terry82

i would like to add a amp.i want to amp two 6x9s and a sub.i know how to wire the 6x9s but i want to know what do i do for the sub .do you buy the amp with that feature [subwoofer]or do i just take wires from the amp to the sub just like any other speaker.

markcz

Look for a bridgeable 4 channel amp. Use channels 1&2 for the 6x9s and bridge 3&4 to the sub. If the amp doesn't say bridgeable in the description look for 2/3/4 channel capable.

Most amps can only handle a 4 ohm load when bridged, so get a sub that can be wired for 4 ohms (single coil 4 ohm or dual 2 ohm).

Tone

Ya, what he said,,, and most 4 channel amps have the needed built-in crossovers so you can send only the low frequencies to subwoofer - and some amps even come with a little remote control dial for subwoofer boost that you can mount by the driver.

PS. you may want to check your aftermarket deck to see if it has built-in crossovers too.

terry82

my kenwood deck has a sub on or sub off .is that the crossover?

Tone

No, and if the owners manual doesn't identify crossover frequencies then you have to get amplifiers that have crossovers - if you want to run a subwoofer anyway...

markcz

If your HU has separate RCA outputs just for the sub, then your HU does have some type of crossover that would only send out the low freq signals.

terry82

my kenwood head unit is a kdc-hd545u.it has subwoofer out puts in the back .

Tone

It has a crossover for the sub but the lowest setting is 85hz, and IMO I would suggest finding an amp that will go down to at least 50hz to help tame any potential boominess.