Sometimes we need configurable multichannel amplifiers for experiments or for use in offices or schools. Here is a multi mode audio amplifier circuit based on TDA1554Q, configured for multi-mode function with four channel outputs.
Multi mode audio amplifier circuit
The circuit of the simple 4-channel multi mode audio amplifier is shown in Fig. 1. It has four channels and each channel can provide around 11W over a load of 2-ohms and around 6W over a load of 4-ohms. The circuit will also work with loads of 4-ohms to 16-ohms.
The multi-mode function includes single-channel and bridge-tied load (BTL) modes. These are controlled using switches S1 and S2. In bridge mode, output power can be around 22W on a 4-ohm load with a good heat-sink, power supply and montage.
Gain of each channel is fixed at 20dB in single-channel mode and 26dB in BTL mode.
Input resistance of each channel of TDA1554Q amplifier (IC1) is around 60-kilo-ohm. When two or four inputs are paralleled, resistance is reduced by two or four times. Consequently, input capacitors C1 through C4 should have enough capacity to give the required sound in the low-frequency range.
Download PCB and component layout PDFs: click here
The circuit for the power supply is shown in Fig. 2. Transformer X1 used during testing was rated at 12V AC, 6A. Ratings for X1 can be up to 8A and diodes should preferably be Schotky or other low-drop diodes with 10A rating.