Ethereal Drums

Axis control: The axis control lies at the heart of the design in Ethereal Drums. Conventional drum libraries with a similar number of configurations can be hundreds of gigabytes in size, and in pursuit of giving the user as many tonal options as possible, complicated schemata like bleed matrices are offered as a way of controlling the attenuation of each microphone going into each drum sample. The consequence of this is an exponential increase in the size of the library; every audio file in the original recording process is passed into the end instrument, multiplying the storage size and RAM requirements of the library by the number of microphones used in the sampling process.

The axis control in Ethereal Drums controls an equal power crossfade on each channel between the monaural direct microphone signal and the stereo sum of all off-axis microphones. At center position, both signals are balanced exactly the way were when they were originally recorded; movements to the left and right respectively advance the ratio of signal toward the on-axis or off-axis signal of the drum sample. This achieves two effects: a more than fourfold reduction in the file size of the library (from over 75,000 original samples to 17,243), and a highly-intuitive tonal control that shapes the sound of each kit piece in a way that inspires. A radically different character can be obtained from the same tom drum (from tonally-centered to getting more resonance from the room), same snare drum (from a honky tone- more centered on the fundamental, to a wider sound- more centered on the wires), same kick drum (from a low thud, to more beater sound and more sympathetic ringing from the kit).

Room virtualization: If axis control lies at the heart of Ethereal Drums’ design, room virtualization is the logical extension of that concept. Effective drum miking with live kits converges on the nexus of two concepts: control and phase coherence. Control is the level of influence which can be exerted on a drum mix after it has been recorded, and phase is the relationship of two or more signals coming from microphones on the same sound source. More control means adding more microphones around the drum kit, which means control runs contralaterally to phase coherence: because there are multiple sound sources on a drum kit, it is physically impossible for every microphone to be equidistant from each sound source, and phase cancellation will therefore always occur. This can be managed with reasonable compromise when using close mics and techniques which emphasize the intelligibility of important kit elements- positioning overhead microphones equidistant to the strike position on a snare drum, for example, will result in a more stable snare sound. If not managed well, results can quickly become erratic and disruptive- pulling a room microphone up in a mix may add ambience, but subtract energy and impact from the direct mics, alter the stereo image of the kit, or cause a collapse of the signal on mono playback systems.

However, the character of acoustic spaces is a very desirable thing when it comes to drums! The sound of the drums on Motown Records is the composite of the players, the equipment, and the unique acoustics of the Hitsville U.S.A recording studio. The incredible sound of the drums on Led Zeppelin’s When the Levee Breaks is the result of John Bonham being recorded at the bottom of a stairwell with microphones at the top. The drums on the Black Album by Metallica were famously recorded in a large room with dozens of microphones around the kit. How then do you achieve those effects in a sampled drum kit?

The solution for us was to exhaustively sample 10 real acoustic spaces, and interpolate the information from those samples into 126 impulse responses per room – creating a true room mic that can be positioned to taste.

Because the drums were captured in a small, acoustically-controlled room, the kit can be positioned seamlessly into any acoustic space without risk of multiple reverberant signals clashing. And because the impulse responses are completely unmoored from the original recordings, there is no risk of introducing phase cancellation. With ten spaces to choose from and the ability to artificially expand or contract the size of each room, you can breathe the perfect amount of life into any drum performance.

Microphone modeling: All pieces were captured in a heavily acoustically-treated room with the Earthworks DK7 drum microphone system. To model the other microphones offered, they were placed in the same environment and a combination of sine sweeps, white noise bursts, and snare drum strikes were used to create an audio data set. A general regression neural network was then trained on data from the different microphones, and the average frequency response and transient sensitivity needed to translate the reference microphones into each of the modeled microphones was then interpolated into impulse responses. The end result, while not identical to using a different microphone, comes extremely close; close enough to pass a blind A/B test! 13 microphones have been modeled in addition to the original unaltered signals, giving yet another intriguing way in which the sound of Ethereal Drums can be shaped to your needs.

Standard mix options/ADSR/Tuning: As well as microphone modeling and room virtualization options, a fully-featured mixer with all the conventional options you would find in a DAW are offered, allowing all the mixing to be done from within Kontakt. This includes volume control per channel, panning, mute/solo/phase, an SSL-style 4-band EQ, a transient controller, and an SSL-style bus compressor. As well as conventional mixing options, per-channel ADSR is offered, send values to independently-controlled room and reverb channels, and tuning control over any kit piece in a range of 5 semitones above or below. If more processing options are desired, channels can also be routed out of Kontakt to separate channels in your DAW, allowing the kit to be processed and mixed the same way a live kit would be.