M-Audio BX Guide D'utilisation page 9

Adjusting the Back Panel Controls
Variable Crossover Control: We have touched on this topic already, but here are a few more points
to keep in mind:
•
The crossovers of most audio/video home theater systems are set to 80 Hz (assuming they are
being used with a subwoofer). So if you are mixing multichannel material using the BX
Subwoofer, we recommend starting with the 80 Hz setting as a reference to approximate a
typical end-user listening environment.
•
For easy compliance with Dolby
calibrated markings on the crossover dial for 80 Hz, 100 Hz, and 120 Hz positions (in addition
to 50 Hz and 200 Hz).
•
If you are using the BX Subwoofer with direct-field monitors in a two-channel setup, we
recommend starting with the crossover frequencies listed below (depending on your monitor's
driver size) and adjusting it to suit your particular environment:
5" (127 mm) drivers (such as the M-Audio BX5 Carbon or BX5 D2): 80 Hz.
o
6" (152 mm) drivers (such as the M-Audio M3-6 or BX6 Carbon): 65 Hz.
o
8" (203 mm) drivers (such as the M-Audio M3-8, BX8 Carbon, or BX8 D2): 50 Hz.
o
•
Check the documentation of your direct-field monitors to see if it recommends a specific
subwoofer crossover frequency.
Phase Selector: As we mentioned before, this switch inverts the signal (the phase angle from 0° to
180°) that goes to the subwoofer amplifier. This function does not affect the signal going to your
direct-field monitors. Set the appropriate position of this switch by listening to how the sound from
the BX Subwoofer blends with the rest of your system. There is no "right" or "wrong" position, but
the subwoofer should be "phase-coherent" with your direct-field monitors at the crossover
frequency and have no audible energy cancellation. You can determine this by playing a sine wave
signal at the crossover frequency and putting the Phase Selector in the position that gives you the
strongest output.
Volume Control: You should always send a line-level signal to the subwoofer's inputs. When the
Volume Control is all the way up, 85 mV of pink noise at the input will produce a 100 dBA output
SPL at one meter from the front baffle. The Volume Control affects the level going to the subwoofer
amplifier, not the level of the subwoofer outputs send to your direct-field monitors.
Generally, we recommend trying to get the flattest, most even system response between your
subwoofer and your direct-field monitors. Depending on the acoustics of your environment and the
setup of your signal path and levels, spend a few minutes calibrating the respective levels of the
subwoofer and each of your main monitors. If you have access to pink noise signals and/or swept
sine waves (linear and logarithmic), they can help ensure your system has the smoothest tonal
balance from top to bottom.
Subwoofer Bypass: This 1/4" (6.35 mm) mono input is for connecting a non-latching footswitch like
the M-Audio SP-1 (or any similar sustain pedal for a keyboard controller). In two-channel scenarios,
toggling the footswitch triggers a relay circuit that mutes the subwoofer's output and re-routes the
full-bandwidth audio signal to your direct-field monitors. In essence, this removes the subwoofer
(with its crossover) from the signal path so you can easily audition your mixes both with and without
the subwoofer's low-frequency extension. This can also be useful in multichannel operation.
When the subwoofer is in Bypass Mode, the LED Indicator on the front panel flashes red.
Note: More information on using a subwoofer for multichannel applications may be found at
dolby.com, dts.com, or thx.com. These websites are examples only and are in no way associated
or affiliated with M-Audio or inMusic Brands, Inc. M-Audio does not guarantee the performance or
availability of these services. The BX Subwoofer is not endorsed, sponsored, or approved by these
companies.
® ®
Digital, DTS , and THX
9
®
recommendations, we have provided