How Drum Replacers Can Save Your Session

Keep the groove. Improve the sound. We rounded up five of the leading drum replacement apps and discovered that each offers something unique.
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Keep the groove. Improve the sound. We rounded up five of the leading drum replacement apps and discovered that each offers something unique.

Anytime I talk with my techie friends about drum replacement, it’s all about fitting square pegs into round holes. You know, switching out a hip-hop kick that’s lacking boom for the clubs. Or replacing a fat acrylic snare that could really rock the track “if only it were a Pearl brass piccolo.” Granted, many of these folks are mix engineers and don’t have the luxury of calling drummers back to re-record.

However, drum replacement is useful for any musician working from a home or desktop studio. A wise producer once told me, “Much like love, magical moments in the studio tend to come and go when you least expect . . . so capture them when they happen, and cherish those recordings once they’re gone.”

That’s so true — early scratch takes and casual jam sessions captured under less-than-ideal acoustic or technical conditions often have emotional impact that’s difficult to recapture in subsequent big-studio sessions. Thanks to modern software, though, we can improve the sound quality while retaining much, if not all, of the original emotion. This is a crucial advancement.

We put the five most popular drum replacer apps to the test. While they all basically work via filters and trigger thresholds, three — WaveMachine Labs’ Drumagog, Digidesign’s TL Drum Rehab, and ApulSoft ApTrigga 2 — are sample-based and get inserted as realtime plug-ins on a channel in your DAW. The other two — DTM from Massey and Drumtracker from Toontrack — work offline to export MIDI files you can later use to play your virtual drum instrument of choice. Most importantly, it’s each product’s unique detection and sensitivity controls that make it best suited for a particular job.

WAVEMACHINE LABS DRUMAGOG 4 PLATINUM

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For the past eight years, Drumagog has been one of the most highly regarded drum replacers out there. To this day, competitors are seen borrowing from its feature set and trying to match the scope and finesse of its detection engine.

Incorporating a 4GB library of highly expressive acoustic and electronic kicks, snares, toms, hi-hats, and cymbals, played with brushes as well as sticks, proprietary GOG files can each contain upwards of 48 velocity and positional multi-samples. You can also import WAV, AIF, SD-II and GIG samples to create custom GOGs; this lets you arrange and save your own sample sets in a single file that’s easily exchanged with others online. Some of the best sounding GOGs come from users in the Drumagog forums.

Using it is a simple matter of inserting the plug-in onto a mono or stereo drum track, selecting a replacement sound, and letting Drumagog do the rest. You can adjust the mix of original and replacement audio.

Incoming audio shows up as a scrolling half-height waveform, with crosshair-style controls superimposed for trigger sensitivity (the volume threshold for incoming peaks) and resolution (the minimum space between peaks that will separately cause triggers). In this way, you can quickly teach Drumagog how to react to incoming drum sounds that hit very close to one another — e.g., flams, paradiddles, and rolls — or, conversely, to ignore errant ghost notes by widening or narrowing the resolution in milliseconds. Audio that scores a “hit” (a candidate for replacement) is displayed as a white dot, so it’s easy to see a history of exactly which peaks caused Drumagog to trigger.

This turned out to be the most intuitive and flexible method for automating peak detection of any app in this roundup. Note, though, that Drumagog’s detections are always automatic and don’t let you add or remove triggers manually.

If the source audio is complex enough that you need to roll up your sleeves, you’ll find plenty of parameters for fine-tuning the detection process. In the pre-trigger filter section, there’s a choice of high-, low-, bandpass, and notch filters, each with adjustable frequency, Q (bandwidth), and input levels. I really like that there’s an audition button here, letting you hear exactly how much source signal is actually making its way through to the detection engine.

The intriguingly named “Stealth mode” allows all the original audio to pass through unchanged, until the trigger threshold is reached. This could be especially useful for home studio recordings where limited microphone availability causes both the snare and hi-hat to end up on a single track. Drumagog will pass the hi-hat through, quickly crossfade into the replaced snare sample when the snare drum is triggered, then crossfade back into the hi-hat again!

