Comparing quality headphones – not easy
Dec 6, 2014 at 9:02 PM Thread Starter Post #1 of 5

Tassie Devil

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Note in what follows I’m not saying judgement is impossible, just that there are so many variables involved it is too easy to come to the wrong conclusion.
 
These variables are:
 
·       The person judging.  No two people (even identical twins) have exactly the same brain and the same environmental influences which lead to value judgements
·       The headphones themselves, their impedance, the nature of their construction and importantly, the place of the ones being tested in the production run
·       The headphone cable
·       The quality of the DAC
·       The impedance and other factors of the headphone amplifier
·       The quality of the digital audio input and quality of the original recording.
 
All the above has come home to me in the last few days when a modified Sennheiser HD 525 arrived claiming to be an HD 650 in disguise.  First listening was not impressive using the output from a newly acquired Sony NWS-X17 and appeared far inferior to the other HD 650s here so the evil thought was I had been conned. It turned out to be a rushed and incorrect judgement.
 
The previous owner assured me that recent 650 modules had been inserted + new padding was recently installed so I went back to a more serious evaluation.
 
The first discovery was the affect of the unbalanced headphone cabling.  The 650s were fitted with a rather nice cable purchased from a headfier some time ago,  Plug them into the modded 545s and the AQ was far more similar.  Further investigation was required.
 
A balanced cable came with the 545 but it was terminated with a 4 pin XLR plug that was removed and replaced with two Neutric 3 pin units.  This made headphone comparison on the main unit possible with quality FLAC files from a Meridian Sooloos server feeding to a Vaughan DAC & a HeadRoom Blockhead amp.
 
But comparisons were not as simple as expected for two reasons – 1. There was a 2 to 3 db difference in headphone sensitivity and 2. There was a significant time lag between listening as the cable was unplugged from one and inserted in the other.  Auditory memory is questionable at the best of times and it was difficult to pick as preference.  Every time I thought a decision had been made it changed on listening to a different (mainly classical) item.
 
To add fuel to the fire, from time to time I inserted the HD800s into the listening trials.  They clearly gave a greater ambience, slightly better resolution and better air around the instruments but at a greatly reduced sensitivity.  I’m not regretting their purchase but one pays heavily for the increased fidelity so are not recommended for anyone on a tight budget.  Why not?  Well both the HD 650s and the modded HD 545s were capable of giving immense musical enjoyment over a wide variety of music types.
 
But the abovementioned caveats do not mean any of these Sennheisers will suit everyone.  As I discovered the synergy between components, with the headphone cable a surprisingly significant item in the chain, will vary from set up to setup so preferences will differ. And I’ve made no reference to the AKG 702s so far and am reluctant to damn them as inferior to the Sennheisers due to a huge difference in impedance with the Sennies around the 300 ohm mark while the AKG is only 55 ohms. Yet the AKG should sound better on the Sony as it appears to favour Sony headphone with a 24 ohm impedance, but I prefer the Sennies so what to think?
 
And, as I write, I’m listening, with great enjoyment, to classical fare via the Sooloos system fed into a modded Benchmark so the very comfortable modded 545s are proving a good purchase which can be used in a variety of situations here.
 
So what conclusions have I drawn from all this?  The most important one is not to rush into judgement as different setups have different synergies and altering just one factor like the headphone cable can turn opinion around.  Second, equally, if not more important, conclusion is not to get obsessed with impedances etc as the bottom line is to enjoy the music. That is what this “hobby” is supposed to be about, although it often seems to descend into playing with audio toys!!  But who cares - both are enjoyable :)
 
Dec 7, 2014 at 12:44 AM Post #2 of 5

Me x3

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But the abovementioned caveats do not mean any of these Sennheisers will suit everyone.  As I discovered the synergy between components, with the headphone cable a surprisingly significant item in the chain, will vary from set up to setup so preferences will differ. And I’ve made no reference to the AKG 702s so far and am reluctant to damn them as inferior to the Sennheisers due to a huge difference in impedance with the Sennies around the 300 ohm mark while the AKG is only 55 ohms. Yet the AKG should sound better on the Sony as it appears to favour Sony headphone with a 24 ohm impedance, but I prefer the Sennies so what to think?

