CASA-28BA User Manual
Rear panel layout
Setting up
Position your CASA-28BA active subwoofer on a stable surface capable of supporting the load and vibrations from the
cabinet. For maximum sound delivery, position with the back close to a solid wall or in a corner of the room. The cabinet
may be stood upright for a minimal footprint or on its side with the 35mm pole socket facing upward. A standard 35mmØ
speaker pole can be inserted into this socket to support a full-range or mid-top cabinet to form a full PA stack.
Aim the CASA-28BA sub cabinet towards the audience or listeners and not in direct line of sight with any microphones
that are connected to the sound system. This is to avoid feedback (howling or booming caused by the microphone
“hearing” itself amplified). Also, keep microphone stands away from the subwoofer to avoid vibrations being transferred
to the microphones.
Connect a standard line level (0.775Vrms @ 0dB) output from a mixer or other audio source to the line input of the
CASA-28BA via either balanced XLR connection or 6.3mm (jack) plug. If the signal is to be daisy-chained onto another
active cabinet (full-range or sub), connect the XLR line output from the CASA-28BA to a line input on the active cabinet.
The output of the CASA-28BA is filtered to produce only low frequencies with controlled dynamics using an internal DSP
for optimal performance but the line output is unaffected by this.
Ensure that the output level control is turned fully down and connect the IEC mains inlet to a suitable mains power outlet
using the IEC mains lead provided (or equivalent).
Operation
Switch power on to the CASA-28BA cabinet and whilst playing a line signal into the input, gradually increase the output
level control to the required output level.
A boost switch on the rear panel will add a pre-set increase to the the CASA-28BA output. To avoid damage, do not
switch this in when playing at high volume. It is recommended to turn down the output level control, press in the boost
switch and then increase the output level again to the required volume.
There are 3 LED indicators at the top of the CASA-28BA rear panel, which are labelled CLIP, SIG and POWER.
When the unit is powered up, the POWER LED will be lit. When the subwoofer is playing at normal levels, the SIG LED
will light periodically in sync with the audio signal. If this audio level exceeds the normal levels, the amplifier will “clip”
the signal, producing an aggressive and distorted output and the CLIP LED will light. If this LED lights any more than
momentarily, the output level control should be turned down to a lower setting to avoid overdriving the internal amplifier
or damaging the subwoofer drivers.
Due to the long wavelength of lower frequencies, it is easier for different speakers to be out of phase with each other,
which can have a detrimental effect on the output level. If phase cancellation is suspected between 2 sub cabinets, try
switching the phase switch between 0° and 180° to see which is the loudest or least affected setting. This switch can
also help to avoid feedback with certain microphone placements or types of musical instrument.
Turn down the output level control before powering down the CASA-28BA to avoid loud noises and disconnect from the
mains supply if not being used for long periods.