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Audio Science Review VS Sound & Recording : who has the more accurate on-axis measurements?

daftcombo

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#1
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daftcombo

daftcombo

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Thread Starter #4
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Sancus

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#6
Personally I would only EQ under 1khz(or wherever your room takes over for you) based on in-room measurements, as the measurements of the speaker have so little to do with the result in that region.

People often post heavy EQ in Amir's reviews, but IMO, especially for the cheaper stuff, that EQ is only valid for the unit Amir measured. I looked on ADAM's site but wasn't able to find manufacturing tolerances for this speaker. So safe to say it's at least +/- 1dB and could even be as high as +/-2dB. Add that to the microphone and methodology margin of error...There was a thread on here about some(expensive) speaker where someone posted an EQ suggestion and the manufacturer responded, basically "one of those filters looks possibly useful, but the rest are all <1dB, so you are just trying to EQ the manufacturing tolerance and that's not going to work." (competent) Manufacturers of active speakers are perfectly aware of EQ/DSP and if they are using it less aggressively there is usually a good reason for that.

For the T8V, I might try bumping up the region between 1.5khz and 3khz a little bit, and shelving down the treble maybe 1dB and see how that sounds, but that's about it. Those areas are fairly similar between S&R and ASR. The high Q dip between 4-5khz seems best left alone and all the other variations seem too small in magnitude to work on.

Of course, you can always try to do nearfield measurements of your own unit(s), this should be useful especially at higher frequencies.
 
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daftcombo

daftcombo

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Thread Starter #7
For the T8V, I might try bumping up the region between 1.5khz and 3khz a little bit, and shelving down the treble maybe 1dB and see how that sounds, but that's about it. Those areas are fairly similar between S&R and ASR. The high Q dip between 4-5khz seems best left alone and all the other variations seem too small in magnitude to work on.
You are right that EQing a speaker under 1 kHz is probably not so important, since the room problems will be more important.

But how do you account for the measurement differences? If they are different in the same way from review to review, it cannot be simply a unit to unit variation each time.
 

Vincent Kars

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#8
Aus dem Messlabor…
… unter reflexionsfreien Bedingungen stammen die folgenden Messungen zum Frequenzgang, zum Abstrahlverhalten und zu den Verzerrungswerten. Der Klasse-1-Messraum erlaubt Messentfernung bis zu 8 m und bietet Freifeldbedingungen ab 100 Hz aufwärts. Alle Messungen erfolgen mit einem B&K 1/4″-4939-Messmikrofon bei 96 kHz Abtastrate und 24 Bit Auflösung mit dem Monkey-Forest Audio-Messsystem. Messungen unterhalb von 100 Hz erfolgen als kombinierte Nahfeld-Fernfeldmessungen.
My understanding of German is a bit feeble but might it be they are using a anechoic room instead of a Kippel?
 

andreasmaaan

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#9
But how do you account for the measurement differences? If they are different in the same way from review to review, it cannot be simply a unit to unit variation each time.
I'm not sure I see a consistent difference from measurement to measurement. Do you see a specific frequency range where Amir and S&E's measurements differ in the same way regardless of the DUT?
 

Absolute

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#10
You are right that EQing a speaker under 1 kHz is probably not so important, since the room problems will be more important.
Resonances should be EQ'd both above and below 1 kHz. The more I try the more I realize that room correction is a minefield where every step could potentially send the sound quality to hell.
I have an example where I used room correction through Audiolense that didn't sound good. It fixed all the issues below 1 kHz, but something was clearly way off.

Skjermbilde (11).png



So I measured before and after with MMM technique and this is what I found;

Audiolense is RED, normal M2 tuning without room correction is BLUE.

MMM original M2 (Blå) vs MMM Etter Audiolense (Rød).jpg


One thing is the clearly degraded overall tonality with way too thick upper bass and mids, another thing might be the flipside of the coin of doing room EQ. If we consider the importance of speaker resonances for audio quality as per Dr. Floyd "we must avoid resonances at all costs" Toole it might suddenly make sense why room EQ may come with a cost we can't afford;

As I said, because loudspeaker transducers are minimum-phase devices one can use electrical parametric EQ to attenuate the mechanical resonances in transducers - using anechoic data of course. So, if you add a hump to an otherwise neutral/resonance free speaker you have added a resonance. This is why it is crucial to pay attention to what "room equalizers" are doing. If they "see" a ripple in a measured curve caused by acoustical interference of direct and reflected sound, and try to flatten it, they may be adding a resonance and degrading a good loudspeaker.

https://www.avsforum.com/threads/ho...-science-shows.3038828/page-241#post-58530898

(thanks to @thewas for this excellent thread with all kinds of beautiful info lined up)

But how do you account for the measurement differences? If they are different in the same way from review to review, it cannot be simply a unit to unit variation each time.
I've noticed this as well since it was a bigger issue before Amir found a solution to avoid the strongest reflections from the protection cage around the mic.
Reflections is probably the obvious answer still - and the reason you should hang your microphone from the ceiling with a wire or two instead of microphone stand :)
 
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daftcombo

daftcombo

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Thread Starter #11
I'm not sure I see a consistent difference from measurement to measurement. Do you see a specific frequency range where Amir and S&E's measurements differ in the same way regardless of the DUT?
You must be right. I don't neither have an example of a frequency range being affected by the same variation on the three examples I gave. Only examples for two of them. That probably rules out my theory.

