Recording - July 2010 - 19

Figure 3: The note-detection display in Drum Rehab. take(s). When lack of foresight to have done this prohibits MIDI replacement, the other option is to use the audio waveforms from the drum recordings themselves to trigger the replacement samples. I was recently called in by a friend doing an album project to do this for a set of live recordings he was mixing, and I thought the resulting adventure was worth a write-up, for those who might be interested in (or in need of) using this technique, but haven’t been able to explore the process yet. The job at hand My involvement in this project came about when Yianni Papadopoulos, a local engineer and mixer here in NYC, called me to assist on a mix he was starting. The tracks had been recorded at another studio, live, with everybody playing together in the room, followed by additional overdubs. The music was instrumental hard rock/experimental, lots of crunchy guitars and synth drones mixed with aggressive drumming, with plenty of odd meters (i.e. 7/4 and the like) throughout the collection of songs. The drumming ranged from solid grooves to almost free-form jazz-rock flights—right away, I got the idea that this had the potential to be more challenging than most such tasks. The recorded drum tracks were pretty consistently comprised of “close”-miked kick, snare, high tom, low tom, and stereo overheads. The songs were not lined up with a click, and, due to the complex meters, there was no plan to beatmap them. When we began soloing the individual drum mics, I could see what he was up against right away—there was very little isolation of the individual drums, at least in comparison to what one usually expects to hear in a multi-miked drumkit nowadays. Now, this is not necessarily a bad thing in and of itself. While having lots of leakage in close-miked drum tracks increases the potential for phase issues and other problems, it doesn’t necessarily stand to reason that there will always be such problems, and the leakage can often contribute to a pleasing sense of air and ambience.

Figure 4: The main note-detection parameters in Logic’s Audio-to-Score: Velocity Threshold, Granulation, and Attack. In this case, the mixer had two main issues. One was that the drums did tend to get a bit, well, “mushy” (for lack of a better descriptor) when all the tracks were brought up. And two, the drum sound itself was not one he thought would work especially well for that particular music. The wide-open drums and very ringy snare probably cut through the guitars very nicely when live in the tracking room, but the sound was a bit thin, with some fairly harsh overtones that apparently became worse when he attempted to apply the usual corrective/creative eq and compression to the tracks.

Course of action As an experienced engineer with a lot of mixes under his belt, Yianni decided that the best course of action was to replace at least the main drums, kick and snare, with samples better suited to the particular project. He had a couple of specific sampled drum kits in mind as candidates, including some drumkits comprised of samples he and I had recorded at his studio a while back and set up as an elaborate drum Instrument in Apple Logic, using multiple EXS24 sampler plug-ins (included in Logic) and a complex Environment to tie all the elements of the kits together. Naturally, given my involvement in setting up the sampled kits of choice, he called me in to work on the replacement. Initially, the band members were nervous about this approach. They didn’t want the engineer who had recorded the tracks to be offended, and, of course, they worried that the drummer’s performance might be altered (unintentionally) in the process. Both are very legitimate concerns. The band were persuaded that the finished drum sound wouldn’t be so drastically different from the original as to make the recording engineer feel his work was being rejected out of hand—it would, if all went well, simply sound like a fuller, more studio-quality version that would sit better with the other instruments. Even more importantly, we would take great care that the process of replacing the kick and snare wouldn’t screw with the drummer’s timing or performance—the new samples would be matched carefully to the original sounds in both timing and dynamic response, to fully preserve the musicality of the drummer’s solid, energetic grooves and fills. Once these concerns had been addressed, we set out to begin the task at hand. Tools of the trade There were two ways for us to go about substituting our drum samples for the audio waves of the individual close-miked kick and snare tracks. One way was to convert each hit to a MIDI note with an appropriate velocity, and then use the resulting

Figure 5: Detected notes in Audio-to-Score.
RECORDING JULY 2010

Recording - July 2010

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