Audio Blind Testing

[pkane2001]

 

2 hours ago, fas42 said:

 

Things like interconnect cable differences will always fail in DBT - that's because the time factor aspect is never part of the test - first rule of science: always make sure you are really testing what you think you are attempting to verify, rather than doing a show off demo of the fact that you can play "scientist in a lab coat".

 

What does time have to do with the blind aspect of the test? If you think that a blind test must only be done with a rapid A/B switching, then you might be right, but who said you have to do that?

 

If you can tell a difference in a fully sighted test, then try to repeat exactly the same test, blind. Same time frames, same comparisons,  same material, except that you don't know which cable is in the system. If you fail to distinguish them while blind, you can be fairly confident that whatever differences you heard while testing sighted was not real. And if you're afraid that the pressure of a blind test or performance anxiety will skew the test -- take a Zanax.

 

 

[pkane2001]

54 minutes ago, fas42 said:

 

As a following post emphasised, it's to do with all the materials in the path stabilising - as the most straightforward example, the metal to metal contacts at either end of the cable are initially "clean", from the wiping of the contact surfaces - then they steadily build up corrosion contaminants, which affects the sound. Slowly the construction of the cable comes into play, altering the spectrum of distortion artifacts.

 

Regardless of any supposed 'settling' or 'break-in' issues related to cables, the point is that a sighted test is subject to exactly the same constraints as a blind test as far as time is concerned. What would cause a cable longer to stabilize in a blind test compared to the same cable in a sighted test?

 

Out of curiosity, do you have any references to measurements or other objective studies of  cable stabilization time?

[pkane2001]

18 minutes ago, fas42 said:

 

We could be talking hours, days for conditions to stabilise - makes it difficult to run ABX under those circumstances! Other times, the variation is almost immediate - depending upon precisely what is is causing a 'problem'.

 

Things taking a long time to stabilise are a curse in any field, I used to run my system 24/7 decades ago, because of this behaviour - a waste of power, etc, but I hated the loss of quality that occurred every time there was a switch on from cold, which took ages to settle down.

 

I can't recall coming across any measurement data, or other studies - usually anecdotal, which would draw an "Ah Hah!" of recognition from me ... the best I can do here.

 

As I've said a number of times, my goal would be for a system, assembled from scratch, to reach acceptable quality about 5 minutes or so after power on - I've never achieved this ... perhaps down the track ...

 

Frank, that's a very tenuous explanation for why a DBT might fail to detect a difference. You are basing this on anecdotal evidence of cable 'stabilization'. And, you are missing the point, again: the same cable behavior applies whether or not you are doing sighted or unsighted testing. So, any findings of different sound between cables (or no difference) is just as valid or invalid in both cases.

 

There's nothing special that makes a DBT test more susceptible  to timing due to cable stabilization than a sighted test. Unless, of course, you claim some quantum mechanical effect related to a wave function collapse in a sighted test

 

 

[pkane2001]

2 hours ago, sandyk said:

different construction can sound quite different due to differences in capacitance, immunity to RF/EMI  etc. A Blue Jeans LC1 for example , with just over half the capacitance of many other interconnects can sound quite different to a typical coaxial construction type cable of the same length due to interactions with the output stage of the DAC, Preamp etc. 

 

Alex, I just looked up LC1 cable. For a 6ft length LC1 has capacitance of 73pF, resistance of 0.204Ω . In comparison, a 25ga zip cord of the same length has 96pF C and 0.3Ω R. If this is enough to cause a problem with an output stage designed for audio frequencies, then I'm afraid it's just not designed well at all!

 

And here are the filtering characteristics of  a 6ft LC1 cable over 10-30,000Hz range:

 

 

 

 

And here's one of a 6ft, 25ga zip cord:

 

 

If you think you can hear the difference of under 1/1,000,000,000 of a dB at 30KHz, I'd be extremely impressed!!! 

 

[pkane2001]

4 hours ago, sandyk said:

For starters, nobody in their right mind would use a Zip cord for an Interconnect !!!

...

Before you jump down my throat and tell me that drums are LF and the cables can't possibly have any effect, have a look at the attached below which shows the VERY fast rise times of the envelope.

 

Sure, but if a zip cord has nearly the same LRC characteristics as LC1, then what accounts for the difference?

 

You do realize that in order to have an 'audible' change of -0.5dB @ 96KHz (I'm being extremely generous here with the definition of audible) the interconnect must have a capacitance of about 2μF? Of course, nobody can hear into 96KHz, much less a -0.5dB roll-off at that frequency. And no normal IC cable has a capacitance approaching anywhere near 2μF.

