Logic Pro has built‑in tools for drum sample replacement.
Professional mixers use drum replacement so much that you would be surprised to learn how many rock albums contain little, if any, of the original kick and snare in the final mixes. For the most part, sample replacement is used on multitrack drum recordings to provide several worthwhile benefits. Rather than put a badly recorded kick drum through a half dozen plug‑ins to beef it up or give it more snap, simply replace it with a sample that has all of the characteristics you need — or enhance it with just the attributes that your original drum lacks. Another application is to replace the snare (while keeping the original in the mix) and use the sampled snare to send to reverb, rooms, and other effects to achieve clean ambience without unwanted leakage.
Kick and snare drums are the usual suspects for replacement, but toms (and just about anything percussive) can also yield results worth exploring. Let’s start with your live kick drum track. This method creates a MIDI track while leaving your original audio track untouched, though I still opt to make a copy of the original drum track to work with. Another option would be to create a duplicate Track Alternative. To copy the kick track and its contents, hold down Option while dragging the track downward.
Now that we have our duplicate track selected, let’s make sure our waveform view is at maximum. Click and hold the Waveform Zoom button (Key Command available) to reveal a slider and turn it up all the way.
Rather than put a badly recorded kick drum through a half dozen plug‑ins to beef it up or give it more snap, simply replace it with a sample that has all of the characteristics you need.
Next go to the Track menu and select 'Replace or Double Drum Track...', or use the keyboard command Control+D. As an aside, I imagine that replacing drums would have to be a major part of your workflow to justify using such a premium key command for the task. Control+D falls off the fingertips so effortlessly that I would prefer to use it for something I need more frequently. Fortunately, it can be reassigned in the Key Command Edit window.
A few things happen once the command is selected: the Library pane opens up and a floating dialogue window appears. Set the top drop‑down menu to the drum you’re working on (in this case, Kick) and choose Doubling. The only difference between Doubling and Replacement is that Replacement will mute the original track once the MIDI track is created. The Relative Threshold slider is the most crucial setting. Slide it left or right to make sure all of the transients in your track are detected, while bleed from other drums is omitted. The MIDI track will update in real time while you do this. Attempt to find the sweet spot where you have exactly one MIDI note per kick. If excessive bleed is making it tricky, err on the side of caution and include some unwanted hits. Removing errant notes is much easier in the MIDI track than adding new ones.
Use the Preview button to solo the track and check it for misfires. (Small gripe, but I wish this button illuminated or changed to Stop while playing; I keep accidentally hitting OK, which closes the dialogue box and puts an end to the discussion.)
While choosing different replacement samples from the library is a good option, I prefer to hold off until the MIDI is created and I’m out of this portion of the process before selecting a sample. If you have a specific sampled drum kit that you plan on using, you can choose the appropriate trigger note. Leaving it on Auto is my recommendation for now, as it will generate notes according to the General MIDI layout. Now we’re ready to say OK and move along.
On the new track, Logic has inserted a Sampler instrument and conveniently opened the library on a selection of kick drums. The MIDI track will have a ‘+’ added to its name for easy identification.
If you feel confident that Logic captured your performance accurately, you can go ahead and delete the duplicate track that we used to create the MIDI track. The benefit of using a duplicate track is that you can edit it to help Logic extract the MIDI more reliably, without those edits appearing in the final mix. More on that later.
I never adopted the Library pane into my workflow, so my preferred method for auditioning the drums is to do it in the Sampler window itself. Use the Next/Previous Patch or Instrument Setting command (or the </> buttons on the top left of the window) to switch between various kick drums on the fly.
In my example, the MIDI kick sounded a bit weak. No problem! On inspection of the notes in the MIDI editor, it was clear to me that the velocities were on the low side. Simply select all and adjust the velocity slider. With all of the notes selected, Logic will retain the relative velocity differences that it captured. Of course, you can also go through the entire track and adjust the velocities one note at a time as well, if you so wish.
In Sampler, with the Mapping tab selected, it’s apparent that these stock sample patches are no joke. With multiple velocity layers that switch in (as low as) five values, these are as powerful as any after‑market sample set! My only complaint is that their names aren’t in the least bit descriptive. If your ears are telling you that your original kick just needs a little more click or a bit more body, you’re in luck. In Sampler, navigate to Factory / Drums & Percussion / Single Drums / Kicks / Layer Kicks. Here you’ll find a host of potential elements that your original drum possibly lacked. Just because we’re dealing with an acoustic drum kit doesn’t mean we are limited to that. Open Drum Synth on your MIDI track instead of Sampler and experiment with an 808‑style palette. Or try playing your kick/snare pattern on congas.
If you need more options, remember that you aren’t restricted to only using Logic’s instruments. Once the MIDI track is created, feel free to replace the Sampler with any third‑party instrument: Battery, EZ Drummer, Kontakt, or anything else.
As previously stated, there are a few traps to avoid when using the Drum Replacer feature. The first issue concerns capturing a reliable MIDI track from your recording. If your audio contains an abundance of bleed from other drums, we may need some additional steps. Toms in particular may require this approach.
The Remove Silence from Audio tool is an effective way to isolate drum hits with a bit more detail and precision than the Replacement dialogue. Additionally, you can manually add or remove sections before committing to replacing. One of the shortcomings of Logic’s drum replacement is that once the MIDI is generated, there’s no going back.
Another way to clean up the source track would be to use a gate. Open a Noise Gate plug‑in on the track and tweak the settings to remove everything but the hits you want included. However, I’ve noticed that the Drum Replacement function ignores plug‑ins on the track, so you’d need to bounce the track for the gating to be factored into the MIDI extraction.
For this reason, I prefer to use Logic’s selection‑based processing as opposed to plug‑ins on the channel. This method incorporates bouncing and so saves a step or two.
If drum replacement is something you do more than once in a blue moon and you find Logic’s kick selection with its generic names uninspiring, here’s a little side project for you. On your Mac, locate the folder where your sampled instruments reside. Navigate to the Drums & Percussion folder (of the Sampler Instruments folder, not the Sample folder). Go to the folder named ‘03 Single Drums’, grab it, and drag down while holding the Option key to make a copy (sound familiar?).
Change the name of the new folder to something like ‘Single Drums Renamed’ or whatever helps you remember it. Navigate to the Acoustic Kicks menu of the renamed folder while auditioning Sampler instruments in Sampler. Make sure to sort the folders by name so they are in the same order as the list in the Sampler.
As you listen to each sample, rename it in the open folder to something that means something to you. So when your kick needs more body, you can try all of your kicks labeled ‘Phatty & Splatty’, for example. To be clear, you aren’t changing any samples, just the names of the (copy of the) instruments. Take the time to do this and you’ll probably find that you’ll have three or four go‑tos and won’t need to do much auditioning. You could then add those to another folder of your Greatest Hits!
While some dedicated drum replacement plug‑ins do indeed have a few advantages over Logic’s method, the included Drum Replacer/Enhancer function has some benefits of its own that may well mean you don’t need to fork out for expensive third‑party software.