Wanting to test this in a different way, I threw a pretty extreme case at it: A song’s floor tom wasn’t directly miked, but instead, picked up only by the overheads. I needed to replace the tom, but didn’t want to jeopardize the rest of the overhead content. With the detection filter tuned to the frequency range of the floor tom, Stealth mode allowed the rest of the kit to pass through around it. I was totally impressed by the seamless and completely natural-sounding results, especially once I’d blended them back into the full mix. A pitch control lets you fine-tune replacement samples.

Especially in urban, pop, and dance music, sometimes all that an acoustic drum sound needs is a little embellishment to make it fit in with an electronic arrangement. For this, the Synth section is a wonderful inclusion, as it lets you blend in a pure waveform (sine, square, sawtooth, three types of triangle, and noise) and tune its level, frequency, attack and decay. Whether adding sub to a kick, buzz to a snare, or putting shaped “fuzz” on handclaps, only Drumagog has this feature.

Drumagog’s sample engine can discern whether the drummer was playing fast enough to warrant an extra “hand;” if so, Drumagog alternates between different samples for the left and right hands, making the replacement sound very realistic during rolls and fills.

Drumagog is available in three versions, starting with Basic at $199. If you own a copy of FXpansions’s BFD or BFD2, Drumagog Platinum (reviewed here) can trigger BFD samples directly, without the need for MIDI or complicated routing setups.

TRILLIUM LANE LABS TL DRUM REHAB

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Combining the best aspects of both a scrupulous user-input process and more hands-off automated approach, Drum Rehab is a Pro Tools-only (RTAS) solution that can detect and replace drum hits, with sample-level accuracy, completely on the fly. Due to it being specifically designed for Pro Tools, the integration feels extremely slick, with the interface sporting an attractive detection waveform view that tightly follows playback as selected from Pro Tools’ Edit window.

Drum Rehab listens to the source audio, analyzing it in real time for trigger points, then storing these internally along a sort of waveform “map.” This lets you jump back and forth within an audio file as Drum Rehab remembers the detected trigger points from sections where you’ve already been. In practice, audio with reasonably consistent peaks (such as a welldefined kick track) need only be analyzed over a short, two- or three-bar section in order to get your detection parameters suitable for the entire song.

In these simplest of circumstances, you can pretty much set the trigger threshold and let Drum Rehab do its thing. The four basic detection modes are: Snare 1, Snare 2, Kick, and Tom. Dynamic variation in the source audio can be emphasized or minimized (down to “No Dynamic Tracking”), and a handy ducking option lets you set the amount of gain reduction that will be applied to the source audio upon output, when a drum sound is triggered. Naturally, you can also blend the input and replacement audio levels to suit.

For audio suffering from excessive bleed or wild dynamics, you’ll need Expert mode. Here, you can address any mistakes made by the detection engine, such as adding missed notes, deleting false triggers, or moving a trigger a smidge to get its peak in the right place.

However, before you can edit anything, triggers must be “committed” to the timeline so as not to be re-detected every time you play back a region. You can always “uncommit” triggers — should you wish to try a different threshold setting, for instance — freeing them for redetection. Because committed triggers are written into the waveform map, none of your painstaking work is lost after you close the session or plug-in window.

The Expert panel also lets you quantize triggers to Pro Tools’ grid, from halfnote to 64th-note, but it’s only as accurate as your session’s tempo map.

For ultra-fine placement, click-holding a trigger point zooms you in to the sample level, highlighting the replacement transient on the waveform in bright green. From here, you can correct for any phase issues a sample might have when blended against the original, offset the timing of the trigger, or adjust its amplitude. This is one leg TL Drum Rehab definitely has up on the competition — the program brilliantly combines an “offline” approach to getting maximum precision with the conveniences of realtime processing.

A large horizontal velocity map lets you define how samples get mapped to the 16 possible zones, which can be resized and crossfaded. Voicing modes are “Choke,” where any newly triggered drum sound terminates playback of the previous one, or “Free,” where samples can play over one another.

