Copying tracks and phase issuse.

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tubedude

tubedude

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Question...
Everyone is saying that if you copy a track to another track, that there will be phase issues. Will there be phase issues if the track is copied directly to another track,and not moved at all in the time range? (If it is perfectly inline with the one above/below it, is what I mean) If they are identicle, they will still cause phase problems? Doesn't make sense.
What about miking snare top and bottom? I hear that you should phase reverse the bottom mic, but dont exactly understand that, either....
Any help in explaining this would be appreciated.
Paul
 
If they are EXACTLY the same then there should be no phase problems. If you add a delay on one of them then yes there will be phase problems, maybe not "problems" exactly but differences, but that's not always a bad thing. That's usually what you do when you double track instruments, add a small delay to one of the tracks and pan them right and left.

On the snare drum when the top head is hit it moves down and at the same time the bottom head moves down also but, to the mic underneath the snare it is perceived as going up because it is upside down. So the top and bottom head are always 180 degrees out of phase, and by reversing the phase on the bottom mic it is then percieved as going down (and not up) which puts them in phase with each other.

I hope this helps

-tkr
 
Digital copy with no time shift at all -- no phase issues...

Analog copy with no time shift -- maybe! If you're using a professional analog multi-track -- no problem... a Tascam PortaStudio - yup - good chance of comb-filtering due to generation loss during the bounce.

Bruce
 
Gotcha... that snare thing was so easy to figure out that it wenrt right past me... makes so much sense that I feel stupid for even asking. Same as a speaker...
Gonna make another post about stereo miking, so that everyone looks again, see what you think about that one...
Oh, and how much delay can be added before you start getting phasey, and how far before you come back full circle?
 
For fun, I tested this very thing with 1 track and its digital copy.... time-based anomalies started to occur immediately at 1mS difference and as you increment the delay time, you will hear the subtractive effects of the distortion, then it will cycle back to a cumulative effect, and so on, until the delay difference becomes a time-event heard on its own (around the 30mS mark).

The length of the anomalie cycle I'm guessing, depends on the nature and mix of frequencies inherent in the signal.


Bruce
 
S'okay

Don't let the IDEA of phase anomolies stop you from using those anomolies. Delayed duplicate tracks (phase anomolies and all) can be a great effect. Especially on distorted guitar. I use/have used delayed duplicate tracks at one time or another on pretty much everything. It is also a great tutorial on what different degrees of phase cancellation will do to your signal. You learn what it sounds like and learn to recognize it where you DON'T want it.

Tom Cram
dbx Senior Technical Support
(801) 568-7530
tcram@dbxpro.com
 
It's not really how MUCH delay will cause phasing problems, but how LITTLE. Generally, the longer the delay, the less chance of phase problems. at 1 sample of delay, you will get some phasing, but it will be almost undetectable. At 10 ms, you will get plenty. but at 300 ms, darned if you can find any.
 
I just got the book "Modern Recording Techniques" and started reading it... it goes into phase and stuff pretty good right from the start. Looks like a good delay time is about 30ms... any comments from anyone?

Something for everyone to think about... I got "The Art of Mixing" and that other one from the public library, and they have a few more on order for me. The price is right.
 
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