Hello all,I wanted to share the details of a full high-end audio build I’m putting together for my Mercedes W221 S-Class. The goal is simple: stealth OEM+ system that hits like a live show but sounds like a private listening room — warm, loud as f***, and zero fatigue. Think Bose 901 energy, but clean, modern, and under control.

🎧 System Overview

Front Doors (3-Way Active):

• Tweeters: Audison AP1
  
• Midrange: Audison AP4
  
• Woofers: Audison AP8
  

Rear Doors (2-Way Passive or Active):

• Tweeters: Audison AP1 (in low OEM location)
  
• Woofers: Audison AP6.5
  

Surround & Center:

• Leaving the factory Harman Kardon Logic 7 speakers in place for these channels (non-critical)
  

Subwoofer:

• Factory Harman Kardon 8x12” rear-deck subwoofer
  
• Will be driven off the M5.11's sub channel

🔌 Amplification + DSP:

• Audison AF M5.11 bit (5-channel, full DSP control):
  • Front tweeters + midrange + subwoofer
    
• Audison AF M4D (4-channel digital amp):
  • Front woofers (AP8)
    
  • Rear fill (AP6.5 + AP1)
    

🔊 Sound Goals:

• Bose 901-style warmth
  
• Big midbass punch without harsh tweeter energy
  
• No shrillness, no listening fatigue
  
• Loud, wide soundstage with excellent time alignment
  

🧱 Extras:

• Dynamat everywhere (outer & inner door skins, door cards, rear deck)
  
• Cooling fans (12V Delta fans, active airflow with grilles, hidden behind trim)
  
• Amps mounted stealth behind trunk carpeting
  
• Short, direct grounds to avoid alternator whine
  
• Factory head unit retained
  

❓ Why Not Prima 8.9 bit?

Because I want real power. This system needs to hit 110+ dB without falling apart, and the M5.11 + M4D combo gives me nearly 1,400W of clean RMS power, active crossover control, and full flexibility. The Prima 8.9 bit started the idea. We will take it a couple of steps further here

💬 Why Audison Everything?

Because the tonal matching, integration, and tuning ecosystem are too good to ignore. No mix-and-match guessing. Everything is voiced to work together and I don’t have to fight phase or impedance battles. I'm keeping it all Audison for sonic cohesion and clean install.

🚀 What’s Next?

Once installed, I’ll be tuning the system with either bit Tune or REW + UMIK-1, targeting a slightly U-shaped curve with a warm top-end rolloff. I’ll post before/after RTA and system impressions when complete.

I was satisfied with the HK for 10 years, however after seeing & thinking about Mike5215's plan all these years I've finally decided to "do it"
https://mbworld.org/forums/s-class-w...1-audio-2.html

 

volume isn't the answer - get around the hideous OEM amps pathetic performance - thats where the fault in all std car systems start
you get one set of ears - ruining with vol is a mistake you'll regret

 

I'd love to see future updates on this.

 

Thank you,

I've ordered all the parts & widgets I need, and we will take the vehicle to an Audison dealer later in June for the installation. One thing I changed today in the decision was the tweeters, instead of the AP1, I went with the Audison Voce AV 1.1 II instead. The rest of the gear is as I posted.

The H&K system was good, very good, but it's finally time to take this to the next level. I'm really excited about this & I commit to posting photos of the procedure as it progresses, i.e. photos of the disassembly, notes, lessons learned, etc etc as I'm sure there will be many moments of excitement as we disassemble and dynamat this old car

Thanks!

 

Wow I'm very excited for the outcome of this. I hope all of it comes together nicely and is beyond expectations. I have the upgraded Burmester 3D in the W222 and it is an incredible system. For any future MB purchases, that option is a must now. The HK in the W221 isn't too bad, but I hate having to play it loud to gauge any "depth." I hope your upgrades come close to the Burmester 3D. That is the best car sound system I've ever heard.

 

from another guy many years ago

all came down to the amp.... https://w221audio.wordpress.com/

 

This is the exact guy that inspired me to do this, I'm following his lead and taking it a notch above where I can!

 

Hello,

Thanks for your feedback. I haven't heard a Burmeister system yet, I went through a moment last year where I had to decide, do I keep the W221 or sell & go to W222. It was a hard decision but I elected to stay on my trusty W221 and replace a variety of very expensive widgets to keep it A++ class. As a result, I won't be seeing any Burmeister for many years, my car was at 170,000KM when I was at the decision point - sell, or keep. These can't be sold well with many miles, and considering the *unbelievable* amount of new parts on mine I elected to keep it.

