FXpansion BFD Premium Acoustic Drum Module Mixing with BFD - Manual (Page 17)

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Mixing with BFD www.fxpansion.com
All the kick drums in BFD, BFD XFL and Jazz & Funk Collection were recorded with both
kick mics facing in the same relative direction, so the above phase concerns do not really
apply. However, the phase-flip switch is provided if you want to experiment with inverting
the phase. The Deluxe Collection kicks were recorded with the ‘inside’ mic actually on
the beater-side of the kick skin, so it is effectively out of phase with the outside mic.
Therefore, you can consider these kicks in the same way as the snares when it comes
to phase. However, please note that the distance between mics relative to the very low
fundamental frequency means that most energy at lower frequencies is in phase.
Also, be aware that playing with the Distance and Width controls for the ambient buses
can also introduce phase shifts relative to each other and to the direct signals for the kit.
It’s very important to remember that phase shifts are an unavoidable real-world
phenomenon and are the reason that effects like stereo make sense to us at all. If
you’re worried about it, investigate using phase meters to check the phase of different
channels relative to each other. Any phase differences up to 90 degrees are nothing to
be concerned about, but anything above this could be a problem. It is good practice to
check your mixes in mono - any problematic phase shifts between different stereo signals
will become apparent when the two sides of the stereo image are are merged into mono
- anything severely out of phase will be prone to cancellation effects.
• Phase shifts with external processing
You should also be aware that plugins and external routing through processors can
introduce phase shifts. Many processes such as EQ also involve phase shifts. Some
plugins or routing functions will delay audio slightly within the host itself, potentially
causing phase shifts. When using hosts without automatic delay compensation features,
you should manually delay tracks to get them in sync with each other.
3:6. Levels and mixing headroom
Some people find that the output of BFD is too quiet compared to other plugins. There is
a very simple reason why BFD’s sounds do not constantly reach 0 dB on your host mixer:
headroom!
Drums have a very large dynamic range - there is no compression used in BFD’s
recordings, so lower velocity layers are very quiet, while higher velocity layers approach 0
dB. Without the headroom inside BFD, there would be a very real danger of clipping.
If two signals in phase with each other are added together, with each peaking at -6db at
the same time, the resulting waveform will peak at a level of 0db. This is a fundamental
truth which cannot be avoided, and it has to be taken into account when mixing in BFD.
Otherwise the outputs would be a distorted mess when not solo-ing one or two Kit-pieces.
As a side-note, although the audio files in BFD are recorded at 4-bit resolution, they
are actually processed at 3-bit floating-point values when loaded into the plugin, so that
there is as much headroom as possible to sum all the sounds together without the risk of
internal clipping.