Jack Simpson
New member
I read something about X-Y placement of mics, what does this mean?
X-Y setup
- Thread starter Jack Simpson
- Start date
MrZekeMan
New member
Here is an old post by Bruce Bartlett:
You asked for more detail about XY and MS. XY uses two directional mics mounted with diaphragms aligned vertically and angled apart. "Directional" means cardioid, supercardioid, hypercardioid, or bidirectional. The angle between mics can be anywhere between 90 and 180 degrees. The wider the angle, the greater the stereo spread or width between far-left and far-right images.
If you mount two cardioids in XY, with a 90 degree angle between them (+/- 45 deg. right and left of center), the stereo spread is narrow. It does not extend all the way between the left and right speakers, unless the sound source surrounds the mic pair in a semicircle.
Sound from straight ahead approaches the mics at 45 degrees off axis, so there is little off-axis coloration of the tone quality.
If you angle the mics farther apart, say 135 degrees, the stereo spread is wider and more accurate. But sounds from straight ahead are hitting the mics 67 degrees off axis, so you probably will get some off-axis coloration -- usually some high frequency rolloff. You can partly compensate for this with a HF boost in the EQ (but only for stuff in the center).
MS or mid-side uses a forward-aiming mic of any pattern (cardioid being most typical) and a side-aiming mic that is bidirectional. When you add these two patterns, you get the left-channel signal. When you difference them (add them in opposite polarity), you get the right-channel signal.
By varying the mid-to-side ratio, you vary the stereo spread or stage width. If M and S are equal, you get something like two supercardioids aiming about 45 deg. left and right. (I have not worked out the exact angle here).
You can vary the M/S ratio during recording or playback, which is a great way to adjust the stereo spread after recording, without having to physically move the mics.
Re drum miking, I don't see a problem with your drum miking except that I wouldn't aim the cymbal mics at the ceiling, unless it sounded cool!
As for a guitarist/singer, I've had luck with miking the singer up close with a cardioid mic with a foam pop filter. The mic aims up at the singer so that its "dead" rear null aims toward the guitar. The guitar is miked with a mini omni condenser mic taped to the guitar body, halfway between the sound hole and bridge, about 1/2 inch from the low-E string. It picks up very little voice. You could use a quality pickup instead, but nothing sounds as real as a mic.
You could use two figure-8 (bidirectional) mics, with the side null of the vocal mic aiming at the guitar, and the side null of the guitar mic aiming at the voice. This is the Blumlein method: two coincident bidirectional mics angled 90 degrees apart.
Of course, you could record the guitar first, then overdub the vocal -- no phase cancellations that way! But some musicians can't perform like that. Anyone else have some ideas on miking a singer/guitarist? We need a new thread.
About hearing phase cancellations from stereo speakers... at each ear, the right speaker has phase cancellations with the left speaker, because of the different sound-travel paths. This creates a slight dip in the response around 2 or 3 kHz, but it's hard to hear.
You asked for more detail about XY and MS. XY uses two directional mics mounted with diaphragms aligned vertically and angled apart. "Directional" means cardioid, supercardioid, hypercardioid, or bidirectional. The angle between mics can be anywhere between 90 and 180 degrees. The wider the angle, the greater the stereo spread or width between far-left and far-right images.
If you mount two cardioids in XY, with a 90 degree angle between them (+/- 45 deg. right and left of center), the stereo spread is narrow. It does not extend all the way between the left and right speakers, unless the sound source surrounds the mic pair in a semicircle.
Sound from straight ahead approaches the mics at 45 degrees off axis, so there is little off-axis coloration of the tone quality.
If you angle the mics farther apart, say 135 degrees, the stereo spread is wider and more accurate. But sounds from straight ahead are hitting the mics 67 degrees off axis, so you probably will get some off-axis coloration -- usually some high frequency rolloff. You can partly compensate for this with a HF boost in the EQ (but only for stuff in the center).
MS or mid-side uses a forward-aiming mic of any pattern (cardioid being most typical) and a side-aiming mic that is bidirectional. When you add these two patterns, you get the left-channel signal. When you difference them (add them in opposite polarity), you get the right-channel signal.
By varying the mid-to-side ratio, you vary the stereo spread or stage width. If M and S are equal, you get something like two supercardioids aiming about 45 deg. left and right. (I have not worked out the exact angle here).
You can vary the M/S ratio during recording or playback, which is a great way to adjust the stereo spread after recording, without having to physically move the mics.
Re drum miking, I don't see a problem with your drum miking except that I wouldn't aim the cymbal mics at the ceiling, unless it sounded cool!
As for a guitarist/singer, I've had luck with miking the singer up close with a cardioid mic with a foam pop filter. The mic aims up at the singer so that its "dead" rear null aims toward the guitar. The guitar is miked with a mini omni condenser mic taped to the guitar body, halfway between the sound hole and bridge, about 1/2 inch from the low-E string. It picks up very little voice. You could use a quality pickup instead, but nothing sounds as real as a mic.
You could use two figure-8 (bidirectional) mics, with the side null of the vocal mic aiming at the guitar, and the side null of the guitar mic aiming at the voice. This is the Blumlein method: two coincident bidirectional mics angled 90 degrees apart.
Of course, you could record the guitar first, then overdub the vocal -- no phase cancellations that way! But some musicians can't perform like that. Anyone else have some ideas on miking a singer/guitarist? We need a new thread.
About hearing phase cancellations from stereo speakers... at each ear, the right speaker has phase cancellations with the left speaker, because of the different sound-travel paths. This creates a slight dip in the response around 2 or 3 kHz, but it's hard to hear.