Testing audiophile claims and myths

[analogsurviver]

   
again look at the waveform I construct - "phase distortion" of 180 degrees of the 2nd harmonic is equivalent to changing the polarity of the tone - so the JAES article I quote is directly relevant - and they say use headphones
 
 
Daisuke Koya's 2000 Master's Thesis, AURAL PHASE DISTORTION DETECTION also warns that it is much more difficult to hear with loudspeakers - so use headphones
 
 
 
and this is head-fi - we should care even if the effect can only be heard in headphones - because we use headphones

I apologize for not looking further in the links you posted - I was busy making (preparations for) recordings - yet another Haydn's Paukenmesse under my belt. I will do it, time permitting, but would really  like thank you for taking the effort.
 
Yes, headphones - or even better - EARSPEAKERS ( Jecklin Float, AKG K 1000, bigger Stax models ) - are the easiest to hear the effects of absolute polarity reversal
etc effect(s) with. You have to build the listening building from scratch in order to approach the subtlety available in best "cans" - and then use speaker system that is preferably full range or at least does not make phase shifts within audio band, particularly not within midrange.
 
I would love once to hear the late SME's president listening room; http://www.the-ear.net/features/sme-steyning-west-sussex-england ; I know a couple of people that had the privilege  ( and were ooching and aaching how good does it sound ever since... )  while the man was still alive, shortly after the SME V arm was introduced. Once I read (and forgot...) how many tens and hundreds of tons of concrete, carpets, drapes etc, etc is built into  this strictly listening room; it was ming boggling then as well as it is now. For us mere mortals, only wet audio dreams ...
 
I have a friend to whom I actually helped to unload a couple of truckloads of bricks for his house; this house is designed from scratch up to make one great sounding listening/living room; no parallel surfaces, floor in 2 (or is it 3 ? ) levels, etc, etc. Running TWICE the entire lenght of the house, from basement to living/listening room) are two exponential bass horns,  built into foundation of the house, with mouths masquerading as fireplaces.
 
You can put a transistor radio ( or nowadays, a better smartphone ) in that room and it would sound great; imagine a high quality speaker system...

 

[bigshot]

  It depends what you are using. 
 
It is one of the reasons why I insist on using my 80 mm full range speakers - they can not play very low or extremely high, they can not go loud (enough with some music - certainly not Mahler) - yet they are inherently uncapable of funny things with phase etc - such as most 2 and more way dynamic speakers. They have no trouble whatsover in discerning absolute phase - nor do Stax Lambda Pro headphones.

 
Here is what I'm saying... I'll go to the trouble of doing a test for myself if you think I should be able to hear it. My system is capable of extremely lifelike and vivid sound... balanced, full range response, inaudible levels of distortion, wide dynamics without clipping... it's a good system. I have never been able to hear differences in absolute phase before, but you are saying that it is "easily audible" with a "good system" (which I have). So I should be able to hear it.
 
Good equipment + the test files + human ears = clearly audible difference. Right?
 
If it requires special hearing ability and equipment with anomalies that highlight something that should normally be inaudible, I'm not interested in spending the time it takes to do a test. If that's the case, I'm just going to chalk it up to "maybe it's real. maybe it's not- but either way it just doesn't matter". I've been down the road on HeadFi too many times of people saying that they can hear "night and day" differences between things that should theoretically be totally inaudible. When I go to the trouble of trying to duplicate their findings, they start backpedaling, saying my hearing is impaired or I haven't spent enough money on my stereo system. Suddenly, the "night and day" differences become "subtle" "refined" things that require exquisite golden ears and equipment of elite and rarified status to discern. So I ask up front to see if "clearly audible with good equipment" really means that before I invest several hours setting up the test.
 
thanks

 

[bigshot]

Quite frankly, some people seem to think that their golden ears and highly resolving equipment are a badge of honor. They march around proudly proclaiming their superior status among audiophilia. But for all the peacock strutting, it doesn't impress me. 99% of the time, I think they're just full of bologna and have nothing real in their lives to be proud of. And I honestly feel sorry for the 1% that might actually have some sort of weird hearing anomaly that makes them extra sensitive. It's miserable to hear frequencies we aren't supposed to hear and to be irritated by distortions that should be aurally transparent. That isn't superior hearing, that is a serious hearing defect as far as I am concerned.

 

[JRG1990]

I find them funny, especially when they argue with each other about silly things like what power cap , op amp , dac chip , cables sound best , I read the threads and posts purley for amusement.

