Major Upgrade

A project log for Customizable 20W Amplifier

4 Input, 3 Way Tone Control and Customizable LCD Display

smartroadsmartroad 12/11/2020 at 11:240 Comments

I have been working on a major upgrade for the amplifier. I wanted to move away from using pre-made amplifier boards and have created a new 70x70W amplifier board. This is using a Class-D amplifier chip capable of two 70W outputs. I wanted more power as the speakers I have are about 80W so using my current setup I have to drive the amplifier quite hard. My design still uses the same pinout as the Adafruit unit for the control and audio inputs, mostly as I envisaged it as an upgrade rather than a full re-design. Hopefully, if this works, I want to design a few different power level amps to go with this, making it more modular.

This new design will have 7 inputs (using a built in version of my Audio Input Expander) and I am upgrading the display to use a full 128x64 graphic display. The Arduino Nano board is out and a custom ATMega644 controller is going to be used instead. This allows for more memory for the display and, hopefully, a nicer more modern look to the amp.

I have the boards for the new amplifier which I hope to get made over the next few weeks. Although I made one big mistake in that I somehow deleted the digital potentiometer footprint and will have to get them remade in the future. For now I can check my design will even work for the amplifier chip, the digital pot is not needed for initial testing.

The case is also getting a full redesign with a more streamlined look. I made a simple amplifier for my retro-computers to use, couple of cheap amp boards from ebay, and I made a case that is much easier to construct than the original one, with fewer screws holding it together.

About the only thing I am having problems with is powering the new amp board. It needs 36V and there aren't many PSU's capable of the power output needed so I may have to look into designing one. Hate the thought of dealing with household voltage levels though!