Amplifier Hums or Hisses — Finding the Cause

Humming is usually caused by a ground loop, a faulty cable, or a poorly shielded instrument. First, swap the jack cable for a different one — this often solves the problem immediately. Plug all devices into the same power strip to reduce grounding issues. Dimmers, energy-saving bulbs, or nearby screens can also cause interference — test whether the hum disappears when you turn or move around. Do not open the amplifier yourself: dangerously high voltages can remain inside even after it is switched off — if the problem persists, always take it to a qualified repair technician.