a4ncar

I am doing a after-market sub-install based on the threads posted in this forum. It looks like pretty much every one disconnected the factory sub, when the new sub was installed. I made my taps at the N40/3 sound amp but cannot find the connectors to the factory sub in the rear deck. Due to the drop-down basket in the rear deck it makes it even more difficult to look for it. Am, I supposed to just disconnect the small bass amplifier that is on the rear deck or there is some other trick to access the connector on the sub? Thanks for all your help.

CaliBenzDriver

Are you looking for this guy??
​​​​​​
HOW do you remove all the inside to access the top deck ??

I want to have a look inside that module for loose power pins...

a4ncar

I assuming this is the secondary amplifier, that also goes to the factory subwoofer. Is this what is everybody is disconnecting? I am thinking this probably runs more than the subwoofer perhaps?

konigstiger

See if attachments help.

Left Coast Geek

which sound system does your car have? The HK Logic7 in my 2016, I thought the fiber optic audio bus went right to the subwoofer, which has its own integral DAC and amp ? its in the floor of the trunk, like here on my wagon (and in a similar place on a sedan)



(Harmon Kardan black box to the right of the spare, and forward of my aux battery... on the sedans I've seen, the battery is on the front side, and the sub is behind it, but otherwise the same module).

CaliBenzDriver

I am not the Benz audio wizard just that I grew up fixing audio gear : speakers and Amps.

That lone Amp only works the sub.

The collection of other speakers are powered from the main Amp unit at the left trunk side. It packs super fancy DSP processing. The Amp section shows integrated chips used instead of power transistors.

Left Coast Geek

and upon closer inspection, ixnay on the fiber to that sub box, its got 4 wires, brown/blue, brown/green, blue, green


according to what I *think* is the right wiring diagram on WIS/ASRA (man, that thing is confusing to navigate), that woofer has TWO drivers inside, blue & brown/blue goes to one, and green & brown/green goes to the other. the brown/XXX wires are the + side, the solid wires are the - side. These wires come from the N40/9 rear woofer amplifier, pins 10,7,1,4 respectively.

per this diagram, that M40/9 rear woofer amp gets IN+ on pin 3, and IN- on pin 2, signal shield on pin 9, always-on power on pin 11, ground on pin 12, and an 'on' signal on pin 8. The IN + / - signals, and the On control signal all come from the main 'sound system control amplifier' N40/3

N40/3 in turn gets its input from the MOST digital media bus, which I believe is optical.

a4ncar

Thanks, seems pretty involved to get to the subwoofer.

You are correct, disconnecting it cleared up the distortion that I was hearing. And rest of the other speakers are seem to be working fine. Removing the rear deck to disconnect the connector seems to be a lot of work. Thanks

The one my 2012 and 2014, setup looks much different than what you show in the picture above. I like your setup especially the way it lifts up. Perhaps this was for the wagon only? Thanks

Left Coast Geek

my setup is a wagon, thats the spare tire access under the 3rd row seat. if you have the harman-kardon logic7 setup, AFAIK, your sub should be next to your spare, too

let me re-enumerate the pins on the sub amp for this per WIS...

N40/9 rear woofer amp...

1. sub2+ - green (1.5)
2. in- - brown
3. in+ - white
4. sub2- - brown/green (1.5)
5. -nc-
6. -nc-
7. sub1- - brown/blue (1.5)
8. turn on - black
9. input shield
10. sub1+ - blue (1.5)
11. always power from fuse 69 - red/grey (2.5)
12. ground - brown (2,5)

(numbers in () are metric wire gauge when given, in mm^2)

and ok, BZZZZZZ, the + and - on the speaker icons do NOT agree with the + and - on the subwoofer amplifier output, and this seems quite intentional.

CaliBenzDriver

long story short ... your sub Amp got killed (my US English for defective) so FYI: take it easy with the audio output level before your main Amp goes silent, one speaker at the time: $$$$

My free work around trick is to open the trunk side panel doors in hope to get more cooling.... including rear seat arm rest opening.

I am planning on visiting this woofer module between November - March knowing already based on main Amp...:
-- Heatsink surface was left un-machined 😅-- Coupling caps are only 16Volts (when car is supplies 14.9v + spikes!)

This Amp system was designed (16v caps) and built (bad heatsinks) to need repairs after abuse.

It's easy to make it work fine before it's fried: (Integrated Amps are non-replaceable 'cause unmarked unless you find a wizard) : keep audio down on FRI night like it's MON Am !!

Left Coast Geek

I was pretty amused to see Becker aka Harman-Becker on the various A/V components on our E350. Harman not only owns Becker, they also are JBL, Infinity, Mark Levison, Crown, Bang & Olufsen, and I dunno how many other brands.

Except now they are all Samsung. :-O

a4ncar

How about adding plastic louvered vent s) on the side panel and perhaps even adding a computer fan(s)?

CaliBenzDriver

... sometimes easy does it 🙂

The limiting issue of poor thermal contact of power amplifier chips will remain (in cars affected by the batch of sick assemblies).
So the heat sink itself can be well cooled with fans but amplifiers chips may remain toasty.
Try not to stress your audio Amps with high outputs.

a4ncar

The 2014 W212 my 18 year old drives it, so he likes to blast it. I was not able to solder the wires to the pins as my soldering skills are minimal and the problem I saw was the bottom pin #24 would have impossible for me to solder. I did put new heatsink paste on the DSP chips as the old one had become more fluid like. Closed the unit and tapped the wires on the outside. Thanks for your input.