Specifications

horn to the enclosure. On the APL-500, this is most easily accomplished

by using a ball-headed Allen wrench. Pull up on the horn to unseat it from

the gasket.The next step is to lift the horn away from the enclosure and

reach in through the cone driver opening to remove the 7/16" hex nuts

that retain the driver to the horn.This is easier to accomplish with two

people – one holding the horn and one removing the nuts. Make sure to

support the driver with one hand as the nuts are being loosened to avoid

damage. Once the nuts are free, you can disconnect the wires to the HF

driver and lift it out through the cone driver opening.To replace the HF

driver, simply reverse the disassembly process.

There are no user serviceable parts inside the compression driver. It is

not possible to change the diaphragm without detailed knowledge of the

proper procedure and access to the necessary test equipment. If you

attempt to change the diaphragm without the required test equipment,

performance may be seriously degraded.

Replace the compression driver with a new or rebuilt unit by reversing

the procedure described above. Once the enclosure is fully reassembled,

test it to verify that it is operating properly by comparing it to a speak-

er of the same model that is know to be performing properly.

(2) Processor / Amplifier Removal & Replacement

Before attempting service work, be certain to disconnect the power

cable from the unit. Lethal voltages are present inside the enclosure

when the unit is connected to an AC mains supply!

The amplifier package consists of a heat sink assembly attached to the

rear of the APL-220, -500, or -800. It is accessible only from the rear of

the loudspeaker. The heat sink is held in place by thirteen (13) Philips

drive fasteners.

Once the fasteners are free, the plate can be removed. Because the gas-

ket may tend to stick, you may need to provide a little force to the top

and bottom of the heat sink’s fins to pull it free.

CAUTION: The ends of the fins tend to be sharp - be careful not to

cut yourself!

Once free, the amplifier assembly can be easily disconnected from the

processor and drivers. All interconnects are of the polarized quick-dis-

connect type.