Bass combo amps endure a lot of stress that easily can lead to a number of problems, such as strange rattling noises. If the amp is making rattling noises, something in the amp has become loose. Troubleshoot the problem by systematically investigating each part of the amp that could cause a rattle. Once the cause of the rattle has been located, fixing the problem is a relatively easy procedure.
Examine the tubes of the bass combo if it is a tube amp. Tube rattle is a common problem with tube amps. Turn the amp off and allow the tubes to cool down. Gently manipulate the tube in the socket. Remove it if feels loose. Spray the tube socket with contact cleaner and wipe it with a clean cloth. Dirt and debris prevents the tube from fitting as tightly as it should. Reinsert the tubes. Pinch the tube retainers between your thumb and fingers to make a tight fit.
Inspect the speakers by removing the front grill or back panel to access the speakers. Bass speakers endure low-frequency vibrations that easily can cause the speakers to become loose from the cabinet, which causes a rattling sound. Tighten the nuts and bolts if the speaker is loose. Placing a piece of foam between the speakers also can eliminate rattling noises.
Inspect the chassis. Bass amp rattles often are caused by a loose chassis. Tighten any loose screws or bolts. The screws and bolts that secure the chassis to the amp eventually become loose from sound vibrations, transporting the amp from one place to another and general wear and tear.
Troubleshoot the bass amp cabinet. The amplifier cabinet is made from several pieces of wood that are screwed and glued together. The seams may become loose over time, causing the cabinet to generate rattling noises. Tighten all the screws and bolts. Remove the speakers if the cabinet is in very poor condition. Glue and clamp the seams together. Allow the glue to dry before reinstalling the speakers.
Read the amp manual for troubleshooting tips and to make sure you are operating the amp properly.
Unplug the amp before working on it. Refer to the manual for tips on draining the electrical current. Amps contain dangerous amounts of electrical current even when they are in the "Off" position.