V1.3.1 Released

A project log for Customizable 20W Amplifier

4 Input, 3 Way Tone Control and Customizable LCD Display

smartroadsmartroad 01/14/2020 at 22:000 Comments

This version update can now detect the type of amplifier attached to it, currently the MAX9744 or none. Which amplifier it has found is shown in the settings menu and will show "MAX9744" or "Custom". The detection is done on hard power up, i.e. when power is applied/attached.

With the custom option (no MAX9744 board attached) then any amplifier can be attached to the VU output RCA connectors or internally using the RIN, LIN and AGND pins on the MAX9744 connector. With the MAX9744 connected the volume control is controlled by the MAX chip. When it isn't detected then the TDA7439 chip will control the volume.

The advantage of having the MAX chip control the volume is so that the VU output remains at a high output level regardless of the amplifier volume setting. Making it ideal to connect a visualiser to as it will always show the signal that is being fed into the amp.

Eventually I plan to make a daughter board that will connect to the MAX connector and allow it to maintain the VU output functionality while still providing a custom amplifier option. Mostly the thinking is that this allows connection of a more powerful amplifier if you need it.

Bug Fix

In 1.2 the settings menu would sometime keep the last square bracket from the saturation setting when using the RGB display.