fosgate 800 a4 wiring

I do not understand ohms.I have a fosgate 800 a4 that says it is 400x2 at 4ohms.I have 2 dvc memphis pr154d that are 4 ohm.So how do I wire them to get the amp at 4 ohms,and how do you know what your amp's ohms are set at?

Oh dude, you have a real bad match of subs to amp. Your amp is rated as follows

100w rms x 4 into 4 ohms

400w rms x 2 into 4 ohms

200w rms x 4 into 2 ohm

anything  x 2 into 2 ohms = not going to happen and you buying a new amp.

anything x 2 into 1 ohms = not going to happen and you buying a new amp.

There is only one safe way to hook up your subs to this amp. Here it is.

Wiring Option #2

Use channels 1 and 2 to drive front speakers and use channels 3 and 4 in bridged mode to drive the subs until a more suitable sub amp can be found. Keep this amp to power up the front and rear speakers later on.

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Top Secret, I can tell you but then my wife will kill me.

can you wire the pos together and the neg together,or is that a big no no

Series wiring is the wiring together of a + on one voice coil to the - on the other voice coil, so yes, pay attention. Look at the wiring diagram closely when you do this. This makes your dvc 4 ohm sub for all intents a svc 8 ohm sub. Wiring the two subs like this and then wiring them together in parallel yeilds a net 4 ohm load that is safe for your amp to drive.

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Top Secret, I can tell you but then my wife will kill me.

I meant wire the speakers like the diagram & then wire the both pos from the amps together so I get use of the whole amp not just one side

No you cannot do that, your amp is either a 4, 3 or 2 channel amp, not a 1 channel amp. Do what you are thinking and you will be buying a new amp. Your only option with those subs is to wire them as indicated and use the amp in 3 channel mode.

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Top Secret, I can tell you but then my wife will kill me.