4-8 Ohm Speaker

The PAM8403 can drive any speaker between 4 and 8 ohms impedance. Laptop speakers, small hobby speakers, and salvaged speakers all work.

Lower impedance (4 ohm) draws more current and plays louder; higher impedance (8 ohm) is easier on the amplifier. Connect the two wires to LOUT+ and LOUT-.

Testing a speaker with a multimeter

Set your multimeter to resistance (ohms, Ω) - the lowest range, usually 200Ω. Touch the probes to the two speaker terminals. A working speaker reads its rated impedance - typically 4-8Ω. You may see the cone give a small kick as the probes make contact; that's normal.

What the reading means

• 4-8Ω - speaker is good
• 0Ω or very close to 0 - voice coil is shorted, speaker is dead
• OL / open loop / infinite - wire is broken or voice coil is burnt out, speaker is dead
• Anything in between - note that AC impedance at audio frequencies is slightly higher than the DC resistance your multimeter reads, so a nominal 8Ω speaker often reads 6-7Ω on a multimeter - that's fine

Quick continuity check

If your multimeter has a continuity / beep mode, use that instead. Touch probes to the terminals - a beep means the coil is intact. No beep means open circuit (dead speaker). This is faster than reading ohms when you just want a pass/fail result.