whjr15
New member
Just a quick question since we're on the topic... What exactly is "phasing" when talking about mics?? I know what "speaker phasing" is, but have never heard the mic phasing issue defined.
thanks
thanks
Farview
Well-known member
When you have two mics picking up the same source at two different times (one is farther away from the source than the other), when the two signal are combined you end up with comb filtering or phasing.
whjr15
New member
oooh ok... so that delay from one mic to the other is the "phasing" then??
haha I knew that, just didnt know it was called phasing
haha I knew that, just didnt know it was called phasing
C
cpl_crud
New member
The "phase" of a wave is basically where it's "up to" on the sine curve- think about the "phase" of the moon- it can either be full, new, waxing or waning, but all of these representations are part of a full spectrum from new to full and back again.
Wikipedia has a whole swag of info on this topic:
http://en.wikipedia.org/wiki/Category:Wave_mechanics
in particular
http://en.wikipedia.org/wiki/Interference
and
http://en.wikipedia.org/wiki/Phase_(waves)
Since a wave can be expressed as Asin(wt + phi) (where A is the maximum amplitude, w is the angular frequency and phi is the phase shift) we can see that a shift in phase is the same as shifting the time.
Since a sound wave takes a finite time to reach each microphone, mics at different distances from the source will receive the waves at different "phases".
Now we have to look at the principal of superposition, which says that two waves, measured at the same point or combined, will have a total amplitude equal to that of the combined amplitude of the two component waves- ie you can simply add the two waves together. So, if two waves of the same frequency, but of differnent phase, are combined, there will be a drop in the total amplitude.
This is what happenes in your mixer when you combine the two signals.
Another thing to remeber is that the phase also depends on the frequency, and hence the wavelength (wavelength is related to frequency which is related to angular frequency). So, whilst some frequencies may be totally out of phase at a certain seperation, others may be totally in phase, and the majority will be somewhere in between. This is the basis of comb filtering- at every distance there will be a frequency that will be totally in phase and one that will be totally out of phase (as well as their harmonics). If you were to plot the intensity of a specific frequency over a soundfeild (now thinking of two sources as opposed to two microphones) you would get a series of bands. If you go along a single plane, these look like the fingers of a comb.
OK, i'm rushing through this at a rate far too fast for everyone, and I'm too tired to slow down.
In answer to your question, the "phase" of a wave is where it is "up to" along a sine curve, as I said above.
Wikipedia has a whole swag of info on this topic:
http://en.wikipedia.org/wiki/Category:Wave_mechanics
in particular
http://en.wikipedia.org/wiki/Interference
and
http://en.wikipedia.org/wiki/Phase_(waves)
Since a wave can be expressed as Asin(wt + phi) (where A is the maximum amplitude, w is the angular frequency and phi is the phase shift) we can see that a shift in phase is the same as shifting the time.
Since a sound wave takes a finite time to reach each microphone, mics at different distances from the source will receive the waves at different "phases".
Now we have to look at the principal of superposition, which says that two waves, measured at the same point or combined, will have a total amplitude equal to that of the combined amplitude of the two component waves- ie you can simply add the two waves together. So, if two waves of the same frequency, but of differnent phase, are combined, there will be a drop in the total amplitude.
This is what happenes in your mixer when you combine the two signals.
Another thing to remeber is that the phase also depends on the frequency, and hence the wavelength (wavelength is related to frequency which is related to angular frequency). So, whilst some frequencies may be totally out of phase at a certain seperation, others may be totally in phase, and the majority will be somewhere in between. This is the basis of comb filtering- at every distance there will be a frequency that will be totally in phase and one that will be totally out of phase (as well as their harmonics). If you were to plot the intensity of a specific frequency over a soundfeild (now thinking of two sources as opposed to two microphones) you would get a series of bands. If you go along a single plane, these look like the fingers of a comb.
OK, i'm rushing through this at a rate far too fast for everyone, and I'm too tired to slow down.
In answer to your question, the "phase" of a wave is where it is "up to" along a sine curve, as I said above.