 

[analogsurviver]

   
Here is what I'm saying... I'll go to the trouble of doing a test for myself if you think I should be able to hear it. My system is capable of extremely lifelike and vivid sound... balanced, full range response, inaudible levels of distortion, wide dynamics without clipping... it's a good system. I have never been able to hear differences in absolute phase before, but you are saying that it is "easily audible" with a "good system" (which I have). So I should be able to hear it.
 
Good equipment + the test files + human ears = clearly audible difference. Right?
 
If it requires special hearing ability and equipment with anomalies that highlight something that should normally be inaudible, I'm not interested in spending the time it takes to do a test. If that's the case, I'm just going to chalk it up to "maybe it's real. maybe it's not- but either way it just doesn't matter". I've been down the road on HeadFi too many times of people saying that they can hear "night and day" differences between things that should theoretically be totally inaudible. When I go to the trouble of trying to duplicate their findings, they start backpedaling, saying my hearing is impaired or I haven't spent enough money on my stereo system. Suddenly, the "night and day" differences become "subtle" "refined" things that require exquisite golden ears and equipment of elite and rarified status to discern. So I ask up front to see if "clearly audible with good equipment" really means that before I invest several hours setting up the test.
 
thanks

What should be audible IF equipment was "perfect" often does get masked by equipment deficiences.
 
For example, the recordings with heavily assymetrical waveforms ( close miked jazz, specially brass...) DO sound quite differently with DC or very near DC capable electronic than on more limited in the bass variety - and they can all be 0.0 dB at 20 Hz.  With a DC or near DC amp, it will sound more "live" - but it will require MUCH more powerful amp - amplitude of the signal being equal, only on DC or near DC amp TWICE the voltage is required - to be able to maintain that "DC" to sustain the assimetry. Talking about 4 times more powerful amp - 400 W vs 100 W required.  That is expensive - and is repeated in the woofer section of the speaker. No wonder that only handfull is willing to bite this financially sour apple.
 
It is not night and day difference - nor it is subtle. Let's put it this way - it is more lifelike if reproduced in the same polarity as real instruments.
 
I stumbled upon this first when doing listening to prototypes of Benz phono cartridges in late 80s. Various styli tip profiles etc have been investigated , with one variable in otherwise two as same as humanly possible cartridges. After me insisting that two carts that have unknowingly to me been sent with exactly the same everything sound markedly different, it has evewntually been found they differed in absolute polarity. 
 
One might argue that person assembling the cart should be able to orient the magnet the correct way and wire the coil to respective pins correctly. But after experienced first hand how this looks like in practice, how much is at stake if one wants to re-wire the cart correctly, I am no longer that adamant about wiring being correct -at the expense of very real prospect of degrading the performance of the cart just to have polarity correct.
 
There are at least - or to be precise - WERE two records available to establish the absolute polarity in cartridges. From Ortofon ( for its cartridge measuring "computer") and CBS. Denon may also have had one such record available back then - will have to check it. The third I am positive to have polarity test was Audio magazine from Germany - being more interesting by the sheer fact it came in 3 formats - LP, CD and cassette !  

 

[bigshot]

  What should be audible IF equipment was "perfect" often does get masked by equipment deficiences.

 
So it doesn't require "good equipment" to "clearly hear" differences, it takes "perfect" equipment? Do you understand why I'm having problems here? The bar keeps sliding around. I don't know if my equipment is "perfect" but it is capable of a full range response, balanced to quite flat with no audible distortion and the ability to reproduce a wide dynamic range without overdriving or clipping. To me, that qualifies as a "good system". I'm having trouble pinning down your definitions.
 
I'll ask one more time, then I'll give up... Should I be able to clearly hear the difference between different absolute phase using my equipment and ears?
 
I'd kinda rather work out the possibility first so I don't spend several hours trying to hear something totally inaudible just to be told that I couldn't have heard it anyway because of ears/equipment.

 

[jcx]

...I'll go to the trouble of doing a test for myself if you think I should be able to hear it. My system is capable of extremely lifelike and vivid sound... balanced, full range response, inaudible levels of distortion, wide dynamics without clipping... it's a good system. I have never been able to hear differences in absolute phase before...

 
use headphones? - as I highlighted it appears from the literature that it is much more difficult to hear phase distortions via loudspeakers, though not impossible 
 
may want to shift test tone a few octaves up to avoid room modes but keep the harmonic << 4 kHz as the proposed hearing mechanism is the bunching of nerve pulses in positive pressure half waves and the bulk of the nerves can only manage ~4 k pulses per second
 
the 2nd harmonic phase shift required for polarity inversion of the test tone I constructed should be larger than "even small midrange phase shift" that Vanderkooy and Lip****z tested - but still the better chance for detection should be with headphones
 
I wasn't really sure I was hearing a difference in the sighted trials/"training" - but the ABX result was clear - maybe "performance pressure" helps, maybe there is some confounder that other eyes, ears can turn up
 
for now I believe polarity is both audible and so subtle it is likely safely ignored in music recording/reproduction so you may still end up at:

...but either way it just doesn't matter".

