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Testing audiophile claims and myths - Page 218

post #3256 of 3264
Quote:
Originally Posted by Head Injury View Post
 

The 1/8 rule isn't a rule, it's a recommendation. The frequency response will change with any output impedance, even 0.1 ohm. 1/8 of the headphone impedance just happens to be a good number to aim for that achieves inaudibility almost all of the time. Most full-sized headphones will cope with much more. Some IEMs might need even lower.

 

Also AFAIK planar magnetic drivers have flat impedance curves. There was some debate in another thread about whether or not damping factor mattered at all for them.

Yup, and if anybody has looked at impedance curve of dynamic drivers of lower impedance for portable over ears or iems, you will see flat impedance.  Even look at the Sennheiser Momentum, it's flat.  When you get to high impedance designs like the Beyers or Sennheisers with 300ohm nominal the impedance curve shows significant resonance hump.  That hump is resonance where the peak point is where the inducatance and capacitance meet and cancel each other out to be resistive.  That means the left side where it rises is inductive and the right is capacitive.  The Q factor of the resonance changes with the added resistance which shape the resonance.  Within the resonance area is where the added resistance affects the FR.  And a measurement I've seen of the HD800 shows that it happens only when the resistance is pretty significant like a value that is equal to it.  180ohms shows only slight boost.  And, there was minimal FR changes in the region that is close to flat in the mids to high frequencies even with 600ohm output impedance.  Also I read that if you short out the speaker terminal, the cone resists movement, which means that with a resistance in between, it moves more freely.  That means the output impedance would cause less damping and cause less control of the driver.  Close to 0 output impedance would be like a short at the terminals creating maximum damping.  I believe stv posted some distortion measurments of the Beyers showing much higher distortions at the resonance frequencies with added output impedance.

 

I think damping factor is for full sized headphones or speakers that has the characteristics like the Sennheisers or Beyers with the resonance hump and only matters because of the resonance.  I think low impedance iems with non-flat response is different.  Not sure if "damping" really applies to BA iems with skewy impedance response.  Since they are uneven some parts are going to affect the power output relative to others that would change the FR compared to output impedance close to 0.  I would think the reactive areas would be affected differently from resistive areas, but don't know how.


Edited by SilverEars - 10/5/14 at 9:37pm
post #3257 of 3264
Quote:
Originally Posted by Head Injury View Post
 
Quote:
Originally Posted by money4me247 View Post
 

 

I have read that all headphone impedance changes with frequency. The greater your output impedance is above zero, the greater voltage changes will to delivered to your headphones as the frequency changes, so for DAP/mobile phones/amps with higher output impedance, you will get greater frequency response deviations. There is a 1/8 rule of thumb stating if the output impedance is greater than 1/8th the headphone's impedance, you will get variations in frequency response. The variations are more extreme in balanced armature or multi-driver designs of IEMs. Balanced armature IEMs (such as models from shure, etymotic, and ultimate ears) can sound significantly worse with higher output impedance devices as their actual impedance varies with frequency very drastically from their rated impedance on the spec sheet.

 

If you are passionate about multi-driver or balanced armature IEMs, you will need to invest in sources with really low (near zero) output impedance to eliminate the audible distortions.

The 1/8 rule isn't a rule, it's a recommendation. The frequency response will change with any output impedance, even 0.1 ohm. 1/8 of the headphone impedance just happens to be a good number to aim for that achieves inaudibility almost all of the time. Most full-sized headphones will cope with much more. Some IEMs might need even lower.

 

Also AFAIK planar magnetic drivers have flat impedance curves. There was some debate in another thread about whether or not damping factor mattered at all for them.


yup, in fact the 1/8 or 1/10 is a middle ground between power efficiency and damping factor impact. in truth having a damping ratio of 1/100 is just as good for sound so it should be called  the "at least 1/8 rule". 

still following it is a no brainer. the fact that it doesn't always blow up when we don't do what's expected isn't reason enough to do whatever we want. it's still electricity and will always work best when we do as advised. if they make headphones and amps for impedance matching in mind, I'll be glad to follow a 1/1 rule instead.

at least for electricity I do as I'm told ^_^.

 

@money4you

  etymotic is a bad example as the er4 is the most famous in ear for getting "better"(er4s) with added impedance. I think I've come across 3 or 4 IEMs thinking that a little more impedance could sound good(like the W4). for the rest, it either sounds like crap, or doesn't matter (I have the ety mc5 in my ears right now and they don't seem to care about impedance much, +100ohm seems to sound pretty much the same to me(minus the huge loudness difference).

post #3258 of 3264
post #3259 of 3264

Most interesting - and I *guess* there is no scientific proof satisfying all the statistical requirements to be accepted

by regular science at the moment - to prove her claims wrong or false. It is certain that humans with this ability exist and that they must be extremely rare; depending on circumstances, the time and place they were/are discovered, they might end up as guinea pigs in some lab, supreme sorcerers, royalty or simply being "disposed of " if they insist on their special ability - people tend to be hostile to things they can not understand and do not fit in the "accepted" drawer.