M
mixsit
Well-known member
There's another thing you can get working to help with the hollow combing sound. As you pull the second mic back farther to get more of the random room reflections, that tends to fill in or average out the holes in the response. It might not be a direct enough sound for the style you're going for, but some where in between it might work out.ericlingus said:
Wayne
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mixsit
Well-known member
Yeah, always different but not necessarily better.metalhead28 said:
Seems like in many cases on things that don't ride real high on fidelity, snares, cabs, mic and DI bass for example, that the strongest, most well aligned version isn't the most fitting. Sometimes it's just sounds louder and piled up. Slightly off kilter might have a more interesting tone anywho.
E
ericlingus
New member
I don't understand what you said really. So you're saying have one mic up front and the other farther back? That's what i'm doing. Does anyone else have advice on getting an atmospheric black metal guitar tone? I'd really appreciate it. Should I just have both mics close miked and just add a lot of reverb? Or maybe put them both back about a foot or so?
E
ericlingus
New member
I don't understand what you said really. So you're saying have one mic up front and the other farther back? That's what i'm doing. Does anyone else have advice on getting an atmospheric black metal guitar tone? I'd really appreciate it. Should I just have both mics close miked and just add a lot of reverb? Or maybe put them both back about a foot or so?
metalhead28
Hates Raymond
ericlingus said:
"Black Metal" means so many things to so many people. There is no way to tell....
If I was doing it it would be nothing but a close mic and maybe some reverb.
Adding in the off axis mic up close will add alot of bottom end and sort of smooth out the sound of the on axis mic. I doubt that you want that for what you're after, but I could be wrong. I wouldn't want alot of low end in the guitar sound for "atmospheric black metal".
Do you have an example of the sort of guitar sound you're after? Maybe a link to a clip?
E
ericlingus
New member
well what bands have you listened to that are atmospheric black metal? I like the guitar tones of burzum,summoning,mithotyn, and emperor. Those are some that come to mind. Here is a link to some sample summoning songs. Listen to track number two on the stronghold album.
http://www.anus.com/metal/summoning.html#oath_bound
http://www.anus.com/metal/summoning.html#oath_bound
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ericlingus
New member
metalhead do you have AIM?
Farview
Well-known member
That really does sound like a close mic and a bunch of reverb. You won't get that sound out of a distant mic unless your room sounds like that. You would also have to stereo mic the room.
metalhead28
Hates Raymond
ericlingus said:
Nope.
And I agree with what Farview just said.
E
ericlingus
New member
yeah I was thinking the same thing actually. Thanks guys 
How many tracks do you think that riff is? Anything else you can comment on it?
How many tracks do you think that riff is? Anything else you can comment on it?
Farview
Well-known member
It's hard to tell with those really bad mp3s. It could be a pod and a reverb.
E
ericlingus
New member
I know they used an amp for that album. Well it depends what one you listened to. Did you listen to the oath bound album sample or the Stronghold album sample? The stronghold one is what im going for. Although I like the other one too, which by the way was recorded with an amp modeller software.
M
mixsit
Well-known member
The point of this (if the sound of it works for you), is if you're having phase issues, try pulling the far mic back more. The room reflections can help smooth over the peaks and holes in the sound. This would be where there's a mix of direct sound from the cab and room sound.ericlingus said:
It's just another tool; Time alignment or mic position changes the phase tone effects, relative volume of the two mics and/or added room reflections to moderate the depth of the phase effects.
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ericlingus
New member
okay thanks for the info
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Chang
New member
how can you tell when phasing is happenning?
Folks: i'm reading this thread with interest, as I have recently started recording acoustic instrument-based music. Perhaps I've been lucky (beginner's luck) in not having encountered any sound problems, but how would I even know whether I was having a phase problem? Is there a distinctive sound that results as a consequence? I'd appreciate if someone could advise/describe what "symptoms" might suggest phase problems.
Thank you so much.
Folks: i'm reading this thread with interest, as I have recently started recording acoustic instrument-based music. Perhaps I've been lucky (beginner's luck) in not having encountered any sound problems, but how would I even know whether I was having a phase problem? Is there a distinctive sound that results as a consequence? I'd appreciate if someone could advise/describe what "symptoms" might suggest phase problems.
Thank you so much.
tarnationsauce2
Welcome to the jungle.
Generally:Chang said:
Loss of punch, or bass,
If you solo one track, it's louder than the two tracks combined.
If you pan each hard opposite, the stereo image will be strnage and incoherant, not wide and full sounding. Also the loss of bass.