 

[bigshot]

Thanks! That helps me!

 

[analogsurviver]

   
So it doesn't require "good equipment" to "clearly hear" differences, it takes "perfect" equipment? Do you understand why I'm having problems here? The bar keeps sliding around. I don't know if my equipment is "perfect" but it is capable of a full range response, balanced to quite flat with no audible distortion and the ability to reproduce a wide dynamic range without overdriving or clipping. To me, that qualifies as a "good system". I'm having trouble pinning down your definitions.
 
I'll ask one more time, then I'll give up... Should I be able to clearly hear the difference between different absolute phase using my equipment and ears?
 
I'd kinda rather work out the possibility first so I don't spend several hours trying to hear something totally inaudible just to be told that I couldn't have heard it anyway because of ears/equipment.

In a word - yes.
 
Contact with real sound helps a lot - there is no way one can hear polarity reversal with real unamplified acoustic voices/instruments. If recorded/reproduced sound sounds vaguely strange - chances are good absolute polarity got reversed at some stage. Best to use for this are binaural recordings - because it is impossible to fiddle with anything that can alter it.
 
This is a VERY good primer to demonstrate the binaural at its best - as video clearly show the position of each and every musician at any given moment - and headphones earspeakers ( AKG K 1000, Jecklin Float, Stax Lambda w/diffuse field EQ ) will reproduce it perfectly. YT limits the audio to some MP3 - but where binaural really shines is when recorded to and reproduced from DSD - natively. The higher DSD, the better.
 
It gives "you are there" sensation, unmatched by anything else.
 

 
Worst are multimiked recordings - they are totally useless for this task, as the resulting total output may well include instrument/voice  A
picked up by mic 1 in correct polarity, by mic 3 ( or 8 or ...985 ) in reversed and/or phase displaced way - add to that mastering and it is clear to see that multimiked recording can not be used for this ( or any other real... ) purpose.
 
I have included the listening room of SME in one of previous posts - it is trough use of full range crossoverless speakers (stacked Quad 63s in this example ) in well designed acoustic space that the quality of reproduction via loudspeakers can approach that of good binaural recording via earspeakers. Provided such a system is fed with simple 2 mic ( or, at worst, Decca "tree" ) recordings .
 
At a cost ...

 

[saiB]

Could we please go back to 'science' and stuff, instead of subjective anecdotes ?

 

[analogsurviver]

  Could we please go back to 'science' and stuff, instead of subjective anecdotes ?

 As "science" will try to convience one redbook CD is enough, and will leisurly take some good chunk of time, like decades, to catch up with the real state of affairs, if and when allowed to do so, I can not produce more than "anecdotes". I think it was Koss' slogan Hearing is believing (please correct me if I mistook it for someone else's ). As two of the members most pro redbook CD have openly stated not to be in possesion of native DSD playback - I can not even send them DSD files, as they will have to be converted to PCM one away or another prior to listening.
 
Whenever I am opposing anything, I do it for a reason - and only observe the proceedings if I have no or too limited knowledge/equipment/whatever to at least try to grasp what it is all about. I would not say CD is bad if I had no or limited experience with it. 
 
An "anecdote" that is ANYTHING but fun; a while ago, in the meantime banned head-fi member XNOR has devised a blind test with various resolutions of PCM - and "cheating" by removing the real content above 20 kHz by inclusion of some random noise. And got me fooled - along with my friend. But we WERE both very uneasy about the REAL best resolution PCM - and STILL chose the one tampered with random noise as "the best".
There is a VERY sound reason for this - like it or not, I HAVE to listen to CD - given the finances, all my recordings have been issued so far as CD only - and we tend to "accept" the CD, with all of its limitations, as "standard". After that experience, my CD player gathered dust for more than half a year - the only diet being analog recorded vinyl and DSD - NO PCM whatsoever. It took me about a month to re-adapt myself to the correct thing - although exposed to real sound on at least weekly basis, it still is not everyday experience, as reproduced.
 
I will try to make some "gadget" that will allow ABX level matching to below 0.1 dB - because I agree it does matter. Given the cost of GOOD attenuators/potentiometers/digital volume controls capable of repeatedly and reliably selecting volume within 0.1 dB among ABX, it will not be soon - although I would have preffered it having yesterday. But if I run across some great vintage analog device, which I was never able to afford when new, it will ALWAYS have priority over the ABX "gadget". 
 