 

I am most interesting if this does get researched and explained scientifically - but with all the science, at least one another human being with the same ability will have to be independently used for confirmation; one can not create a scientific apparatus if it is not known what to look for and one single person might be simply telling ferytales upon which wrong set of scientific parameters would end up being used. 

post #3260 of 3264

the only uncertainty here seems to be how she really sees. when she looks at a chair, it's still a chair. and the spectrum of light hitting the chair and coming back to the eye is also still the same. reality doesn't change. checking that she has more kinds of cones is not at all at the limit of science. but sure if we could cut one eye open it might make things easier ^_^.

in fact we have a rough idea about how a lot of animals see things and what frequencies they can perceive. it's how they interpret the data that is always the unknown factor.

 

 

Quote:

"You might see dark green but I’ll see violet, turquoise, blue. It’s like a mosaic of color.”

 

hey I'm a tetrachrothingy!!! I've got tonnes of pictures done with my camera where shadow areas are dark green and full of violet and turquoise and blue. I used to call it noise and try to remove it. :veryevil:
 

post #3261 of 3264
Quote:
Originally Posted by castleofargh View Post
 

the only uncertainty here seems to be how she really sees. when she looks at a chair, it's still a chair. and the spectrum of light hitting the chair and coming back to the eye is also still the same. reality doesn't change. checking that she has more kinds of cones is not at all at the limit of science. but sure if we could cut one eye open it might make things easier ^_^.

in fact we have a rough idea about how a lot of animals see things and what frequencies they can perceive. it's how they interpret the data that is always the unknown factor.

 

hey I'm a tetrachrothingy!!! I've got tonnes of pictures done with my camera where shadow areas are dark green and full of violet and turquoise and blue. I used to call it noise and try to remove it. :veryevil:

 

I think the point of bringing up that rare example is to claim that there are certain individuals within this community that can hear sonic differences that normal people can't.

 

The more interesting example of people with 'special sensory gifts' would be synesthesia, where people hear colors or see sounds, due to neurons being cross-wired between traditional divisions of senses in various regions of the brain.

 

Note that these types of phenomenon are extremely rare and not really applicable to the average population. Also, the processes behind them can be understood through science and research though some of these areas have not been well-studied.

 

The traditional audiophile claims made around here of being able to hear certain sonic discrepancies due to an genetic golden ear or intensive ear training are mostly anecdotal without any rigorous testing using the scientific method. There have been certain cases where blind testing revealed something beyond mere chance, but I would imagine further objective testing would be required to verify the actual scope and accuracy of such personal claims. The existent of expectation bias is certainly well-established and not being blinded to the equipment drastically changes preferences. fun quick summary. http://en.wikipedia.org/wiki/Golden_ear

post #3262 of 3264
Quote:
Originally Posted by money4me247 View Post

I think the point of bringing up that rare example is to claim that there are certain individuals within this community that can hear sonic differences that normal people can't.

The more interesting example of people with 'special sensory gifts' would be synesthesia, where people hear colors or see sounds, due to neurons being cross-wired between traditional divisions of senses in various regions of the brain.

Note that these types of phenomenon are extremely rare and not really applicable to the average population. Also, the processes behind them can be understood through science and research though some of these areas have not been well-studied.

The traditional audiophile claims made around here of being able to hear certain sonic discrepancies due to an genetic golden ear or intensive ear training are mostly anecdotal without any rigorous testing using the scientific method. There have been certain cases where blind testing revealed something beyond mere chance, but I would imagine further objective testing would be required to verify the actual scope and accuracy of such personal claims. The existent of expectation bias is certainly well-established and not being blinded to the equipment drastically changes preferences. fun quick summary. http://en.wikipedia.org/wiki/Golden_ear
Interesting that it's only women that can have the necessary chromosome mutation, leading to this condition, a corresponding mutation in men leads to color blindness. Presumably therefore a similar phenomenon with hearing would also only apply to women, the result in men would be "cloth ears" not "golden ears". wink.gif

There is evidence that hearing can be trained, but it's not improving hearing, it's improving listening, two completely different things.
post #3263 of 3264

If you actually go and find out what sort of exceptional hearing that people with exceptional hearing have, you find out that it isn't that much more than regular hearing. Just a few notes higher in the scale. And music wouldn't sound any different to them because most music doesn't contain those frequencies, and those frequencies are way beyond the range of being perceived as a musical note. Exceptional hearing is something you can test for and identify, but in the real world, it's no real advantage at all. In fact, it is often a detriment because high frequency squeals of fluorescent lights and TV monitors can become irritating.

post #3264 of 3264
Quote:
Originally Posted by bigshot View Post
 

If you actually go and find out what sort of exceptional hearing that people with exceptional hearing have, you find out that it isn't that much more than regular hearing. Just a few notes higher in the scale. And music wouldn't sound any different to them because most music doesn't contain those frequencies, and those frequencies are way beyond the range of being perceived as a musical note. Exceptional hearing is something you can test for and identify, but in the real world, it's no real advantage at all. In fact, it is often a detriment because high frequency squeals of fluorescent lights and TV monitors can become irritating.


but there are a lot of cures for that one problem. rave parties close to the speakers are just one of many.

 

 

as you say it's easy to test people for their hearing : http://en.wikipedia.org/wiki/The_Mosquito.

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