I drive softly, slowly, and don't care about performance anymore. I have melted *more* than my fair share of rear tires over the years, some in a single night, but this stage passed for me. I need peace, quiet, stability, and silence.

So, back to audio, yes the HK is excellent no doubt, however I wanted more. I've always wanted to have a truly unbelievable sound system that's invisible - and thanks to that amazing subwoofer in the rear deck, and the huge speaker sizes afforded to us in the front doors, the W221 can deliver my dream.

This will be a multi-day job of course, however I'll collect as many photographs as possible as it progresses. I've done sound systems myself before on more simple cars, i.e. W123's, E38's, etc, but this one is not like that - hence, straight to an Audison dealer for the installation. The way Mike5215 (https://w221audio.wordpress.com/2015...-audio-system/) described this whole experience, and the results, really sold me on this project.

Every word he used to describe the before & after, is *precisely* what I'm looking for.

I'm very excited & looking forward to driving 5KM/hr below the speed limit in the far right lane, with the Audisons working in my favor

 

I feel like your expectations are very very high and you've set yourself up for disappointment.
I don't know very much about car-audio, and i've only ever replaced radios and speakers and amps in a few cheap cars, but they always kind of disappointed me in the end.
I hope you find what you're looking for though.

 

manufacturers use budget kit - with amps with 1/4 of the power we need

the world changed to compressed junk with all the elements that make it sound special, and now talentless computer driven music as the bands today don't know how to make a noise an a musical instrument
that change had allowed us to pretend to have bass, when the amp isn't actually capable of producing any - the compression removed the transient spikes that real musicians and real recordings had - its why live music by a talented band sound so very different to the digital crap we get in a hire car with a $10 dollar systems and a $15 screen

speakers sound rubbish and die because the amp is mostly running out of its depth two fold over at 35% vol level

speakers are the last bit of any system to change - buy a real amp with stupid power output say 100 real watts not the pretend RMS measurement USA use which is a quarter of of what it needs (so 400w RMS) and plug it into a set of 20 watt speakers and the sound will be crystal clear - as the amp can drive the speaks faithfully following the crap that is 95% of content made in the last 40 years - likely the first time you'll ever have heard what the computer technician achieved in the mixing studio - from a sample of noise from the talentless media personality we pretend "recorded it". It will also be able to go 3 times louder without it descending in to muddled incoherent mush - which is where we go wrong on a std system, destroying our ears as you wind the knob further and further round trying to hear what’s going on

the mush comes anywhere from 25% vol in std systems as the speaker cones are now on their own special journey - occasionally directed by the odd bit of the recording being played that its notices. Its those transient spikes a real band, with real musicians have in their live music, that then needs the crazy power output of a good amp to move the speaker cones in a controlled manner - when we listen to it as a recording - its this new found ability for the speaker cone to follow the recording that creates the quality that’s hidden in some content - think Pink Floyd on a 25k system in a decent room set up to cope at home, vs compressed over the air Sirius junk inside a $60 a day hire car - there is no comparison - it might as well be a different track from another band


'

 

Incredible post.
I couldn't have said it better myself. Pink Floyd/Cigar will play first when this is done, followed by Uriah Heep/July Morning.
This type of music, (real music) doesn't play well on the silly sound systems MB delivered.

 

Audio in w221 is awful. For comparison, hear a Lexus Ls460 mark levinson system which is amazing.

This is a wonderful project and I wish I had the motivation and funds to get it done. But I simply don’t think I’ll be keeping the car that much longer. Also the price involved in labor and parts would be 3-4 k easy,

There is no music I want to hear so well in the car anymore at my age. I have two good audio setups at home.

But just for kicks. What amp is out there that’s great and can tap into the stock amp output for input. And have as many channels out.

 

on my old BM car a USA guy does plug and play looms to connect real amps to BM cars without the aggro
https://technicpnp.com/#homepage His website is a pile of poo - moved to suit rich kids instead of allowing a user to see what they want to buy !

