Absolute polarity test

Discussion in 'Audio Science' started by MLegend, Oct 14, 2020.

  1. MLegend

    MLegend Friend

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    I recently received a balanced 1/4 TRS to connect my audio processor to my interface and while recording a sample I noticed that the waveform was traveling 180 degrees in reverse (downwards) instead of up. When I listened to the sample, it sounded different and off compared to how my microphone normally sounds. So I inverted the track in Audacity and by doing so the polarity was correct again and it sounded normal.

    This made me curious and led me to create a profile post asking if anyone else can hear the difference between absolute and reverse polarity. I think this is pretty interesting and I thought it would be fun to see what anyone who wants to compare the two thinks.

    Here are the tracks. This is the same recording, the only difference is one of the tracks is inverted.
     

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  2. purr1n

    purr1n Burned out

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    I know with speakers, the answer is definitely yes with the effect more consistent and perhaps notable with classical and simple mic'd recordings vs. studio recordings. The soundstage becomes quite different. (@ChaChaRealSmooth: have you played with this yet?. This is from pressing the polarity invert button on the Yggdrasil DAC. I wish the Yggdrasil had a remote for this button.
     
    Last edited: Oct 14, 2020
  3. Azimuth

    Azimuth FKA rtaylor76, Friend

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    I feel like there is a difference in soundstage as well. Phase gets totally messed up in studio recordings...too many mics, early reflections, micing underside of the snare or the back of the guitar cabinet.

    Anyway, my Theta has a polarity reversal switch and is instantanious. The polarity flip on the other vintage DAC I have takes some relay switching and there is always a delay. Not sure if there is a delay on Yggdrasil or Bifrost 2.

    For those of you guys using moOde, there is an internal polarity flip, but that requires a restart of the MPD.
     
  4. Metro

    Metro Friend

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    There was a good discussion on the topic in the Schiit thread on Head-Fi starting here:
    https://www.head-fi.org/threads/sch...most-improbable-start-up.701900/post-15386152

    It can make a difference when playing some recordings, but the problem is that some audio equipment (either recording or playback) may flip the polarity and there is no consistency in commercial releases. You can only listen to both polarity and see if one sounds better than the other (and it may change from track to track even in the same album).
     
  5. mitochondrium

    mitochondrium Friend

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    Last edited by a moderator: Jun 20, 2022
  6. purr1n

    purr1n Burned out

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    With headphones (harder for me because I suck at hearing headstage on headphones)
    upload_2020-10-14_13-29-52.png
     
    Last edited: Jun 20, 2022
  7. ChaChaRealSmooth

    ChaChaRealSmooth SBAF Poopsmith

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    Yes, played with this with both Yggdrasil GS and Wavelight on both speakers and headphones. In summary, I don't think I have any recordings that invert the phase, nor benefit from having the phase inverted.

    What phase invert sounds like to me is really messed up stage where it almost sounds like the center of the stage becomes extreme left/right and the sides of the stage become center.

    I will say that on headphones I could see how someone might interpret phase inversion as expanding the stage and being beneficial, but as they gain more experience I don't think this thought would hold.
     
  8. squishware

    squishware Friend

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    Audirvana has a setting to "invert for tracks with INVERTPOLARITY comment"
    I have been leaving it enabled lately.
    I fiddle with the BF2 polarity to check it is correct, occasionally. I always end up with the light on.
    I cannot describe the difference in sound but it sounds a hair louder when it sounds right.
     
  9. gixxerwimp

    gixxerwimp Professional tricycle rider

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    None of my music seems to be affected by the polarity button on BF2. Maybe people who can hear this can list specific recordings on which this can be more easily heard.
     
  10. ergopower

    ergopower Friend

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    What I hear on @MLegend 's 2 tracks
    Raw track I hear the male voice clearly centered with some studio reflection that appears to come from the physical position of the left and right speakers
    Inverted track I hear the male voice centered but slightly diffused, and it's harder to place the location of the reflections. They're there, but not as pinned down.
     
  11. Biodegraded

    Biodegraded Friend

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    Guys should post what amps you're using, and see if you can find out if they invert. Many do.
     
  12. dmckean44

    dmckean44 In a Sherwood S6040CP relationship

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    Everything in the signal chain can invert, many dacs, cd players, phono stages, phono cartridges and preamps invert too.
     
  13. Hammy

    Hammy Friend

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    I hear a difference. The inverted sample has a more open sound, a more transparent sound (I define transparency as being better able to hear through the gear and hear into the recording space). The raw sample sounds constrained, restricted, constipated. The inverted sample achieves a "you are there" style of sound. Which I can kinda attempt to describe as being a sense of my ears are the microphone in the room.

