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Testing audiophile claims and myths - Page 159

post #2371 of 2956
Quote:
Originally Posted by analogsurviver View Post

What I meant were two recordings from the same microphone in the same position - one in correct, another in inverted absolute polarity.

How is that different from reversing the polarity after the fact during playback?
Quote:
DSD is superior to PCM in time domain/pulse response - whichever you prefer. PCM is just plain too slow

Why do you believe this? Do you have any Wave files or FFT graphs or oscilloscope images that show PCM can't capture transients whose rise times equate to 20 KHz?

Again, I look forward to hearing one or two files you post that sound different when the polarity is reversed.

--Ethan
post #2372 of 2956
Quote:
Originally Posted by bufferoverflow View Post

'soundstage' is a ridiculous' term .

 

And since your 'dB-meter' is only accurate to one dB there could easily be more than 0.2dB level-mismatch

between the 2 amps - And that IS audible, you just won't perceive it as 'louder' but better - 'soundstage' for example -

 

 

http://productionadvice.co.uk/level-matching/

 

I  am not the one claiming anything here, there is general agreement that levels must be matched to less than 0.2dB

or the louder kit will sound better (or be reliably recognized in a blind-test - But they are probably also 'ridicoulous' in your little tweaker-dream) .

 

I'm real happy you joined head-fi so you could come in here and start name calling other members whose DBT don't match your notions. It really makes doing this whole ordeal for the benefit of others worthwhile :rolleyes:

 

edit - ah, nice ninja edit to remove your petty insults, but it won't make you more convincing to me.

 

On that thought and considering i apparently wasted my time only to have to read the following drivel, you'll pardon me if I put an end to this endeavor here and now.

 

Enjoy your future discussion.


Edited by elmoe - 3/2/14 at 10:15am
post #2373 of 2956

https://web.archive.org/web/20110101113016/http://www.ocf.berkeley.edu/~ashon/audio/primer1.htm does concentrate on phase coherence - some of the info supports absolute polarity discrimination - page down past the missing graphs

Quote:

 

Although not in large numbers, previous research in investigation of the audibility of phase distortion has proven that it is an audible phenomenon. Lip****z et al. [7] has shown that on suitably chosen signals, even small midrange phase distortion can be clearly audible. Mathes and Miller [8] and Craig and Jeffress [9] showed that a simple two-component tone, consisting of a fundamental and second harmonic, changed in timbre as the phase of the second harmonic was varied relative to the fundamental. The above experiment was replicated by Lip****z et al., with summed 200 and 400 Hz frequencies, presented double blind via loudspeakers resulting in a 100% accuracy score.

the 2nd harmonic relative phase shift test does amount to a test of polarity inversion audibility when the phase between the fundamental and the 2nd shift relatively by 180 degrees

 

don't confuse the 180 degree phase shift of symmetric waveform, 1/2 period delay with polarity inversion - polarity can only be seen with a asymmetric waveform - requires a specific harmonic structure

 

200 Hz + 400 Hz/90 degrees sines 1:1 amplitude:

 

 

no amount of phase shifting, time delay of the above waveform will let you put the positive and inverted version on top of each other - both have 0 DC component, and a absolute polarity

 

reading diyAudio and hydrogenaudio threads on the subject shows much confusion about the basic terms, assumptions


Edited by jcx - 3/2/14 at 12:14pm
post #2374 of 2956
Quote:
Originally Posted by KingStyles View Post

Why do we even do this hobby if the source, transport, amp, and cables all sound the same? We would only need 1 forum to discuss the different sound signatures of headphones. Why go to cam jam? So we can plug our headphones into everybody elses equipment and congratulate them on just making a prettier version of something that sounds exactly the same as your own? Sorry about the sarcasim, but while maybe some amps and dacs etc very well could sound the same, there are plenty of products out there that sound different. Take for instance the amp test. The testers when picking out the equipment may have listened before hand and tried to pick equipment with sound signatures that all resembled each other rather than amps that tend to have a more drastic differences. Also, at what level did they set the db at. If the level was perhaps higher clipping or a lack of drive may have been found in the amps that didnt produce as much power. Anybody can setup a test to try to get the outcome they want, even if they use a wide range of equipment from different prices. We dont know if they were trying to prove that they dont make a difference thus slanting some of the equipment they choose. Just food for thought. I appreciate the time on this write up, but have to disagree with some of the findings. There is another forum that is talking about blind test that I agree with a lot more than this, or at least a different take on things.
Controversy of ABX testing | Computer Audiophile

 

Seems to me that people are fooled by Marketing, advertising, and claims of the companies making this stuff. I am not experienced in any of this so I know I don't have much credit for what I say but the only thing that really makes a difference for me is the headphones themselves. I did AB testing with 3 headphones, Panasonic RP HTX 7, Sony MA900, and Audio Technica ATH-M50 having them plugged into my laptop directly, and my Fiio E17 and heard no difference at all. I used the same track for all 3 in FLAC format on Jriver.

