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In Reply to: "Tests show that reversed polarity is more audible than 11.5% intermodulation distortion." posted by clarkjohnsen on May 23, 2006 at 10:28:20:
Many things appear in print that are patently silly. This is but one of them.
Follow Ups:
s
Can you give us some details on these tests? All evidence I've read before supports the conclusion that absolute polarity is not normally detectible without non-sonic cues. For all we can tell, "reversed polarity" could mean one channel reversed in, say, a stereo system, which I agree would be audible.-Bob
Absolute polarity is quite audible, Bill. But one has to train their ears, like any other sensory skill. I'm not ashamed to say that it took me a decade of listening to be able to recognize it.
Polarity is more easily identifiable in wind instruments and voices. Tongued attacks will sound like a breath attack. Consonants loose their crispness (consider the difference between voicing a P and a B). Generally speaking, I find that whenever a video buff moans about the fact that his effects are drowning out the dialogue, the soundtrack is reversed. In fact more often than not, when the significant other yells that the TV is too loud, the chances are the programming is likewise reversed in polarity, making the dialogue sound like everyone's slightly mumbling and hence the need for more volume.
Other audible clues, since many waveforms are asymmetrical, are a slightly louder volume when in correct polarity.
All this, assuming the speakers used are phased correctly. Since all too many speakers have drivers in mixed polarity, the test or a switch in polarities will often result in a mixed reaction. Of course many record producers deliberately mix polarities in order to achieve certain effects, but that is another issue.
Actually, I'm a bit surprised that you bring this up. Early QSC amps, the series 1, which I liked very much, BTW, had their 1/4 inch jack inputs inverted to the terminal strips. I was told this was done to protect the speakers from blowing out if the jacks were accidentally pulled out while the amp was running. The speaker cone would move backward and bottom out, rather outward and ripping the VC wires out. I guess, commercially, bad sound is better than no sound.
8^)
Stu
.
Picking up on incorrect AC polarity, now that takes longer.clark
"But one has to train their ears, like any other sensory skill."With the exceptions of Scotch and women any sensory pleasure that you have to learn how to enjoy is too much trouble to be worth the effort.
I'm sure sampling various Scotches was worth the effort and definitely so were the women, but I would extend that to beers, foods, games (golf, etc.), and many other little pleasures in life. I watch my God daughter growing up and she's already progressing beyond the MacD's happy meals....
My life is about expanding one's consciousness. Music is just one facet. I don't pursue it super rigorously, but I do enjoy it and also did even before my awareness of polarity and many other issues. Refining my choices and increasing my awareness has been more than worth the part time analyzing. It has led to greater appreciation and satisfaction to be able to control my sound.
Of course YMMV. That's life. You make what you will of it.
Stu
Well I guess that leaves out learning music, skiing, diving ... inter many alia .clark
Regarding tip-negative inputs on early QSC amps: You were told wrong, Stu. The real reasons are published.-Bob
Stan Lipshitz on Absolute Polarity:"Indeed, in a double-blind demonstration, the accuracy score was 100% on the summed 200Hz and 400Hz tones over loudspeakers, and over-all, including musical excerpts, the results on the audibility of the polarity inversion of both loudspeakers represented a confidence of more than 99% in the thesis that acoustic polarity reversal is audible." -- JAES, 9/82
"An effort should be made to standardize the polarities of the whole recording chain.... It also serves as a warning to those who conduct A/B comparisons on audio components without taking into account the possible relative polarity reversals which such components can introduce." -- Wireless World, 5/77
"Differences in components can frequently be greatly reduced, or even eliminated, by assuring that acoustic polarity is maintained when switching from Amplifier A to Amplifier B." -- HFN/RR, 1/78
"I believe that failure to maintain polarity is one of the most serious shortcomings of many A/B tests and one of the main causes of audible differences between components compared in this way." -- The Audio Amateur, 3/78
"Polarity must be taken into account when comparing two components." -- TAA, 4/79
clark
Is that first one in the paper titled "On the Audibility of Midrange Phase Distortion in Audio Systems"?I don't know if I'll be able to find the original articles of the other four quotes, but they could be inferred as admonishments against unnecessary, arbitrary, and careless polarity reversals, which is understandable because it could affect the relative polarity among signals, not necessarily that the overall absolute polarity is audible.
