Drum phase prevention and fixing.

The 3:1 rule of thumb works for sources and mics, assuming the far mic is on another source. If you have spaced overheads you want the left mic to be three times as far from the right sources as it is from the left sources. You want the right mic to be three times as far from the left sources as the left mic. Both perspectives are important. Obviously that will be impossible in some cases. Also, this assumes similar volume coming from the different sources which won't always be the case. And the type of mic does matter since you can use pickup pattern to minimize bleed at most frequencies. Cardioid mics have a linear null at 180° off axis, supercardioid mics have a conical one around 128° off axis and figure 8 mics have a planar one at 90° off axis.

Phase is frequency dependent. A 1ms time offset puts 1kHz approximately 360° out of phase, 500Hz about 180° out of phase and 250Hz about 90° out of phase. Any phase shift between two versions of a signal greater than 90° and less than 270° will result in decreased response at the given frequency. Less than 90° and greater than 270° causes an increase at the given frequency. If the one signal is lower by 6dB or more the effects of the phase cancellation on the other signal are negligible.
 
bouldersoundguy said:
The 3:1 rule of thumb works for sources and mics, assuming the far mic is on another source. If you have spaced overheads you want the left mic to be three times as far from the right sources as it is from the left sources. You want the right mic to be three times as far from the left sources as the left mic. ..
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Actually you might be better off staying even more literal with it being two mics, and two unique sources- where you don't want unwanted cross feed/bleed. :D
The problem with attempting to have '3:1 apply on overheads for example- would be all those other parts/places on the kit that are neither center to both, nor hard left or right on the tape measure!

Equal height- for Shure :)
 
the 3:1 rules applies to both multiple sources and multiple micing of the same source and is based on the same principles, and as steenamaroo pointed out it doesn't fix necessarily phasing issues, it just makes them less noticeable.
 
bouldersoundguy said:
There is comb filtering with or without time alignment. Whether it sounds better to align things depends largely on how the kit it miced. With spaced overheads there is no common reference point to align to so it's futile. With a coincident pair or single overhead there is a common reference point so it can be done. It's not about getting zero bleed, it's about correcting the worst of the phase misalignment which is going to be between each close mic and the overheads. It can significantly, even drastically, tighten up the sound. And if it doesn't it can be undone.
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Well, that's a given, isn't it? The only difference is that you get to adjust it before you press record to a pleasurable result and that is the art of miking a kit. If you're silly enough to make miking mistakes from the outset, time-aligning is only going to be clownfuckery and you'll only get mediocre results (if that). And I never said it was about getting zero bleed. My reference to bleed was to point out that if you move one thing to align to another you're going to get comb filtering BECAUSE of the bleed. Forget "comb filtering" or any other phase related jargon. You'll get an unwanted TONAL CHANGE. You know, jumping to conclusions about what you think I'm saying is hazardous. Believe me, I get this whole thing very well.

OK, so you move the snare in relation to your one over head and now what? The hi hat or kick might change in tone. You move the kick in relation to your one over head and now something else changes in tone. You move the tom in relation to your one overhead and now the other toms change in tone. It can go on and on. There's more to the kit than that one overhead, isn't there? Your idea about one reference point is flawed because the overall sound of the kit is the combined reciprocation of ALL the mikes so whether there's one overhead or twelve, the causality is still the same. I'm going to go out on a limb and say that this whole technique is just bad practice to remedy another bad practice and I'm sticking to it.

I'm sorry but I've never done this successfully and you'll always be chasing your tail. I just don't agree and that doesn't mean I lack any understanding about the state of the facts.

bouldersoundguy said:
Whether it should be done is a matter for people do decide for themselves. Your opinion says more about the limits of your knowledge than it does about drum mixing.
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I'll just let my work speak for itself, thanks. It's there in my sig so be my guest. Jumping to conclusions about the limits of my knowledge and getting personal is poor form. Poor form.

Cheers :)
 
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I just want to say something else.

The best drum recordings are pure and simple. Yes, we have phase and all the other technical aspects to worry about but at the end of the day, the simplest solution is often the best one.

