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Thread: Does PHASE matter on a single source?

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    Does PHASE matter on a single source?

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    What is my "phase button" doing to change the sound on the DI?

    I been reading and dont really get it.
    I understand two mics on a snare on-top and below is what seems the most common discussion/example....but when I plug something into my preamp DI or Mic...the PHASE button has two distinct sounds. One has more bass /low freq the other less low freq.

    Any inputs appreciated...

    if it's not happening in the room, it ain't gonna happen on tape.-H.Gerst

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    I assume you mean the almost universally mislabeled polarity switch. In most cases it would be nearly impossible to tell the difference. With some sources you might feel a difference on initial transients.

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    The manual says nothing, I dont even know if its IN= LED is ON, is it IN Phase...and when its out=led off the polarity is out,,,,,

    seems I heard some difference, oh well. its a mono preamp, with DI.

    yeah...its labeled PHASE...typical clone manual which means it has nothing, as compared to designers like Ted Fletcher whose manuals are like a history thing coffee talk.. and each component purpose is described...or the old JVC JBL manuals...

    thanks.

    if it's not happening in the room, it ain't gonna happen on tape.-H.Gerst

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    The audibility of "Absolute Phase" has been debated forever in audiophool circles but, like so many of these claims such as 'One way cables" none of the people nor firms that claim these effects are audible have ever put money where gob is and paid for independent, double blind tests.

    I am certain "AP" is "BS". From first principles, if my ear is 10 ft from a big drum when struck, yes the struck skin will initially move inwards, the pressure wave will move through the drum and cause the outer skin to first deflect toward me (and if we say it is a BIG big drum a foot from skin to skin, the P wave will take 1mS to get there*)

    Thus a pressure wave is launched at me, followed closely by a rarefraction. Now, I will only get the positive pulse IF I am some exact multiple of the distance from the skin (which is itself DELAYED by 1mS from the 'real' beater hit!) And of course, I must not move!

    "Phase" can only be detected in conjunction with another source, e.g. the comb filtering you get from poor microphone placing.

    The other claim is the ear can detect the polarity of asymmetrical waveforms? Might be true for electronically generated signals but music signals are shifting shape mS to mSec, as anyone who has ever used a 'scope will attest.

    *The pressure wave cannot move faster than the mean particle velocity of air molecules which is of course about 1100fSec (340mSec)

    Dave.

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    Even the big brands with mega R&D departments never sorted the polarity vs phase labelling, and often talked themselves about phase, but I guess it really stems from the concept of phase rather than absolute measurements of it because in everyday life nothing is ever chase coherent. Probably the closest we get is a DI'd instrument with IEMs in your ears. Yet - we all argue endlessly about latency, which is of course a phase linked phenomenon. 9ms in the latency department is a phase delay. I guess that practically fiddling with the phase switch is a starting point and then you can delay or advance your tracks even further to cure or enhance?

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    Quote Originally Posted by CoolCat View Post
    but when I plug something into my preamp DI or Mic...the PHASE button has two distinct sounds. One has more bass /low freq the other less low freq.
    This will be the case if you're monitoring yourself whilst playing because the audio you hear through speakers/headphones will be interacting, to some extent, with what you hear from, or feel through, the physical instrument.
    If you just record and play back solo bass and use a plug to toggle polarity there should be no audible difference.
    ---------- Steenaudio Website ----------

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    I thought this was just for reducing noise. Like a ground switch on a DI. Not needed most of the time but can help reduce induced RF or something. Dave?
    Win 7 Ult Dell i7 4core 6700ghz 32 GB, 1,2x2, 4 Tb Barracuda HD's running Pro tools 2019 through Allen&Heath Qu-32

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    ok, the head-internal skull thing,

    yes I was using headphones and pushing the button in and out and it was much more drastic with the microphone. like a bass freq boost.

    so the real DAW track isnt really going to capture any sound difference, only my ears due to headphones and some weird physics.

    ok, I was just wondering if it was miswired or something. thanks

    if it's not happening in the room, it ain't gonna happen on tape.-H.Gerst

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    Quote Originally Posted by Gtoboy View Post
    I thought this was just for reducing noise. Like a ground switch on a DI. Not needed most of the time but can help reduce induced RF or something. Dave?
    Polarity switch is there because audio is recorded as positive and negative voltage swings. If you capture the same thing with two microphones but one microphone, or cable, or preamp (or combination) is resulting in reversed polarity,
    then one capture is going to have negative where the other has positive, and vice versa.
    In perfect conditions that'll mean total cancellation when it comes to playing the two tracks back together - In reality with differences in mic position and equipment accuracy it means heavy/partial cancellation and a thin sound.

    Flipping polarity literally just inverts a the signal so positives become negatives and vice versa. It's not destructive.


    Balanced audio technology uses polarity, and comparison, as a means of removing noise that may have been picked up along the way - Spikes from lights being turned on, hum from a transformer, etc.
    If you send a sine wav through some cable but are also sending and inverted copy then, in theory, the two combined at the receiving device should cancel each other out..
    Any noise picked up along the way is going to affect each conductor equally (same polarity on both) so combining the two signals at the other end will cancel intended signal and leave then unwanted noise only.
    Armed with that, picked-up noise can be removed from the signal.
    ---------- Steenaudio Website ----------

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    Polarity flips can also be useful to combat feedback in a mic/speaker PA setup.

    Set gain so the systems is just at the ring point then flip the mic phase/polly. The ring should get better or worse. If possible repeat the exercise for the speaker polarity (rarely have the option these days) You can often get up to 6dB more gain before ring with this technique.

    If you cannot decide which is "flipping best" go for the lowest ring note.

    This reminds me. I did some tests with mics a couple of weeks ago and I suspected the Behringer 8500 dynamic was OOP with the rest of my mics? Must check into that.

    Dave.

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