Do i need sub equalizer to get lows from factory headunit

[Amit_112dB]

passat 2012 tdi se, I have a JL w3v3 sealed, 4ohm, and sony xm1s amp pumping 40v or 400rms through it.
My headunit is not giving me frequencies below 50hz. I have my amps(40hz center) gain set to 10db, which is the max and i would prefer keeping it low as its boosting the low bass but unfortunately also the high bass

60-100hz 40volts
40hz 25 volts
30hz 12 volts

my sealed sub has a 3db cutoff of 43hz in 40 liter sealed enclosure

Is there are 12-14 volt equalizer for cars which can help me control this bass

or the cabin gain should balance this.

 

[joesch1999]

never heard of a head unit not allowing lows I have heard of head units not having sub pre outs, your head unit no matter what one you have should allow all frequencies, unless you turn them off via head unit or amp etc.

 

[Amit_112dB]

the factory unit did not have sub out and the installer used the wire of rear speaker to get input to amp. This was possible as my amp supports high level in. My amp has auto turn on feature because i use high level in.
factory headunits ****

I did come across an EQ but dont have a remote wire with headunit

How about using these two ?
http://www.parts-express.com/pe/showdetl.cfm?partnumber=265-3487
http://www.amazon.com/Pyle-PLVHL70-...e=UTF8&qid=1361150163&sr=8-1&keywords=PLVHL70