Overview

The tiny, yet powerful MAX9744 can pump 20 watts of audio to power two stereo speakers. In this tutorial, we going to upgrade a pair of old school Apple Pro Speakers and hook them up to this bodacious amplifier.

This lovely kit includes a power filter capacitor, terminal blocks and a 1k potentiometer to adjust volume. A 3d printed enclosure will houses the components and can be printed in any color to match your style. A 3d printed volume knob in ninjaflex filament makes a panel mount 1k potentiometer smooth to the touch.

3D Printing

Parts are optimized to print on a Makerbot Replicator 2 and sliced with Makerware. Download the parts from thingiverse and print them out using the recommended settings below.
max9744-cover.stl PLA @230
%15 infill
2 shells
0.2 layer height
90/150 speeds
about 20 minutes
max9744-box.stl - about an hour
max9744-bottom.stl - about 20 minutes
potknob.stl Ninjaflex @225
%15 infill
2 shells
0.2 layer height
45/150 speeds
about 15 minutes

Print in your Favorite Color

The cover, box and bottom parts of the enclosure were optimized for printing in PLA on a makerbot replicator 2. The cover.stl piece can be printed in a color to highlight, while the box and bottom parts can be colored in a matching color to create contrast.

NinjaFlex

The potknob.stl part was designed to print in Ninjaflex filament. The potknob.stl file is optimized to work with a panel mount 1k potentiometer.

Circuit Diagram

Analog Control

In this project, we'll use analog control since it's the easiest way to get going with the amplifier board. By default, the amplifier breakout is in digital mode. To put it in analog mode we need to close the three solder jumpers labeled Analog, AD1 and AD2.

Adding Terminal Blocks

The terminal blocks will be used to connect the two speakers to the audio output of the MAX9744. Follow the negative and positive symbols and insert them appropriately. Solder them in to place for a solid connection.

Adding Capacitor

Insert the capacitor with the longer lead going into the pad marked + Push it in all the way and bend the leads to keep it in place while you solder it in.

Volume Control

We're using a panel mount style potentiometer which is a bit bigger than the 1k pot that comes with the kit. Solder three strands of wrapping wire to the pin outs labeled Pot. Vol. Line up the leads of the pot with the pins to ensure turning it to the right will increase the values. Solder the far right lead of the pot to Pot. Vol. pin 3

1K Potentiometer

Add pieces of shrink tuning to the wrapping wire for a safe and secure wire connection. Tin the three leads of the potentiometer to make the wrapping wire stick to the leads better. Solder the wrapping wire to the potentiometer. Position the pieces of shrink tubing over the terminal leads and use a heat source to shrink the tubing.

Naked Circuit

At this point you should have a working naked circuit! In the next page, we'll protect it in a the 3D Printed enclosure box.

Assembly

Mounting MAX9744

The MAX9744 will snap fit into the bottom.stl part with the 4 corner cylinders. The orientation doesn't matter. Gently press the amp down into the bottom part.

Mounting 1k Potentiometer

Panel mount style potentiometers should come with a washer and screw nut. Place the washer on the turning knob. Insert the knob of the pot into the cover.stl part with the terminal leads facing either the left or right side (as shown in the photo). Insert the screw nut onto of the knob and tighten it down to secure the pot to the cover.stl

Installing Cover

Carefully insert the cover.stl part into the bottom of the box part. The box part has an inner lip that allows the cover to snap into place. The tolerances may vary so you may need to secured the cover with either tape, glue or any other adhesive that will bind two plastic parts together.

Adding Speakers

Since the amplifier can pump 20 watts of power, you should use some equally capable speakers. In our project we upgraded a pair of Apple Pro Speakers. You can easily use any other type of stereo speakers. The positive and negative connections of the speakers should align up with the terminal blocks on the side. Use a small screw driver to loosen and tighten the screws of the terminal.

To ensure a secure connection, gently yank on each wire after clamping it into the terminal block, it should be a solid connection, not possible to yank out of place. Loose wires will be a problem!

Enclosing Amp Box

Line up the large opening on the side of the box.stl with the terminal blocks of the MAX9744. Gently press the box.stl part down, snapping it to the bottom.stl part.

Powering Amp

Connect 5-12VDC power to the board using a wall adapter.

Audio Input

Use a 3.5mm male/male cable to connect it to your favorite audio player like a computer or phone. Now your ready to pump some awesome sound!
This guide was first published on Apr 03, 2014. It was last updated on Apr 03, 2014.