Allen&Heath XONE DB4 - Manual (Page 24)

Allen & Heath 24 XONE:DB4 User Guide
BPM ENGINES
The XONE:DB4 has four independent BPM detection engines, one per channel. Tempo analysis is
complex, what might seem an obvious beat to a human requires sophisticated algorithms for a
microprocessor to interpret.
Unlike a DAW (digital audio workstation) the DB4 doesn’t have the complete song file to analyse, it has
to do it real time by “listening” to the audio. To improve the speed and accuracy of tempo analyses the
beat detection engines can be guided to look for a tempo within a given range. This is selected in the
setup menu, under “BPM RANGE”.
The range options are shown Left; choose one that nearest matches the style of
music you normally play. If you tend to play songs with a wide variety of different
tempos, set the detection system to 60 to 240, but be prepared for the occasional
misreading, usually a direct harmonic of the real tempo, especially where there is
syncopation.
If the BPM is obviously incorrect, tap the beat using the FX TIME/TAP control;
this will guide the detection system to trigger off the correct percussive elements
within the track, and assist accurate beat analysis.
EXTERNAL MIDI CLOCK
If your playback source is a DAW running through the built-in USB2.0 multi-
channel soundcard, you can use MIDI clock as the timing source for the DB4, this
will override normal BPM detection and affects all channels. If you select this
mode make sure that your DAW supports sending MIDI clocks, and that this
feature is enabled.
INTERNAL MIDI CLOCK
From Version 2 Firmware, the XONE:DB4 can also generate internal MIDI clocks which can be sent
via USB to a DAW. Refer to the MIDI SETUP Menu option on page 25 for details.
Note - If the BPM engines are set to “MIDI Clock” and the Internal MIDI clock enabled, global tempo
is set by the internal MIDI clock.
TEMPO RESET
The BPM detection system can be forced into a reset by holding down the FX TIME encoder until
the tempo display changes to “- - - .-”. The BPM is automatically reset when a new audio source is
selected, or the range changed in the menu. The BPM cannot be reset whilst a loop is active on
that channel, until the looper is cleared (ROLL LED OFF).
TAP TEMPO
In addition to the previously discussed detection and synchronising systems, a BPM can be ‘tapped’
using the FX TIME encoder. You need to tap a minimum of six times before the tempo will be
displayed. The tap function can be used to force the BPM detection system to lock onto a harmon-
ic of the beat, useful for creating odd time signatures.
Tap tempo can also be used to extend the Loop length for tempos over 120BPM. For instance,
tapping every second beat of a 128BPM track will force the BPM engine to sync to 64BPM, thus
doubling the loop time from 4 bars to 8. Note that the displayed beat fractions will be out by a fac-
tor of 2.
TEMPO LOCK
Current Tempo can be locked at any time by pressing and holding the FX TIME encoder until the
padlock symbol comes up in the display. When a tempo is locked it will not change when switching
to an alternative audio source.