The factory amp has 4 channels of input on it, and our two channels of output from the radio are doubled before the enter the amp. Does this mean we can run both front channels and rear channels from an aftermarket stereo? If so, can someone tell me which pins are feeding the rears, and which pins are feeding the front?

Yellow wire: Is this positive or negative, and left or right? It is feeding both pins 7 and 10 on the amp.
Yellow and Violet wire: Is this positive or negative and left or right? It is feeding pins 6 and 9 on the amp.
Blue: Pos or neg, left or right? It feeds pins 1 and 8 on the amp.
Blue and Brown wire: Pos or neg and left or right? It feeds pins 2 and 3 on the amp.

Any help dialing down what these wires are will help. Which pins feed which speakers would be even better. If I can get both front and back channels fed through the amp, then I can use the fade function to vary the ratio of bass to mids/trebles.

The shop manuals wiring diagrams shown only positives going to one side, and negatives going to the other side, and both front and rear channels from the head unit...its all jacked up.

 

Hmm...i found this. This may give me what I need on the head unit side. Who knows what is going on down there on the amplifier side of things, though.

https://www.crossfireforum.org/forum...9&d=1158341440

 

Do a search for the service manually. It has a schematic of the whole audio system. It's too large to e-mail out. That's how I found the turn on lead wire from the factory amp.

 

Yea, I've looked at that diagram...that's how I got that pin info above...but the diagram that lists what the pins are, is incorrect. I lists only positive leads on the right speakers, and only negative leads on the left, etc. Its showing both front and rear channels coming from the stereo, as well.

What I see from looking at those diagrams, however, is that the left and right positives and negatives go back to the amp, and are doubled before they get there, so that the amp gets two left positives, two left negatives, two right positives, and two right negatives.

This makes me "ASSUME" that the 4 input channels on the amp correspond to the 4 output channels on the amp (a front left, rear left, front right, and rear right), and that we are just feeding both the front and rear with the same signal from the two channel head unit using the doubled wires. With a four channel head unit, why not send 4 channels to the 4 channel amp, and on through to 4 channels of output? This would allow fade to act as a bass bias adjustment of sorts, giving you independant control of the subwoofers.

 

I'm sure your assumption is correct AtomHeart. But the diagram doesn't show which is front and back. There have been threads about running a second set of RCA cables from the amp back to the head unit to do this. Once you run the cables it would be easy to figure out which is front and back.

 

https://www.crossfireforum.org/forum...ead.php?t=9308

 

Max, I have read that thread before, and found it useful, but it doesn't really delve into the issue of running 4 channels to the amp.

I now know the wires for positive and negative left front, and positive and negative right front. If I trace them to the amp, and find where they split into two wires, that's a start because it tells me which 4 pins on the amp are rights and which 4 pins are lefts. It even tells me which two are positives and which two are negatives of those four...but how do I keep from hooking a front positive to a rear negative while trying to figure out which is front and rear? Am I going to need a continuity tester? I'm hardly an electrician, so I'm not sure I'd even know how to use one. haha.

Maybe I can just disconnect all wires from the amp, and connect one front positive and negative pair to two pins at a time until the front speakers come on.

Eric

 

Did you follow the link to the Audio Diagram?
I'm trying to attach it.

 

It might end up with you doing exacyly that: RF on the HU to 7&10 on the amp, see what you get.

Best of luck, I'm going for a Clarion Media player for Xmas (kids want to get me something for the xF! But I'll just use the high level outs to the amp.

 

Yo, Atom heart,

It looks we're on the hunt for the same info.

Have you figured out the front/rear, left/right amp thing yet?

From the Audio System Circuit Diagram (ACSD), it looks to me that power amp inputs 7 and 10 are left inputs and amp inputs 8 and 9 are right inputs: question is which are front and rear? Seems that pairs 7 and 8 would be one stereo pair (front?) and 9 and 10 would be the other pair (rear?)

I never had the original factory unit so a dumb question: did the factory head have a front/rear fader? I would guess NOT based on the ASCD.

Also, are the rear speakers bi-amped? Each rear spkr has four wires which seems to indicate two stereo pairs . . . hmmm.

I sent this message to you in a PM - give that a read please.

 

No fader as the rear is sub only, interested in the rears having four wires each - looks like I need to have a look back there sometime.

 

OK, this is driving me a little nuts so I tore into the amplifer under the passenger footrest area.

I traced and verified all the amplifier input and output wires as shown in the Audio Systems Circuit Diagram (ASCD) previously posted here.

I didn't want to start snipping wires on the amp input connector to determine if the yellow wires went to the front side of the amp and the yellow/violet wires went to the rear side of the amp (or vice versa) but this is what I mapped out for the INPUT connector:

Input connector pins: note-x means no connection

Pin 6= Yellow/violet
Pin 5= Yellow
Pin 8= Blue
Pin 9= Yellow/Violet
Pin 10= Yellow
Pin 11= Brown

--------------------
: 6: 7: 8: 9:10:11: x:
: 1: 2: 3: x: x : 4 : 5:
--------------------

Pin 1= Blue
Pin 2= Blue/Brown
Pin 3= Blue/Brown
Pin 4= Brown
Pin 5= Blue/Dark Green

Yellow is split (in the dashboard) to pins 7 and 10 so that's either Left or Right, one pin being Front and the other being Rear.