So it is probably more about unit to unit variation (which is not such a piece of good news).
 

Absolute

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#12
You must be right. I don't neither have an example of a frequency range being affected by the same variation on the three examples I gave. Only examples for two of them. That probably rules out my theory.

So it is probably more about unit to unit variation (which is not such a piece of good news).
Use loudspeaker explorer for this, otherwise you'll go insane looking at graphs o_O
 

mhardy6647

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#13
You know what we do, in my line of work?
If there's a need for (e.g.) international agreement about the calibration of an assay (or a suite of different but related assays/analytical methods) and a quantitative outcome (e.g., an international standard), "we" (a bunch of relevant laboratories/entities) will do a large, multi-site/multimethod test of a reference material (one or more) to see how the absolute results compare between laboratories. International standards (e.g., the "international unit" for human plasma Factor VIII, a coagulation cascade blood "factor" protein, defects in which cause Type A hemophilia) are calibrated this way, too.

Here's a not-entirely-random (although not up to date) example: https://pubmed.ncbi.nlm.nih.gov/11341497/

"We" could do worse than use a set of "identical" loudspeakers (or, less desirably, one) sent in parallel (or round-robin) to a suite of test facilities -- and then objectively comparing the data.

One of the useful (maybe even "important") outcomes of such a study would be the "envelope of uncertainty" around any given measurement or result. In other words, if two datasets (or data points) cannot be statistically considered different --they're "the same". :)

Maybe this isn't relevant to the current discussion, but -- in my mind, at least, it might be!

Thanks for "listening"!
 

richard12511

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#14
Hi,

I've noticed several times that ASR and S&R measurements differ.

Here is just one example, but you could find many others.

Adam T8V:

ASR:
View attachment 110346
Source: https://www.audiosciencereview.com/forum/index.php?threads/adam-t8v-studio-monitor-review.17118/

Almost flat from 50 Hz to 1 kHz, even a bit raising after 500 Hz.


S&R :

View attachment 110347

Source: https://www.soundandrecording.de/eq...ner-und-u-art-air-motion-transformer-im-test/

Almost flat from 50 Hz to 1 kHz but with a dip between 600 Hz and 1 kHz.


Cheers.
I don't know, those measurements actually bare a great deal of resemblance to my eye.
 

richard12511

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#15
.There was a thread on here about some(expensive) speaker where someone posted an EQ suggestion and the manufacturer responded, basically "one of those filters looks possibly useful, but the rest are all <1dB, so you are just trying to EQ the manufacturing tolerance and that's not going to work." (competent) Manufacturers of active speakers are perfectly aware of EQ/DSP and if they are using it less aggressively there is usually a good reason for that.
Which thread was that? I'd be curious to read.
 

ctrl

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#16
I've noticed several times that ASR and S&R measurements differ.
Here is just one example, but you could find many others.
To be able to really compare the measurements, some preconditions have to be checked:

- Was the microphone position identical in relation to the baffle?
Amir always points the measurement microphone at the tweeter center, S&R takes into account the manufacturer's specifications (as far as I know), which often means that the mic is aligned halfway between the tweeter and the bass-midrange chassis.

- Was the measurement distance identical?
In @amirm's reviews the description of the simulated measurement distance is missing, AFAIK the distance (at least in the current measurements) is simulated for a distance of 2m (the NFS measurements can be transferred to any measurement distance) and the SPL is converted to 1m (as required by the CEA/CTA-2034 ANSI).
The measurement distance for S&R's ground-plane measurements depends very much on the loudspeaker dimensions. Thus, measurements are very often made at a distance of 4m to fully capture the influence of the baffle.
A large measurement distance also reduces the effect of phase shifts on the frequency response caused by the distance between the different chassis.
But possible temperature fluctuations affect the phase behavior at large measuring distances (which is not a problem with the NFS due to the near-field measurements).



If the temperature in Amir's garage is around 20°C, the resolution of the measurements in the low bass should be superior to those of S&R.
S&R's anechoic chamber does extend down to 100Hz, but the "gating" of the measurement smooths out the frequency response somewhat at low frequencies. Below 100Hz it depends on how well the various near-field measurements of woofers, possible ports and the influence of the baffle is simulated are calculated to an approximation of the frequency response below 100Hz.

If the S&R ground-plane measurements are performed very carefully, they should be superior to those of Amir's NFS in the frequency range above 10kHz, since the conversion of the frequency responses measured in the near field to user defined distances becomes less accurate towards very high frequencies (or needs a lot of data points and time to be accurate up to 20kHz, e.g. 7h measurement for one speaker).
.
 
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daftcombo

daftcombo

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Thread Starter #17
What bothers me the most is not the measurements and their differences. It is the attempt to EQ speakers based on measurements whereas other measurements would lead to try other EQ presets.

Hence, the EQ recommendations made here and compiled on this forum can be less pertinent than expected.
 

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