Amplifiers and cabinets

Heat and dust are important factors in the life of many amplified devices.

Do not block grilles and ventilation openings with fabric, objects or dust build-up. Check that fans and external vents are unobstructed and provide the clearance specified by the manufacturer.

Cleaning the exterior and ventilation area does not mean opening the chassis. Dangerous voltages may be present inside amplifiers, especially valve designs, even after power has been switched off.

Periodically move controls through their normal travel and test inputs, channels, loops and switching functions that are used less often.

If noise appears, note exactly when it occurs: while turning a control, touching a jack, on one channel only or after several minutes of operation. This information is far more useful than a general description such as “it makes noise”.

Avoid spraying products randomly into potentiometers; both product and procedure must be suitable for the component.

A valve should not be replaced merely because it is old, and not every noise should automatically be blamed on valves.

Loss of power, microphonics, noise and instability can have different causes. Some amplifiers require specific procedures after certain valves are replaced.

If you are unfamiliar with the circuit and safety procedures, limit checks to the exterior and use a technician. Keep removed parts where they have historical relevance or can help document the service history.

A vibration or rattle does not necessarily come from the speaker itself.

From the outside, inspect handles, casters, panels, grilles, screws and objects resting on the cabinet. Inspect the cone when visible without unnecessary touching, and make sure external cables and connectors are suitable for the connection.

If a speaker or internal wiring fault is suspected, avoid tests that could overload the amplifier and verify that impedance and connection follow the system specifications.