
Regarding the polarity of the DC jack commonly used in an effects unit’s power supply, in almost cases the inner center pin is “minus (–)” and the outer sleeve is “plus (+)”, with a 2.1 mm center pin diameter. Therefore, commercially available AC adapters and power supply units mainly support this specification. But there are effects units that use mini-plugs, inverted polarity “center plus”, or a ø2.5 mm center pin in the DC jack. A DC conversion cable has to be used to connect such an effects unit to a common adapter or power supply unit.