-Bob
a
The reason I ask is because I have a copy of that paper, and it doesn't conclude that absolute polarity is audible; in fact, Lipshitz, Pocock, and Vanderkooy wrote this in it:"This experiment does not demonstrate that polarity reversal of both channels (or monaural polarity reversal if the signal is applied to one ear only) is audible."
-Bob
Okay, but I'm not going to buy your book just to investigate your assertions.Again, I ask: Is your first quote from the paper titled "On the Audibility of Midrange Phase Distortion in Audio Systems"? Please answer. Thanks.
-Bob
Thank you. I will try to look those up and gether the context as well.-Bob
You're right, you'd never find anything remiss in such a publication, just as you would not in the NY Times or Newsweek. Or the Congressional Record. I stand corrected.
...and look what happens when it does.Guess people will forever be shifting their lines of demarcartion.
clark
PS The JAES published research similar to Stodolsky's by Lipshitz & Vanderkooy, Hansen & Madsen, etc. etc. That makes a phalanx of professors and doctors with DBTs under their belts arrayed against your opinion, but don't let that thwart you.
I've not known of John Vanderkooy to espouse that absolute polarity is audible, but I could be wrong. I'll be sure to ask him when I next see him. Can you cite anything from the JAES that I might be able to look up? I'm still highly skeptical; I believe I could correctly identify absolute polarity about 50% of the time. Thanks.-Bob
a
Being a full member of the AES myself I don't shudder and quake at the sight of anyone's credentials. I'm quite sure that all of the esteemed people mentioned put their pants on in the same fashion as I do, one leg at a time, and are neither more nor less likely than myself to come to either a correct or incorrect conclusion based upon any set of facts. I've tried phase reversal many times and I can't hear any difference.Cue: This is where you tell me that I don't know how to hear.
Maybe you don't know how to *listen*, but that's different and I would never say that anyway.What I *will* say is, chances are 9 out of 10 that your speakers are phase incoherencers. No one ever hears polarity over such as those.
But I do wonder, given all the reported DBTs that have proven polarity audibility with recorded music to the 99% confidence level, do you reject that regimen as now useless?
clark
PS Polarity is about the only thing that DBTs have ever proved in audio.
"phase incoherencers"
That's almost as good as "the decider". Before you know it Will Farrell will be doing you on 'Saturday Nite Live'.
Both are in AES literature by the way -- and explain why you don't get polarity.clark
What I'm saying is that I cannot take anyone seriously who lacks command of the English language. That applies both to you and to our esteemed 'decider in chief', G.W.Bush. You might get some respect if you wrote like an educated person rather than the village idiot. At least use Spell Check.
So I lack "command of the English language"? If such command allows one to become an internet bully, then I guess I'd rather not have it.But maybe you should take that up with my editors, who have been publishing my work for over twelve years. Would you like their addresses?
"Spell check"? Perhaps you've not heard, but it is considered the height of boorishness on the Net to draw attention to a person's spelling and typing, and in any event the only error I find is "demarcartion", clearly a typo. You grasp at straws, sir.
That incoherence I spoke of in your speakers? Perhaps its a manifestation of their owner.
clark
"Perhaps you've not heard, but it is considered the height of boorishness on the Net to draw attention to a person's spelling and typing"Perhaps amongst 15 year-olds, not amongst those who claim a professional status. If you do not find what you're saying to be worth the time that it takes to properly espouse it then it's not worth my time to read it.
x
You guys need to relax and have a beerLife is to short to try to out do each other on a thread
If a tree falls in the woods and no one is there to hear it
Is there sound?
Is it in phase or out of phase?
Explain the reflection off of everything in the forest
Turn your music on...keep your loudspeakers in phase or out
of phase with each otherEnjoy the music
Have a beer (or a cocktail)BTW Bill
PIEZOS SUCK
:)
And using that to take me down.Such idiocy surely should not go unremarked?
Cheers to ears,
clark
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