 

4 hours ago, sandyk said:

 You would be surprised to see what small differences many members are capable of hearing, even the effects of improved screening on a couple of feet of D.C. cable !

 

Hmm, having done at least some of these DC cable mods per instructions on that list, I can report that I found no difference whatsoever. And this was in a high frequency digital device (SU-1) that operates into the range of a few dozen MHz.

[pkane2001]

Just now, sandyk said:

 I have already answered some of these things in my reply to George.

A Zip cord for example has very little RF/EMI rejection.

 

 Nothing , myself or others are likely to say on this subject is ever going to change either George's or your minds.

I am simply reporting my observations, and I am only one of a large number of members who report hearing similar differences.

Just because you are unable to hear the differences that John and others have reported, doesn't mean that they don't exist.

If you have been closely following the thread, you will have noticed that I also found the reports a little unbelievable, especially as I use D.C. cables of no more than 2 feet long salvaged from redundant 2 pin mains leads. In other words , fairly heavy duty wire. However, if John Swenson reports these things and others verify them independently, I will bow to his superior knowledge of the subject. I have since obtained 2M of the cable described, and will eventually try this for myself, despite my reservations.

 

http://www.ebay.com.au/itm/2M-Canare-L-4E6S-Premium-Balanced-Quad-XLR-Microphone-Cable-Made-in-Japan/261917497557?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

I got about 20m of Canare 4E6S. Most of it went into multiple headphone cables, but some into DC cords since I had some left over. I'm not against experimenting, but I don't bow to JS or to anyone else just because they say something. Especially if that something is highly improbable. Doveryai, no proveryai is my motto 

 

4E6S makes for a wonderful balanced headphone cable even at a 10m length. But, it's nothing special as a DC cord, IME.

[pkane2001]

51 minutes ago, sandyk said:

Even if I don't hear the improvements that John and others report, I won't  be claiming they are wrong, as my hearing is far more aged than theirs, and not every setup is the same.

 

But you would defend their findings without being able to confirm them yourself and without any objective evidence to support them? I'm much more skeptical when it comes to these claims, but I'm always open to hearing real evidence to the contrary.

[pkane2001]

15 minutes ago, sandyk said:

 

 I didn't say that I would defend their findings, but I certainly wouldn't post  that an experienced E.E. like John was wrong , just because I was unable to hear them for myself.

 I would still invite others to try it for themselves though, to see if others were able to confirm his results, preferably using non sighted testing to rule out Expectation Bias.

 

 

Alex, we are in agreement

 

[pkane2001]

7 hours ago, audiventory said:

 

I meant that comparison of 2 resolutions or DSD vs. PCM is technically non-correct (methodologically impossible) in general case. It do not depend on equipment.

 

Wait... Ultimately, what matters to me is the analog output. Why is it that I can't compare analog output produced from DSD to that produced from PCM? I assume that you mean that one can't draw a general conclusion about DSD vs PCM from such a comparison, but I can certainly do a comparison in my own set up, no?

[pkane2001]

6 minutes ago, audiventory said:

We can't claim that DSD better PCM (and contrary) for all cases.

We can't claim that 24 better 16 bit (and contrary) for all cases.

 

Of course, there's no general set of factors that can be applied across the board for such a comparison , nothing that would declare one format as overall better than the other.

 

But, if you pick some specific factors to compare, you can certainly make a comparison and reach a conclusion that one format is better than the other in respect to these factors. For example, noise levels, frequency response, dynamic range, etc.

[pkane2001]

2 hours ago, audiventory said:

 

Format (description and figures) declare approximatelly technical potential.

Implementation can release the potential or not.

 

If we compare DSD and PCM we can't compare noise level, dynamic range, frequency response. Because noise shaping may be applied different ways.

 

When we compare 24 and 16 bit implementation, we compare also clock generators' stability, noise of amplifier chips into DAC, etc.

 

When we compare mathematically modeled signal that stored into 16 and 24 bit files, we can discuss about format comparison in digital domain.

 

When we compare mathematically modeled signal that stored into PCM and DSD files, we can't discuss about format comparison in digital domain, because implementation of noise shaping is matter.

 

Yes, so, as I said:

Quote

 I assume that you mean that one can't draw a general conclusion about DSD vs PCM from such a comparison, but I can certainly do a comparison in my own set up, no?

