Specifications

AMP2-T assembly instructions. © 41Hz Audio / www.41hz.com Revision 1.0T boards
has a cooling slug that helps transporting heat to the PCB or a heat sink. There are
mounting holes through the PCB for optionally using an external heat sink on top of the
chip.
3. Gate drive resistors and protection diodes. These are between the driver chip and the
FETs and control the switching speed and indirectly also the heat dissipated by the driver
chip. Also, the current sense resistors are here.
4. This is the main power supply rail with positive, ground and negative supplies. The rail
has high ripple, low ESR, bulk capacitors that the MOSFETs draw current from. There
are also decoupling capacitors and protection diodes.
5. This is where the power switching MOSFETs are. There are normally two MOSFETS for
each side; one for the negative side and one for the positive side. Most users will
probably use only the standard MOSFETs. Each of the four FETs has a gate drive resistor
and protection diode. Between the power rail and the MOSFETs there are current sense
resistors for over current detection / protection. These shut down the output in case the
curret is too high, such as if the speaker cables are shorted (don’t try it…). The 10V
SMPS generator components are also located here. For the low side FETs, the gate drive
voltage must be 10V above the negative power rail. The TP2350B chip has a built in 10V
SMPS output that drives an external MOSFET and generates this voltage. The VN10
generator has its own inductor and capacitors to smooth out the ripple. Up to 200 mA
current is drawn from the negative rail for this.
6. Left channel output section. The output part for each side has filters that remove high
frequency patterns from the power switches that could otherwise recombine into audible
noise. A second order, two pole filter is used. It consists of a toroid inductor, some high
ripple filter capacitors and a snubber resistor. The corner frequency is in the order of 100
kHz. This section also holds the connection points for the loudspeaker leads.
7. The same as section 6 but for the right hand channel.
Components not included in the kit
The following parts / components will at some stage be needed to complete the amplifier, but is
not included in the kit:
- Heat sink with screws and heat conductive paste to mount the heat sink. One of the great
advantages with PWM mode amplifiers is that the heat losses are small. However, this is
a high power amplifier and even if only a small percentage of the power is dissipated as
heat, the heat can be considerable for a high power / low impedance application.
- Copper wire for the inductors. About 2.5 meters (8 ft) of 1.2 or 1.3 mm (AWG 16)
enamel insulation copper wire is needed. “Litz” type multi-strand wire of the same
equivalent area can also be used and is recommended as it is much easier to wind and has
good high frequency characteristics. However, Litz wire is expensive and a bit hard to
source.