If you have four subs, each one with dual voice coils at 2 ohms, and a mono amp under a 1-ohm load, here’s an explanation of how to wire that…
Your amp has a + and a -, and each sub has two +’s and two -’s.
Each of the subs should have a bridge wire to connect one of the +’s with one of the -’s on the same sub. This leaves both posts empty on the amp still, and each sub with one empty + post and one empty - post.
Next, you’ll connect the +from the amp to the empty + on the first subwoofer (not the + that is already bridged with the - on the same sub.) Run another wire from the +on the first sub (the one that’s also connected to the amp) and connect that to the empty + on the second sub. Next, connect the same + wire from the second sub to the empty + terminal on the 3rd sub, and then connect the + on the 3rd sub to the + on the 4th sub. Do not connect the4th sub back to the amplifier, the first sub is already connected to the amp.
Now, run a wire from the -terminal on the amplifier to the empty - terminal on the first sub.Connect the - on the 1st sub (the one that’s connected to the amp, notthe one that’s bridged) to the empty - terminal on the 2nd subwoofer.Connect the same - on the 2nd subwoofer to the empty - on thethird subwoofer, and do the same to connect the - on the 3rd sub to the -on the 4th sub. Once again, don’t connect the last subwoofer in the series backto the amp, because the 1st sub already connects to the amp to complete thecircuit.