Glen Johns/Recorderman - Is everything "really" in phase?

Why are the mic's used within the "Glyn Johns" or "Recorderman" methods suppose to be equal distance from the snare "IN-PARTICULAR""? Even if mic's are equal distance from one point, won't the rest of the drum pieces still be out of phase? For example: it's easy to get the snare drum in the center of the phase relation - but pieces like the ride or hi-hat will always be off center because they're at different & unequal distances. I understand why you would want the snare drum to be in the center of the phase relation, it's the other pieces of the drum set that will be out of phase that I'm not clear about. Thanks...

That would be true of any setup to a greater or lesser extent, even XY.

The reason the snare is given special consideration is that is by far the loudest component of the kit and therefore the most susceptible to obvious phase problems. Phase works on a continuum of affectation, so it is normal for everything to be slightly out of phase. In fact, it's rare (practically impossible) that everything is totally in phase. The snare needs to be more in phase that the rest because the effect would be more obvious.

mediocrefunkybeat said:

That would be true of any setup to a greater or lesser extent, even XY.

The reason the snare is given special consideration is that is by far the loudest component of the kit and therefore the most susceptible to obvious phase problems. Phase works on a continuum of affectation, so it is normal for everything to be slightly out of phase. In fact, it's rare (practically impossible) that everything is totally in phase. The snare needs to be more in phase that the rest because the effect would be more obvious.

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Wow... You know, I was thinking that I was going to get a bunch of unclear explanations. You seemed to have had a logical answer right away. What you said makes sense. So I guess there's no way of having everything perfectly in phase anyway. This sets me free! It of-course also makes sense that the snare drum would be the most susceptible to phase. Thanks allot! This really helped me out. Much appreciated!

it's the phase "issues" that give the stereo picture. meaning, the time it takes a sound to arrive at mic 1 is different at mic 2. it's how you will perceive a sound coming from the far right (think floor tom) and how you will hear something coming from the left (hi hats). if a tom sound gets to the left mic first than you will hear it coming from that side. generally you want the snare to sit in the center of the stereo field so you want it equidistant from each mic so that the sound arrives as close to simultaneously as possible.

Retrovertigo said:

it's the phase "issues" that give the stereo picture. meaning, the time it takes a sound to arrive at mic 1 is different at mic 2. it's how you will perceive a sound coming from the far right (think floor tom) and how you will hear something coming from the left (hi hats). if a tom sound gets to the left mic first than you will hear it coming from that side. generally you want the snare to sit in the center of the stereo field so you want it equidistant from each mic so that the sound arrives as close to simultaneously as possible.

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Technically, you're sort of right.

There are fundamentally two methods of stereo perception. Volume perception and phase perception. Your ears use both to work out the stereo image. It makes sense that your right ear would hear something more obviously loudly on the right side and the timing would be slightly different, but the whole issue is then complicated by the reflections in the room, which is where volume perception really comes into its own by being able to locate the first instance of sound (unless you get into distance from source and the inverse square rule).

Microphone setups work mostly in one way or the other. Most setups try to use volume difference and avoid obvious phase difference by being placed directionally toward certain sources or a certain side of the stereo field (XY Coincident, AB Spaced) but a Mid-Side setup actually uses the phase difference to calculate the stereo image rather than volume. M-S is a little more complex to understand as a result, but is really great for mono compatibility.

There's a lot more on this out there if you go digging. But the majority of microphone techniques you'll probably see day to day use volume differentiation rather than phase differentiation.

i'll agree with that. good call.

my original intention was to address this in the OP but i totally forgot about it...

"pieces like the ride or hi-hat will always be off center because they're at different & unequal distances"

that's the idea of a stereo mic setup... to give some idea of left, right and center.

"Phase" differences will create two effects. Comb filtering, which will affect the timbre or tone of a source. And blurring of time. With a really fast impulse like a snare rimshot, the effects are magnified. Also, since the snare drives the music, it gets priority in keeping the timing straight. At least that was the justification I heard when I first came across this. And I've been pretty careful with it and happy with the results ever since. Often in SR I'll only use one overhead to speed set up and keep this out of the equation.

I didn't mean to abandon this thread for a while. Everybody had some helpful thoughts - and I really appreciate it. Here's another question to contribute to the subject of these microphone techniques. "Does it matter whether both microphones are the same volume"?

MickeyPiedmont said:

I didn't mean to abandon this thread for a while. Everybody had some helpful thoughts - and I really appreciate it. Here's another question to contribute to the subject of these microphone techniques. "Does it matter whether both microphones are the same volume"?

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Not with regard to phase. The technical term is 'Gain', not volume.

The gain of the microphone affects the amplitude, not the wavelength. The wavelength affects the phase - but a difference in amplitude should not. Read up on basic wave theory and this will make a lot more sense. Fundamentally, two matched mics recording in the correct position at different amplitudes should not introduce extra phase.

There could, however, be difficulties in post-production if this is not compensated for as a result of how the human ear works. I'm not going to get into complex psychoacoustic theory here, but it's always easier if you can match the input gain to begin with, it makes mixing much easier for starters.