 

[pkane2001]

5 hours ago, sandyk said:

Music lovers have no interest in having their findings peer reviewed or published in Scientific journals !

 

True, but they should probably be interested in whether that $5000 cable actually makes an audible difference or if seeing the many zeros in the price tag causes a catastrophic failure of common sense.

[pkane2001]

6 minutes ago, sandyk said:

 

 Of course they should, but perhaps by carefully sorting through the wheat from the chaff in reports about their performance in more than just one forum or review.

 

You should've seen how many folks jumped on me when I posted that I prefer to see some measurements of equipment before I buy it. This is no longer permitted by audiophile ethics, apparently. Seems I'm only allowed to rely on subjective reviews of people I don't know, whose hearing is suspect, and whose room, system, and taste in music are all completely different than mine. Go figure!

 

[pkane2001]

58 minutes ago, Ralf11 said:

 

I can guarantee that an assumed high price will make your wine taste better, and your cables sound better even if they are cheap.

 

The former was tested by scientists with remarkable results, and published in one of those peer-reviewed journals that some try to kick sand at.

 

Confirmation Bias is insidious which is why any prudent purchaser will take steps to guard against it.

 

Just saw this blind test. Look up Mike Lavigne if you don't know who he is. Opus Transparent cables (around $40k at the time of the test) compared to the run of the mill Monster ‘cheap’ cables:

 

http://www.avsforum.com/forum/86-ultra-hi-end-ht-gear-20-000/941184-observations-controlled-cable-test-2.html#post12255000

 

 

[pkane2001]

1 hour ago, esldude said:

Yes good to see that brought up. 

 

Comedy Gold!

 

Comedy because Lavigne learned the wrong thing from this experience.  Doubled down on wrongness.  

 

Obviously a man that holds on to his conv...errr....biases

 

[pkane2001]

16 minutes ago, semente said:

 

To reproduce it you must first be able to capture it.

 

So what is it about ‘live’ sound that is missing during the recording? Sound waves are pretty simple, and I assume any two competent microphones coupled with good ADC can capture all the frequencies and phases of the various sound waves hitting the two ears, their reflections, etc. So what’s missing?

[pkane2001]

1 hour ago, esldude said:

I think some people have in mind this idea stereo sound can work like holography.  That two sources might set up an interference pattern replicating the actual sound field recorded.  It doesn't work this way however.  It is using how our hearing works to perceptually trick it,  not recreate an actual sound field.  

 

Now holography creates a pair of sources in light that interfere around objects and record that interference pattern that can be recreated with laser light. I think for the same idea to work with sound on the playback end, it might work best if we had a defined area of ultrasonic sound that could be modulated to produce such an interference pattern.  The modulation would be something like class D amps only in the air.  It does NOT work with audible frequencies because they vary too much in length so no stable interference pattern can be established.  

 

Even if you managed this for playback, I am not sure how it would be accurately recorded.  It might be created from nothing for pop type music.  Not sure how you would record it in a venue however. 

 

There has been some work in sound field reconstruction at least back to the 1920's and 1930's.  You end up needing so many channels it is impractical.  

 

Dennis, so are you saying that for a true 'live' sense and feel of reproduced audio, the listener must be able to move through the sound field and sample this field at slightly different points to get the correct illusion? Similar to holography that looks  2D if you just look at it from a single point, but becomes 3D as you start moving your head around it?

 

If that's the case, would I also get only 2D, not truly 'live' sound impression at a concert hall if I sit with my head perfectly still?

[pkane2001]

21 minutes ago, semente said:

No. In the hall you immersed in reality. Perception of source location is given by phase and level and time differences between ears and by ambience cues.

 

Then what is it that's not being recorded by microphones? Phase? Frequencies? Ambience cues, reverb, reflections, even sound wave interference all translate into a set of frequencies with a certain phase relationship. If we can record all the necessary frequencies and their phase relationship, then what's missing?

 

[pkane2001]

1 hour ago, semente said:

 

The pair of mics is capturing what someone in the audience would have listened but the speakers (in a room) will not be able to recreate the soundfield of original event as it was listened.

 

See these posts:

 

https://www.computeraudiophile.com/forums/topic/38125-audio-blind-testing/?do=findComment&comment=766034

 

https://www.computeraudiophile.com/forums/topic/38125-audio-blind-testing/?do=findComment&comment=766027

 

https://www.computeraudiophile.com/forums/topic/38125-audio-blind-testing/?do=findComment&comment=766030

 

 

 

Problems with speaker systems I understand (and these are not related to what's captured by mics, btw). They obviously cannot reproduce the same waveforms, phases, etc. at the listening position due to many factors, from room interactions, to cabinet resonances, to sound wave interference, reflections, etc.

