A and T Labs
K6 Audio Power Amplifier Assembly Manual
2001 A and T Labs Inc.
AMK6a
12
3.3 HEAT SINKS AND MECHANICAL ASSEMBLY
Both the amplifiers and the inverter are designed to edge mount their power
components on the board, with their attachment to the heat sinks via a linear flange or
flat mounting scheme. Figures 6 and 7 show the two basic enclosure designs for the
5 ¼” natural convection and 3 ½” fan cooled units, along with their heat sink flange
arrangements.
The 3 ½” unit has fans and is the preferred configuration for sound re-enforcement and
other heavy duty applications. The 5 ¼” high design is intended for home installations in
which the fan noise may be objectionable, and uses natural convection cooling. For
this, more heat sink area and vertical fin orientation is necessary, and the unit height is
increased to 5 1/4", with the heat sinks across the back. The amplifiers are mounted
one above the other, with the power supply at the bottom. For this physical design, it
will also be necessary to run wires to the front panel mounted LEDs.
The flanges for both amplifiers and the power supply will be prepared at this time and
the power components mounted for the power supply. Use the circuit boards or artwork
as drilling templates to locate the transistor mounting holes. The flanges also need to
be match-drilled with the heat sinks per the drawings. The lateral positioning of the
flanges on the boards for the 5 ¼” unit is approximately centered. The mounting of the
flanges to the heat sinks can be accomplished with three holes per flanged, drilled to
avoid conflict between parts on the board and the screw driver or Allen wrench that will
eventually mount the assembly to the heat sink. Drill holes through the flanges such
that they are close to vertically centered on the flange, and fall midway between heat
sink fins. The easiest approach is to drill and tap the holes in the heat sink.
Alternatively, with careful spacing, nuts may be used. Lateral positioning of the
amplifier assemblies is such that the input RCA jacks sit just inside the holes on the
right side of the enclosure.
For the 3 ½” unit, the lateral positioning of the amplifier flanges is centered on the board.
Lateral mounting of the assembly on the heat sink is chosen to align the front edge of
the board with the front of the heat sink, such that the board mounted LEDs can
protrude through their respective front panel holes. Vertical positioning of the holes
should be such that the holes fall midway between heat sink fins.
Be sure to remove all burs from holes, as they may cut through transistor mounting
insulators and cause short circuits, or cause the flanges not to lie perfectly flat against
the heat sinks. At this time, prepare the mechanical assembly of heat sink components,
drilling the flanges and heat sinks.
Mechanical Assembly
Prepare mechanical assembly
