[kemmler3D]

Great post. Looks like this tells us something we already knew (their low frequency data is not accurate) and maybe something we didn't - those deviations at 10khz and 20khz weren't on my radar.

Also, the typical deviation from anechoic seems pretty large. Like at least a few dB for any given measurement... some of that is probably due to differences in LW vs. 30deg averages, but hmm...? Did you compute any stats on average / median deviation from anechoic?

 

[DSJR]

In my crude and now highly amateurish way, I simply take 3dB or so off their ~120Hz region to get a basic impression of a speakers' possible bass performance. The extreme top however, often tallies fairly well with other more thorough measurements I think, especially those of speakers with hf that takes off on axis...

It's the HFN plots that look truly suspect to me...

 

[staticV3]

Did you compute any stats on average / median deviation from anechoic?

Not yet. Though if anyone wants to analyze the data more thoroughly, that'd be much appreciated.

 

[mlsstl]

Interesting, but I find the variability of bass in recordings often renders the accuracy of a speaker setup's bass in a room somewhat meaningless. Lots of recordings where the bass is way overdone while pretty much nonexistent on other recordings. Sometimes the results are funny. I recall listening to an old Peter, Paul & Mary recording from the early 60s that was quite enjoyable until I added a subwoofer to my system a few years back. The sub was setup with room equalization so hadn't been overdone. However, on this recording, it brought out all the thumping present on the recording, apparently from a creaky old wooden stage. A good recording turned into an annoying one!

That's why I don't get overly obsessed with chasing the last nth degree of performance from my system -- the variability of recordings for the wide range of music I enjoy often exceeds any deficiencies of my system.

 

[kemmler3D]

Interesting, but I find the variability of bass in recordings often renders the accuracy of a speaker setup's bass in a room somewhat meaningless. Lots of recordings where the bass is way overdone while pretty much nonexistent on other recordings. Sometimes the results are funny. I recall listening to an old Peter, Paul & Mary recording from the early 60s that was quite enjoyable until I added a subwoofer to my system a few years back. The sub was setup with room equalization so hadn't been overdone. However, on this recording, it brought out all the thumping present on the recording, apparently from a creaky old wooden stage. A good recording turned into an annoying one!

That's why I don't get overly obsessed with chasing the last nth degree of performance from my system -- the variability of recordings for the wide range of music I enjoy often exceeds any deficiencies of my system.

Just because the view along the drive isn't always good, doesn't mean you shouldn't keep your windshield clean...

 

[kemmler3D]

Not yet. Though if anyone wants to analyze the data more thoroughly, that'd be much appreciated.

Totally fair, I felt lazy even asking, but should be a good exercise for someone with a spreadsheet and some spare time...

 

[mlsstl]

Just because the view along the drive isn't always good, doesn't mean you shouldn't keep your windshield clean...

Agreed. I think my point was more to note that it is easy to become obsessive about looking for perfection in the system. Besides the recording, there is also the room itself. One can have a speaker that tests perfectly but throws much of that away the minute it is placed in a listener's room. Amazing how many expensive speakers are placed in a room with no RC or acoustic treatment.