Two entirely different sets of sounds can be loaded at a time, each with their own set of attack, sustain, and EQ controls. This is great for programming hits on multiple drum head positions or mimicking a dual mic setup (say, top and bottom mics on a snare), and the Blend A/B control (which you can automate in Pro Tools) lets you crossfade between them. Sadly, there is no sample pitch control — a fairly major omission — and Drum Rehab doesn’t support stereo samples or panning of mono samples.

One very cool, if inadvertent, use that comes from Rehab having not only a minimum but also a maximum trigger threshold setting (none of the others in this roundup do) is that you can focus on any tiny or incidental percussion that might be buried in a track. This let me replace a lackluster shaker, recorded amidst a sea of hand drums, with one that had more gusto. I also augmented a rather drab hi-hat, recorded in a Beatles-style single-track drum take, with a clangorous tambourine sample, which gave the track much more sonic interest.

APULSOFT APTRIGGA2

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Rounding out the realtime replacers, ApTrigga2 also gives instant results, but you’re completely dependent on the plugin’s automatic detection to identify beats in the source audio. Short of fine-tuning the detection parameters, there’s little you can do to correct false triggers, add missing beats, or tighten up timing. Since it comes only in AU or VST formats, Pro Tools users will need FXpansion’s VST-to-RTAS Adapter, available from fxpansion.com.

The interface has four main sections. A Filter pane has lowand high-cut bands with conjoined EQ frequency, gain, and bandwidth settings. The Trigger section lets you set threshold within a convenient peak-hold style input metering display. You can also adjust trigger hold time and “smoothing,” which determines how fast the trigger reacts to signal changes. Other trigger modes include One-Shot — which always plays samples to their ends unless they are triggered again — and Loop mode.

Although it doesn’t ship with a factory library, you can quickly drag-and-drop any combination of AIFF, WAV, or SD-II sound files into the Sample pane. Up to nine mono or stereo files can be here at a time. Naturally, these slots are intended as velocity layers for a single instrument (i.e. snare), but nothing stops you from loading in samples of differing drum types for multi-instrument replacement based on discrete trigger thresholds. You can adjust an individual sample’s level and pitch (up to one octave higher or lower in very fine steps), as well as its panning in a stereo instance of the plug-in.

ApTrigga can convert MIDI note-ons into trigger events, making it possible to audition samples with a controller keyboard. As a special feature, it’s also possible to modulate ApTrigga’s engine with a controller such as a pitch wheel. This means you can “play” volume, filter cutoff, pitch, and dynamic sample selection all while the sample is being played back. This is exclusive among our roundup candidates.

I found the GUI a bit too small, especially when trying to maneuver a bunch of velocity crossfade handles in the crammed dynamics bar. I also wish there were separate input filters for each sample slot so that I could hone in on the warm, woody timbre of a snare with one sample, for instance, and use the more crisp, sidestick portion of the sound to trigger another sample. Nonetheless, ApTrigga 2 gives more options in multisample mode than any other replacer. Aside from typical dynamic, random, and round-robin playback modes, you can stack all loaded samples to be mixed and played back at once; stack samples according to velocity intensity; or manually select samples using an automatable control.

MASSEY PLUG-INS DTM

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Formerly an employee at Trillium Lane Labs and a major figure behind TL Drum Rehab, Steven Massey recently broke away as an independent, producing his own line of elite plug-ins at ridiculously low prices. And, in the case of Drum to MIDI (DTM), you can’t get any lowerpriced than free!

DTM is remarkably uncomplicated. In fact, it’s the simplest of the lot. Available only for Pro Tools as an AudioSuite plugin, DTM analyzes the selected audio track offline and converts it to MIDI data, which you can then drag back onto a Pro Tools MIDI track. Though it won’t save files directly for use in other programs, you can easily export the resulting track as a MIDI file from Pro Tools.