 

Maybe you could argue the point that those headphones don't scale as well as higher end headphones and make there's the point that this is all budget gear, but still. I spent $130 on a piece of equipment that makes no difference in the sound quality to me. I keep it for looks, and just to feel cool that I have an amp/dac :D

post #2375 of 2956

It's difficult to run a solid test if you don't know the right terms to describe differences. You need to understand the variables to be able to control them and that takes a bit of research. You can't just plug two amps in side by side and expect to get a fair test. And you have to be able to accurately describe the differences if they exist, so you can track down the source of the differences.

 

Quote:

Originally Posted by elmoe View Post
 

And no, a 1dB difference will not show any significant difference in soundstage, that's just a ridiculous claim.

 

1dB can definitely make a difference in perception of dynamics and frequency response. Level matching is the hardest part of any A/B comparison.

 

Soundstage is a function of microphone placement, the mix and your room acoustics. An amp can't affect that unless it's defective and has tons of crosstalk between channels.

 

As for the dynamics, did you have both amps set for 8 ohms on the speakers? If the Onkyo defaults to 4 ohms, that would cause a significant difference in dynamics.

 

Frequency response imbalances are the most likely differences between amps, especially with an AV amp that is designed to be equalized to the room. But equalizing both amps to the same curve (or EQing one to match the other)  should produce identical results. That's why earlier I asked you to try adjusting the tone controls on the Onkyo to see if you could match the sound of the mono blocks. (I'm assuming you don't know how to use the equalizer built into the amp).

 

The Onkyo has a ton of tone adjustments that the mono blocks don't. You need to work in the menus a bit and figure out how to set all those settings so it produces the same output as the "one size fits all" setting of the mono blocks.

 

P.S. Was your test double blind?


Edited by bigshot - 3/2/14 at 12:37pm
post #2376 of 2956
So basically, I won't be able to tell a difference unless I know what differences there could be and what differences to listen for?
post #2377 of 2956

Without knowing what you are listening for, it's very difficult to set up a test that compares apples to apples. If the Onkyo was a basic amp, without all the AV settings, it would be a lot easier to set up the test. But unless you've gone through all the menus and determined how to set it to match the mono blocks, it isn't a straight test.

 

When you understand the terms used to describe sound, and know the common reasons why an amp might deviate in one way or the other, it's a lot easier to chase down problems with your testing procedure and determine why there is a difference.

 

Why is actually more important than If in this case. I can take two amps, one of which has the treble attenuated and can say that one sounds muffled. But that doesn't mean that the amps sound different. They're just set differently.

post #2378 of 2956
Quote:
Originally Posted by bigshot View Post
 

 

1dB can definitely make a difference in perception of dynamics and frequency response. Level matching is the hardest part of any A/B comparison.

 

Soundstage is a function of microphone placement, the mix and your room acoustics. An amp can't affect that unless it's defective and has tons of crosstalk between channels.

 

As for the dynamics, did you have both amps set for 8 ohms on the speakers? If the Onkyo defaults to 4 ohms, that would cause a significant difference in dynamics.

 

Frequency response imbalances are the most likely differences between amps, especially with an AV amp that is designed to be equalized to the room. But equalizing both amps to the same curve (or EQing one to match the other)  should produce identical results. That's why earlier I asked you to try adjusting the tone controls on the Onkyo to see if you could match the sound of the mono blocks. (I'm assuming you don't know how to use the equalizer built into the amp).

 

The Onkyo has a ton of tone adjustments that the mono blocks don't. You need to work in the menus a bit and figure out how to set all those settings so it produces the same output as the "one size fits all" setting of the mono blocks.

 

P.S. Was your test double blind?

In principle, you are right.

 

In practice, amps DO influence sonics. I thought that channel separation of 90 dB 20Hz-20kHz was enough, that any further improvemnt will bring nothing.

