The relevance of measurements to audible quality of sound

[dc655321]

Why should headphones be anything but flat?

To compensate for the absence of the room and acoustic interaction with the outer ear (pinna, etc)?

 

[oivavoi]

To compensate for the absence of the room and acoustic interaction with the outer ear (pinna, etc)?

Perhaps. I would just like to have a valid acoustic or psychoacoustic explanation for it.

 

[dc655321]

Perhaps. I would just like to have a valid acoustic or psychoacoustic explanation for it.

Fair enough.
But, to which I would ask for your definition of "valid", in this context.

 

[Grave]

The absence of channel interaction which would normally cause high frequency attenuation, and also the shape of your ear.

 

[Headphonaholic]

Hello,

In this forum we see specific measurements posted regarding many devices.

Recommendations are made on the basis of these measurements. All very scientific, which I like.

I mean who would buy a Car on a vague concept "how it drives"?

We know top speed, torque, mpg etc. and can rely on these together with convenience features (how many cup holders, size of the trunk and how easy to access) a shape and colour that pleases us to get a good choice.

No need to test drive, right?

Now with a car I can follow the value of these measurement numbers. I can understand why a car with good torque, top speed, mpg and convenient layout would be reasonably recommended over one that falls down in one or several of these areas, though it has not stopped the buying public from buying inconvenient and inefficient cars, myself included and yes, I test drive and decide ultimately on many factors including how it feels driving on what I buy.

While the measurements presented here seem of a similar kind (Distortion, Noise, Jitter), I would ask for the scientific background.

If we elevate specific qualities as a measure of the recommendability of a device to listen to music with, there ought to be good scientific evidence that shows that lower distortion is always better sounding, that lower noise is always better sounding and I mean not in a relative sense as in: "Above a certain limit lower distortion always sound better" or "Above a certain limit lower noise always sounds better", but in the absolute sense in which it is presented here.

Alternatively, if these is a consensus about what levels of distortion, noise and jitter are actually audible, it would be interesting to know what they are and how tested devices results compare to those limits.

Also, if there are such limits and all tested devices are below the audibility threshold, should recommendations based on the measurements still be made?

Ideally the proponents of "low distortion uber alles", "low noise uber alles" and "low jitter uber alles" simply have reliably scientific tests to present that support their position and then we can continue measuring and recommending on this basis. My own research failed to provide such tests and evidence, however surely no-one scientific inclined would test result based recommendations without good and solid evidence that these test results are meaningful in the context.

Magnum Innominandum

I honestly don't know why you are on this particular forum but if you want to tweak the sound of your HD6XX I would recommend you check this software out: https://www.sonarworks.com/truefi I own it and it's quite interesting. Not something I use often but it is interesting. I personally own the HD6XX and feel that the bass response is good... adding more sounds like a bad idea to me.

 

[Grave]

I honestly don't know why you are on this particular forum but if you want to tweak the sound of your HD6XX I would recommend you check this software out: https://www.sonarworks.com/truefi I own it and it's quite interesting. Not something I use often but it is interesting. I personally own the HD6XX and feel that the bass response is good... adding more sounds like a bad idea to me.

These headphones are obviously lacking in deep bass. They have plenty of mid bass.

 

[Headphonaholic]

These headphones are obviously lacking in deep bass. They have plenty of mid bass.

That is a fair distinction, but then again also not terribly surprising considering it's an open back headphone with velour pads. Could try swapping pads, I would probably go with hybrid pads since that would hopefully not change the signature too much but should boost the bass some. I think Dekoni makes pads for the HD600 series.

Not sure how much quality deep bass you can expect to get out of them but that Truefi software will be a good bet I think. If someone was looking for a bassier open back headphone I would likely point them toward Phillips X2 not HD650's.

 

[Sal1950]

18dB is not needed at al. It is waaaayyyy too much.
That would make it a basshead headphone !
+7dB is more than enough otherwise the HD650 starts to sound bloated and 'fat'.

This whole discussion of heavy bass enhancement on the Senn 650s has me a bit confused. Now I have never heard anything like these recommended curves, but my Emotiva DC-1 has a built in (defeatable) 2 db boost at 20hz and the bottom end on my HD650 sounds very good to me. My imagination tells me that another 5 db "or more" might sound a bit heavy and excessive sending it's effects into the lower midrange. Guess I'd have to hear it to understand for sure.

