Connections and Settings

Inputs:

The amplifier inputs are coupled via 1.0uF capacitors so they can handle single ended or differential signals.

For Single Ended signals (shown on left), connect:
  • R+ to R+
  • GND to R-
  • L+ to L+
  • GND to L-
For differential signals, connect:
  • R+ to R+
  • R- to R-
  • L+ to L+
  • L- to L-
For volume control, a dual 50K audio taper pot can be wired in series with the inputs as shown.

Outputs:

This amplifier is designed to drive moving coil loudpeakers only. Speaker impedence must be 3ohms or more. The output signal is a 360KHz PWM square wave with a duty cycle proportional to the audio signal. The inductance of the speaker coil serves as a low-pass filter to average out the high-frequency components. Do not try to use this as a pre-amplifier.

The outputs of each channel are "Bridge-Tied" with no connection to ground. This means that for each of the two channels, the + and - alternate polarity to create a single channel amplifier with twice the available power.
However, that means you cannot bridge R and L together, so don't try to connect ROUT to LOUT, it will damage the amp! If you only need one speaker, just connect to either ROUT or LOUT and leave the other output set alone

Connect your speakers using the 3.5mm screw-terminal blocks.

Gain:

Gain is configurable for 9, 12, 15 or 18 dB. For higher level outputs such as from a WaveShield, you will want to select a lower gain. For low-level outputs such as from an iPod or MP3 player, a higher gain setting works best. To set the gain, install the jumper in one of the 4 marked positions on the 4x2 header.

Power:

The amplifier can be powered by 2.7 to 5.5v DC. Good power sources are:
Connect the negative wire to GND and the positive wire to VDD.
This guide was first published on Jan 27, 2013. It was last updated on Jan 27, 2013. This page (Connections and Settings) was last updated on Aug 22, 2019.