One amp for highs and lows how would I separate them

[chilly.hott45206]

Please help!!! I have two twelves and four door speakers on an after market radio and I need help

 

[kanewolf]

You need a 5 or 6 channel amp. Something like this -- https/www.crutchfield.com/p_158GS6DSP/Sony-XM-GS6DSP.html

 

[doolittle]

Get an active crossover like this which has adjustable frequency points for high/low pass.

Just connect the low-level outputs from your radio/amp to the input, adjust to your liking, connect the outputs to your amps - good to go!

EDIT - ok so if you are just using one amp as kanewolf mentioned not much choice you need passive crossovers like this 80 Hz High Pass 4 Ohm for your door speakers and something like this 80 Hz Low Pass 4 Ohm for the subs. May be more economical to just get a 4-channel amp for the door speakers and a separate sub amp which would have an adjustable low-pass filter.