Boy, was I wrong. I went from approx 90 dB to approx 100 dB (or more, could no longer see the crosstalk on the oscilloscope ). It WILL NOT show up on A/B test - because the switch/difference is too small in duration. After listening to a "90 dB separation" amp and switching to a "100 dB separation" amp , long term impression is one of simply more close to the sound heard live - tiny details we tend to glaze over in quick A/B ing emerge, and they are sorely missed when going back to "only 90 dB separation" amp. 

 

In truly critical positions, I insist on dual monaural approach. Although NOT to the degree/extent of one stereo preamp from Mark Levinson - SIX boxes, phono, line, power supply, duplicated for stereo - the whole preamp had exactly 4 controls, volume control and input selector/each channel - NO on/off switch, it was on if plugged into the wall outlet.

 

I ALWAYS tend to listen to the long term effects of so small diferences as described above while doing the chores, like dusting. etc. If it does feel overall more natural, comfortable, etc while listening in a totally relaxed mode, it IS better.

 

I am certainly not against A/Bing, precise level matching, etc - but it is not the ultimate indicator whether the device under test is truly superior or not. No prospective buyer in the market for new violin ( or any other instrument ) is likely to decide between two comparable instruments in A/B lasting only few minutes...

post #2379 of 2956
Quote:
Originally Posted by analogsurviver View Post
 

I am certainly not against A/Bing, precise level matching, etc - but it is not the ultimate indicator whether the device under test is truly superior or not. No prospective buyer in the market for new violin ( or any other instrument ) is likely to decide between two comparable instruments in A/B lasting only few minutes...

 

No one says A/B tests have to last for only a few minutes. But level matching, direct switching, and blind comparisons all prevent incorrect conclusions that are very easy to fall prey to. I don't believe that there is a human on earth who can consistently identify the difference between channel separation of 90dB and 100dB at normal listening levels in a fair test. But remove the blindfold, don't accurately balance line levels, multitask while performing the test, and don't compare directly with an A/B switch and I bet there are a lot of human beings who THINK they can.

 

Again, it's about understanding how to describe and quantify sound... understanding what various frequencies sound like and how big a dB is. If you are listening to music with a peak level of 70dB, how can you possibly hear crosstalk 90dB down? If you turn the volume up enough to hear 90dB over a 30dB room tone, you are into the territory of the threshold of pain. That just plain doesn't make sense if you know what those numbers mean.

 

The theory of it makes no sense + uncontrolled testing procedures = incorrect conclusion


Edited by bigshot - 3/2/14 at 1:37pm
post #2380 of 2956

no, basically when "just listening" for a difference your brain will more often than not perceive differences - we seem to be strongly biased to create these correlations even when the input is objectively random - like "magic thinking", superstitions

 

this is in part because the relatively few bits of information in conscious perception is is way removed from the flood of data coming in on the tens of thousands of auditory nerve fibers - your brain has processed it way below conscious perception, throwing in everything possible - including your beliefs about the equipment

this is not subject to "intellectual honesty", you can't just decide to turn off the processing and just evaluate the sensory input - if you are human

 

that is why the Science of Perceptual Psychology is deeply committed to Blind testing, and removing all known clues except the variable being tested - small level differences have been proven to be heard - even though the listeners couldn't identify one as louder at the smaller fractional dB differences

 

 

focus and training do come into the sensory discrimination equation - you can miss some features if concentrating on others, you can learn to make fine distinctions of some things with practice

 

but you need to control for all other "clues" to make valid listening tests - and learn to deal with the fact that much audiophile accepted "wisdom" simply can't be verified in controlled tests - you can reject true "ears only" evidence or decide to live in the socially constructed marketing pushed "audiophool"  bubble

post #2381 of 2956
Quote:
Originally Posted by elmoe View Post
 

 

I'm real happy you joined head-fi so you could come in here and start name calling other members whose DBT don't match your notions. It really makes doing this whole ordeal for the benefit of others worthwhile :rolleyes:

 

edit - ah, nice ninja edit to remove your petty insults, but it won't make you more convincing to me.

 

On that thought and considering i apparently wasted my time only to have to read the following drivel, you'll pardon me if I put an end to this endeavor here and now.

 

Enjoy your future discussion.

Quote:
And no, a 1dB difference will not show any significant difference in soundstage, that's just a ridiculous claim.

He got what he flame-baited for ..

