Impedance & Power
What Happens If Speaker Impedance Is Too Low
6 min read
Running an amplifier into too low an impedance is one of the few wiring mistakes that can actually damage equipment. Here is what happens, and how to stay clear of it.
More current, more heat
Lower impedance lets more current flow. Below the amplifier's rated minimum, that current climbs past what the output stage and power supply were built for. The result is heat — in the amplifier, not the speakers.
What you'll actually see
- Protection shutdown — a well-designed amp senses the fault and mutes or shuts down. Annoying, but it saved itself.
- Overheating — fans ramp up, the chassis gets hot, and the amp may cut in and out as it thermally protects.
- Distortion — the amp can't supply the demand cleanly, so the sound breaks up.
- Failure — with no protection, sustained overcurrent can destroy the output devices.
How people get there by accident
The usual cause is wiring too many speakers in parallel. Four 8Ω speakers in parallel land at 2Ω — below many amps' limits. The fix is often series or series-parallel wiring to keep the load up.
How to avoid it
- Know your amplifier's minimum impedance before wiring anything.
- Calculate the total load first with the impedance calculator.
- If parallel wiring drops the load too far, switch some connections to series.