Routing cable from head unit to boot - W212 2012

[jlb777]

Hi All,

My Merc E Class arrives on Monday and I want to add a PNP Amp and sub to the boot. Can someone very kindly explain and/or point me to some instructions as to the easiest way to run cables from behind the Audio 20 head unit to the boot?

Very big thanks in advance ........

James

 

[sinewave]

Yeah, ask the dealer to install a duct from front to rear with some draw string in prior to delivery!

 

[shorty]

The best way is down the drivers side along with most other cables , also the rear SAM is on the drivers side so it should be easy to pick up a live feed . Theres wire duckts leading from the centre consul to the sill then another duckt running along the cill . The consul and drivers seat would need to be removed to access these .
To pick up a live feed for the amp in the boot I would connect onto the white fuse pannel on the rear SAM , this is where the power feed for the auto close boot/tailgate it picked up and this uses a 40 amp fues . The feed will power up when the cars unlocked.

 

[jlb777]

Thanks Shorty - really appreciate your reply...... quick question though please sir:

When you say there are wire duckts leading from the centre consul to the sill then another duckt running along the cill - what do you mean by / where is the "cill"? and do you mean behind the Audio 20 head unit when you say centre consul?

Really sorry if I am sounding a bit dumb? Bit of a noob is me

 

[Sp!ke]

Follow the lead for the aerial would be my first thought.

 

[richard]

I'd run the audio cabling down the left hand side rather than the right hand side. This is because there are very few cables there to create noise interference on the low level audio signal.

There is also room behind the left hand boot carpet, and if there isn't enough you can buy the left hand boot carpet for Harmon Kardon, which gives you much more space as the HK amp would be on the left hand side.

Getting the power across from the right to left is easy enough in the boot.

There are holes between boot area and body area near the top of the seat bolsters, so the wires run up behind the seat bolster and through into the boot.

Harmon Kardon wiring is also run on that side. It is also easier to remove the cover above passenger footwell below dashboard than the other side as there is no diagnostic connector or bonnet opening handle in it.

There is a wiring duct next to the sill down the car.

R

 

[richard]

Also, use a proper amplifier wiring kit, with the correct size fuse, and connect to the battery if you can, or a big fat power feed - bigger than the cables you are connecting.

Do not connect the amp power feed to any switched feed - you risk blowing up whatever is doing the switching, and amps want permanent power. Do not remove the consul, just the Audio-20, the plate above passenger footwell, and the door sill covers, and the rear seat squab and some of the boot trim. You do not need to remove any seats either. I know I have contradicted everything Shorty has told you.

There is a low current turn on feed for the amp. This should be connected to the appropriate output on the Audio-20 (can't remember which pin number) that comes on and off when the stereo is turned off (NOT when the ignition is turned on and off, or it won't work when the ignition is off and you turn the stereo on).

Richard

 

[jlb777]

Crikey Richard - what a detailed response, I would like to say a very big thank you for the info.

Can i kindly ask just a couple of questions of you please sir?

How easy is the plate above passenger footwell, the door sill covers, and the rear seat squab to remove? Being a lease car, I dontwant to damage anything. Any rough guidance you can offer will be greatly appreciated.

I am putting in the Helix PP50 "pnp" AMP and Helix PP7 Sub - the cables go directly into the back of the existing Audio 20 (Nav 50 for me) head unit and will run the route of the car that you have suggested. I will not need to worry about a power source as it is taken from the main head unit cabling, also the AMP is fused and the Sub powers from the AMP.

I am very nervous about the process, but looking forward to having a stab.

Thanks again inadvance.
James

 

[npuk]

Blaupunkt do a 'pnp' range too. You could probably use the short connection lead and actually install the amp in the passenger footwell, they arent big.

 

[jlb777]

It is funny you say that, I was actually just thinking to forgo the £400 Helix DSP PNP AMP and go for the more cost effective non DSP based Blaukpunkt THA 475 instead?

