i just started learning how a center tapped smps works and i did some test but now i am confused about the dual power distribution, i mean if a device input power rating is a centered tapped, say +12_0_-12 VDC, when we measure it with a multimeter the +12 and -12 the voltage is 24VDC but we can't use the 24VDC on a single 12v:0v device it short circuits the smps. When we measure the +12 and the GND the voltage is 12VDC and we can even use the +12v:GND(ignoring the -12VDC) with a single 12VDC device, so my question is, does the center tapped device actually uses the 24VDC or the device splits the 24VDC into 12VDC/12VDC. Thank you.

I want to understand, just say a 500watt RMS Mosfet mono amplifier the maximum input VDC is rated at 56_0_56VDC, when we test with a multimeter the +56v and -56v voltage is 112VDC. so i want to know does the amplifier uses the entire 112VDC or it splits the voltage into two 56_0_56VDC because if the amplifier uses the entire 112VDC then i think the 112VDC is a lot of voltage and could burn the amplifier. Thank you.

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  • \$\begingroup\$ Why do you think there's a difference between 0-12V-24V and -12V-0-12V? \$\endgroup\$ – Ignacio Vazquez-Abrams Nov 26 '16 at 19:42
  • \$\begingroup\$ Because i used a PC SMPS to power a subwoofer Low Pass Filter which has a +12_0_-12VDC and it worked but when i tried to power a single +12V:0V with the +12v and -12v to make the voltage 24VDC on a 200watt RMS Mosfet mono amplifier the SMPS short circuit. Thank you. \$\endgroup\$ – lima toshi Nov 26 '16 at 19:53

It's just a matter of earthing

Your PC power supply has its 0V internally connected to your mains earth.

The same is most likely to be true in your amplifier too, or in its source (radio, CD player, TV set or whatever) at least.

So when you power the dual supply amplifier everything is going to be okay


simulate this circuit – Schematic created using CircuitLab

Troubles arise when trying to power the 24V single supply amplifier


simulate this circuit

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  • \$\begingroup\$ Thank you, this is a great help for a new beginner in electronics like me, appreciated. \$\endgroup\$ – lima toshi Nov 27 '16 at 6:09

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