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Author Topic: OH vs snare/kick phase  (Read 10767 times)

luis Markson

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absolute phase
« Reply #15 on: July 12, 2011, 06:50:11 am »

As always all of the other replies on here are great, and I'm late to the party, but here's a method of dealig with your phase issues. Start with one mic on the kick drum with no eq. have the drummer hit it a few times while you punch the phase button in and out. The kick will be fuller sounding one way or the other, and providing your amp, speakers, cables etc are all wired the same way (either pin 2 or pin 3 hot depending on which country you are in, or where your gear is from). This is called absolute phase.

Could you expand on "absolute phase"?

I was under the impression that phase was an inherent property of interaction?

How can flipping the polarity of a single source impact on itself?
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Cass Anawaty

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Re: OH vs snare/kick phase
« Reply #16 on: July 12, 2011, 10:38:25 am »

Polarity.
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Cass Anawaty, Mastering Engineer
www.sunbreakmusic.com

JohnTravis

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Re: OH vs snare/kick phase
« Reply #17 on: July 12, 2011, 07:26:59 pm »

"I was under the impression that phase was an inherent property of interaction?"

You are correct in that phase is always relative, but if a sound source is recorded with a mic that has one polarity and played back using an amplification system with the opposite polarity that recorded sound will not be in absolute phase with itself and, depending on the amount of low frequencies in the original sound source, reversing the phase on it may give you a fuller sound. With this stuff there is usually not a right or wrong, but there sometimes a "that sounds great" and a "damn that sounds even better".
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MagnetoSound

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Re: OH vs snare/kick phase
« Reply #18 on: July 14, 2011, 04:36:56 am »

Polarity.


John, Cass is right, this is called Absolute Polarity.

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Dan Sansom
Magneto Sound
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luis Markson

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Re: OH vs snare/kick phase
« Reply #19 on: July 14, 2011, 07:15:04 am »

This wouldn't apply to live sound would it? Assuming that system optimisation has been completed and the fact that the source and reproduction system is one and the same...
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JohnTravis

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Re: OH vs snare/kick phase
« Reply #20 on: July 20, 2011, 02:22:46 am »

Actually Magnetosound  and Cass it is called both absolute phase and absolute polarity, but absolute phase is actually the way most big studio techs refer to it.

http://en.wikipedia.org/wiki/Absolute_phase

Absolute phase refers to the phase of a waveform relative to some standard (strictly speaking, phase is always relative). To the extent that this standard is accepted by all parties, one can speak of an absolute phase in a particular field of application.

In the realm of high fidelity reproduction of music, absolute phase refers the phase of the reproduced sound waves relative to the original sound waves, or to the relative phase of the various channels of stereo or multi-channel reproduction. In most cases, it is actually a question of the polarity of the channels, i.e., an equal phase shift of 180 at all frequencies. Some audiophiles claim[1] that reversing the polarities of all the channels simultaneously makes a perceptible difference in the sound quality, even though the relative phases of all the channels are preserved.


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Fletcher

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Re: OH vs snare/kick phase
« Reply #21 on: July 21, 2011, 07:47:13 pm »

In the realm of high fidelity reproduction of music, absolute phase refers the phase of the reproduced sound waves relative to the original sound waves, or to the relative phase of the various channels of stereo or multi-channel reproduction. In most cases, it is actually a question of the polarity of the channels, i.e., an equal phase shift of 180 at all frequencies. Some audiophiles claim[1] that reversing the polarities of all the channels simultaneously makes a perceptible difference in the sound quality, even though the relative phases of all the channels are preserved.

...and those "audiophiles" would be correct.  Much like the Easter Bunny there is no such thing as a perfectly symmetrical amplifier so the bottom of the wave form in ANY[/i] amplifier will be different from the top of the wave form which [among other things] is a form of "phase distortion" [never mind the travel direction of the reproduction driver which is another kettle of fish in terms of human hearing / perception].

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CN Fletcher

mwagener wrote on Sat, 11 September 2004 14:33
We are selling emotions, there are no emotions in a grid


"Recording engineers are an arrogant bunch
If you've spent most of your life with a few thousand dollars worth of musicians in the studio, making a decision every second and a half... and you and  they are going to have to live with it for the rest of your lives, you'll get pretty arrogant too.  It takes a certain amount of balls to do that... something around three"
Malcolm Chisholm

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Re: OH vs snare/kick phase
« Reply #22 on: July 31, 2011, 09:58:32 pm »

It's not only the amp that isn't symmetrical - the waveform itself (like a kick) is highly asymmetrical.  Absolute Phase can have an effect on such sources.  Other words, if the kick is asymmetrical (as it will be), then one polarity orientation will emphasize the compression (positive pressure) and the opposite polarity will emphasize the rarefaction (negative pressure) of the transient through the reproduction system.  I personally can't hear a big difference, but there is a difference with regards to absolute polarity and reproducing the asymmetrical waveforms that are present everywhere in music...

This can go as far as debating if the "Drummer's Perspective" is correct (rarefaction as the beater pushes the head away from the drummer's ears), or if the front-of-kit/audience perspective is correct (compression/positive pressure as the beater pushes the head towards the audience).

Relative polarity/phase is a much larger component of getting everything jiving.  Absolute Polarity is fairly miniscule by comparison IMNSHO.

 8)
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Randy Visentine
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fossiltooth

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Re: OH vs snare/kick phase
« Reply #23 on: September 08, 2011, 01:58:20 pm »

I'd agree with that. Absolute polarity is a factor, but maybe not an essential one.

Relative polarity is crucial, but will never be "perfect". Perfect phase would be one microphone split into two pairs with nothing changed at all: an exact double. What's essential is that an engineer learn to listen for subtle comb-filtering effects and move mics, or listen for dramatic cancellation by toggling polarity switches.

There will always be some phase discrepancy when recording drums with more than one mic. That's the nature of the beast. We just have to make sure those discrepancies don't suck royally.

As an aside, sometimes drums sound great with just 1, 2 or 4 mics. In those cases making relative phase decisions can be more straightforward and more powerful.
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