4 Ohm 3W Square Mini Speaker with 150mm Dupont Lead | ShillehTek Product Manual

Overview

This square mini speaker is a simple way to give a project a voice. It is a passive 4 Ω driver with a supplier-listed 3 W rating (the supplier calls it a “2831 type”), mounting tabs on the frame, and a 150 mm red-and-black lead that ends in a two-pin Dupont-style connector — small enough for handheld builds, loud enough for alarms, spoken prompts, MP3 playback, and game sound effects.

“Passive” is the important word: there is no amplifier inside. A 4 Ω load on a 5 V signal would try to draw more than an amp, while a microcontroller pin can supply only a few tens of milliamps — so the speaker always connects to the output of an audio amplifier, never to a GPIO pin. Good matches are small 5 V Class-D boards: an I2S amplifier such as the MAX98357 (up to 3.2 W into 4 Ω at 5 V), an analog-input module such as the PAM8406, or an MP3 player module with its own speaker output.

This manual covers how to connect the speaker to the common amplifier options for Arduino, ESP32, Raspberry Pi, and Pico, what the 4 Ω and 3 W numbers mean for volume and power-supply sizing, which wire is which, and short test programs to confirm everything works.

At a Glance

Specifications

Wiring Guide

Three rules cover every setup: the speaker goes across an amplifier’s two speaker terminals and nowhere else; neither speaker wire ever connects to ground, because small Class-D outputs are bridge-tied; and the amplifier needs a supply that can deliver about 1 A at full volume. If your amplifier has no matching header pins, bridge the Dupont connector with two jumper wires, or trim it off and strip the two leads for screw terminals.

Code Examples

Each example plays a short test sound so you can confirm the wiring before building anything bigger. Start at low volume.

Arduino (tone test through an amplifier)

// Speaker tone test - Arduino Uno / Nano
// D9 -> 1k resistor -> amplifier INPUT (never straight to the speaker)
// Amplifier output + / - -> speaker red / black

const int AUDIO_PIN = 9;
const int NOTES[] = {262, 294, 330, 349, 392, 440, 494, 523};  // C4 to C5

void setup() {
  Serial.begin(9600);
  Serial.println("Playing test scale...");
}

void loop() {
  for (int i = 0; i < 8; i++) {
    tone(AUDIO_PIN, NOTES[i], 250);   // 250 ms per note
    delay(300);
  }
  noTone(AUDIO_PIN);
  delay(2000);                        // pause, then repeat
}

ESP32 and Pico (MicroPython, I2S test tone)

# I2S test tone - MicroPython with a MAX98357 amplifier
# ESP32 pins: BCLK = 26, LRC = 25, DIN = 22
# Pico pins:  BCLK = 16, LRC = 17, DIN = 18  (LRC must be BCLK + 1)
from machine import I2S, Pin
import math
import struct

BCLK, LRC, DIN = 26, 25, 22   # change to 16, 17, 18 on a Pico

RATE = 22050      # samples per second
FREQ = 441        # Hz - exactly 50 samples per cycle at 22050
VOLUME = 0.25     # 0.0 to 1.0, start low

audio = I2S(0, sck=Pin(BCLK), ws=Pin(LRC), sd=Pin(DIN),
            mode=I2S.TX, bits=16, format=I2S.MONO,
            rate=RATE, ibuf=4000)

# Build one cycle of a sine wave as 16-bit samples
n = RATE // FREQ
cycle = bytearray(n * 2)
for i in range(n):
    sample = int(32767 * VOLUME * math.sin(2 * math.pi * i / n))
    struct.pack_into("<h", cycle, i * 2, sample)

try:
    for _ in range(FREQ * 2):     # about 2 seconds of tone
        audio.write(cycle)
finally:
    audio.deinit()

Raspberry Pi (enable the MAX98357 and test)

# Raspberry Pi OS Bookworm and later: /boot/firmware/config.txt
# Older releases: /boot/config.txt
sudo nano /boot/firmware/config.txt
#   1) Put a # in front of this line:   dtparam=audio=on
#   2) Add this line:                   dtoverlay=max98357a
sudo reboot

# After the reboot:
aplay -l                        # the MAX98357 card should be listed
speaker-test -c2 -t wav -l 1    # plays a spoken channel test once

Frequently Asked Questions

Related Tutorials