 

[Grave]

The Sennheiser HD 650's and the Sennheiser HD 660 S's deep bass sounds excellent to me if turned up, as I have already said. I have owned duller open headphones such as the Audeze LCD2 and the Sennheiser HD 58X, but I did not like them as much.

I like the Dekoni ear cushions. I have leather ear cushions on my Sennheiser HD 650's and I have leather ear cushions for my Sennhesier HD 660 S's coming soon. I do not think that these ear cushions affect the sound significantly, but they maybe add a tiny bit more bass.

 

[Headphonaholic]

The Sennheiser HD 650's and the Sennheiser HD 660 S's deep bass sounds excellent to me if turned up, as I have already said. I have owned duller open headphones such as the Audeze LCD2 and the Sennheiser HD 58X, but I did not like them as much.

I like the Dekoni ear cushions. I have leather ear cushions on my Sennheiser HD 650's and I have leather ear cushions for my Sennhesier HD 660 S's coming soon. I do not think that these ear cushions affect the sound significantly, but they maybe add a tiny bit more bass.

I've heard great things about the 660s, I would love to hear them. The 58X are fairly similar to the 6XX.

I'm a bit shocked that leather pads didn't change the sound much. I would have expected a good bit more bass and very likely more treble as well. I feel like I have a pair of Dekonis for my 6XX somewhere, I don't think I've tried em yet since I really enjoyed the stock sound.

 

[Grave]

The 58X are fairly similar to the 6XX.

Nope, the Sennheiser HD 58X's are much duller than the Sennheiser HD 650/6XX's which are similar to the Sennheiser HD 660 S.

 

[Sal1950]

I've heard great things about the 660s

Nope, they are much duller.

Imagine that, we have difference of opinions.
I'd give mine but I have to keep that secret till next months issue.

Boy has this debate on Senheiser EQ made a mess of this thread supposedly to investigate
The relevance of measurements to audible quality of sound

 

[Headphonaholic]

Imagine that, we have difference of opinions.
I'd give mine but I have to keep that secret till next months issue.

Yup! A fantastic example of why measurements are the great equalizer!

Ha, that's a shame, I'm sure your opinions are interesting.

 

[Grave]

Headphonaholic said:
I've heard great things about the 660s
Grave said:
Nope, they are much duller.

I did not say that the Sennheiser HD 660 S's are duller.

 

[solderdude]

Boy has this debate on Senheiser EQ made a mess of this thread supposedly to investigate
The relevance of measurements to audible quality of sound

At first I thought the OP was just another subjective troll... later it turned out he just wanted a headphone amp to drive his HD6XX and wanted to 'compensate' the FR because he read of Olive-Welti research and made sense to him.
So the title should have been: Help me choose a headphone amp for my HD6XX.

The original title would have been more interesting to debate, but would, yet again, turn to be all audibility thresholds.
In hindsight the thread title makes a bit more sense when it would have been called: The relevance of headhone measurements to audible quality of sound.

 

[solderdude]

.... I would just like to have a valid acoustic or psychoacoustic explanation for it.

Me too.... it seems the jury is still out on this one.
I made up my own mind and find some 'explanations' found here and there plausible and do validate my suspicions.

Absence of room reflections = bass region.
Different Pinna interaction = 2 - 6kHz region. There is no 'single' solution for this as all headphones interact differently.
Soundstage difference ... less easy (impossible ?) to solve though head tracking DSP seems to help (never heard it).
channel separation = entire freq range and 'solutions' are all over the place and generally should 'narrow' the stereo-width inside the head.

My opinion? The best (as in most realsitic) sounding headphones turn out to show a pretty 'flat' response from the drivers but depending on its interaction with Pinnae may have a certain recession (not deep/sharp 'dip') in the 2 - 6kHz region as to not sound too 'forward/clear'.

How much the (sub) bass needs to be raised seems to depend on personal preference and reference and above all personal average listening levels.
In general a few extra dB (of lower bass) gives 'flat measuring' headphones a bit more 'speaker-in-room' alike 'body'.
When a headphone needs too uch correction it usually does not 'improve' that much and distortion level in the bass goes through the roof.
You need something excellent to start of with. Otherwise a $ 10.- headphone could be made to sound as good as a $1000.- one... the can't.