In my opinion, when you start getting too deep into fixing problems and time stretching and adjusting phase, etc, you're on a dark road of pot luck that often ends in mediocrity or, worse, disaster. Again, in my opinion, it's better practice to make sure you're satisfied from the beginning so you don't have to do much besides maybe a few simple edits and a couple polarity reversals to get the sound going. With a good drummer and a decent selection of mikes, this shouldn't be too difficult.

It's all to easy as an engineer to feel responsible for every little flaw in the recording, sometimes including the performance. Problem is, most flaws are DUE to the performance and there's not a lot we can do to fix that which is why we come up with all these little studio tricks to make up for it. The part that you can control, however, is where you put the mikes and that is why it's an art form in our trade. It's the first line of defence against a bad recording.

Also, the fewer mikes the better in my opinion. It's well known that the more mikes you use the more tangled that can of worms will become. Ever try time aligning a kit miked with 17 mikes? Case in point...

I once attended a session of a colleague of mine, who is a very well known engineer with many hit albums here and a Grammy (yes, all the way from South Africa!). He is a very competent engineer and he runs one of the best studios in the city. Anyway, a couple of years ago he was recording a band who are friends of mine in a large studio in our national broadcaster's (SABC) studio complex. They've got a vintage Neve A3339, a whole slew of outboard and a mike locker filled with expensive and vintage mikes. So anyway, while we're shooting the shit we take walk out into the recording room - a big, expansive space perfect for drums - to take a look.

He had seventeen mikes in there.

I was at a loss for words. There were mikes in every corner of the room, in the store room, behind the drummer, in the booth and all over the place. I couldn't help but wonder how one handles the phase problems that might be associated with so many mikes and to tell you the truth, I thought he was punting a bit.

So, I go back into the control room to take a listen, and to be honest - and no disrespect to him because I respect him immensely - the drums didn't sound good at all. I thought, "Oh, it's just tracking so maybe they'll sound good when they're mixed."

They didn't.

Listening back to the final product I was convinced that despite all those mikes and big ideas, the Neve console, the outboard, the nice room, etc, Pro Tools (which I'm sure he used to the full) the drums still sounded bad to me. I couldn't help but think all those mikes came back to bite him.

What that day taught me was that too much thinking about a recording or a mix will kill it. And I know, it's easy to think too much. Simple recordings are the best and I strive for them. If I had a room and a collection of mikes that sounded good enough so that I could omit tom mikes, I would do it.

Don't be taken in by the techologies at your finger tips, either. They can be the devil. Another case in point.

One of my best friends and colleagues is engineer for one of our most (if not THE most) famous jazz trumpeters. He also happens to be a drummer (my engineer friend, that is). For the past few weeks (in between touring the world) he's been recording an album with said trumpeter and Larry Willis and most of it has been taken down live, which means multiple mikes and lots of bleed and phase considerations. Luckily he a highly competent engineer and thus he handled tracking very well. He's got the knowledge and lots of good mikes and mic preamps.

Anyway, they finished tracking a couple of weeks ago and my friend proceeded to mix. Nothing too hectic was done. I mean, he added some saturation, a little EQ here and there and some subtle reverbs and then handed in his first pass for evaluation.

Said trumpeter didn't like it. He told him to go back to his initial rough mix and go from there. Needless to say, my friend was very stressed and started doubting his talents. However, his talents had already served him because he recorded the material beautifully so he obliged and returned to the rough mixes and said trumpeter loved them.

So what was his mistake? He over thought the entire thing. He let his engineer mind get the best of him because the engineer mind is always looking for flaws, sometimes without actually LISTENING to the music. Sometimes we just have to let the flaws be for the sake of the music and let it speak for itself. Learning how to get out of the way and just let the music happen is a dark art that is slowly being lost.

That is all.

Cheers :)
 
Thanks guys.. haha I feel a bit like I just got dropped from the team, but hey Im still watching from the sidelines!:eatpopcorn:
Ive learnt a fair bit, its amazing how much mis-information there is out there on other instructional websites and youtube etc.
Thanks again
 
I'm not advocating alignment as the one right way to get good drum sound. It's just one tool in the box. Sometimes it makes things sound better, sometimes not. The only way to know is to try it.
 
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