Q: “Are there any basic guidelines that I can follow to make sure my new Marshall amp stays in good working order?”
A: If you follow these simple guidelines you will ensure that you get the longest possible life from your valves (in deference to the British heritage of Marshall we’ll refer to tubes as valves throughout this Tech Tip) and maximum performance from your Marshall amp (However, much of this information could apply to many guitar amps).
- With any valve amplifier, always switch on the mains switch two minutes before switching on the Standby. This allows the valves to reach their full working temperature before use. There have been other Tech Tips covering the purpose and use of the standby switch in more detail. If your amp has this feature be sure to check them out.
- When replacing output valves, always replace the whole set, preferably with valves of the same make.
- Never mix valve types. So if your amplifier has EL34 power valves you should replace them with EL34s. If it has 5881 or 6L6 valves you must use those. In some amps it is possible to swap out an entire set of valves for a slightly different type to achieve different sounds, but this should only be attempted by a qualified technician who can also make the other necessary adjustments inside your amp to ensure proper operation.
- When replacing valves, always make sure that the pins on the base line up exactly and fit the valve base on the amplifier perfectly. Generally a qualified technician should be involved, as quite often it is necessary to tweak the bias voltage whenever valves are changed.
- If possible, always allow the amp to cool down before moving it.
- Always use high quality guitar and speaker leads and check them regularly.
- Never store your amp in damp or overly humid conditions. Garden sheds, greenhouses or garages – not a good idea.
- Always ensure that any cabinets used have sufficient capacity to handle the full power of your amplifier (bearing in mind that an amplifier can give peaks far in excess of its normal rated wattage).
- Always make sure that the amplifier has the correct impedance selected to match the cabinets being used.
- Always have your amplifier serviced by a qualified technician.