Bass down and Trebble up with karaoke; hardware or software?

Discussion in 'Effects and the DSP' started by TiagoTiago, Jun 18, 2010.

  1. TiagoTiago

    TiagoTiago New Member

    Dec 17, 2004
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    I'm using the karaoke effect (with Max's fixes) to turn my omnidirectional stereo mic into a bidir mono mic, it works wonders, but i've noticed it looses quite a bit of the lower frequencies, and the higher frequencies sound slightly louder.

    I don't have enough knowledge in the areas involved to figure out if this is due to physics (the distance between each half of the stereo mic and the wavelengths involved) or if it is an artifact of the way the karaoke effect was coded; any idea?

    ps:I've confirmed it's not just subjective by tunning my TV in an empty channel (so it was all static, image and more importantly sound, kinda white noise) and watching the readout in a spectograph program, low frequencies get weaker and higher frequencies get stronger when i'm using the karaoke effect.
  2. Russ

    Russ Well-Known Member

    Jan 17, 2005
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    Well I am no expert, but:

    As for how the karaoke effect was coded, it is nothing more than the following:
    Out_Left = In_Left - (In_Right * Level)
    Out_Right = In_Right - (In_Left * Level)

    It is not just components that appear equally in each channel that are affected, anything that is in both channels will be attenuated, and the amount of attenuation will depend on how much is in each channel (and there is also possible phasing effects that can result).

    If you feed the plugin a mono signal, and pan it from one side to the other, watching the output on a peak plugin, you will see that the level goes down more and more as it is panned toward center.

    I do not know how your Mic's are setup, etc, but it would seem that both Mic's are picking up the low frequencies (maybe not equally, but enough to attenuate it somewhat), while the high frequencies are only being picked up by one of the Mic's (I am not sure why the high frequencies would be amplified)?

    Low frequencies have a longer wave length and as such can more easily refract around obstacles, etc then high frequencies, so maybe your setup is able to block high frequencies (from the front, etc) from reaching the second Mic, but not the low frequencies (and without enough of a delay to make much difference?)?

    You might try recording 2 mono tracks (one channel for each Mic) and compare them to see what frequency components got picked up by each Mic. You also might try doing the karaoke effect manually in your recording application (e.g. invert one of the tracks and then mix them together) and see if the result is any different.

    I do not know, just some thoughts...
    Last edited: Jun 19, 2010

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