The interface consists of a waveform analysis window that shows the currently highlighted section of audio (which is why in the screenshot above, it’s shown in the context of a Pro Tools session), along with automatically detected trigger points. Beyond a simple threshold control, fine-tuning the sensitivity slider will ultimately affect the number of detected triggers. A “compression” dial scales the dynamic range of MIDI velocities generated, which can be a bit of a blind effort since you can’t do audible auditions in DTM. False trigger points can be erased, but you can’t manually adjust the triggers for placement or velocity.

Once it came time to drag the generated data onto a track, I discovered a rather irksome behavior having to do with the fact that Pro Tools imports MIDI as an entire track. If you’re replacing a short region, or want to work in sections, you’re forced to work from the end of the song and progress your way toward the front, with Pro Tools’ edit mode set to “Spot.” Otherwise, you’ll be forever slicing the empty front sections and adjusting MIDI data into place.

The good news: DTM’s final results are very accurate. On difficult jazz snare and triplet hi-hats, the detection algorithm tracked beautifully, duplicating tiny dynamic details with razor-sharp peak alignment, nearly every time. Unfortunately, if a “buried” trigger manages to fly under the radar (common with all drum replacers), you can’t add triggers in DTM. Sure, you can insert an extra MIDI note here and there using Pro Tools’ MIDI editor, but it’d make life easier if you could add triggers in the plug-in itself.

A feature that really blew me away — once I discovered its undocumented powers — is that the Clear button essentially makes certain triggers invisible to detection. This comes in handy for removing interfering bleed signals from a track. One of my snare tracks actually had a kick bleed that was louder than the snare’s ghost notes, causing all sorts of unwanted triggering and replacement. With an instance of the kick bleed selected, I clicked “Learn Drum” — causing all kick instances to come into focus — then I hit Clear. When I flipped back to the primary trigger view, the triggers that had resulted from the kick bleeds were totally excluded. Way cool.

TOONTRACK DRUMTRACKER

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Taking the attitude that to do the job right, you must break away from the confines of host software, Drumtracker is a standalone program. The interface is split into a waveform pane on top and file inputs section below, divided by a horizontal transport and navigation bar. Like DTM, it generates MIDI files, not audio. But the similarities end there.

What immediately sets Drumtracker apart is that it can load multiple audio files (mono or stereo) at once; these get listed as “parts.” This lets you work with the source tracks of an entire multitracked drum kit, and hear the part you’re working on in context, as you would if using a plug-in replacer in your host DAW. Only one part can be in focus at a time, though. Three pre-trigger filter presets are given — optimized for snare, kick, and hi-hat — while adjustable controls let you set the filter to high- or low-frequency detection, tune its bandwidth, adjust its overall attack sensitivity and trigger resolution (filter hold value), and save your settings as a user preset.

For an even bigger trick, Drumtracker analyzes audio polyphonically. I immediately dreamt of this being useful in situations calling for individual drums in a kit to “break out” from a track recorded with overhead or room mics. As much as I like to believe in miracles, this isn’t very practical. While each input file lets you assign upwards of ten separate instrument detection tracks, only a single instrument (snare, kick, hi-hat, etc.) can be filtered per selection of audio, and these selections can’t overlap. Therefore, if multiple drum types fall on the same beat, it won’t work. Not to mention, it took me ages to manually separate envelopes per region and modify varying detection thresholds along the timeline.

To its credit, the polyphonic detection method can be a useful means of extracting articulations from a single instrument file. On snare drum, for example, I used it to distinguish the “regular” hits from any sidesticks or press-hits. Though this is time-consuming, it works quite well. You can set independent mappings for each articulation, with a MIDI note corresponding to the relevant sample in your drum module.

MIDI mapping templates are offered for XLN Audio Addictive Drums, FXpansion BFD 1 and 2, Toontrack EZ Drummer and Superior Drummer 1 and 2, General MIDI, GM Extended, and generic note numbers. The 24 factory sounds are good enough for auditioning purposes only (as intended). Very usefully, you can run a standalone instrument, such as Superior Drummer, alongside Drumtracker via a virtual MIDI port in the settings dialog. Do this, and you’ll be able to hear the track exactly as it will sound when you import the MIDI back into your DAW project.

