I've been using this board:2 1 TPA3116 Class D Digital Amplifier Board 100W 50W 50W 50mA | eBay for a while now, and i've been noticing some really big flaws, like the large pop when the amp is powered on and the unbeleivable mess they've made with the filters for both the sub and the "tweeters", nevertheless i did some reverse engineering on this board and came up with a sketch, does it make sense to anyone? because i am really having a hard time figuring out what some of the opamps and passives are doing here, like the reason for so many buffers and even capacitors in series..
An externally hosted image should be here but it was not working when we last tested it.
Here's the sketch i came up with
The 68uF cap in the input circuit will take some time to charge up, during this time period there's gonna be a DC error on the output. The AC coupling chips going into the TPA also have to charge up. If MUTE is grounded, the amp will just start up right away and there's gonna be a turn-on thump.
If MUTE is grounded, I'd lift the pin or cut a trace, and add a power on delay circuit.
For a quick bodge, get a 1K resistor, 4.3 to 5.1V zener diode and a MCP101 power on reset chip. Make a little shunt regulator powered from the SDZ signal with the resistor/zener, power the MCP101 chip from that. Lift the MUTE pin and wire up the MCP reset signal. It'll buy you ~250mS of power on mute delay, hopefully long enough to soften the thump.
If MUTE is grounded, I'd lift the pin or cut a trace, and add a power on delay circuit.
For a quick bodge, get a 1K resistor, 4.3 to 5.1V zener diode and a MCP101 power on reset chip. Make a little shunt regulator powered from the SDZ signal with the resistor/zener, power the MCP101 chip from that. Lift the MUTE pin and wire up the MCP reset signal. It'll buy you ~250mS of power on mute delay, hopefully long enough to soften the thump.
By adding an input transformer, it could help or totally eliminate the pop on start up and shut down.
id like to know more about the filters. been looking at 2.1 tpa3116 amps and been wondering how the filters are configured? does the subwoofer freqs get filtered off/taken away from the main stereo speaker signal? or is it more like two amps both sharing the same audio feed built into one board, with a filter in front of the amp for the subwoofer?
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