Recording The Robo-Kit

Producer Kent Sparling is a multi-instrumentalist, composer, and film mixer/sound designer with several big credits to his name, including Sofia Coppola’s Lost In Translation, Spike Jonze’s Adaptation, and James Cameron’s Titanic. Over the years we have also worked together on a number of independent music CDs, mostly for Vanessa Lowe, Kent’s wife and music-making partner. For our most recent studio outing — Lowe’s Stars Of Bean Hollow — Sparling devised a “robo-kit” to supply unique percussive underpinning.

The components of the robo-kit are a programmable drum machine, computer recording software, an amplified playback system that routes drum-machine tracks to small speakers, plus standard (and non-standard) parts of an ordinary drum kit, which are miked in a room. No sticks were harmed in the making of this record! This is the story of how it was done.

The Concept

After producing three Vanessa Lowe albums with the unfettered creative energy of Tobias Hawkins on drums and percussion, it was decided that the current recording should be focused more on the voice and songwriting, and that the rhythmic backing would exist in a supporting role. It seemed clear that to ask a primarily improvisational drummer to lay down simple quarter-note hats and 2/4 kicks and snares inspired by soul and country-and-western records would be akin to harnessing up an Arabian racehorse to a country doctor’s buggy. Clearly, another plan was called for.

As far back as 1987, with songwriting partner Matt Rohr, Sparling had experimented with feeding keyboard and drum-machine sounds out to real-world “modifiers,” and recording the augmented sound on a separate track, to be blended with the original, “dry” signal. There is something unmistakable about real instruments in real environments moving air molecules — call it “energy,” “excitement,” or “juju” — which is too often lacking in modern music.

By blending drum machine sounds and the close and room mikes of the real drum kit, Sparling envisioned a way to craft an organic drum sound that would support perfectly Lowe’s original songwriting and her inventive rhythmic finger picking on acoustic guitar. Thus, our robo-kit was born.


With only a little prior knowledge of techniques for recording drums triggered by speakers, there was some trial and error involved in the setup of our robo-kit recording session at Guerrilla Recording in Oakland, California. First, trigger parts for kick and snare were programmed into a Yamaha RX5 drum machine, using both the “factory preset” sounds as well as others from the “Jazz” and “Electronic” Voice ROM cartridges issued by Yamaha in 1988. These patterns were recorded on separate tracks into Pro Tools sessions, syncing the RX5 to Pro Tools using MIDI clock.

For several of the songs, duplicate trigger sources were recorded for both kick and snare, as well as additional percussion parts, using sounds from Native Instruments’ Kontakt sampler. Finally, discreet click tracks and hi-hat guide tracks were recorded, so the players could listen to a mock-up of the finished full rhythm, or any submix of their choice (more click, less kick-snare, etc.) while recording.

The next step was to route our kick and snare trigger sounds to an amplifier and two transducers, which would each “excite” a single drum. We had a small battery-powered Dayton Audio DTA-1, 15W “T-Amp,” which gave us a stereo input on a hacked 1/8" mini plug, and outputs on speaker-wire terminals. The T-Amp was ideal for percussion sounds because of its reputation in the “hi-fi” world as being an extremely good amplifier for reproducing fast transients. One of the hardest parts of the process was field stripping RCA cables to make the proper wiring connections — a little more planning ahead of time will save you studio time on this part of the rig.

To trigger the drums with our prerecorded sounds we used an old Radio Shack 5" dual-driver speaker, set face down on the top of the snare drum, and for the kick we used a Sonic Impact 5029 Soundpad, which is basically a “stick-on speaker.” The Soundpads have a standard magnetic speaker coil which is attached to a sticky-backed piece of cardboard — when you stick the cardboard to a large, thin, vibrating surface, such as a sheet of metal or a window or a kick drumhead, the sound is transferred to that surface as though it were the speaker cone — perfect for our kick drum trigger. We placed the Soundpad on the kick head right about where the beater would hit from the kick pedal.

Getting the tracks routed out of a Digi 002 rack, with easily accessible level control for the kick and snare speakers, proved to be an additional challenge. What we settled on was to route a rough mix of the music tracks — including the robo-kit mikes being recorded, as well as copied drum machine tracks — to the studio monitors, while simultaneously routing the drum machine tracks from the headphone output jack on the Digi 002 to the T-Amp in the drum room. Since there were only two signals being sent (kick and snare) this was easily accomplished by running a single stereo headphone extension cable out from the control room.

The headphone level control on the Digi 002 rack allowed us the convenience of making volume adjustments to the levels being sent to the drums, while monitoring the resulting tones from the control room. This saved us a lot of trips down the hall to the drum room! Adjustments to the levels being sent to the individual kick and snare tracks could also be made within Pro Tools, of course, and this was done when we sent a blend of more than one drum machine sound to trigger the real drums. Not surprisingly, in this part of the process we found that adjusting the volume level of the trigger tracks had a dramatic effect on the attack, tonality, and resonance of the actual drums.


