Stereo 3.
Guide Contents Guide Contents Overview 2 3 Specifications: What is a Class D Amplifier? 3 4 Other Audio amps available at Adafruit Assembly 4 6 Solder the header: For breadboard use: For use with connectors: And Solder! Add Gain Selection and Speaker Terminals 7 7 7 8 8 Connections and Settings Inputs: Outputs: Gain: Power: 9 9 10 11 Build a Portable Sound System Materials: Mount The Speakers Mount the Controls Wire it up! Mount the Amplifier Add some stuffing Plug And Play! Downloads Files Schem
Overview This incredibly small stereo amplifier is surprisingly powerful - able to deliver 2 x 3.7W channels into 3 ohm impedance speakers. Inside the miniature chip is a class D controller, able to run from 2.7V-5.5VDC. Since the amp is a class D, its incredibly efficient (over 90% efficient when driving an 8Ω speaker at over a Watt). This amplifier is perfect for portable and battery-powered projects.
Spread-Spectrum Modulation and Active Emissions Limiting Differential Inputs Five pin-selectable gains: 6dB, 9dB, 12dB, 15dB and 18dB. Select with a jumper or by setting the G and G' breakout pins (see schematic for breakout board showing gain pin settings (http://adafru.
You can shut down each channel separately. Setting the gain is easy on the onboard DIP switches. Its a good choice where you don't need to drive 3Ω speakers or if you ever want to turn off only one audio channel. If you need 24dB gain this amp can do it. Like the MAX98306, it has differential inputs, bridge tied outputs, and can run from 2.7V to 5.5V Available from Adafruit! (http://adafru.it/987) © Adafruit Industries https://learn.adafruit.
Assembly The amplifier breakout board is fully assembled and tested. To easily integrate the amplifier into your project, we include the following: A 9-pin header for use with breadboard or connectors 3.5mm screw-terminal blocks for your speakers A 2x4 header + jumper for setting the gain © Adafruit Industries https://learn.adafruit.
Solder the header: Cut the header to size (9 pins) and insert it into a breadboard (long pins down!) to hold it steady. For breadboard use: Place the amplifier module faceup over the headers. Prop the back-edge up with the leftover header strip to align it. For use with connectors: If you are going to build this into a project and want to connect from the front side, place the amplifier module face down for soldering. © Adafruit Industries https://learn.adafruit.
And Solder! For tips on soldering, see our Adafruit Guide to Excellent Soldering. (http://adafru.it/aTk) Add Gain Selection and Speaker Terminals Solder the 2x4 pin header for gain selection to the top of the board as shown. Also solder in the 3.5mm screw terminals for the speakers. © Adafruit Industries https://learn.adafruit.
Connections and Settings Inputs: The amplifier inputs are coupled via 1.0uF capacitors so they can handle single ended or differential signals. For Single Ended signals (shown on left), connect: R+ to R+ GND to RL+ to L+ GND to LFor differential signals, connect: R+ to R+ R- to RL+ to L+ L- to LFor volume control, a dual 50K audio taper pot can be wired in series with the inputs as shown. Outputs: This amplifier is designed to drive moving coil loudpeakers only. Speaker impedence must be 3ohms or more.
coil serves as a low-pass filter to average out the high-frequency components. Do not try to use this as a pre-amplifier. The outputs of each channel are "Bridge-Tied" with no connection to ground. This means that for each of the two channels, the + and - alternate polarity to create a single channel amplifier with twice the available power.
Power: The amplifier can be powered by 2.7 to 5.5v DC. Good power sources are: 5v 2A power supply (http://adafru.it/276) 3xAA (4.5v) battery holder (http://adafru.it/771) Connect the negative wire to GND and the positive wire to VDD. © Adafruit Industries https://learn.adafruit.
Build a Portable Sound System Materials: To build a portable sound system, you will need: 1 Adafruit Stereo Class-D Amplifier (http://adafru.it/987) 2 speakers (3 ohm minimum. 3" to 4" is a good size) 1 3xAA Battery Pack (http://adafru.it/771) 1 Power Switch (http://adafru.it/482) 1 Phono Jack (We used a 1/4" here) 1 50kOhm Stereo Audio-taper pot 1 knob Jumper wires (http://adafru.it/266) © Adafruit Industries https://learn.adafruit.
1 Box (We used the case from a power tool. But any lunch-box sized enclosure will work as well) 2 Speaker Grilles (We used some 4" fan grilles here) Screws & nuts to mount the speakers. Polyester batting or pillow stuffing Mount The Speakers © Adafruit Industries https://learn.adafruit.
Cut holes in the box to fit your speakers and mount them in the box with screws. Here we used 4" speakers with 4" fan grilles and mounted them with 3/4" 6-32 machine screws and nuts. Mount the Controls Drill holes to fit your power switch, volume pot and phono jack in a convenient location and mount the controls. Here we used a 1/4" phono jack. Smaller plugs can be accomodated via adapters. Our volume pot has a Spinal-Tap compliant volume scale that "goes to eleven".
Mount the Amplifier Some double-sided foam tape will hold it securely inside the box. Add some stuffing Loosely stuff the back of the box with some polyester batting or pillow stuffing for a less 'hollow' sound. © Adafruit Industries https://learn.adafruit.
Plug And Play! For an iPod or similar player, you will want to use the highest gain setting. © Adafruit Industries https://learn.adafruit.
Downloads Files MAX98306 Datasheet (http://adafru.it/e7o) Fritzing object in Adafruit Fritzing library (http://adafru.it/aP3) EagleCAD PCB files on GitHub (http://adafru.it/rJc) Schematic PCB Fabrication Print Dimensions in inches © Adafruit Industries https://learn.adafruit.
© Adafruit Industries Last Updated: 2016-10-06 02:39:49 PM UTC Page 18 of 18
