While EQ is usually applied to taste in recording and mixing, there are situations where the tonal adjustment needed is determined for you'"this can happen whenever you need to EQ something to match the tonal quality of something else. Several common scenarios may impose this requirement. In mixing, say, you might encounter a track with a punched-in overdub (like the guitar solo in Fig. 1).
Fig. 1: A track with a section punched in'"a possible tonal mismatch for the rest of the audio.
Usually, this is not a problem'"the replacement take is recorded shortly after the original take, and blends in seamlessly with it. But occasionally, the blend is not so seamless'"if the performer adjusts his tone, or changes position on the mic, then the tone of the punch may be different enough to make the replaced section stick out, even if the performance is perfect. Likewise, when multiple takes of a part'"like a vocal'"are comped together to create a final, ideal, performance (Fig. 2), slight differences in tone may prevent the final comp from sounding like a single take, even when the musical blend is seamless.
Fig. 2: A vocal comp pieced together from several takes, which may or may not blend together tonally.
And in mastering, when multiple tracks are being prepared for an album, too-obvious differences in tonal balance, from one song to the next, might be distracting.
In all these situations, the solution is to EQ whichever songs or regions are clearly tonally mismatched, to achieve a tonal balance that's a proper match for the rest of the audio. But doing this by ear can be tricky, often requiring small adjustments, which may be hard to get just right. Enter Logic's Match EQ, which finds the right EQ settings for you, or, at least, gets you 90% of the way to an acceptable tonal match.
Fig. 3: Logic's Match EQ.
When a section of audio doesn't tonally match another section closely enough, Match EQ performs a spectral analysis of both sections, determining the overall tonal balance of each. It then generates an EQ curve based on the difference between the two analyzed sections, and applies this to the section that needs to be changed, bringing it in line with the desired tonality of the rest of the audio. The Match EQ plug-in can either be Automated to become active only for the regions where it's needed, or the mismatched audio can be moved to a duplicate track, and Match EQ instantiated there.
In use, Match EQ is pretty straightforward. I'll assume the audio to be processed is on a duplicate track (Fig. 4).
Fig. 4 A punched-in audio region ready to be processed by Match EQ.
You'd instantiate it on the track to be processed'"the one with the tonally-mismatched audio. You'd first set it to analyze the Reference by clicking on the Template Learn button'"the regions that already have the desired tonal balance. If they're on a different track, then you'd temporarily move them (or the plug-in) to do this.
Fig. 5 Match EQ set up to capture (learn) the Reference/Template audio's tonal balance.
You'd play the reference audio'"around 10'"15 seconds is probably enough. Match EQ will now have the desired spectral balance.
Fig. 6 Match EQ has captured the Reference/Template curve'"the desired tonal balance.
Switching to the section/region that needs to be EQ'd, you'd set Match EQ to capture the Current (Target) audio's (mis-matched) tonal balance.
Fig. 7 Match EQ has captured the Current/Target curve'"the tonal balance of the audio that needs to be EQ'd.
It's also possible to drag audio files from the Project Audio Browser directly to the Template/Current buttons and Match EQ will analyze the files automatically.
Now, switching to the '=' box will show a curve that's the difference between the two'"this will be applied to the target audio (the punch-in, here), to match its tone to the original take.
Fig. 8 Match EQ generates a difference curve'"an EQ curve to match the target's tone to the reference/template.
But this EQ curve may be a bit too spiky, and the EQ'd audio, though now better matched to the rest, may not have as smooth a tonality as you'd like. To remedy this, you can adjust the two sliders on the right'"'Apply', and 'Smoothing'. 'Apply' can reduce the intensity of the matching EQ curve, in case it's too much, until the blend between the original and EQ'd sections is just right.
Fig. 9 The 'Apply' slider adjusts the intensity of the matched-EQ curve, for a better blend.
Likewise, 'Smoothing' can soften the peakiness of the applied EQ curve, again, until the blend is as seamless as possible.
Fig. 10 The 'Smoothing' slider softens any excessive peakiness in the matched-EQ curve.
These last two adjustments are often the key to getting the most seamless blend between the original tonality and the Match-EQ'd sections'"as I said, Match EQ gets you 90% of the way there, the last 10% is still up to you.
Audio Example 1 A punch-in without Match EQ:
Audio Example 2 The same punch-in with Match EQ:
So, while the final results are, ultimately, still up to your ears, Match EQ can be a great time-saver whenever you need tonally-different bits of audio to blend seamlessly. Another useful tool in the extensive Logic toolbox!