Audiophiles - What's this effect called?

Discussion in 'The Guru's Pub' started by Extraordinary, Oct 24, 2016.

  1. Extraordinary

    Extraordinary Guest

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    I used to do this on dual tape decks as a kid, play the exact same track on both decks, and gently touch the pause button to get one of them to go in and out of sync with the other, causing some weird stereo cancellation effect when they both sync'd up perfectly and then slowly separated again

    Can hear it here
    https://youtu.be/B_7_MFlsVrY?t=57s

    Any idea what it's called?
     
  2. XP-200

    XP-200 Ancient Guru

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    It called don't let you dad catch you doing this to his Andy williams tapes, or else. lol

    Sound like you doing a cheap Analog Tape Echo effect, did cassettes deck's ever come with a speed control, my wee dad's pye had a speed contol for the turn table but i cannot remember if it worked on the built in cassette player as well, we were not allowed near it, when he was in lol
     
  3. scatman839

    scatman839 Ancient Guru

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    I think sine wave is what you're describing for shifting in an out with each other (you were approximating manually).

    And the effect it's causing is a delay shift on a sine wave?

    edit, yeah, phase shifting synced to a sine wave.
     
    Last edited: Oct 24, 2016
  4. Extraordinary

    Extraordinary Guest

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    lol yea, that was what I originally was doing, getting the echo, but when they were just the right speed each track sort of cancels the other ones bass out, makes a weird stereo effect

    Was wondering if there is a name for that, I've heard it on a few things so it must be a real thing

    Doppler shift, I`ll have a search on that name cheers, yea that's what I was causing by shifting them in and out of sync
     

  5. scatman839

    scatman839 Ancient Guru

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    Yeah sorry I just updated, I believe it's phase shifting. Your end result pattern I think is due to changing the phase with a constantly increasing horizontal phase (as in, the phase constantly moves right).

    Or if the phase is going back and forth, then it's a crude sine wave of a phase shift (in your case more likely sawtooth since it was manual).
     
    Last edited: Oct 24, 2016
  6. Extraordinary

    Extraordinary Guest

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    Looks like Phase shifting is the one thanks, just found this
    https://www.youtube.com/watch?v=q689Cxc84_0

    Not as obvious as it is when you play two identical tracks, but has the same sound

    With two tracks, as they slowly sync up, it's almost as if your ears are popping, the sound gets eaten up by itself and goes pretty tinny, until there is almost no sound, and as it comes back out of sync the other way, it does the same in reverse

    Was trying to do it with MP3s and VLC with audio delay control, managed it sort of but not as easy as it was with analog manual tape decks lol
     
  7. HeavyHemi

    HeavyHemi Guest

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    It's the same concept behind how noise cancelling works. There's a microphone that picks up the ambient sound and emits a sound out of phase with the ambient sound. Lower frequencies are more easily affected. Basically, if you have two sound waves of opposite phase, they cancel each other out. You can get the same effect by reversing the wires on a set of stereo speakers.
     
  8. Extraordinary

    Extraordinary Guest

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    Ah right, nice cheers, yea I watched someone with Ableton Live iirc flipping a sine wave and playing it with a copy of itself the other way around, and there was no sound when flipped
     
  9. XP-200

    XP-200 Ancient Guru

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    A 50Hz sine wave walk's into a bar, the bartender say's 'Hey, Why the long phase?'.

    [​IMG]

    Tough room. :p
     
  10. AsiJu

    AsiJu Ancient Guru

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    Haha, lols. Physics jokes :nerd:
     

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