Care And Maintenance; Maintenance Information; Testing Procedure; Check Of Transducer And Enclosure Acoustic Behavior - L-Acoustics SB28 Manuel D'utilisation

SB28
Subwoofer Enclosure
USER MANUAL
VERSION 1.1
8

CARE AND MAINTENANCE

8.1

Maintenance information

®
The L-ACOUSTICS SB28 enclosure is a technical product designed for various, intensive indoor and outdoor sound
reinforcement applications. To fulfill such demanding conditions L-ACOUSTICS
high grade and reliable components:
• Weather-proof transducers made of materials with high immunity to oxidation.
• Baltic birch plywood-made cabinet.
• High resistance, non biodegradable ''Airnet'' front grill fabric.
•
Cataphoresis-coated steel grill.
•
Screws and rigging points resistant to oxidation.
However, in order to ensure product performance and safety, it is essential to frequently inspect the SB28 cabinet and
its internal components. These checks need to be done on a regular basis depending on the conditions of system use.
The testing procedure consists of three steps as described in section 8.2. If a speaker needs to be replaced follow the
procedure described in section 8.3.
8.2

Testing procedure

8.2.1

Check of transducer and enclosure acoustic behavior

Use a sweep frequency generator with a maximum voltage of 0.5 volts (-4 dBu, -6 dBV) connected to the active input
of the LA8 amplified controller. Apply a sweep from 25 Hz to 100 Hz: the sound should remain pure and free of any
unwanted noise. If not, check the mechanical assemblies and if necessary contact an L-ACOUSTICS
representative to repair damaged components (see also section 8.3).
!
0.5 volts is a maximum value that can generate very high sound levels at given frequencies.
Use ear protection to set the sound level before testing.
WARNING
Whenever an 18" loudspeaker is replaced wiring polarity should be checked using a phase checking device. If a
transducer is out of phase invert the cables connected to the transducer electrical socket. Cabling procedures are given
in section 8.3.

8.2.2 Check of mechanical assembly and rigging parts

Check for absence of cracks on the cabinetry. Inspect the general aspect of assembly and check that screws are locked
tight (on rigging elements, loudspeakers, and grill). Check the quality of contact and locking action of the Speakon
socket. Also check the integrity of rigging elements (no signs of deformation, cracks, or rust). If necessary, contact an L-
ACOUSTICS ® authorized representative to replace damaged components.
8.2.3

Check of external aspect

Remove the dust from the grill with a vacuum device. If needed, repaint the cabinet.
!
If paint is applied protect mechanical parts.
Do not apply paint to the front grill fabric as it could fill the fabric holes and deteriorate the acoustic
transparency of the material.
IMPORTANT
SB28_UM_ML_1.1 w w w . l - a c o u s t i c s . c o m
® has designed the SB28 enclosure with
® authorized
®
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