Do you think this will make much of a difference in power/overall quality of sound compared to the amp built into the Audio20\nav50 head unit of my W212?

Is there a battery in the boot of the W212 that I might be able to power an existing Alpine SUB / AMP to?

What would be the easiesit and least risk (in terms of damaging the car) of getting a sound source to the amp in the boot of the car?

Thanks for your help.....

James

 

[richard]

Hi

Battery is in the boot on the C class, I just can't remember on the E class. I suspect there is a big feed into a block in the boot if the battery isn't there.

The panel above footwell is 2-3 Torx TX20 screws along the front edge. The sills just pull up, but there is a hook at one end, so be careful not to break it.

The boot trim is just a couple of TORX screws holding down the tie down clips (for luggage nets) and some black 2 part clips, where you pull out the centre section which then releases the outer section and that pulls out. I think there are 2 of those quite high up on the carpet, and the screws are at the bottom.

Open up a coat hanger and cover one end in lots of insulating tape so its not sharp, and use that to push the cables along under the carpets. (or go to the local electrical supplier and buy some pulling rods!)

Everything is quite strong on a Mercedes

I've tended to use the little Alpine 10" powered sub of a bit of extra base - or the Rockford Fosgate version that is in a thin cabinet that is easy to mount against the back of the rear seats. Or installed Harmon Kardon instead (we've done a couple of W212 recently with Harmon Kardon)

Cheers

Richard

 

[jlb777]

SUper - you are a complete star Richard, tahnks.....

I may have ot stage my purchases a little bit, as such I think I may leave the AMP for a few months. I already have an Alpine Sub AMP & Sub, just need a new box enclosure for it to go in as it is currently in a specially moulded one for my old Jag S Type.

If i dont bother adding the Blaupunkt pnp AMP, what would be the best and easiest way to feed the sub amp in the boot?

Thanks again......
James

 

[richard]

It depends on the sub amp

Its easiest to feed it with speaker level feeds from the speaker outputs of the Audio-20 (as it has no RCA/Phono level outputs)

This assumes the amp has speaker level inputs - if not, you need a level converter to convert speaker level outputs of head unit to RCA/phono levels.

Cheers

Richard

 

[jlb777]

Thanks Richard - the amp currently recieved a speaker cable feed rather than phono, so sounds good.

Do I just run new cable from the rear of the head unit? Do I just jam it in to the existing terminal in head unit

 

[richard]

Does it take 1 input or more. I'd personally strip some of the insulation on the speaker cables and solder the feed to the amp onto them. Easy enough to undo,and decent connection ..



Richard

 

[gIzzE]

You would probably be fine with the Blaupunkt, I used the 555 in a BMW set up and was pretty impressed.

The Merrc head units have all sorts of adjustments on them in the engineer menu.

You have crossovers with 3, 6 and 12db slopes for each speaker, you can then chooe between a standard and paramentic EQ with different Q factors.
I only found it yesterday while seeing of there was a way to adjust the aux input gain, so haven't delved in yet, but might well do.
Thinking if you could amp the fronts and rears and then send only signals below 400hz to the rear and change the crossover slightly on the front you could have a pretty tasty sounding system with the stock speakers.


Oh, and regarding the aux in, you can't, but you can add 6db to the overall output, which is double the volume and makes the aux usable with an ipod/iphone, just be careful when going back to CD/Radio.

 

[gIzzE]

Here is a link to my thoughts on it and some pretty standard install pics I took, most of it can be used on other marques..

Blaupunkt Plug'N'Play Amp install..... - BMW

 

[jlb777]

Thanks gIzze.......

How would I get into the engineers menu on a audio20/nav50 system?

Also, what eq settings etc would you suggest I set the head unit to in order to achieve deepest bass tones?

Thanks in advance.
James.

 

[gIzzE]

You hold down the hang up+1+# for 5 seconds.

I wouldn't want to recommend any settings until I have looked at it properly.