tonydt1g3r

So I took apart the back seat and stuff to get some measurements to see what options we have to replace the stock ML sub. Its so small back there I am accustomed to alota bass, my old car has two 12" fosgate HX2's and a 800a2 amp pushing out over 1000 watts. So i've always read that the older sc you could put a 10" in there so I was hoping it was the same way. NOPE the mounting diameter is about 7"-7.25" wide and about 4"-4.5" deep. If you could even find the old 8" JL free air sub that is discontinued it would fit great but I doubt u can since its hard to find. Now you not left with many options. After reading countless post in the audio section Image Dynamics makes a 8" free air but I doubt its going to fit the magnet is just too big and I really doubt its going to fit. But hey what the hell I figure I can make it happen to I ordered one anyways. But I am almost 100% its not going to fit without a buncha work. So now this is where I need help. I've worked with systems a long time but I never used a stock head unit. I've read that I need a line converter but I am not sure which one I need. I asked for help in the audio section to no avail. All the ones I have looked up online have a right and left channel input into the line converter, but I dont see why I couldnt just tap into the stock sub wires which only consist of 2 wires and put that into the line converter, but then I would only get one channel I think. So I have no clue what line converter to use and this is going to hold me back from trying to upgrade the stock sub, which I am sure some of you guys want to do. I'll be the test dummy in this one I just need some help on which line converter to get and how I should hook it up. Pleaseeee help me out and dont move me?

hmm ok after studying my old fosgate amp that i had laying around I saw it has a high level input with 4 input wires. So should I just take the stock sub woofer wires and tap 2 wires to one channel and 2 wires to the other channel so that I could get both right and left channel input?

Arraco

I wanted more bass in another (bose equipped - A8) car...I tapped into the speaker level leads running from the Bose amp to the rear shelf factory subs...I then ran them to a line level adapter from C'field (it was about $15 - they are pretty generic). The line level RCA inputs then mate to the amp of your choice...the sound was spectacular, in fact I had to run the bass at between -2 and -4 to keep the bass "in line". I can't comment on the physical space/fitment in the SC, but I can tell you that tapping the existing sub speaker leads is the way to go - you get full control from the head unit and no ancillary gizmos to operate (once you get your initial levels set). Just watch your grounding so as to eliminate ground loop hum

Good luck,

Bill

tonydt1g3r

so you had 2 subs in the back? to connect to the line level adaptor? one for right one for left channel? the sc only has 1 sub so I dont know what to do about the other channel

Arraco

The BOSE sub was mono (two drivers, however). Just run the speaker level out put to only one "side" of the adaptor (then run to a MONO power amp). There is no reason you need to use the other (or all) channels of the adaptor.

tonydt1g3r

My assumption is that if you had bass just coming fron the right or left side then you would want to tap both sides. And in alot of songs u can hear bass just coming from one side or the other.

Arraco

If you had two bass channels, yes, however, the BOSE in the Audi is monural (like the SC). Not sure what the SC cross over point is, but I suspect the door 6x9's handle most everything down to about 80 - 100hz (where you do, if you are really a good listener, can still hear some separation). Below that goes to the sub.

tonydt1g3r

well if the amp has crossover inputs for both right and left channel, should I just tap both Right and Left channel wires to the 1 set of subwoofer wires, and set the crossover to low pass. Also what should I set the frequency to on the amp? 80 hz?

GSoup

just tap the wires from the sub in the back (just 2 wire +/-) and add the LLC there run that to the amp (get a mono amp - 1 CH) . Put the amp on LP and adjust it from there...its not that complicated...

tonydt1g3r

Why would you need a LLC when the amp has a built in crossover

GSoup

your right i misread the thread because i multiple windows open.. i was thinking of OEM setup when you need the LLC to hook up aftermarket sub..

tonydt1g3r

so tap both Right and left channels to the one set of sub wires?

GSoup

hold up.i mixed myself up again.. thats what happens when you take tooo many pills for your sinuses...

If your using the stock head unit you have to use the LLC at the back on the subwoofer wires and you connect that to the new amp and connect the sub to the amp

THE LLC has nothing to due with the crossover it has the do with speaker level signals...

tonydt1g3r

the amp has high level inputs, there are 4 wires there one for right one for left. on top of that there is a switch for HP, full and LP. I was asking if I should just hook up those 4 wires to the one set of sub wires and set it to LP

GSoup

oh ok.. gotcha... you can use the high level inputs and yeah select LP..

The sub in the back only has 2 wires... i take it your talking about the harness to the high level input has 4 wires . correct? well you have to bridge it since its a 2 channel amp so you get one channel..

which amp is it? the model number?

tonydt1g3r

its an old fosgate punch 360a2 I had laying around for years, I have a punch 800a2 but its too big to fit in the car and too powerful for an 8" sub

also what should I set the frequency on the amp to be? I am guessing around 50-80 hz any suggestions? BTW thanks a bunch for all the help