Fxpansion BFD2: How it Works

BFD2 is one of the most impressive electronic drum instruments I’ve ever used. The fact that it’s a Pro Tools plug-in makes it all the more amazing. Creating drum tracks in Pro Tools with BFD 2 can yield some truly unbelievable results. So, being in a BFD kinda mood, I thought I would post this explanation of the inner workings of BFD 2 which will illustrate why it’s not just another drum sample player.1

Disk-streaming multi-channel sample playback engine

At the heart of BFD2 is a sample playback engine that streams multi-channel audio recordings of drum, hihat, cymbal and percussion instruments – called kit-pieces – being played in various ways, and recorded with multiple sets of microphones.

There is an inherent latency when accessing files on a hard drive. Because of this, BFD2 caches a short segment of the start of every sound in system memory. Therefore, even though BFD2 can use a lot of RAM, it allows you to use sounds with detail levels far beyond conventional RAM limitations. Hard disk space is far cheaper than RAM, and will be for the foreseeable future.

Dedicated interface for working with multi-channel acoustic drums

Rather than having to work with a generic sampler interface and sample libraries designed within its limitations, BFD2’s user interface allows you to work with its hyper-detailed sample library as if you were playing and mixing a real drumkit.

There are functions dedicated to building the custom kit of your dreams in seconds, tuning and damping kit-pieces, and high-end studio quality mixing tools. It features simple-to-use mapping tools, and dedicated support for electronic drumkit systems. Meanwhile, the flexible Groove engine lets you lay down convincing drum tracks quickly and easily.

Anatomy of a BFD 2 kit-piece

Articulations

A kit-piece is made up of one or more articulations. These were referred to as ‘hit types’ in previous versions of BFD. An articulation is an individual way of playing a percussive instrument such as a drum, cymbal or hihat. For example, hihats feature up to 11 articulations – a pedal-down sound (‘foot-chick’) and tip and shank (edge) sounds when the hihat is closed, fully open and at three positions in-between.

Good use of multiple articulations allows greater realism than using conventional sample-sets, because of the expressive range possible on a drumkit.

Velocity layers

Each articulation is made up of a number of audio files, called velocity layers. These audio files are recordings of the articulation being played at varying intensities from soft to hard. As well as the amplitude (‘loudness’), the timbral response of percussive instruments varies greatly with playing dynamics.

The high amount of velocity layers in BFD2’s sounds lets you recreate the sound of dynamic drumming, giving convincing results when using accenting. This is very important in the formation of realistic grooves.

Multi-channel audio files

Each velocity layer is an audio file made up of multiple channels. These are recordings from several sets of microphones used to capture each kit-piece. Real drum recording situations commonly use multiple mic setups in order to capture a variety of different elements.

Firstly, a kit-piece may sound different depending on where a mic is placed. Snares sound very different when mic’d from above compared to from below – a mic placed on top captures the ‘pop’ of the skin being struck, while the crunch and sizzle of the mesh snare is captured at the bottom. Meanwhile, mics inside kick drums tend to pick up the ‘snap’ or ‘click’ of the beater striking the drum. The main ‘thud’ and low-end power is captured by a mic outside the kick drum.

Drum recording situations also make use of stereo sets of mics to capture the kit as it sounds as a whole within a space. They capture the projection of the kit and its reflections within the room much more effectively than individual directional close mics on various parts of the kit, which sound very dry in comparison.

Articulations

Here is a summary of possible articulations in BFD2. Please note that some kit-pieces do not contain all possible articulations.

Kicks Hit
Snare Hit
Rim
Sidestick
Drag
Half-Edge
Hi-Hats Pedal
Closed tip
Closed Shank
1/4-open tip
1/4-open shank
1/2-open tip
1/4-open shank
3/4-open tip
3/4-open shank
open tip
open shank
Toms Hit
Cymbals Hit
Bell
Edge
Percussion Hit
Alt

Mic channels

Fxpansion BFD2: How it Worksmixer signalrouting 300x190

Each velocity layer sample of each Kit-Piece articulation possesses 12 mic channels (3 stereo, 6 mono)

Ambience channels (stereo)

Overhead The signal from the stereo Overhead mic set, above the kit.
Room
- M/S Room in BFD2
- Stereo room in most previous BFD libraries
The signal from the room mics. BFD features an M/S room mic set. BFD’s mixing engine decodes each M/S-recorded kit-pieces on the voice level, so you can mix and match kit-pieces with previous BFD libraries, most of which feature a stereo Room.
Amb3
- Room in BFD2’s library
- PZM in most previous BFD libraries
The signal from the third set of ambient mics. The wide, high placed Room mics in BFD2 and PZMs in previous libraries all tend to sound huge!

Direct Mics (mono)

Kick In The signal from the mic inside the kick drum.
Kick Out The signal from the mic outside the kick drum.
Snare Bottom The signal from the mic underneath the snare drum.
Snare Top The signal from the first mic above the snare drum.
Snare Top 2 The signal from the second mic above the snare drum. BFD2’s library is the first to contain this mic channel, which does not exist in previous BFD libraries.
Multi The signal from the direct mic for all Kit-Pieces except kicks and snares. This is usually empty for kicks and snares.

Primary direct and bleed channels

The kick and snare mics are used for all Kit-Pieces, as bleed signals are recorded through them.

A Kit-Piece’s own close mic’d direct signal is known as the primary direct mic channel. For a kick, this is in the Kick In and Out mic channels, and for a hihat or cymbal, it is in the Multi mic channel.

The Kick In/Out mic channels are the primary direct mic channels for the kick. Bleed from the kick appears in the Snare Bottom/Top mic channels. The Multi mic channel is empty for kicks, except on certain BFD XFL kicks, which feature bleed captured through the hihat mic.

The Snare Bottom/Top mic channels are the primary direct mic channels for the snare. Bleed from the snare appears in the Kick In/Out mic channels. The Multi mic channel is empty for snares, except on certain BFD XFL snares, which feature bleed captured through the hihat mic.

The Multi mic channel is the primary direct mic channel for all other Kit-Pieces, whose bleed appears in the Kick In/Out and Snare Bottom/Top mic channels.

Bleed is only present in the kick and snare mic channels. Bleed from the other mics is not included, because the levels were too low and not useful enough to justify the extra RAM and hard disk bandwidth required. In any case, bleed can be, in many cases,an annoying side-effect of the drum-recording process, which is often minimized during post-processing by using noise gates.

What Next?

  1. The content of this page is from pages 7-10 of the BFD2 Manual and is used with permission from the copyright holder.

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  1. [...] For those who might not be familiar with BFD 2 – a quick explanation: BFD is an acoustic drum production environment that works as an RTAS plug-in within Pro Tools. BFD 2 is easily one of the most powerful and flexible drum production tools ever to hit the market. You can read a more detailed explanation of how BFD2 works, here. [...]