Absolute polarity in your playback gear and/or your favorite music - audible or not?

Discussion in 'Music Corner' started by Thomas_A, Jul 6, 2018.

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  1. Thomas_A

    Thomas_A Forum Resident Thread Starter

    Location:
    Uppsala, Sweden
    Ok,

    I'll bite on this topic. It was discussed in

    Why were CDs recorded in 16-bit/44.1khz?

    but was very out of topic for that thread. I hope this is ok to start a new one, Steve.

    So the first question is:

    Is absolute polarity audible?

    The answer is yes, given that you listen to a certain waveform that is asymmetric. This has been known for many years and is also explained by the physiology and psychoacoustic effects of hearing ("half way rectifier"). The sound of such signals change in pitch and timbre when inverted. Some expect the difference to be in "attack" since the waveform change - however, the difference is most audible as a change in pitch and timbre. So you cannot actually hear the changed phase, but only the effects of it as frequency spectrum change.

    Examples that you all can test yourself can be found in the thread linked above.

    Now: the second question: Does it matter when listening to music?

    I would say >99 % of cases: No.

    You need to have asymmetric signals and not not much other things going on. These other sounds will mask the change in pitch and timbre of a putative asymmetric and inverted music signal. That said, you could probably find some examples where this could be audible. But then: what can you do about that? Absolutely nothing, since you are unaware of that it just happened.
     
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  2. eflatminor

    eflatminor Forum Resident

    Location:
    Kalifornia
    Yes, audible.
     
  3. Steve Hoffman

    Steve Hoffman Mastering Engineer Your Host

    It matters because you have a choice. It's almost like a mix choice, different mixes.

    It goes like this. Your favorite rock album was recorded on 24 analog tracks and mixed to 2. Chances are there will be different polarity for some of the instruments and vocals, not by choice but by accident or carelessness. When you flip polarity (via the button on your CD remote control, or the HARD WAY by reversing both speaker leads for both channels) you will experience a different mix flipped than you would unflipped. Some instrumental air will be going out while some will be going in. It's neat to hear how they screwed up over the years if you dig that sort of thing, almost a treat to hear the sounds of your favorite song in a different way. Your next step (of course) is to finally chose which way you like the song best and then mark it on your CD with a sticky. On to the next song, might be totally different, could all be in correct polarity, could be mixed, could all be out. And so on.

    Mastering Maven Stan Ricker and I would spend many minutes flipping back and forth with his console AP switch to figure out the best way to proceed for each song, even in mono. Do the drums sound better one way and the acoustic guitar the other way? Which is more important to the overall presentation? Not easy questions to answer but crucial to a good mastering.

    If your gear is flipped somewhere down the line, it means your speakers are moving in when they should be moving out. I don't know about you but stuff like that keeps me up at night. With a little meter you can fix all down the line, or at least at your speaker leads. Read your gear manuals, some (like VAC) will state if their line stage (for example) inverts AP. If so, and your amp does NOT, you need to flip both of your speaker leads for both channels. But, if your CD player does as well, you do not, you’re back in correct AP again. See? And if some of your gear has only a two-prong plug, it MUST be plugged in the correct way or you're out.

    Capiche? Such a simple fix, why not do it?

    BTW, an interesting fact. When recording the CROSBY, STILLS, NASH and YOUNG album Deja Vu, one of our favorite engineers kept his scope on his eight track to make sure absolute polarity was kept for all channels. Did that make it to the final two track mix? How about to the CDs or LP's? You tell me!
     
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  4. Thomas_A

    Thomas_A Forum Resident Thread Starter

    Location:
    Uppsala, Sweden
    I understand that completely.
     
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  5. Steve Hoffman

    Steve Hoffman Mastering Engineer Your Host

    Not many people will care, but they SHOULD care. It affects how their music is reproduced. And such a simple fix.
     
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  6. Thomas_A

    Thomas_A Forum Resident Thread Starter

    Location:
    Uppsala, Sweden
    Yes, I could check my listing space. But I cannot do anything for a all the records I have.
     
  7. Plan9

    Plan9 Mastering Engineer

    Location:
    Toulouse, France
    If you have the Peter Gabriel III (Melt) SACD, try inverting its absolute polarity. I find it is pretty audible on this one.
     
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  8. Steve Hoffman

    Steve Hoffman Mastering Engineer Your Host

    Nor I, but at least be sure that all your gear is correct, or at least when it gets to the final speaker leads. Then, let the "chips fall where they may" as they say in my country.
     
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  9. Ignatius

    Ignatius Forum Resident

    If I understand (?) the term and my old Hendrix books there were a number of fake "alternate mixes" of Hendrix songs on boots that used the polarity thingie.
     
  10. Thomas_A

    Thomas_A Forum Resident Thread Starter

    Location:
    Uppsala, Sweden
    Point 1 was that there was quite much debate about whether it is audible or not. It is proven and explained to be audible with certain waveforms, and it has been known for a long time. So it is not always audible, but since you never know when, keeping check about polarity through the whole recording and playback chain is only a good thing.
     
  11. Steve Hoffman

    Steve Hoffman Mastering Engineer Your Host

    I don't know how that would change much. You don't mean "in phase" and "out of phase" do you? Not the same thing as AP. You can go out of phase by reversing ONE SET of your speaker leads, not both.
     
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  12. Tim S

    Tim S Senior Member

    Location:
    East Tennessee
    >

    How do you maintain absolute polarity between 8 different sources? Am I misunderstanding the term as it is being used in this thread?
     
