Phase problems using 2 vocal mics

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Fractal vision

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I like to use a dynamic mic run through a distorted/reverb effect real close to my mouth, right against it. I then put up a large diaphram condenser about 8-12" away and record them to two separate tracks in pro tools. I then blend as disired later.
My issue is i get some phaseing problems and lose focus.
I've been looking at the UAD phase align plug but not sure if that will help me.
Anyone know if that or anything else would work to produce a more focused sound?
Thanks a bunch.
 
You can simply flip the polarity on one of the tracks....Or, line them up visually in your DAW.
 
Yeah, they are not 180 out of phase and i've tried to slide region to line up but they are not consistant.
So it gets confusing how much to move it. And even when i get tracks to line up roughly i still have a talking into a bucket sound.
 
If you have two mics 1 foot different in distance to the source and you are mixing them together, your are always going to have phase problems. Sound travels, I think, at about 900 ft per sec. To make the math easy, let's call it 1000 ft per sec. So your mic 1 ft out is going to receive the same sound the close mic receives, but 1ms later. Suppose you are singing a note at 500 hz (just above A440). Think of a sine wave with 500 cycles per second. That's two milliseconds per cycle. So if the first mic receives a +1 peak in this wave form, the other mic 1 milliseconds later is going to receive a -1 peak. These two will exactly cancel each other out, so that when you sing this note, the fundamental will drop out, along with all the even overtones to some degree (I think I'm thinking about that right). Conversely, when you sing a note one octave higher, at 1000hz, with a 1ms peak to peak, you will double the fundamental, and similarly boost the harmonics that dropped out at 500. At multiples of these frequencies the same thing will happen. It will alternate bewteen doubling when the +1 peaks line up at 1ms apart line up and cancelling out altogether when a +1 peak lines up with a -1 peak. This is called a comb filter because if you graph its frequency response on a logarithmic scale it looks like a comb where the teeth are the frequencies that are doubled in strength and the valleys between the teeth are the frequencies that cancel out.

Bottom line: 2 mics a foot apart in distance from the same source is generally a baaaaad idea unless your looking for that wierd comb filtered sound as an effect.

There's some rule of thumb for mic placement about 3 times something or other that prevents this, but I can't remember how it goes...

J
 
jjjtttggg said:
There's some rule of thumb for mic placement about 3 times something or other that prevents this, but I can't remember how it goes...
Click to expand...
That's the 3 to 1 rule, which doesn't apply here. It's for micing more than one source.
 
Scratch the reference to the 3:1 rule. I looked it up. A couple of sources misstate it as being like what you are talking about, but it really is something different, althought the same phenomonon drives it. The 3:1 rule says that when micing 2 DIFFERENT sources, the mics should be at least 3 times as far from each other as either of them is from the source they are micing. The point here is that two mics picking up the same source will ALWAYS create a comb filter. The presumption in the 3:1 rule is that the two sources are of something like the same level, so that the sensitivity of the two mics is similar and by the time the sound reaches the second mic in either case it will be attenuated enough by the distance that the comb filtering effect will not be noticable.

In your setup, you are meeting the three to one rule... if the second mic were there to pic up somebody singing right into it as loud as you are singing into your mic. In that case you'd have no problems other than possibly the other singer's bad breath. :) By mixing the second mic in at a meaningful level for what it picks up of you, though, you are bringing the comb filter back into play, thus defeating the 3:1 rule.

The 3:1 rule would say with the first mic at 1x the second mic would be at 4x or greater. The sound level at the second mic, then would be 16 times lower than at the first or lower, so that the cancellation and boost effects would be minimal.

I guess by implication, as long as you keep the level of the second mic way low you should be ok in terms of phasing???? I don't know. What is it you are looking for with the second mic anyway?

J
 
While jitg is absolutely right that the distance will cause a phase mis-alignment because of the delay caused by the slow speed of sound, sliding one of the tracks back and forth in the editor timeline until they line up would fix that if it were the only problem. But since the OP says that's not enough to fix it, there's probably more than just that going on. My guess is a difference in first reflection timing coming off of either the floor, ceiling or side wall(s).

The only real way to fix that would be to eliminate those first reflections with some quality absorbers/diffusers/deflectors at the reflection points, or to move the location of the vocal recording someplace where first reflections are not a problem.

Or, even easier, eliminate the distance difference between the mics. You can still get a good dual-mic blend without having to have them that far apart. Keep the dynamic under your nose, and hang the condenser off-axis by just a few inches *vertically or horizontally* instead of a foot back on the Z axis, an you might find you can get a similar sound without the reflection phasing.

G.
 
Why don't we just change the choreography, so the dwarfs don't trod upon it?

Wouldn't the simplist solution be to put both mics the same distance from the singer?
 
If you want to use what you have and not re-record with a different mic technique...

...you can take those two mic tracks and pan them appart a little rather than both in the same spot. The comb filtering will dissipate. The further appart you pan them the less there will be...but of course, it will also change the total effect of the two mics working *together*...so you have to just spin the knobs and see what sounds good to you.
 
I can kinda understand the desire to swallow the dynamic for the proximity effect and at the same time not swallow the condenser for plosive, humidity and physical impossibility reasons. But that can be accomplished by putting the condenser off-axis and not just distant.

G.
 
Wow. Thanks for all the replies. I guess i like to sing into the dynamic, with the mic in the stand, holding it like you would if i was singing on stage or with a band. The condenser is to get a fuller quality sound since the dynamic is distorted. My voice is very plain sounding with no character to it so the distortion adds some harmonic content. I've tried the capsules at the same spot before but dont get what i'm looking for outta the dynamic unless i'm right on top of it and need to be further back from the condenser to get what i want outta that.
I would just get a real singer but am a total hermit recluse and have no one else around. I write,play and record everything myself. I think the music sounds great but then when it comes time for vocals, i fall short. The two mic deal is just a technique i use to make up for my vocal shortcomings.
Would the UAD phase align plug do anything for this?
Thanks again for all the time spent answering my question everyone. :)
 
Fractal vision said:
i like to sing into the dynamic, with the mic in the stand, holding it
Click to expand...

I don't know if you already mentioned that, but I didn't notice. That could be the reason your out-of-phase-ness is not consistent. If you're moving the stand of one of the mics around, that could cause problems when you're double micing.
 
Haha! No i'm not jumping around like mick jagger. I keep it consistant. That was a funny vision tho. :)
 
Fractal vision said:
Haha! No i'm not jumping around like mick jagger. I keep it consistant. That was a funny vision tho. :)
Click to expand...

Hehe...That's not what I meant. We tend to at least slightly rock a mic stand a little back and forth when we hold it. Just make sure you're not doing that. :)
 
Maybe i should come up with a new approach. Using just the condenser.
I have an allen and heath system 8 24/16 analog mixer. I bought it a year ago to run tracks through from pro tools and to use it as an analog summing mixer. But dont know much about routing signals around it.
If i sang into the condenser, into the UA 6176, into the mixer, split the signal somehow and add effects to one and the other clean then outta mixer onto two separate tracks in pro tools?
How can i split the signal? Then how two isolated outputs?
Pan one track hard left the other right and use mixer main LR outputs?
 
Fractal vision said:
Maybe i should come up with a new approach. Using just the condenser.
Click to expand...

Have you ever tried using some chorus on a single mic track? Using subtle chorus can give a "big" sound without the phasing headaches of a second mic on the same source.

How about double-tracking the vocal (recording the part 2x)? You can either use both tracks at the same level or use one as the main vocal track and the other at a lower volume to thicken the sound of the first.
 
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