If a pop/rock/dance track doesn't have a great drum sound, you're in trouble. Big trouble. The Drum Replacement 101 solution is to have a drummer come along and play with the original track, then erase the old drums. But this doesn't always work, and if you try to add drums after the fact to a track that doesn't have them, the process becomes even more complex.
This was brought home to me when I produced an album by Michael Kac and the late Linda Cohen that had a tasty harpsichord/classical guitar duet. After one of the tracks was done, we decided it would sound great with drums . . . oops. This was years ago, so I worked for hours doing digital audio stretching to get some loops to line up.
Then there was a cover version I did of Julian Cope's "When I Dream" that was mixed with a scratch drum track. I wanted to resurrect it, but no longer had the original tracks, just the mix - and the drum part was useless. Oh well.
But today's tools can salvage those kinds of tracks, and more. Here's how.
Replacing Drum Hits via Drag-and-Drop
Sometimes a tune is basically okay, except perhaps for a questionable kick or snare sound, or an electronic cymbal that would sound far better as a real one. In this case, you may be able to just drag in samples to "double" what you're hearing.
Fig. 1 shows a Cubase project with a two-track mix in the top track. Below it, in orange, are kick hits dragged over from a Discrete Drums sample CD. The magenta clips are snares, and the yellow, "accent" snare hits for flams and such. Because these are lined up exactly with the existing hits, they "mask" the bad sounds with good sounds.
Replacing all hits in this manner can be tedious, but is likely less time-consuming than bringing in a drummer to play over the track, then moving some of the hits around so they fall exactly on the existing hits.
Drum Replacement Software
Several software solutions can analyze a file and generate triggers for alternate samples. SoundReplacer, part of Digidesign's Music Production Toolkit or available separately for $395, is an AudioSuite (non-real time processor) that can pick transients out of a file, and split them into three velocity zones for triggering multisamples that get mixed back into the file.
An RTAS real-time option, TL Rehab ($495), works as an insert and allows real-time auditioning of samples. Its principle of operation is similar to Drumagog, which is a more universal solution as it's a cross-platform plug-in that works with VST, AU, and RTAS systems. Drumagog is designed to be used with multitracked drums, where you have separate tracks for snare, kick, etc. It includes a set of excellent samples you can use to replace existing drum sounds; othersample sets are available, or you can create your own drum sample sets to work with Drumagog. (Drumagog Pro lists for $289; a Basic version costs $199, and a Platinum version, $379.)
To replace a drum sound, you insert Drumagog as a plug-in, then adjust its Sensitivity and Resolution controls for reliable triggering. A visual mode (Fig. 2) shows the incoming drum hits to be replaced, along with a dot that indicates triggering; the height of the dot indicates the level (Drumagog's triggers not only follows hits, but tracks the level as well). This is vital when triggering drums multi-sampled at various velocities.
Drumagog also has filtering if you need to isolate the drum from bleed - I've even used this feature to pull a drum sound out of a mixed track with some success, although the results depend on how "buried" the drum is in the mix.
In addition to replacement, it's also possible to alter the sample pitch and the blend of the original and replaced sound. Latency is low - 3 ms worked fine in my system - but you can always bounce the track and slip it forward a bit to line up with existing drums.
Drumagog is surprisingly effective and also offers some advanced features, like a "ducking" option (e.g., your "old" snare sound remains in an overhead mic track; duck the snare sound in the overhead track when the "new" snare hits). Drumagog can also generate a MIDI out if you want to trigger a soft synth or hardware synth with drum triggers. (Note that there's a downloadable 14-day demo at Drumagog.com) .
Matching Project Tempos to Clips
Another approach is to use loops to "cover up" a bad drum part, like I ended up doing with the cover of "When I Dream" (check out the followig audio example). This was recorded on tape over 20 years ago, and the original multitrack couldn't be salvaged, so all I had to work with was a 2-track 1/4" master tape with a less-than-stellar drum part. So I transferred the song over to Sonar, and got to work.
Because drums tend to hit on the beat, adding a drum part on top of the file with a drum part already mixed in tends to mask the original sound. So, you bring the original file into a host program, use the host's tools to match the project tempo to the rhythm of the file, and then you can insert loops or other drum parts into other tracks. Following are examples using both Cakewalk Sonar and Ableton Live.
Sonar's AudioSnap feature can analyze a clip, and place markers at transients. Generally, transients line up with beats; we can then "assign" a beat to a marker, thus causing the tempo map to conform to an existing piece of music. Here's how to do this using Sonar's "Set Measure/Beat at Now Time" option; the "Extract Timing" command seems better suited to clips with regular, well-defined transients, not program material.
- If there's an existing tempo map, clear it.
- Import the clip into a Sonar audio track.
- Right-click on the clip and choose "AudioSnap Enable."
- If the AudioSnap palette isn't showing, type Shift-A.
- Set the tempo as closely as possible to the file's tempo. This isn't necessary, it just makes life easier.
- Either place the Now time exactly on a transient marker that should line up with a particular measure and beat (e.g., measure 3, beat 1), or better yet, use the AudioSnap palette's "Go to next transient marker" button or "Go to previous transient marker" to "park" the Now time on the desired transient.
- Click on "Set Measure/Beat at Now Time."
- In the dialog box that appears, enter the measure and beat you want to "pin" to the chosen transient.
Basically, Fig. 3 shows that you're creating a tempo map. If the tune has a fairly constant tempo, and you've set the project tempo pretty close to the song's tempo, find a transient marker that's close to the end (making sure you know the measure and beat to which it corresponds!) and pin the correct measure/beat to it. If you're lucky, this will "distribute" the correct tempo throughout the song. If not (or if the tune contains significant tempo variations), slog through the file a measure at a time, or a beat at a time if absolutely necessary, and you'll eventually get the entire tune mapped.
At this point, you can start adding in loops; assuming they're "acidized," they'll fit along with the tempo. If not, you can grab a loop's edge and while holding down the Ctrl key, "slip-edit" the length to fit a particular number of measures.
Ableton Live's "elastic audio" feature allows matching clips to tempo very easily; even better, Live does most of the work for you. The process starts by bringing a long file into Live's arrangement view. Live analyzes the file, and creates "warp markers" at rhythmically important places within the file (Fig. 4). Live's ability to find these is uncanny - in many cases, you won't have to adjust the markers at all, and the file will slip right into the tempo.
However, suppose you're bringing in a file that was played by humans, and the song's tempo varies around 120BPM. By matching warp markers to transients that indicate the start of a measure or beat, you can "tweak" the tempo to match the file. You do this by simply dragging the warp marker to the transient; if Live hasn't put a warp marker where you want one, double-click on the beat in the timeline to create a warp marker, then line it up with a transient.
After you've used warp markers to define the desired measure boundaries, if you then insert loops into the song, they will automatically time-compress/expand so they fit into what the markers define as a measure. (To hear an excerpt from another song called "Modern World" that I updated using drum loops from Discrete Drums, check out the following audio example.)
Live's on-line help gives an educational example of how to "elasticize" a piece; even if you don't read manuals, you'll master the process a lot faster if you follow along with the documentation.
The bottom line: Never give up just because the drums don't make it - many times there is indeed a fix.
Originally published on Harmony Central. Reprinted with permission.