 

But I don't care about the sound field in the room if I'm using headphones, do I? Can the two mics capture enough information to be reproduced through a set of hi-fi headphones? These are much less affected by room interactions, reflections, interference, cabinet resonances, etc. Do the mics capture enough information to enable reproduction of the illusion of the original venue when using headphones and if not, what's missing?

 

[pkane2001]

6 minutes ago, semente said:

 

I don't listen with headphones but I suppose that a recording using a binaural head would in theory produce a more credible illusion although I haven't tried.

Regular recordings feel to me as if the sound is being generated inside my head instead of surrounding me.

(I'm referring to classical music recordings)

 

Yes, cross-feed helps a bit there, but obviously, it's altering the originally recorded sound by introducing some cross-pollination between the two ears that wasn't in the original recording. I'm curious if the problem with the 'in your head' sound is due to the mastering process that destroys the true phase relationship between left and right channels. I have some recordings that sound wonderfully spacious and 3D through the headphones, with a sense of depth without crossfeed, and then some that simply require crossfeed for me to be able to even listen to them. 

[pkane2001]

13 hours ago, fas42 said:

 

The "in your head" sound with headphones is because the acoustic clues are too indistinct - one's ear/brain can't interpret their true meaning - so the sound "pushes inward". The equivalent with speakers is that the sound is trapped in the cabinets, the imaging doesn't lift out and lay beyond them.

 

The solution in both cases is to improve the reproduction chain; the better resolved acoustic data now is clearly understood by the brain - and the soundfield then stretches beyond the transducers.

 

Sorry, Frank, but that can’t be right. I listen to speakers and headphones using the same exact system. Headphones sometimes produce in-your-head sound while speakers never do. It’s not the reproduction chain, it’s how the sound transducer delivers sound waves to my ears.

[pkane2001]

11 hours ago, esldude said:

Some info I have read indicates head movement is important for the illusion of space.  So having your head held still or wearing headphones so the soundfield never moves, impacts your ability to hear space and imaging at a distance.  

 

This is very interesting.  This is certainly the method used for 3D vision, but I never considered that hearing might work the same way. I’ll have to think about how to test this. Thanks for the paper reference!

[pkane2001]

1 hour ago, Abtr said:

Shouldn't a stereo recording done with two small microphones placed inside your own two ears and then played back to you through headphones reproduce much of the original soundstage?

https://gizmodo.com/clever-earbud-microphones-bring-3d-audio-recording-to-y-1740527800

 

Thats a cool gadget, the downside being that I have to attend every performance I want recorded and that nobody can listen to my recordings, since their ears and head are not shaped the same as mine 

 

 

[pkane2001]

6 hours ago, gmgraves said:

And it's not right - like most all of fas42's "theories" (notions?). Headphones produce images that are seemingly inside of one's head for the simple reason that headphones are isolatory. In normal hearing all sounds are heard by both ears. Localization occurs due to the time delay and complex phase relationship between the arrival of a sound to each ear. In headphone listening, the sounds each ear hears are isolated from the sound that the other ear hears, thus confusing the "auto-locating" facilities in the brain. Without those cues, the brain doesn't know precisely where to locate the sound source in space, so it locates everything either at the individual ears or between them.

 

 

 

 

That’s got to be at least partially true, since crossfeed introduces some extra clues into the recording that seem to help the brain place the sound outside my head.

[pkane2001]

23 minutes ago, fas42 said:

 

Sorry, you didn't read my post right - I said, "The equivalent with speakers is that the sound is trapped in the cabinets, the imaging doesn't lift out and lay beyond them" - speakers only create a weird, in-your-head sound when connected out of phase with each other, and you're dead centre between then.

 

And, it's all about effective quality of the reproduction chain - the audio friend I visted a couple of days ago uses a rig that most here would look at with scorn - but he using my methodologies, and I would take listening to the sound he gets over almost anything you hear at a high end audio show.

 

 

Ah yes, I should’ve read your post a bit more carefully, sorry about that. But that doesn’t change the fact that the same system has spectacular imaging ability through speakers, and yet, produces sounds dead center in my head on some of the best recordings when played through headphones.