Drum Talk

For each song we tinkered with decisions about how hard the drums should be “hit” by the speakers, as well as making the kind of miking and tuning decisions that would typically take place on a drum-recording session. One interesting discovery at this stage was what a difference it made in the real drum sound to feed different sounds as triggers. Depending on the needs of the song we would choose either the RX5 sounds or the Kontakt samples as triggers, and occasionally a mix of the two. This was an area that could certainly yield many great results with further experimentation, and we plan on delving deeper into these kinds of experiments on our next project together.

Of course the drums themselves play a huge role in the ultimate sound of these tracks, and we based our recordings on the funky little home-build kit that Lowe’s drummers have used live for many years. The kick drum is actually an 18" Gretsch floor tom, modified to accept a kick pedal and sit happily on its side. The snare is a 14" x 8" maple Gretsch. Heads were by Evans and Remo. The drums are both warm and snappy when they need to be, and provide the perfect complement to what is essentially an acoustic band.

The kick was miked with a Sennheiser 502 large-diaphragm dynamic, which was positioned either inside or just outside the drum on a song-by-song basis. The snare was miked with an older Electro-Voice 402 supercardioid dynamic placed a couple of inches from the upper hoop of the drum. A room mike (Neumann TLM 103) was also recorded with each drum pass, as an additional source for blending the kick and snare tones and giving them a bit more of a live ambience.


There were a few songs where we went beyond the simple kick/snare treatment; for “Go Little River” the drum pattern actually used three different snare drum samples and a rack tom sample, all of which were “sub-mixed” before being sent to the amp that triggered the snare. Each one of these very different trigger sounds reacted and interacted with the real snare in different ways, and some time was spent finding the right blend of trigger sounds to achieve the desired result. For this song our complex preparation yielded an improved sense of dynamics and tonal variation, as though the drummer were playing different parts of the drum, hitting the hoop, etc.

For the song “Now,” which had always been conceived by Lowe to be a percussion-based song, we moved away from the kick and snare alone, and sent additional trigger sounds (such as electronic toms, cowbells, and noise shots) to both the snare drum and a metal paint-roller tray, which we filled with coins and keys. To trigger the metal tray we used both the Soundpad and an old pair of “Walkman”-style headphones. The Soundpad got the keys jumping in the tray, while the tinny sound of the little headphones acted as a prefilter on the trigger sounds, adding another interesting layer to the processing of this rhythm track.

And although our experimentation stopped there, further creative exploration of this technique of sending vastly differing trigger sounds to various drums is guaranteed to yield many exciting results. Imagine triggering a variety of instruments and percussive objects this way: acoustic guitar, large metal cans, cardboard boxes, hand drums, etc.

More Drum Production And Mixing

After a long but rewarding day of recording, the robo-kit drum tracks formed the basis of a hybrid electro-acoustic drum kit. And yet there were still more elements to add. Over numerous additional sessions, Sparling recorded hi-hats miked very close in a dead room, shakers and hand percussion in a semi-live environment, and finally tom fills (from a child’s miniature drum kit), assorted wood blocks, and Pete Engelhart metal percussion in the empty wood-and-plaster living room of a 1920’s Berkeley bungalow. With a wide array of sounds from different sources and environments it was now the task for Sparling and engineer Ian Pellicci to fuse them all together in the final mix. Sparling comments:

“What made mixing these tracks unique for me was the ability to fine-tune the ‘shape’ of the drum hits, depending on the balance between the original, dry drum machine trigger sounds and the true drums. If it seemed like the song needed a more laid-back feel, then I was able to dial down the drum machine tracks (or lose them entirely, as we did on a few songs) and rely only on the ‘softened’ sound of the triggered true drums. Conversely, the samples could add a distinct and very different attack to the ring-out of the true drums that followed.

“Some really interesting effects were created by treating the machine sounds and the true drums with very different compression settings, and then blending the results. In addition, the percussion overdubs each had a roominess of their own built in to the recordings, and it was interesting to hear the close, dry hi-hat playing alongside the live and roomy tom fills. We ended up using the room mike from our original kick-and-snare session quite a bit to ‘bind’ the whole effect together, and create a unified sound.”

The Takeaway

The techniques described here could be thought of either as a new way to expand the palette of a drum machine, or alternately as a method to bring a greater level of control and repeatability to elements of the traditional drum kit. The robo-kit can be employed to execute parts that would be maddeningly sparse for most drummers, or even too fast to be played by human beings. Stylistically there are no limits — any feel that can be imagined and programmed can be brought to life in the drum room. And of course there is also unlimited creative potential in this hybrid approach to concoct new percussive textures for electronica, dance music, and more experimental music genres and forms.

It is important to remember that the robo-kit as we implemented it is just one way to combine the precision of the drum machine with real-world drum sounds. This method was arrived at mostly through experimentation, and is not the only way. Make this approach as simple or complex as you wish, but make it your own, and have fun with it.