L-Acoustics MTD Series, Operator'S Manual

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L-ACOUSTICS MTD Manual V1.2 30-11-04 55
b) LF Service
The 8”, 12” or 15'' loudspeaker components of the coaxial assemblies used in the MTD108a,
MTD112b and MTD115b are not field-serviceable. For field service, the entire coaxial assembly
should be removed and replaced.
To remove the front grille, lift the edges of the acoustic foam and remove the screws. Screws can be
found where the edges of the foam are not glued onto the grille - there is no need to completely
remove the acoustic foam in order to remove the loudspeaker grille.
The damaged loudspeaker should be returned to your distributor or directly to L-ACOUSTICS for
warranty examination and reconing.
c) Polarity Check
Whenever a HF diaphragm or loudspeaker component is replaced, wiring polarity should be checked
with a polarity checking device. Both LF and HF components should operate with positive polarity.
d) Periodic Check
The frequency response of the enclosure should be checked periodically to check for any deviations
due to wear, shock or other damage. This should be done on an annual basis for systems not
subjected to demanding use. For systems being used on a daily basis for sub hire or touring,
enclosures should be checked every month (or even more frequently).
A frequency response check can be performed with a high resolution RTA (real time analyzer), or
preferably using WINMLS, SMAART, SPECTRAFOO, TEF or MLSSA measurement systems. Refer to
the on-axis amplitude/frequency response to determine if your MTD enclosure is within specification.
In addition, a response sweep using a sine wave generator is useful for checking for coil rubs, buzzes,
air leaks or other undesirable mechanical vibrations as part of the periodic quality control procedure.
The mechanical attachment of both low frequency and high frequency loudspeakers should be
checked periodically since mount screws can become loose after being submitted to intense, long
duration mechanical vibrations. Similarly, it is a good idea to periodically check that the high frequency
diagram and rear cover for the compression driver are solidly attached. The quality of the contacts
and locking action of the SPEAKON connector should also be checked periodically.
7.2 SPARE PARTS
MTD108a
HP BC12 1" driver 8 Ohms HS BC12 Diaphragm for 1" driver
HS PH82 8" recone kit HR PH82 8" recone kit inc. labour
CM MTD108a Front foam MC MTD108aGRL Front grill
MTD112b
HP BE121 12" coaxial speaker 8 Ohms HS BE21 Diaphragm for 1,4" driver
HS BE121 12" recone kit HR BE121 12" recone kit inc. labour
CM MTD112b Front foam MC MTD112bGRL Front grill
MTD115b
HP BE151 15" coaxial speaker 8 Ohms HS BE21 Diaphragm for 1,4" driver
HS BE151 15" recone kit HR BE151 15" recone kit inc. labour
CM MTD115b Front foam MC MTD115bGRL Front grill
CD COLNEO
Neoprene glue in spray 500ML (for attachment of grille foam)