Editing old DJ mix, beats slightly out of phase

[Satchel]

Hi,

I found an old vinyl DJ mix on CD that I did about 15 years ago. A few of the mixes are slightly out of phase where the kick drum gets fatter and in a couple places you can barely hear 2 kicks where there should be one. Is there a way to edit these mixes to make the kicks sound a little more normal? I am using 2.0.5 on Windows 8. Thanks!!

[steve]

If you can post a couple of short samples in WAV format, then we can take a look.
Include one sample (just a few seconds) that has "normal" beats, and another that has the "out of phase" beats.
The two samples should be as similar as possible in all other respects.

See here for how to post an audio sample: http://forum.audacityteam.org/viewtopic ... 49&t=72887

[Satchel]

Thanks for the fast response! This is probably the best I can do to satisfy your request. The normal clip is not completely normal, but it represents what I would consider acceptable, and is as similar in all other respects as I can reproduce.

Phased

Phased.wav

(928.04 KiB) Downloaded 63 times

Normal

Normal.wav

(624.04 KiB) Downloaded 51 times

[steve]

I see what you mean, and yes it was probably caused by phase problems between sounds that were being mixed.
The only effective way that I can think of to fix that is to take a "good" beat and use it to patch over the damaged beat. This is moderately tricky as you need to get the good beat to precisely match the waveform that it is replacing so as to avoid clicks.

Here I've marked (labelled) a good beat in the upper track, and a bad beat in the lower track. I've done this on two tracks just so that you can see both at the same time.

tracks000.png (25.04 KiB) Viewed 998 times

You can see how the "bad" beat becomes "thin" in the middle, compared to the "good" beat.

What we need to do is to make a duplicate copy of the good beat and use that to replace the bad beat.
It's easiest if you duplicate a bit extra, then you can trim it down as necessary once it is aligned.
Select the good beat and use Ctrl+D to duplicate it.

Click on the duplicate so that the original track is not selected, then use the Time Shift tool to slide the good beat directly below the bad beat.

tracks002.png (24.03 KiB) Viewed 998 times

Zoom in really close to get the start of the beat carefully aligned:

tracks001.png (16.93 KiB) Viewed 998 times

Also check the end of the "patch". We want the patch to start and end just as the waveform is crossing the centre zero line:

tracks003.png (25.23 KiB) Viewed 998 times

You will need to make a judgement call to get the alignment as close as possible. What we want to avoid is a mismatch between the original waveform and the "patch" as it goes from one to the other.

When you have the selection as you think best, use the "Up" cursor key to move focus to the top track and press ENTER so that the upper track is also selected (The "Enter" key toggles the selection on/off).
Then press Ctrl+i to create "splits" at each end of the selection.

tracks004.png (24.82 KiB) Viewed 998 times

Double clicking on any of the "audio clips" will select that clip.

Silence the parts that we don't want (Ctrl+L)

tracks005.png (21.26 KiB) Viewed 998 times

and that is the patch complete.

When you export the track(s) to create a new file, they will automatically be mixed together.
If you prefer to mix them before exporting then Ctrl+A to select All, then from the Tracks menu > "Mix and Render".

Here's the "before and after":

before-after.flac

(851.58 KiB) Downloaded 54 times

[Satchel]

Thanks for your very detailed response! I don't think this is a very practical solution for me as I would have to repeat this process close to 100 times throughout the mix. However, I did learn a few things which is always good.