    Gear for this listening comparison:
    Eitr to Gungnir MB A1 balanced to Cavalli Liquid Gold X low gain balanced to balanced LCD-2 Classic headphones
     
  14. ergopower

    ergopower Friend

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    Windows laptop > Groove Music > Bluetooth > Yamaha A1060 AVR. No way to know how many times the track has been inverted and which of the 2 tracks are which
     
  15. Hammy

    Hammy Friend

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    One thing I'll add. I generally hear good high-res to help make absolute polarity changes more obvious compared to redbook res. Doing listening samples like this in high-res might help some people better hear the differences compared to the 16/44.1 redbook resolution samples.
     
  16. Kouon

    Kouon Rando

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    Wasn't there an entire section on the CTH thread about it inverting the polarity?

    I likely can hear the difference, the recording being mono probably wasn't doing me any favours. I usually listen to soundstage/imaging cues when ABX testing stuff.
    Got 8/10 the first time round, failed the next 2 rounds due to listener fatigue, then came back with a 10/10.

    [​IMG]

    Edit: I found Archimago's blog post on the matter (http://archimago.blogspot.com/2019/06/musings-and-listening-on-absolute.html). He (I assume?) and his family was able to tell a difference.

    I've inverted the polarity going through my DAC using the foobar2000 plugin Matrix Mixer, simply setting the values for FL (Front Left) & FR (Front Right) to -1 respectively. Once that is done I was able to easily toggle the DSP on and off.

    Suffice to say I'll keep pre-inverting the polarity from foobar2000 so it comes out "the right way 'round" out the CTH. It just sounds more correct and more precise to me, especially with piano.
     
    Last edited: Oct 14, 2020
  17. MLegend

    MLegend Friend

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    Since I'm only using headphones, I'm not entirely sure how this recording sounds on speakers, but I think the reflections you're hearing are my computer fans in the background before the noise gate in the DBX closes. Nothing studio-quality here, by the way. This was recorded in my untreated bedroom.

    I could be wrong here, but I think the reason why the reflections you're hearing sounds like they're coming directly from the speakers with the raw track (reverse polarity) is similar, if not the same, as what many others have mentioned here already. The drivers aren't pushing the signal completely out due to a limited amount of excursion, which then creates a small or completely flat soundstage.
     
  18. Metro

    Metro Friend

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    But you can't count on one setting to always be the better choice. It can be different for each track depending on the polarity of the recording.
     
  19. Hammy

    Hammy Friend

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    I have found that the majority of professionally produced and mastered albums get the absolute polarity correct the vast majority of the time. Professional mastering engineers know how to hear absolute polarity and make the correct decisions during the mastering process. I can hear absolute polarity problems and I'm not constantly flipping the absolute polarity for different albums or tracks. At least for the music I have in my personal collection.

    There are some periods and styles of music that can have more absolute polarity problems. Like some periods of jazz recordings. Some jazz recordings can end up with the bass in one absolute polarity and a solo instrument in another absolute polarity. There is no best setting for something like that. You'll flip back and forth depending on whether you want the bass or the solo to be more correct. But recordings like that are not common in my collection. What I tend to have more problems with are some of the less professional recordings that didn't go through a professional mastering. Some of those can have wrong absolute polarity.
     
  20. Psalmanazar

    Psalmanazar Most improved member; A+

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    There are some ringers. And the whole era of music that was done on cocaine aka the 80s.

    Massive phase mangling has been around since the mid 80s. Early converters and ADAT had thousands of degrees of treble phase shift. Out of phase monitors were very common from the early 90s to today so they can't even hear it. Focals and Genelecs are smeary for a reason. Now you have people tracking with cheap bad converters, mangling phase with overuse of digital parametric eqs at 44.1 and 48 kHz instead of the optimal filters... some of which have been around since the 60s and the most common digital EQs are cramped" so they start aliasing and going nuts with anything in the treble.

    And for the ones that have linear phase oversampling and good anti-aliasing filters, half these guys aren't turning that on judging from commercial mixes, multitracks I've received from "producers", and youtube videos. And they're not mixing at 96 or 192khz. 99% of everything not a hollywood movie is 44.1 and 48.

    Not that current Hollywood is much better. They don't clip and brickwall but use even worse tools. The utilitarian stock DAW FX, Ozone, and Isotope behave way worse than the old Fairchilds, Telefunkens, and SSL buses that were used from the 50s-90s. Hollywood isn't paypaling some German wiz kid programmer / mastering engineer 50 to 200 bucks or letting $1000-30000 (yes I mean 30,000 dollars or 250 a day to rent, kills tubes, and will outlive us all) rack mount gear with working and very well thought out multiple time constants touch anything but the movie music. Hence the "clear but not clean" stereo and surround mixes with WTF levels.
     

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