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#1
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In phase?
Digging around the web for advice about recording electric guitars, I came across http://www.homerecordingconnection.c...ry&id=140#q131 The author suggests using two mics on a single cabinet (one further back than the other) and spending a lot of effort to tune the relative placements of the mics to get them "in phase." Does that make any sense? As I posted on that page, "Unless I'm missing something, it's only possible to get two mics to be "in phase" w.r.t. particular frequencies. Getting the mics to hear the signal in phase depends on the spacing between them a multiple of the wavelength of the sound. If they're off by half a wavelength, they'll be perfectly out-of-phase. Since different frequencies correspond to different wavelengths, it seems to me you can never get them in phase for all the notes a guitar will play." So, what *am* I missing? -- Dave Abrahams Boost Consulting www.boost-consulting.com |
#2
Posted to rec.audio.pro
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In phase?
David Abrahams wrote: The author suggests using two mics on a single cabinet (one further back than the other) and spending a lot of effort to tune the relative placements of the mics to get them "in phase." Does that make any sense? Technically, they'll only be in phase at one frequency (and its harmonics). What it really means is that you adjust the position of the mics so that it sounds better when you combine them than when you use just one or the other. This sometimes is a function of certain frequencies or reflections being out of phase and partially cancelling so they don't detract from the sound you're trying to achieve. The idea of a distant mic is to get the sound of the amplifier in the room. If that sounds good, you can use it in your mix. If it sounds bad, then it's better not to use it at all. You just have to listen. |
#3
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In phase?
"Mike Rivers" writes:
David Abrahams wrote: The author suggests using two mics on a single cabinet (one further back than the other) and spending a lot of effort to tune the relative placements of the mics to get them "in phase." Does that make any sense? Technically, they'll only be in phase at one frequency (and its harmonics). That's what I thought. What it really means is that you adjust the position of the mics so that it sounds better when you combine them than when you use just one or the other. This sometimes is a function of certain frequencies or reflections being out of phase and partially cancelling so they don't detract from the sound you're trying to achieve. To me they seemed to sound a lot better together no matter how far apart they were. The idea of a distant mic is to get the sound of the amplifier in the room. If that sounds good, you can use it in your mix. If it sounds bad, then it's better not to use it at all. You just have to listen. Well, that's not why the author of the article uses two mics, and the 2nd one isn't really distant (see the picture at http://www.homerecordingconnection.c...w_story&id=140). He's doing it to capture all the tonal qualities present in the guitar sound: There are two fields of thought on Mic usage when mic'ing guitar cabinets / amps. Using a Dynamic mic like a Sure SM-57 gives a very "gritty" sound, but often lacks top end sparkle that makes the sound cut through in a mix meaning you have to apply lots of EQ and / or reverb to get a usable sound. Using a Condenser mic will often give a more detailed sound with more "fizz", but often lacks lower-frequency response and as a result can sound too "thin" and "transparent". Interestingly, in my session it seemed to be the condenser that provided the missing lows. -- Dave Abrahams Boost Consulting www.boost-consulting.com |
#4
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In phase?
On Thu, 08 Jun 2006 06:33:40 -0400, David Abrahams
wrote: The author suggests using two mics on a single cabinet (one further back than the other) and spending a lot of effort to tune the relative placements of the mics to get them "in phase." Does that make any sense? As I posted on that page, "Unless I'm missing something, it's only possible to get two mics to be "in phase" w.r.t. particular frequencies. Getting the mics to hear the signal in phase depends on the spacing between them a multiple of the wavelength of the sound. If they're off by half a wavelength, they'll be perfectly out-of-phase. Since different frequencies correspond to different wavelengths, it seems to me you can never get them in phase for all the notes a guitar will play." So, what *am* I missing? You can use a close mic and a distant mic on a guitar cabinet. They will sound different. When you mix them together, particularly if you boost the gain of the distant mic to equalise its volume to the close mic, you may get phase effects at certain frequencies. You may like these effects, you may not. Play with the mic positioning, relative levels and stereo panning (but check mono compatibility, if relevant). |
#5
Posted to rec.audio.pro
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In phase?
David Abrahams wrote:
Digging around the web for advice about recording electric guitars, I came across http://www.homerecordingconnection.c...ry&id=140#q131 The author suggests using two mics on a single cabinet (one further back than the other) and spending a lot of effort to tune the relative placements of the mics to get them "in phase." Does that make any sense? As I posted on that page, "Unless I'm missing something, it's only possible to get two mics to be "in phase" w.r.t. particular frequencies. Getting the mics to hear the signal in phase depends on the spacing between them a multiple of the wavelength of the sound. If they're off by half a wavelength, they'll be perfectly out-of-phase. Since different frequencies correspond to different wavelengths, it seems to me you can never get them in phase for all the notes a guitar will play." So, what *am* I missing? The whole POINT of setting up two mikes on the cabinet is that you get comb filtering when the two are combined. By moving the mikes around, you change the relative phase betwene them and you therefore move around the poles and zeros of the comb filter and change the frequency response. So, there is some frequencies where they are in phase and some where they cancel out. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#6
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In phase?