K702s need 50% more voltage and much more power than HD650 to sound at the same level. (Approx. 12 times more power).
K702 also need an amp with a much lower output impedance in order to preserve its sound signature (less than 8 ohm preferably)
 
So K702 are much harder to drive.
 
Dec 7, 2014 at 1:00 AM Post #3 of 5

Head Injury

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  ·       The person judging.  No two people (even identical twins) have exactly the same brain and the same environmental influences which lead to value judgements
·       The headphones themselves, their impedance, the nature of their construction and importantly, the place of the ones being tested in the production run
·       The headphone cable
·       The quality of the DAC
·       The impedance and other factors of the headphone amplifier
·       The quality of the digital audio input and quality of the original recording.

 
My brief thoughts in order:
  1. Definitely an issue. The listener is the largest bottleneck in making fair comparisons. There are too many complex biases at work to even trust one's own comparisons, let alone expect other people with different ears and tastes to use those comparisons for buying decisions
  2. Well I would hope the headphones are variables when they're what's being compared, otherwise there's not much point in the comparison
    tongue.gif
  3. Not an issue unless the cable's broken
  4. Not an issue unless the line out voltage causes problems with adequate gain or volume matching (see below)
  5. Sometimes an issue when there are impedance problems or too little/too much power, very often a user issue when volume isn't being properly matched between headphones (but that one's hardly the fault of the amp)
  6. Quality of mastering definitely changes the sound quality, and is probably the largest factor in sound quality, but it shouldn't be a big obstacle in an objective comparison. Stuff like "This headphone has more treble" will be constant across most mastering unless the EQ is seriously jacked up, but you might like it more or less depending on the mastering
 
Dec 11, 2014 at 12:08 AM Post #4 of 5

Visualista

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Variables? Let's not forget that each person's ear, from outer to inner ear, is made slightly differently. Some people have large pinnae, others small. Some have large auditory canals, others have them long and sinuous. That is why some companies offer custom earspeakers, aided by wax molds. Each person's ear shape is giving a slightly different sound to each person's brain. (And each person's brain is slightly different as well.)
 
Can we trust the frequency-response graphs recorded by microphones embedded in dummy heads? Whose inner and outer ears do those dummy heads resemble? Certainly not yours or mine!
 
Nothing is more subjective than headphones. Trust your ears 'cause you can't exchange them! 
 
Dec 11, 2014 at 12:47 AM Post #5 of 5

Tassie Devil

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  Variables? Let's not forget that each person's ear, from outer to inner ear, is made slightly differently. Some people have large pinnae, others small. Some have large auditory canals, others have them long and sinuous. That is why some companies offer custom earspeakers, aided by wax molds. Each person's ear shape is giving a slightly different sound to each person's brain. (And each person's brain is slightly different as well.)
 
Can we trust the frequency-response graphs recorded by microphones embedded in dummy heads? Whose inner and outer ears do those dummy heads resemble? Certainly not yours or mine!
 
Nothing is more subjective than headphones. Trust your ears 'cause you can't exchange them! 

Fully agree.  I was implying that when I posted no two brains are the same - ears attached, but what you say expands that significantly.  It is not only how the brain interprets what is fed in, it is how the ear mechanism generates the nerve impulses and of course those nerve receptors are damaged throughout our lives adding yet another complication.
 
So, what appeals to a person at 20, might not generate the same appeal at 50 or older!
 
All of which makes futile any one who rages on about someone being stupid because they like or dislike certain speakers, headphones or whatever.That said, when many people do like item A it is an indication, but not a guarantee, someone will find A appealing.
 
And one omission from my list was the "new toy syndrome" which generates great excitement over any new toy.  Unsurprisingly that simmers down over time and that indicates to me that the initial enthusiasm is because the new toy sounds different, rather than "better".  Been there, suffered that!
 

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