Fix phasing with nudging?

[Travis Mitchell]

Any thoughts on "fixing" phasing issues by nudging the recorded audio? Do any of you do this? How do YOU do this?

There have been more than a few times that I have had to make sacrifices on a drum sound because of phasing issues, and I am looking for a solution.

[gh10606]

Maybe this is just a semantic distinction, but strictly speaking, you can't fix phase problems with nudging. You can fix TIMING problems (such as arrival time differences between close drum mics and overheads -- or between the brass section of an orchestra and the cellos -- or plug-in delays) but not phasing. The way to change phase is with the phase reverse button on a plug-in (such as the one-band EQ).

I hope this helps.

Glenn

[daniel_c]

Yes phase issues can be treated by nudging regions. If the situation calls for it. More often than not , using the phase reverse button on a plugin is the quickest and easiest way to check phase.

And by the way , phase and timing are essentially the same thing. Phase deals with delays (timing) below 60ms (however , many people say they can distinguish distinct delays as low as 40 ms).

There are a few threads about phase and drums already , so try a search in some of the other forums. [img]images/icons/smile.gif[/img]

[Travis Mitchell]

I'm aware that phase and timing are the same thing, and that nudging can fix it. I just was wondering who did it / how they would go about measuring the delay, etc.

[daniel_c]

Here is something I tried at college and haven't used since.

The drum kit was set up in a room. I started with a stereo mic for the overheads. Using a stereo mic gave me a stereo image of the kit as in phase as it possible could be. You can use any stereo micing technique for this. This was my starting point. All the other mics on the kit were compared to the overheads for phase

Then I miced up the kit as usual , kick , snare , toms , hi hat , rooms , etc.

Once I had all the individual sounds right , I measured the distance from the overhead mic to each individual mic.

When it came time for mix down I checked my notes and worked out the delay time required for each mic to be in "phase" with the overheads using the formula t=d/v

t is the delay time in seconds between the two mics
d is the distance between the overhead and the individual mic in metres (or feet for those stuck in imperial)
v is the velocity of sound in metres per second.

I left the overheads where they were and nudged the other tracks by the amounts calculated.

Try it by all means. But when you think about it , the kit is bleeding into all the mics , snare into the toms , toms into the hi hat etc. You can't compensate for that as well.

The best method is to get it right in tracking using the phase reversal buttons and moving the mics.
e.g. you are comparng the phase of the overheads and the snare top mic. If there is more low frequency with the phase rev button pressed in, the signals are now more in phase. but that might not be the sound you want , whatever.

Hope thats not too confusing. Good luck

[daniel_c]

[QUOTEv is the velocity of sound in metres per second[/QUOTE]

Or feet per second if you are taking measurements in feet

[where02190]

Yes phase issues can be treated by nudging regions.

And by the way , phase and timing are essentially the same thing. [/QUOTE]

Absolutely incorrect.

Phase refers to the wave in reationship to its position in the cycle in degrees. two waveforms that are out of phase (except if if they are exactly 180 degrees apart) can never be corrected by time alignment. If one is say, 36 degrees different from the other, time shifting one will not chage the phase relationship, only the time relationship.

When it came time for mix down I checked my notes and worked out the delay time required for each mic to be in "phase" with the overheads using the formula t=d/v [/QUOTE]

What you calculated was time alignment, not phase alignment. Personally I never time align mics as you did, as that relationship is part of the sound of a kit. Not eveything is in exactly the same place, nor does the waveform travelt to meet the listeners ears at exactly the same time. IMHO aligning drum mics as you did creates a very flat, two dimensional sound. However, that is my opinion only, and if you and your client are happy with the results then that is all that matters.

However, again, you have changed any of the waveforms phase, only the time.

Yes there is a relationship between phase and time, however time shifting alone cannot correct phase issues. there was a very long thread regarding thsi several months back, which is well worth searching for and reading, as there was some excellent information, references, etc regarding this issue.

Hope this is helpful.

[daniel_c]

Phase refers to the wave in reationship to its position in the cycle in degrees. two waveforms that are out of phase (except if if they are exactly 180 degrees apart) can never be corrected by time alignment. If one is say, 36 degrees different from the other, time shifting one will not chage the phase relationship, only the time relationship.

<font size="2" face="Verdana, Arial">Yeah yeah , im not going to get into that , its beating a dead horse , but from an acoustical point of view and listening to the results i stand by what i said.

IMHO aligning drum mics as you did creates a very flat, two dimensional sound. However, that is my opinion only, and if you and your client are happy with the results then that is all that matters.

<font size="2" face="Verdana, Arial">Read my post again , i said i used it once and only once at college , for myself to see what it was like , and yes it is not a very impressive sound [img]images/icons/smile.gif[/img]

However, again, you have changed any of the waveforms phase, only the time.
Yes there is a relationship between phase and time

<font size="2" face="Verdana, Arial">Careful , thats almost a contradiction [img]images/icons/smile.gif[/img]

[where02190]

Originally posted by daniel_c:
<blockquote><font size="1" face="Verdana, Arial">quote:<hr /><font size="2" face="Verdana, Arial">However, again, you have changed any of the waveforms phase, only the time.
Yes there is a relationship between phase and time

<font size="2" face="Verdana, Arial">Careful , thats almost a contradiction [img]images/icons/smile.gif[/img] <hr /></blockquote><font size="2" face="Verdana, Arial">Not if you had quoted the entire sentence it's not.

[daniel_c]

Yes there is a relationship between phase and time, however time shifting alone cannot correct phase issues.

<font size="2" face="Verdana, Arial">Still a contradiction [img]images/icons/wink.gif[/img]