[cathul]

If you got a Harman Kardon Logic 7 system in your Mercedes there is no low-level signal to the first stock amplifier, but a MOST-bus signal.
Therefor you need a MOST-bus adapter. This is the only way to circumvent the stock processing like bass rolloff and stuff like that.

 

[Jroo]

If you got a Harman Kardon Logic 7 system in your Mercedes there is no low-level signal to the first stock amplifier, but a MOST-bus signal.
Therefor you need a MOST-bus adapter. This is the only way to circumvent the stock processing like bass rolloff and stuff like that.

I did a quick google search and saw a few others in MB forums that did aftermarket. As mentioned they used a MOST adapter of some type. My Volvo is similar and I am looking at the piece from Helix. OP needs to solve this first

 

[bentz69]

If you got a Harman Kardon Logic 7 system in your Mercedes there is no low-level signal to the first stock amplifier, but a MOST-bus signal.
Therefor you need a MOST-bus adapter. This is the only way to circumvent the stock processing like bass rolloff and stuff like that.

I honestly have no idea what a most-bus signal is. You're telling me something like the kicker keyloc that these guys mentioned won't work? Can you link me to a product

What about the signal from the stock secondary amp? I believe it's considered high level and during the first install I used those wires for the JL box.

I still have the posi-taps on the 4 wires coming out of the secondary amp.

 

[cathul]

I honestly have no idea what a most-bus signal is. You're telling me something like the kicker keyloc that these guys mentioned won't work? Can you link me to a product

Unlikely that the key will work.
Regarding MOST bus: https://en.wikipedia.org/wiki/MOST_Bus

Check m0bridge for devices: https://mobridge.us/

What about the signal from the stock secondary amp? I believe it's considered high level and during the first install I used those wires for the JL box.

I still have the posi-taps on the 4 wires coming out of the secondary amp.

That signal is already processed and inherits bass rolloff when volume rises and all kind of other problems.
With higher end factory systems the old technology like LOCs don’t really work. You need special integration devices like those from m0bridge for that.

 

[Jroo]

I honestly have no idea what a most-bus signal is. You're telling me something like the kicker keyloc that these guys mentioned won't work? Can you link me to a product

What about the signal from the stock secondary amp? I believe it's considered high level and during the first install I used those wires for the JL box.

I still have the posi-taps on the 4 wires coming out of the secondary amp.

think of it like this. It is like a fiber optic cable. The head unit is sending info through that fiber optic cable down to the factory amp. The rolloff is already decided and done before the factory amps you are trying to tap into. You are trying to tap into the amp and nothing you do behind it will change that. The most devices we are telling you intercept the information the head unit is sending and fix it and then send it down stream. That will allow you to plug in amps and not have the issues you are having.

What year car do you have?

 

[bentz69]

Those most units are pricey but I guess ya gotta pay to play.

I have a 2016 MB CLS63

Edit.. Will a audio control lc2i do the job? I called both Crutchfield a d audio control tech support and both feel the lc2i will do fix the problem

 

[cathul]

No

 

[bentz69]

No

So by that statement every single person with a harmon kardon system or similar must be using a most bus unit like you suggest or they are just living with the problem of bass rolloff and wasting money on different types of signal processors

 

[cathul]

In the end, yes. That’s why you read a lot of threads in Mercedes forums in Germany where people are not happy with their aftermarket setups where they used LOCs.
Basically no shop in Germany that I know uses LOCs in BMWs or Mercedes with MOST controlled systems anymore. If it's not MOST controlled people use the HELIX Match amplifiers with enough inputs and sophisticated DSPs built into them to clean up the system, but not LOCs (well, technically they are using LOCs as these are builtin into all DSPs on the market afaik).

edit due being in front of my computer now and not typing via smartphone keyboard.

It's basically the same with almost every other upgraded stock system. Look at Hyundai f.e. You need a very sophisticated DSP to overcome the allpass filters and response on the output of the stock amplifier. Or you go with an optical signal integration, which provides a flat, unaltered signal. But in this case you need the ability to control the volume of the DSP via CAN-Bus f.e. Anyway, a Kicker Keylock will never be able to integrate correctly after the stock amplifier.

Look at Ford A2B bus. To get rid of Active Noise Cancellation in these systems, you need some kind of integration device for the A2B-bus instead of using LOCs after the stock amplifier.

Anyway... for the upgraded stock system in 99% of all cases you want some form of integration before the stock amplifier, just to get a clean signal. And the old technology of LOCs is just not doing this anymore.
If you got a basic system without a stock amplifier and only front/rear output, then maybe yes, but still i would always check first if there is a way to reprogramm the headunit to variable line output in these cases just to prevent the need of a LOC.
But that's just me. I never understand people using Line Output Converters if there are much better ways to integrate.

 

[bentz69]

In the end, yes. That’s why you read a lot of threads in Mercedes forums in Germany where people are not happy with their aftermarket setups where they used LOCs.
Basically no shop in Germany that I know uses LOCs in BMWs or Mercedes with MOST controlled systems anymore.

I suppose in Germany thats the norm and probably preferred for a more advanced install. My full day of reading today and stopping by 2 installation shops suggests the accu bass function on the LC2I will compensate for that bass rolloff known to occur in many modern day vehicles. The kicker keyloc will likely not be the right product for me . It might not be perfect but for the majority of us not trying to win a competition, it will more then suffice.

