Amplifier Runs Excessively Hot
Warm is normal. Too hot to keep your hand on the heatsink for more than a second or two is not. This page is for finding the cause before heat turns into shutdown or damage.
Most overheating comes from four things: no airflow, too much power for the amp class, too low an impedance, or long-term clipping.
What Counts As Too Hot
- Warm but manageable - roughly 40-55 C / 104-131 F is common under load.
- Warning zone - once the heatsink is painful to touch for more than a moment, treat it as overheating.
- Critical - protect mode, thermal shutdown, or a hot smell means stop and inspect immediately.
Most common cause. Sealed mounting cavities, face-down mounting, or zero clearance trap heat.
Fix: Leave 2-3 inches of space above the fins, keep a clear intake path, and add a fan if the compartment is tight.
Low impedance equals more heat. A hard low-ohm load can cook an amp even when it is not clipping.
Fix: Confirm the actual speaker wiring and rewire higher if needed.
Class AB runs hotter than Class D for the same output because it wastes more power as heat.
Fix: Reduce sustained power demand or move heavy-duty bass work to a Class D amplifier.
Long clipped playback raises average power and can push both the amplifier and the speakers harder than expected.
Fix: Lower gain, verify source level, and stop using distortion as the loudness target.
Fast Check Order
- Look at mounting position and airflow first.
- Confirm the actual speaker load at the amplifier terminals.
- Check whether the amp is being pushed into clipping or sustained near-full output.
- Measure supply voltage under load to make sure low voltage is not forcing higher current and more heat.
Common Mistake
Do not blame temperature on "bad amp design" before checking the load and the mounting. A healthy amplifier in a sealed cavity on a low-ohm load will still run hot.