Installing sub, removing bass from door speakers

[Bellend]

Hi, I have a Kenwood KDC-W4534. It's powering four speakers. 6.5" Pioneer speakers up front and back and dash tweeters. Normally only the fronts are on, unless people are in the back.

I've just put in a 200W amp & sub. This is perfectly loud enough believe it or not, don't need any more bass.

Crossover is on low. However I want to remove the bass from the door speakers or at least turn it right down. Is there a way of doing this? Turning bass down on the HU turns the sub down. Do I need to buy some crossovers?

Just want it turned down at least, can turn bass down on HU and turn the gain up on the amp but is there a better way?

Eventually I want to buy another amp or two to run the sub and keep the current amp for the front door speakers.

Cheers. 

[trog_nfs]

More expensive headunits have direct sub drives and high pass filters which will let you independently adjust speaker and sub outputs.

[benny1234black]

best just to run a second amp for the mid range and treble on your door speakers with the low pass turned right down on that amp

[Bellend]

Cheers.

Bought a 5 channel amp. 

[Benrevs]

You can wire a capacitor into the +, depending on what one you use it will cut out certain frequencies. Will try and find the guide
 

[Benrevs]

http://www.matey-matey.com/capacitor_crossovers.shtml