 

[cathul]

In Germany they use integration devices even for the so called basic installs if the car demands such a solution due to the upgraded stock stereo system.
Beside that, the use of LOCs in Germany is almost non-existant anymore as almost all amplifiers and all DSPs have a LOC already built in.
The typical basic install in reputable shops in Germany is around 2.500,-- € to 3.000,-- €. Plenty of budget for a good DSP-amplifier, at least a 2-way front, a sub and lots of deadening.

 

[BubbaB]

Hi, I have been dealing with same situation. They speak the truth. You need to by pass amp. It will never work right with out a lot of work and equipment. Helix, or mobridge makes units. Takes a lot of power to get a benz to bounce. I have been down that trail Your on. Car is made in Germany and doesn't change here. HELIX.
I have a bunch of equipment, new in box I can sell You are learn from my mistake. Have questions get in touch.

 

[llebcire]

Lots of great advice in this thread!

I have a 12" Type R in a 0.9 cubic ft sealed enclosure at 300w and it's excessive easily overpowering my mid/highs at 100 watts (Morel).

The AudioControl will likely make a difference (patented Accubass) for less money than an adapter designed for your vehicle, but in my opinion you should search for a deal on the correct adaptor. According to everyone posting here with knowledge, it will solve your bass problem.

-Eric

 

[Jroo]

I suppose in Germany thats the norm and probably preferred for a more advanced install. My full day of reading today and stopping by 2 installation shops suggests the accu bass function on the LC2I will compensate for that bass rolloff known to occur in many modern day vehicles. The kicker keyloc will likely not be the right product for me . It might not be perfect but for the majority of us not trying to win a competition, it will more then suffice.

My local shop was able to test output after my factory amps. They were able to confirm if signals needed to be summed and if I had some processing or something happening to response. I have a Volvo but had to go down this boat. The shop that tested told me, 100 percent go with a most adapter. We also found through contacting some of the companies, Helix could guarantee it would work and read the information coming from my Volvo head. Other companies being honest told me it might work on my model Volvo. My shop also confirmed it would be a waste to go speaker level with something like audio control. It was nothing against the brand, it all had to do with the signal we were tapping into with the Audio Control unit. Basically, spend a few more dollars, do it correctly and wont have to come back.

I just mention that vs someone telling me it wont win a comp it will suffice. If your car is MOST, and it were me/my car, I would look at those units first. I would much rather know I have clean flat signal to tap into vs speaker level that could be sorta right. Also if you have some volume dependent processing present, anything speaker level is going to have a tough time fixing that.

 

[DaveG]

Don't know anything about the M-B but my wife has a 2019 Audi with Bose and of course it had the bass roll off. I simply installed a Kicker Key500.1 using the oem sub speaker lead for input and guess what? No more bass roll off! I also swapped the sub out too but like I said, no more roll off. The transformation was pretty incredible for it's simplicity! Why can't this be done in your M-B? It's been sometime since I did this but I think the Key500.1 can accept up to 40v input and I doubt your oem sub amp is putting that much out.

 

[BubbaB]

I have been researching the situation for a while and have talked and listened to different setups. The systems that went with the most adapter seemed to sound and work really well. I've seen a few who went hi level first then ended up going with the adapters. I guess it's because We're never satisfied. Lol. You know we start with just adding a little this or that then.. I don't know, that just seems to be the case. Everyone that I came across with a MB and HK system seemed to eventually go to with a Most adapter. Please let me know how Your project works out. Keith

 

[bentz69]

Im not doubting anyone in this thread and a most adapter may be the "best" solution. I read quite a few threads on Mercedes forums and many stated the accu bass function on the lc2i will restore that lost bass from roll off. The lc2i was only 100$ and I can install it myself and tune it myself in maybe an hour. For me its a worth a shot to see if if works. If it doesn't then Ill return it and put out the money for a most unit

 

[bilboaudio]

Correct me if I am wrong, but on a helix dsp, would you be able detect the bass roll off in the signal input analyser screen and see the bass frequencies drop when you cranked the volume up?

 

[cathul]

Not in realtime, but yes.
With several measurements at different volume levels you could see that.

 

[Sounds_Insane]

Im not doubting anyone in this thread and a most adapter may be the "best" solution. I read quite a few threads on Mercedes forums and many stated the accu bass function on the lc2i will restore that lost bass from roll off. The lc2i was only 100$ and I can install it myself and tune it myself in maybe an hour. For me its a worth a shot to see if if works. If it doesn't then Ill return it and put out the money for a most unit

You can try the LC2i or the Kicker KeyLoc. The Key will do everything you are wanting, although it sets itself, so there is no adjustment other than setting it up with different tracks or setting your radio's bass level higher or lower prior to setup.

Here is a video on how it works and how to set it up.

You may find more information on the LC2i because it's been around a lot longer then the Keyloc. Like I said before, the LC2i I had, one channel died within a couple months (could have been a fluke, so don't base AC quality on my experience), I haven't install the Keyloc yet, my brother has in his car and said it made a big difference (he also has the LC2i). I'm sure there are people here that have used and tested both.

Obviously the best solution would be some sort of interface to the factory system, but it's not always practical or necessary for a simple upgrade.