Add Extra Speakers To Your Guitar Amp safely with Speaker Ohms Calculator

When connecting extra speakers to a guitar amp, you must keep the load Impedance, which is measured in Ohms within the specification rating for your amplifier. If the amplifier is rated at 8 Ohms, then the total impedance of your speakers should be 8 Ohms, regardless of how many speakers you are connecting to the guitar amp. Failure to do so will damage your amplifier!

When more than one speaker is connected together then the total impedance is a combination of the impedance of each speaker, and is different depending on whether the speakers are connected in Series or Parallel or a combination of both. Diagrams of Series and Parallel connections are shown further down the page.

To calculate the total impedance (Ohms) when connecting speakers in Series is straight forward, just add the impedance (Ohms) of each speaker together. E.G. If you have two 4 Ohm speakers in series, the total impedance would be 2x4 = 8 Ohms. If you have three 4 Ohm speakers in series, the total impedance would be 3x4 = 12 Ohms.

For Parallel connections it's a little more complicated. The calculator below will work out for you the total load impedance in Ohms for speakers connected in Parallel.

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Enter value impedance of speaker in ohms, followed by the 'Tab' key to calculate Total Impedance