.... and things get worse when you use distortion on your guitar....
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#7
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In phase?
David Abrahams wrote: To me they seemed to sound a lot better together no matter how far apart they were. That's not unreasonable. The distant mic (if the room is live at all) will have so much stuff in it that's going to be partially out of phase with the close mic, and very little that's phase-coherent (or phase-opposite) so you'll only get a little cancellation, and a lot of room ambience, which in general makes a recorded instrument amplifier sound better. Well, that's not why the author of the article uses two mics, and the 2nd one isn't really distant (see the picture at http://www.homerecordingconnection.c...w_story&id=140). He's doing it to capture all the tonal qualities present in the guitar sound: That's another approach. Same with acoustic guitars, violins, irish bagpipes, you name it. You get different sounds coming off the instrument in different directions (even roughly the same direction but coming from different areas of the speaker cone as this article suggests from the photo) and it's OK to try to combine those for a pleasing effect. The idea of using a distant mic is that when you get far enough away, all of those sounds are going to blend in the room and that's what the distant mic will hear as the "guitar" sound. It's kind of like what you hear when you're a sensible distance from the amplifier. But if you want to close-mic everything and you want to get those sounds that miss one mic, you have to up another one. And since there will be about the same amount of direct, and hence phase-coherent energy in each of the two mics, you need to play around with their distance to be sure you don't cancel anything important. I'm not sure I get the "gritty" part, but perhaps that's what's emphasized when you put an SM-58 fairly close to the center of the cone. Interestingly, in my session it seemed to be the condenser that provided the missing lows. I'm not surprised. Putting two different kinds of mic at roughly the same position is kind of a gimmick. It might be effective, but chances are you can find one mic that will capture the full sound nicely, and adding the second mic gives you something that you don't hear live. But if that's what sounds good, no reason not to do it. I've never worked with a guitar player who is fussy enough not to like the sound of a reasonably good mic a couple of feet away from his amplifier - as long as his amplifier sounds good. |
#8
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In phase?
David Abrahams wrote in
: Digging around the web for advice about recording electric guitars, I came across http://www.homerecordingconnection.com/news.php? action=view_s tory&id=140#q131 The author suggests using two mics on a single cabinet (one further back than the other) and spending a lot of effort to tune the relative placements of the mics to get them "in phase." Does that make any sense? As I posted on that page, "Unless I'm missing something, it's only possible to get two mics to be "in phase" w.r.t. particular frequencies. Getting the mics to hear the signal in phase depends on the spacing between them a multiple of the wavelength of the sound. If they're off by half a wavelength, they'll be perfectly out-of-phase. Since different frequencies correspond to different wavelengths, it seems to me you can never get them in phase for all the notes a guitar will play." So, what *am* I missing? easy money and great sex, like everybody else, but consider that a 1KHz signal has a 1.05 foot wavelength. so that spacing is critical with 6 inches putting you out of phase. at 100 Hz moving the mic that 6 inches will shift the phase about 20 degrees, which has minimal impact. Since music is distinct frequencies, you can find phase relationships that seem to work well for getting most of the notes in phase, and the out of phase frequencies occur "between the notes". -- Bob Quintal PA is y I've altered my email address. -- Posted via a free Usenet account from http://www.teranews.com |
#9
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In phase?
In article ,
"Federico" wrote: ... and things get worse when you use distortion on your guitar.... or better, depending on your point of view. Edwin |
#10
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In phase?
"Mike Rivers" writes:
I've never worked with a guitar player who is fussy enough not to like the sound of a reasonably good mic a couple of feet away from his amplifier - as long as his amplifier sounds good. That's where my condenser is sitting, but the sm58 near the speaker cone is definitely adding some missing brightness. And yes, my AC30 sounds *really* good -- Dave Abrahams Boost Consulting www.boost-consulting.com |
#11
Posted to rec.audio.pro
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In phase?
David Abrahams wrote:
"Mike Rivers" writes: I've never worked with a guitar player who is fussy enough not to like the sound of a reasonably good mic a couple of feet away from his amplifier - as long as his amplifier sounds good. That's where my condenser is sitting, but the sm58 near the speaker cone is definitely adding some missing brightness. And yes, my AC30 sounds *really* good An SM-58 is adding brightness? There's something goofy going on there (possibly that it's actually removing something else). If you want brighter, move to the center of the cone. If you want less bright, move to the edge. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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