The correct type of fuse is important. It is the fuse that protects your equipment from serious damage and from bursting into flame. They are also there to prevent a fault in the amplifier causing the case to become live and thus electrocute any guitarist plugged into that amp. The purpose of the fuse is to limit the current flow in the circuit.

A 5 amp fuse will safely carry 5 amps and it will not blow until the current exceeds double that value for about half a second. The higher the current overload the quicker the fuse will blow. All fuses are not instantaneous, and they will only blow after a time determined by the current overload. This overload causes the fuse to overheat and melt. Some amplifiers with large power supplies will draw a high current at switch on (due to charging of capacitors in the power supply) This will blow the normal type or quick-blow fuse. These use a different type of fuse, called a slow-blow or thermal delay. This type of fuse is marked with a T alongside its value.

A (T-type) fuse should never be used to replace a quick blow.

A quick blow may be used as a temporary replacement for a slow-blow of the same value (It will just blow more often).

How to check your speakers

A 9 volt battery, when placed across the speaker, will cause it to move in a direction dependent upon the current's direction. The speaker will click when you connect/disconnect the battery. If this Happens then the speaker coil is working. Carefully push the cone of the speaker in. Does it move easily or does it scratch the surface of the magnet? If it scratches, the speaker is faulty. Also check the condition of the cone, check for splits and water/beer damage.

A speaker works the opposite way around to a moving coil microphone, so a working speaker can be used as a microphone.

Wire the speaker you are testing to the input of your amp and talk into or gently tap the speaker. You should hear it being amplified on the output speaker on your amp.

Changing a faulty speaker

If you look at the speaker terminals you will see that one one of the terminals there is a + sign. Note the colour of the wire attached to this terminal. When you fit the replacement speaker ensure that same wire is connected to + on the new speaker. This will make sure that that speaker is in phase with other speakers i.e. it goes one way with one direction of current and the other direction if the current or voltage is reversed.


  • Replace your speaker with one of the same impedance/resistance.
  • Too low an impedance will blow your amp and your speaker.
  • Replace your speaker with the same power rating as the original speaker.
  • A higher power speaker will not sound louder, and if the amp is unable to provide the power to control the larger power speaker, it will distort and may split the speaker cone.