To me a flat measuring (at 1m) nearfield monitor with the speakers spaced apart and away from walls sounds quite close to a 'flat' measuring headphone when it comes to tonal balance.
Set the same speaker up in an 'average' living room near a wall and they sound totally different.
Usually more boomy (the bass boost of a room) and rolled-off for higher freq. (depending on many factors)

Pick your poison but most of all enjoy the music.

 

[Magnum Innominandum]

1 resistor of 120 Ohm between the output + of an amplifier and the plug ring (and left channel tip) of the HD6XX One of the - connectors (assuming the amp is not balanced) to the common of the headphone plug.
+ in parallel to the headphone (so from ring to common and also one from tip to common a series circuit consisting of a 12 Ohm resistor + 47uF capacitor.

Should you want to try the 7dB boost simply change the 12 Ohm for 47 Ohm.
Tip: use a 100 Ohm potmeter and make it stepless, dial it in and measure the resistance to know how much boost is needed.

Thank you. Now I need to find someone to solder this for me...

Magnum Innominandum

 

[Magnum Innominandum]

Boy has this debate on Senheiser EQ made a mess of this thread supposedly to investigate
The relevance of measurements to audible quality of sound

I would still like more answers and especially the scientific research upon which they are based, just out of intellectual curiosity.

Looking at the Olive/Welti research regarding headphone target curves it seems very solid to me, well executed, using large number of listeners and solid statistics. Which is why I am considering to take their recommendation "on faith" and just follow it.

I had expected more suc research on subjects like distortion audibility etc. to underpin the relevance of measurements and why we should aim for specific limits or why we should always try for the best.

Yet so far no solid research has been cited and it seems limits are a matter of who you ask (everyone has a number they work with) and Amir kind of measures because he can measure and recommends on the concept of "better engineering", which kind of makes sense to me but seems just another belief (better engineering is desirable in the context of good sound).

Magnum Innominandum

 

[Wombat]

I would still like more answers and especially the scientific research upon which they are based, just out of intellectual curiosity.

Looking at the Olive/Welti research regarding headphone target curves it seems very solid to me, well executed, using large number of listeners and solid statistics. Which is why I am considering to take their recommendation "on faith" and just follow it.

I had expected more suc research on subjects like distortion audibility etc. to underpin the relevance of measurements and why we should aim for specific limits or why we should always try for the best.

Yet so far no solid research has been cited and it seems limits are a matter of who you ask (everyone has a number they work with) and Amir kind of measures because he can measure and recommends on the concept of "better engineering", which kind of makes sense to me but seems just another belief (better engineering is desirable in the context of good sound).

Magnum Innominandum

I concentrate on the best we can hear. Beyond that it is academic and speculative. For end-users RBCD capability(measurable) is technically enough. One level above that is enough for doubters- it is not difficult, thereafter you are entering vampire territory(hearing of bats).

 

[solderdude]

I would still like more answers and especially the scientific research upon which they are based, just out of intellectual curiosity.
..............
Yet so far no solid research has been cited and it seems limits are a matter of who you ask (everyone has a number they work with) and Amir kind of measures because he can measure and recommends on the concept of "better engineering", which kind of makes sense to me but seems just another belief (better engineering is desirable in the context of good sound).

Magnum Innominandum

Not very much solid research has been cited in this thread. A LOT can be found scattered over many 'audibility threads' but you need to look for it.
I agree that it depends on who you ask ... this is because of beliefs (audio religion) and experiences those people had simply differ.

I have said it before and will say it here again. It does not matter what others have researched and which articles they have written. It is about your OWN audibility thresholds. Once you find those you also know what matters to you. Who cares what matters to others.

It looks like you prefer universal science based knowledge pre-chewed and ready to go.
In the world of 'personal observations' it does not work that way ... too complex.
IF you want to play it as safe as possible do it Amirs way. Look for the best possible measurements.
Or research the papers that exist and find the 'lowest' values that research found and make a list of it.

I think you should take some online audibility tests (granted you need suitable equipment for that which currently you are trying to find) and determine your personal limits.
You will find they aren't nearly as extreme as some papers claim they are.
Reasons could be 'training' or incorrect conclusions that were drawn or factors that have not been considered in the conclusion or not really suited gear or methods have been used or other reasons.

You will find, among other things that +18dB at 20Hz is waaaayyy too much 'compensation'.