1, the 48-volt to 12-volt DC converter, replaced by 48-volt to plus or minus 12-volt DC converter;
2, the purchase of a SD card decoding board and a 7805 three-terminal voltage regulator;
3, the transformer in the chassis together with the AC input line removed, the position of the transformer to install DC DC converter, from the AC input hole into the red and blue two thicker soft 48-volt input wire connected to the DC converter input;
4, the DC converter positive 12-volt, welded in the corresponding position of the rectifier output;
5, the SD card decoder board is fixed to the edge of the speakers at the appropriate place, processing a mouth facing outward, the card insertion mouth facing outward, easy to insert the SD card;
6 The positive 12-volt voltage will be connected to the 7805 input, the output of 5-volt positive and negative poles connected to the decoder board;
7, the decoder board output of about 1-volt audio signal of the two wires, distinguish between positive and negative polarity to the amplifier's audio input terminals, the left and right channels are connected to the negative pole to ground, the original signal input line removed without;
8, will be connected to a 48-volt power supply, inserted into an MP3 or WMA format song SD card. MP3 or WMA format songs can be inserted into the SD card to audition.