Specifications

AMP2-T assembly instructions. © 41Hz Audio / www.41hz.com Revision 1.0T boards
- Ground the signal inputs to signal ground (connect IN1 and IN2 to AGND on connector
J2). Do NOT connect the speakers yet.
- Connect the +5V supply and its ground. A 100 mA fast fuse is recommended. Important;
If the +5V supply is higher than 6V the chipset will be permanently damaged. The 5V
supply should be well stabilized and filtered. A good option is to use a type 8705 with a
1000 uF before and another 1000 uF after the regulator. Voltage regulators should always
be bypassed with a 0.1 uF or similar at input and output, close to the chip. The regulator
data sheets usually give suggested schematics for this.
- Connect the power supply. Double check the polarity of the power supply. Wrong
polarity will permanently destroy some components, including the Tripath chipset. For
the first testing, use current limiting resistors as described above.
- Turn on the power.
- When muted and with no speakers connected, the +5V should draw about 20 mA and
each main rail should draw about 1mA.
- Switch the MUTE setting from Mute to Awake
- Check the fuses. If they have blown, disconnect the board and check all components and
solders.
- With the amp unmated (awake) the +5V should draw about 50mA and the positive rail
should draw about 80mA, the negative about 200 mA.
- If the fuses are OK then, adjust the trimmer pots until the speaker output signal is as close
to 0V as you can get it. This minimizes turn on/off pops and minimizes DC through the
speakers. You should be able to trim the offset to below 10 mV. Do not run the amp for
extended periods without speakers or a dummy resistor connected.
- Shut of the power.
- Connect the speaker wires
- Connect a signal source with music.
- Set the volume on the signal source very low
- Turn on the power and check if you get any sound.
- If everything seems OK, switch off power, replace the power supply fuses for larger fuses
like 1A and try again at slightly higher volume. (The 5V fuse should remain about 100-
200mA).
- For testing at low power no heat sink is required. For low to medium power applications
the amplifier housing may be sufficient as a heat sink. For high power outputs, you
should have an efficiency of 90-95% with 8 ohm loads and 85-90% with 4 ohm loads.
The rest of the power, 5-15%, can be assumed that is dissipated from the MOSFETs. I.e.
if you drive the amplifier to 2x150W into 8 ohms you will have 15-30W of heat
dissipated. If you drive the amp to 2x300W into 4 ohms you will have 60-90W of heat.
Select a heat sink / cooling method that can handle this. Keeping the FET temperature
down is important for reliability and lifetime. The MOSFETs must be electrically
insulated form the heat sink. Using thick pads between the FETs and heat sink is a good
idea s this decreases capacitive coupling between FETs and heat sink, and thereby
minimizes the EMI that may otherwise be emitted by the heat sink.
- Connect the amplifier to your power supply and change the power supply fuses to the
proper value.
- Enjoy!
- Please note:
• Speaker leads must be grounded to the PCB connectors, not to the power supply.
The modulator feedback has separate returns from these connections. The
speaker returns are grounded in a star point on the PCB.