97 Prelude speaker problem

I have a 97 prelude in the shop for exchanging the stock speakers. The customer wanted to keep the stock radio but put in aftermarket speakers. He has the acoustic feedback system. I did the fronts no problem but then when exchanging the rears i lost a lot of bass. I looked at the factory rear speakers and found this wierd circuit board. If anyone knows what to do to get some bass back let me know.

It's a black box mounted near or on (can't remember now) the rear deck. You will need to get rid of that box, which is the actual AFBS. Those tiny mics on the rear speakers work with that box to eliminate distortion...if memory serves. Run new wire from hu to the rear speakers and it should work fine.

I just tried jumping the inputs of the amp to the aftermarket speaker and it still sounded ok but he got a lot more bass with the stock speakers.

I just put the stock speakers. After I swapped the stock speakers back in it actually sounded a lot better than just throwing the aftermarket ones in. I told the customer that if he wanted a better sound from his rears he would need to get a new radio and 4 channel amp. It actually did sound pretty good with the stock rear speakers in.

The stock speakers I believe are 2 ohm. Aftermarket ones are probably 4 ohm. Maybe that is why they had less bass? Less watts, less bass... Or maybe it's just a low-quality speaker.