How to Wire a Guitar Speaker Cabinet

With the right tools and knowledge, it is relatively easy to modify your guitar speaker cabinet with replacement speakers or higher-quality speakers to give your live electric guitar sound an added boost. Before you make any changes, though, be sure you understand the power capacity of the amplifier as well as the impedance. The important numbers are watts and ohms. The new speakers you wire into the amplifier may not possess a total wattage that exceeds the limit on the amplifier itself. Thus, a 50 watt amplifier that possessed two speakers, each speaker should carry a 25 watt rating. The impedance rating for the entire amplifier would be equal to the impedance (measured in ohms) of each speaker. With an 8-ohm impedance rating, each speaker would possess that amount of resistance. This is known as series/parallel wiring.

Step 1: Remove the Rear Cover

Remove the screws from the back of the speaker cabinet and pull off the rear cover. Be careful of any wiring that is attached to the input jack. 

Step 2: Remove Old Speakers

The speakers are held in place with screws on the inside of the cabinet. Before you remove the screws, heat up the soldering iron and detach the speaker wire from the current speakers. Remove the screws and pull out the old speakers. 

Step 3: Mount the New Speakers in the Cabinet

Place the new speakers in the cabinet in the spaces provided. The speakers must be the same size as the old ones in order to fit into the appropriate holes. Mount the new speakers using the same screws that held the old speakers. With a 4-speaker configuration, looking at the cabinet from the rear, there will be a top left, bottom left, top right and bottom right speaker.

Step 4: Solder the Speaker Wire

The connections are as follows: positive terminal in top left speaker with negative terminal in top right; positive in bottom left with negative in bottom right; negative in top left with negative in bottom left; positive in top right with positive in bottom right. Make sure the soldering connections are clean and secure. It does not require a tremendous amount of solder to hold the wire correctly in place, so be sure not to overdo it. 

Step 5: Connect the Input Jack

Connect wire between the negative terminal on the input jack with the negative terminal on the bottom left speaker. Connect the positive terminal on the input jack with the positive on the bottom right speaker. For both of these connections, there will be a terminal with two wires running to it. 

Step 6: Check the Connections and Reattach the Cover

Make sure the soldering connections are all solid and in no way loose. Replace the cover and reinsert the screws. 

Plug the amplifier in and attach a cable between the amp and the cabinet. Plug your guitar into the amp, turn it on and let it warm up. The speakers should be working perfectly. Crackling noises are indications that there is a bad connection somewhere. Remove the cover again and double check your work if that is the case.