During the recent recording of Haydn's Paukenmesse, I used during rehearsals two Korg MR1000 DSD recorders in paralel. The recorders were both set at exactly the same gain - despite having normal analog potentiometers - namely 0dB or full gain and gain adjusted correctly in the microphone preamp. It is DOUBLE test - DSD128 vs PCM44.1/16 AND modified vs stock recorder - where modified one was used for the DSD of course. I will first ask performers a permission to post a short clip from either resulting recordings - without the need for level matching ( they are the same, within production tolerances, NO gain resistor changes in modified unit ).
And that IS - night and day - difference. Essentially - "All amplifiers (when used within their operating envelope) sound the same" and "CD vs DSD" test in one.
And no, I will not buy yet another MR1000 in order to make more tests with the exactly same recorders - on the contraray, the other still stock one will get modified ASAP.
 
Then, theoreticians can dissect, evaluate, measure, WHATEVER it takes - to arrive at what is essential for approach to the perfect reproduction. I do not have the means necessary  to PROVE BEYOND ANY SHADOW OF A DOUBT what I can hear. I am no super hearing monster, my hearing is about normal for my age - 53. But listening to music live as a listener within the audience and comparing that to recordings over decades must bear some "anecdotal" weight...

 

[EthanWiner]

go to your DAW, add the 200/0 degree + 400 Hz/90 degree sines 1:1, then shift the 400 Hz by an additional 180, add to same 200 Hz/0 degree sine - look at the waveforms - think about their polarity

But that's shifting only some of the content in a file using an all-pass filter, which is not the same as polarity reversal which reverses everything regardless of frequency.

more evidence you haven't fairly read my posts - the diyAudio link where I attached the zipped .wav files only shows a single download of the file as I write this

I missed that because the link was within a quote, which I thought was you quoting someone else in this thread. I just tried to download the file but apparently I have to be a DIYAudio member to get it. The file is less than 1 MB so can you just email it to me? My email address is here:

http://www.ethanwiner.com/

I do want to hear this file, and try to see what's going on and if polarity is audible. I still assume if reversal is audible then it's due to driver non-linearity, but I'd like to see and hear it for myself.

--Ethan

 

[bigshot]

In a word - yes.

I listen almost exclusively to acoustic music... classical and jazz. Much of it isn't multi-miked. I've never been able to discern absolute phase. I've been told now that hearing it on speakers is impossible. I have some first class headphones right now, and I've listened to binaural recordings on them. They sound very lifelike, but still I doubt that I would be able to discern absolute phase differences.

I'm asking clearly how I can set up a test where I can reproduce your claims of being able to easily hear differences in absolute phase and you're giving me unclear answers full of anecdotes and off topic comments on other things. I give up. I think you're making this all up as you go along. You're an interesting conversationalist, but I don't think you have ever attempted to verify any of your subjective impressions with objective testing.

In other parts of head fi, rambling impressions are fine. But in sound science we get to put impressions to the test to understand how things really work, nott just how we think they work. If you ever get interested in doing that, we're here to join in and help.

 

[jcx]

I keep getting resistance to my "180 degree 2nd harmonic phase shift is equivalent to polarity inversion" argument for my test tone
 
how about this visualization  - I add a phase dependent offset (magneta) to the dynamic sum (sum in blue, magenta is "0" line for blue) to show the +/-90 plots mirrored about the x axis so polarity should be clear by eyeball
 
I move both the fundamental and the 2nd phase to center the +/-90 sum's peaks on the y axis - "48" in the algebra pane is just the value of alpha when I did the screenshot
 
but the trick is the relative phase of the 2nd harmonic is shifted a total of 180 degrees relative to the fundamental over the course of the animation - showing that it results in polarity inversion
 
we do all agree that green and red are opposite polarity?
 

 

 
membership at diyAduio isn't onerous - is  free, so far I get <1 official email from the site per month - you don't have to show your email address in your public profile
 
it is about designing, building, measuring - some even claim to listen, too - several industry "names" in both electronics and loudspeakers regularly participate
 
the headphone subforum isn't a scratch on head-fi though - even compared to just the diy section here - but there are more amp than cable threads at diyAudio

 

[Steve Eddy]

I just tried to download the file but apparently I have to be a DIYAudio member to get it. The file is less than 1 MB so can you just email it to me?

Just sign up and create an account. I'm rather surprised you don't already have one over there.

se