Yellow/Violet is also split to pins 6 and 9 so the same applies except for the other channel, again either Right or Left depending on the previous sentence. The Blue and the Blue/Brown wires are just ground for the audio signals above.

I'm not drawing the output side of the amp because that's pretty straight forward from the ASCD and it would take a l-o-n-g time (it's an 24-pin connector), however, I could NOT understand why the Left and Right rear speakers have four wires each.

Initially, I thought maybe one pair to each speaker was audio signal and ground & that the other two were power and ground but why run power from the amp to the speakers? My other thought was that maybe the rear speakers were coaxials so one pair for sub-bass and the other for midrange & hi-freq stuff)......Hey, it's a German designed car so who knows.

Out came the headphones and I listened to Pink and Dark Green pair (pins 6 and 16 on the output side of the amp) and all I heard was low frequency bass guitar and bass drum....OK. Then I listened to the Blue & Brown/Red pair and I heard the EXACT same signal...HUH? Why run two pairs of the same signal to the speaker twice? The rear speakers are obviously NOT coaxial and the two signal feeds are both nothing but low freq. stuff.

Then I listened to the other rear channel speaker pairs (1st pair Blue/Red & Black/Yellow and 2nd pair Violet & Red/Yellow) and once again the EXACT same audio - bass guitar and bass drum low frequency stuff !!!

I'm more a recording studio guy so this didn't make any sense to me at all. A factory head with no front/rear fader control, split stereo left/right signal to the full range/tweeters in the doors with no tweeter level control and two subwoofers (stereo) in the rear with 2 pairs of leads for each rear speaker.

It's almost like they took the MBZ SLK fancy sound system and put a down graded Chrysler head in the system - beats me!

As it stands now, I see NO sense in taking the rear amp outputs of my aftermarket 50w x 4 ch head and screwing with the factory amplifier input wiring scheme - there's nothing to be accomplished really since my aftermarket head has a HPF (high pass filter) with several cutoff frequency settings, plus overall bass & treble controls and an 8 channel graphic equalizer so I can tweak the EQ to balance the in-your-face tweeters with the in-your-legs full range door speakers.

I'm gonna research the actual MBZ SLK sound system and see if I can find any differences . . .

UPDATE: 12-Nov-2007:

Preliminary results on 2003 Mercedes SLK audio seems to indicate the stock sound system is speakers in the door only but still investigating further. The upgraded audio system was a premium Bose 6-speaker system...hmmm. just like the xFire? tweeter and speaker in each door and two subwoofs in back ???? According to MBZ, the upgraded Bose head had Balance AND Fader control, unlike th xFire . . .

 

US SLKs all use the Bose system. There are two channels from the head unit to the amp. These are 4-5 volt balanced signals, different from the common RCA 2 volt unbalanced signals of most aftermarket systems. The amp has four output channels. A left and right set of outputs runs to the doors, where there is a tweeter/midrange pair in each side. Two more channels run to the rear, where there is a woofer/sub behind each seat. The rear speakers are bigger than the grill suggests. They are actually aimed backwards and at an angle. Bose typically uses active equalization to compensate for speaker and cabin audio characteristics, so the front and rear drivers are getting different signals. I believe this equalization is built into the amp. The US head units are typically sourced from Alpine. There is no fader control, but there is a balance control.

 

Am I to assume no one has yet to figure out ssl92677's question as to which of the pins 7 or 10 and 6 or 9 on the ampifier input is for the front or the back speakers?

 

the amp has actually six channels but only two inputs....the channels go to tweeter, midrange and sub speakers...i install for a living and have worked on like 100 of these...if you have any question just ask me i am the expert indeed!!!!!

 

So, it's basically a "Tri-Amp" system?

 

This might be the dumbest and stupidest question, but I know nothing about car audio.

(My apologies if this is thread-jacking or something of that nature too)

Can we install a subwoofer directly to the amp? I have an aftermarket headunit if that helps..

I want to add a little more bass to my system, but i'm not sure if I will need to buy a new amp or not

 

Hi,

Like so many others, I want to improve the stereo sound but keeping the original look. I'm thinking about installing a Kenwood KGC-4042A Equalizer. The equalizer has subwoofer gain and crossover adjustments. Can I connect the subwoofer outputs of the equalizer to the power amp pins 7&10 (RR) and pins 6&9 (LR)?

Thanks,
Tom

 

Read this first?

https://www.crossfireforum.org/forum...ead.php?t=9938

It's a good start...

 

Thanks, but, I've already done this. I'm just looking for some power amp information.