But of course, I'm the bad guy for pointing out the indisputable fact that a level-mismatch greater than 0.2dB IS audible ..

post #2382 of 2956
Quote:

If you are listening to music with a peak level of 70dB, how can you possibly hear crosstalk 90dB down?

If you turn the volume up enough to hear 90dB over a 30dB room tone, you are into the territory of the threshold of pain.

OH my God, please stop with all this ridiculous 'science' and stuff ..

I FEEL in my gut that it's better !

post #2383 of 2956
Quote:
Originally Posted by bigshot View Post
 

 

No one says A/B tests have to last for only a few minutes. But level matching, direct switching, and blind comparisons all prevent incorrect conclusions that are very easy to fall prey to. I don't believe that there is a human on earth who can consistently identify the difference between channel separation of 90dB and 100dB at normal listening levels in a fair test. But remove the blindfold, don't accurately balance line levels, multitask while performing the test, and don't compare directly with an A/B switch and I bet there are a lot of human beings who THINK they can.

 

Again, it's about understanding how to describe and quantify sound... understanding what various frequencies sound like and how big a dB is. If you are listening to music with a peak level of 70dB, how can you possibly hear crosstalk 90dB down? If you turn the volume up enough to hear 90dB over a 30dB room tone, you are into the territory of the threshold of pain. That just plain doesn't make sense if you know what those numbers mean.

 

The theory of it makes no sense + uncontrolled testing procedures = incorrect conclusion

To be blunt - it was with stock and modified amplifier of the same type, with levels matched to within a scope trace - and you just can not patch all the connections for a true A/B - or at least I do not have that capability. Listening was done at the upper extreme for a normal level listening - nothing out of ordinary, say peak of 100 dB. 

With headphones - to exclude room noise.  It could also be done in the middle of the night with speakers - provided no neighbours in the vicinity.

 

That IS LOUD - symphonic orchestra rarely approaches this figure at a typical listening position. Amplified music is entirely different matter, but recently there is a trend for quality PA regardless limited maximum SPLs - finally.

 

It was VERY interesting to observe the difference in overall sound of moving coil pre-preamplifier - or precisely said, the power supply for the said pre-preamp. Although I did use extraordinary phono cartridge with over 40 dB channel separation across midrange and stll not exceeding 30 dB at 20 kHz, and the channel separation should be limited by the cartridge, it DID sound quite markedly different with dual mono configuration. I bet if running a graph there would be both times the same - channel separation of the cartridge. Yet the sound as heard was much better with separate power supplies. Levels are inherently matched in this scenario - cartridge and pre-preamp gain remain constant. You just can not control an experiment better than this.

post #2384 of 2956
Quote:
Originally Posted by analogsurviver View Post
 

To be blunt - it was with stock and modified amplifier of the same type, with levels matched to within a scope trace - and you just can not patch all the connections for a true A/B - or at least I do not have that capability. Listening was done at the upper extreme for a normal level listening - nothing out of ordinary, say peak of 100 dB. 

With headphones - to exclude room noise.  It could also be done in the middle of the night with speakers - provided no neighbours in the vicinity.

 

Was your test done blind? How many times were you able to discern which one was which?

post #2385 of 2956
Quote:
Originally Posted by bigshot View Post
 

 

Was your test done blind? How many times were you able to discern which one was which?

No. You can not perform A/B switching of moving coil cartridge signal levels without introducing more problems than different power supplies can cause. These pre-preamps also are quiet enough that for the best performance regarding picking up hum field from nearby equipment, that they require exactly the same phisycal positioning - and two objects can not be at the same time in the same spot.

 

These differences are admittedly small - but they are consistent in the long run. If listened to the better incarnation of this pre-preamp for say over a weekend, after which it is replaced by the worse version (power supply only), there is an immediate reaction: Where did the precision/You are there sensation go ?

 

I have a friend to whom I have been telling similar for ages - and it was trough one ear in, out trough another - for YEARS - UNTIL he heard my equipment first at my place, than in his own system. Needless to say, he does have the same integrated amp modified by me first heard in my system at his place now - along with several other satisfied customers. 

 

This integrated amp has seen improvement to everything - not just channel separation.  The first reaction of friend's wife while at the door entering their flat, after hearing the sound this amp produces, with memory of the stock unit sound :

 

What did you do !?!  

 

And she is a normal human being, not an audiophile by any stretch of imagination. 

 

Differences that big do not require blind A/B testing ... - she possibly could not have predicted what equipment was playing at the other side of the flat - could she ?

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