I found it took a bit of finagling to get consistent, positive results from Drumtracker. Particularly on very rapid playing or rolls, I had to manually discern hits and their velocities, often zooming in on very small sections. Letting the detection engine loose on an entire song-length drum track was rarely successful, unless the playing was extremely basic, with clearly-defined space between hits. I also tried processing the snare track with kick bleed that I’d used to test Massey DTM. With that track, false triggering caused by confusion between soft snare hits and the kick bleed was unavoidable, no matter the filter or threshold settings. I think that rather than Drumtracker’s simple high/lowpass filter, a more elaborate parametric filter that could hone in on a drum’s entire tonal fingerprint (not just the transient portion) could improve this situation greatly, so I’d suggest that to Toontrack as a future upgrade.

I like that you bring in the DAW session tempo map at the final export stage, so that all the newly generated MIDI events are correctly referenced against your project timeline. This worked wonderfully on sessions having even the most wildly varying tempo and time signature changes. By default, Drumtracker converts files to MIDI type 1 format, though type 0 and “split instruments” (one MIDI file per instrument or articulation) are export options.

CONCLUSIONS

While all products in this roundup can handle basic drum and sound replacement duties with ease, each has demonstrated a unique ability or function best suited for a specific task.

If generating MIDI notes is your objective, the choice is between DTM, Drumtracker, and Drumagog. Unlike “offline” solutions — which create entirely new MIDI tracks or audio files — TL Drum Rehab, ApTrigga 2, and Drumagog each stream their outputs as an inline effect; should you wish to turn that into a permanent audio file, you can bus its output to a new track and record it — or solo the drum track and do a bounce-to-disk.

Whether MIDI or sample-based, all drum replacers depend greatly on the expressiveness of the replacement sounds. A lackluster multisample won’t replicate the expressiveness of a drummer, no matter how accurate the detection engine is. To this end, I found the proprietary sample set, programming provisions, and automatable position control in Drumagog to be tops, with TL Drum Rehab riding a very close second.

We need to call out ApTrigga2 for bang-for-buck. At a street price of just over $50, it delivers a solid performance that could only be made better if there were user-adjustable trigger points, MIDI export, and an RTAS version for Pro Tools users.

Massey DTM’s sample-accuracy for peak alignment really impressed me, and it offers the fastest, most reliable workflow of anything in this roundup — even over the realtime plug-ins. True, some extra work is needed to insert the odd missed trigger, but it’s a fantastic tool and you won’t mind having to buy any of Massey’s other commercial plug-ins to join the “registered users club” so you can download DTM for free.

As the only standalone program reviewed, Drumtracker benefits from being completely host- and plug-in format- independent. Multitrack mode conveniently lets you hear a part you’re working on in context with the rest of the kit, just as you would in a DAW environment. Polyphonic mode, though far from perfect, is useful for extracting drum articulations, and lays groundwork for what I hope will be an improved set of polydetection algorithms in future versions. Currently best suited for working on wellisolated and non-compounded tracks, Drumtracker could easily become the “killer app” with a more powerful filter section and the ability to learn triggers from their entire sonic fingerprints, rather than just the frequency range of the initial hit. One to watch, for sure.

Ultimately, and true to its near-decade of praise, I found Drumagog stayed the truest to the nuances of original performances, and could solve virtually any of my replacement needs. It also handled fast playing the best, thanks in part to its variable resolution. Beyond fixing drum and percussion tracks, Drumagog also proved valuable on certain instrumental material. Automating the resonant prefilter together with the visual trigger display, I could pinpoint and follow individual elements within a submix or sample loop, and replace or contort them in real time. It was quite cool to “ghost” percussion samples to follow the distinct rhythms of instrumental parts such as guitar, or to make single-cycle synth waves dance to the beat and dynamics of the original drum groove. In terms of quality, features, and ease of use, Drumagog is still very much the trailblazer.