  13. Jack_Straw

    Jack_Straw Forum Resident

    Location:
    Wichita, KS
    I know you are not a fan of remixing the classics, Steve, but this seems like a good argument for doing a proper mix, paying attention to the polarity on each individual channel/instrument, no?
     
  14. Steve Hoffman

    Steve Hoffman Mastering Engineer Your Host

    Nooooooooo.
     
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  15. BrentB

    BrentB Forum Resident

    Location:
    Midwestern US
    Ok in the absolute polarity are we just speaking of speakers? Say an audio source or track somewhere along the line has out of phase line level polarity? An basic example being an RCA cable with the two leads reversed. Or on a phono cartridge had the +/- reversed on one channel? I was changing out a cartridge once and noticed his old one had the +/- reversed. He had listened to it for years and thought it sounded fine, but his is not really an audiophile type. I think I would have most certainly have noticed and eventually found why the sound just seemed off somewhere.
    I guess my main question is absolute phase only for speakers that produce sound in the room or open air, or also for the electronic circuits as well?
     
  16. Steve Hoffman

    Steve Hoffman Mastering Engineer Your Host

    I'm not sure I understand, everything comes out of the speakers. If you system reverses absolute polarity (say your preamp does but your amp doesn't), all you have to do is flip both of your speaker leads at the speaker. In other words, the reds go into the blacks and blacks go into the reds, both speakers. Now you're in correct polarity again, assuming that everything else is correct. I had my speaker wire flipped for years when I was using VAC gear. When my amp also flipped as well, it evened it all out again out and I could go back to normal again. See?
     
  17. Steve Hoffman

    Steve Hoffman Mastering Engineer Your Host

    Well, you keep everything in phase, using a scope and in AP at the same time. Then, hopefully, if your two track machine and mastering console doesn't flip, you can mix in phase and correct polarity. One flip along the way and you're sunk, unless you have TWO flips of two different things and that evens it out again.
     
  18. BrentB

    BrentB Forum Resident

    Location:
    Midwestern US
    Yes I kinda see. I am just one of those that can overthink stuff like this in the never ending persuit of better sound. Or at least keeeing it good! Dealing with a lot of old tube equiptment I have had systems set with a speaker wired visibly correct, but a an old 60's stereo test record dictated otherwise. Flipping a channel made a big improvement in spite of what the +/- stated.
     
  19. Bern

    Bern JC4Me

    Location:
    Michigan
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  20. c-eling

    c-eling I never dreamed another way.

    Used software for the Japan Duran Duran-Rio, I couldn't detect any difference Thomas if this is what is being discussed.
     
  21. Jack_Straw

    Jack_Straw Forum Resident

    Location:
    Wichita, KS
    So... hypothetically, what if the drums and bass were on 2 separate tracks and mixed down with opposite polarity? Wouldn't that lessen the impact of the two instruments when combined? Or a better example might be 2 harmony vocals on 2 separate tracks - wouldn't it make an audible difference to have "competing" polarities rather than polarity in unison?

    (or are we talking virtually inaudible stuff and I'm just over-analyzing and splitting hairs?)
     
  22. Steve Hoffman

    Steve Hoffman Mastering Engineer Your Host

    Well, we don't know until we "flip" and see. Some famous stereo mixes we are so used to hearing, just a simple flip and things are different, especially on really good playback gear (assuming the gear also reproduces correct AP!)
     
  23. Lemon Curry

    Lemon Curry (A) Face In The Crowd

    Location:
    Mahwah, NJ
    It seems like there are two topics here, both being labeled absolute polarity.

    The one case is for a completed mix that simply has the wires reversed (physically or otherwise) to the speakers. The Stereophile piece mentions that the more asymmetrical the speaker response, the more you will notice a difference when you make this absolute polarity change.

    The second case might be better called Zero Polarity or Equal Polarity, where care needs to be taken at every signal processing step for every input to a mix that a signal inversion never occurs. Or if one does that can't be helped, it must be matched with another to cancel out the change. Steve's posts largely focus on this case.

    An interesting conclusion from Stereophile is that what sounds "good" for absolute polarity changes from speaker to speaker. One could say a 180 degree shift sounds "better" on my monitors, or on my headphones, but with someone else's monitors the opposite could be true.

    I would think the target should always be to have that Zero Polarity (all inputs never flipping phase along the path) and keep absolute polarity at 0 degrees, e.g. the same as the actual live performance. If you do that, it is then the prerogative of the listener to adjust absolute polarity for THEIR setup if they care to experiment.
     
  24. Jack_Straw

    Jack_Straw Forum Resident

    Location:
    Wichita, KS

    Right. Once the mixdown is complete, the only thing you can do is reverse polarity on the finished mix and see if it improves the overall sound - I'm pretty sure that is what Steve is referring to. If there were channels that were "reversed", then you will be making compromises with either polarity and deciding which one sounds best to you.

    What I am asking about is: In a mix where there is reverse polarity on one or more channels, is it worthwhile to go back and remix it to correct that issue, creating a final mixdown where polarity is correct everywhere.
     
  25. Lemon Curry

    Lemon Curry (A) Face In The Crowd

    Location:
    Mahwah, NJ
    This is what I called a Zero Polarity problem. Whether you perceive it as an issue that requires a re-do is if the channel signal involved has the sort of asymmetrical qualities that would be noticeable with absolute polarity changes.
    So, maybe.
     
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