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Impedence Settings

Essentially in any Marshall set-up there are only three possible choices of impedance, 4 Ohms, 8 Ohms or 16 Ohms. If you are using a single cabinet then it is pretty obvious that the amp should be set to the same impedance as that of the cabinet i.e. 4 Ohms for a 4 Ohm cabinet, 8 Ohms for an 8 Ohm cabinet etc.

If you are using two cabinets of the same impedance, you divide the impedance of one cabinet by the number of cabinets being used. So for two 8 Ohm cabinets you would set the amp to 4 Ohms, or for two 16 Ohm cabinets you would set the amp to 8 Ohms.

In situations where you are using cabinets of different impedance's the most likely configuration would be one 16 Ohm cabinet and one 8 Ohm cabinet, in which case you would set the amp to 4 Ohms. As a rule of thumb if you work on the idea that where using two cabinets of different impedance's you set the amp to half the value of the cabinet used with the lowest impedance, then you won't go far wrong. There really is no mystery to any of the set-ups described above, but it is vital to the correct and safe working of any amplifier to always ensure that the impedance is correctly matched.

Sound Setting

As sound is such a subjective thing and there are so many variables involved, from the weight of your guitar strings through to the type of guitar and strength of pick-ups etc. it is very difficult to give serious advice. Generally if you start with everything at 12 o'clock and adjust from there, then let your own ears do the rest. Obviously, the more you increase the gain, the more intense the distortion becomes. Another important thing to remember is that, particularly on valve amps, the EQ is inter-active so adjusting one control can affect the others in relation. The best thing really is to experiment and don't be afraid of being radical as there is no absolutely right or wrong way to set up a sound. If it sounds good then use it.

Top Ten Tips
Here are the answers to the most commonly asked service questions. If you follow these simple guidelines you will ensure that you get the longest possible life from your valves (tubes) and maximum performance from your Marshall.

1. With any valve (tube) amplifier always switch on the mains switch two minutes before switching on the Standby. This allows the valves (tubes) to reach their full working temperature before use.

2. When replacing output valves (tubes) always replace the whole set, preferably with valves (tubes) of the same make.

3. Never mix valve (tube) types. So if your amplifier has EL34 power valves (tubes) you must always replace them with EL34s. If it has 5881 or 6L6 valves you must use those.

4. Always make sure that the pins on the base of the valve (tube) line up exactly and fit the valve base on the amplifier perfectly.

5. If possible always allow the amp to cool down before moving it.

6. Always use high quality guitar and speaker leads and check them regularly.

7. Never store your amp in damp or overly humid conditions. Garden sheds, greenhouses or garages - not a good idea.

8. 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).

9. Always make sure that the amplifier has the correct impedance selected to match the cabinets being used.

10. Always have your amplifier serviced by a qualified technician.

Jacolino: dal 1957 dà fiato alla tua passione.