DSP detritus on many BMs is the first hurdle - you need to code out the stupid errors they do to the music to suit how awful the Upgrade Amps have destroyed things

 

Hello,

Just a quick update, I have dropped the car off @ the Audison dealer, and the installation will start on Monday. I have advised them to photograph every step of the way, for the purpose of firstly populating this post, and secondly so that I can make a detailed write up.

Next Saturday they will be done (21 June) and I will update this post accordingly!

All the best!

 

Looking forward to this! I have a ton of brand new, in-the-box crap set aside that was for a competition system for my Maxima that never came to fruition. I'm strongly considering and sorting through in my mind how to throw it in the S Class as a standalone system without any factory integration. It's pretty easy to do these days and I have everything I need component-wise to do it, and with top-shelf stuff. My only barrier before I decide to make the plunge is how to get bass from the trunk to the cabin through the brick wall that is the rear firewall and the non-foldable rear seats. If I pull the rear deck speaker assembly, that will open up about a 12" diameter vent from trunk to cabin, which is great, but I'll need more. I think I'll be able to pull the rear wall trunk trim and hopefully be able to fabricate (cut a hole) in the center of the rear wall where the center armrest is and make a pass-through that will vent a little more. This will make crazy waveform interactions in the sub-bass range but no one would be able to perceive it except the most hardcore car audiophiles with measuring equipment.

The only other concern I have is 150db+ subwoofer bass destroying some electronic module buried who knows where and disabling the car Lol. This is not granpa's old carbureted station wagon.

 

drive with the rear arm rest down... so long as there's no fridge in the way

 

There's no fridge, but it's walled-off. I'm not quite sure yet what I'll have to do to get a pass-through.

 

nope its not - just trim - there's an option ski hatch with a flap - the rear boot trim is just a slab of nothingness

 

https://nemigaparts.com/cat_spares/e...76/63v/92/096/

part 60

 

Ah, that's great news! I thought it was going to be a wall loaded with modules and crap. I have to pull the trim and check it out.

 

Hello all,

We have the speakers installed, and the amplifiers integrated. We used the Audison wiring harnesses, hence no need for cutting anything.

• The two amplifiers are centrally managed, i.e. one laptop w/USB can control & tune both amplifiers
• What is incredible to me is that there are no dials, screws, adjustments, on the amplifiers, it's all done from the Audison program on a laptop
• Some clips had to be adjusted for the AP4's (midrange 4") to fit in the original brackets
• Too bad the Harman Kardon 8"'s in the front doors had to be destroyed in order to be removed as they were riveted in place.. (rivets??...) I was hoping to build a set of garage speakers out of those. Was not happy about that..
• The surrounds & the center speaker sound terrible in front of the other speakers now, I'm thinking of disabling them entirely.
• The sound honestly is incredible, it feels like you're in a Jazz bar, the kick from the Audison AP8's in the front doors is substantial, provides a very warm and fulfilling sound
• The sound quality is easily 10X improved over the HK system as volume passes over the 75% threshold
• I can certainly see the original HK 8x12 subwoofer going to the afterlife soon, so I'm considering replacing that one sooner than later with an 8" subwoofer with a custom mount
• The wood panel you see the amplifiers mounted in now, has been carpeted and looks great

We are working out the last issues now with misc rattles in a couple of places, and more than likely mid-week the car will be ready for delivery.

I also took this opportunity to install Front & Rear DVR in the vehicle, will post about that after I see it up close.

FYI that red cable visible in the trunk is the 12V power cable that goes to my 12V battery, I have a Mercedes original charger that I use to trickle charge the battery during the months I don't drive it (deep winter)

 

That looks very nice.
Can you share more details about the wiring?
Is the original HK amp still connected?

 

Hello,

Of course, I will share much more, I will have more time to visit the car on Monday and I will provide much more detail so that this is a duplicate-able job for someone else down the road,

Thanks!

 

I thought rivets was weird too. I replaced my driver front door speaker set. I drilled out the rivets and retained a perfect condition housing that I was planning on replacing the drivers in as well. Then I bought a nice rivet gun and rivets and replaced the old blown speaker set with a used unit from eBay and it sounds perfect! I've taken measurements of the housing and just need to source drivers. Pretty cool that the housing is a one-piece two-way.

 

You are already starting to consider what I mentioned in post #15! You'll want at least a 10" subwoofer for that rear deck. Since you're already torn apart back there, maybe consider an IB driver mounted underneath the rear deck and blowing upwards through the open void that once was the factory rear sub and midrange component tray.