# BMW M6 (the dangers of scope creep) Part 1



## Voisin777 (Dec 27, 2010)

As many have already pointed out the combination of the poor quality drivers that BMW use in all of their cars the extensive DSP they apply to the audio signals results in a system that is not musically engaging and for most material just sounds odd. This was going to be a quick little project swapping out the center channel and maybe the front door speakers. Unfortunately one thing led to another as I decided I really could not live with the sound from the under seat woofers. The scope creep continued until I decided (with much help from Ken at MusicarNW) to rip out the entire front soundstage, under seat woofers, add a proper sub, quality amps, and new wiring. If I had been a little smarter and fully appreciated the amount of time that this would take to do myself and may have never started the project. I only figured this out when I was so far into the project that there was no going back.

Here's a schematic for the system:









The install goal was to make the system disappear as much as possible , so I decided to build a simple amp rack and mount it under the rear shelf. The Zapco DC’s are fan cooled and can allegedly be mounted in any orientation. Birch ply and Tee nuts, including nuts for a DC 200.2 in case I decide to take the center channel active in the future. To install solid mounting bolts for the rack the entire rear interior ofthe car from the B pillar back needed to come out before the rear shelf would slide out.









Next I ran 0AWG power from the trunk mounted battery (fused at the battery) to a fused 4AWG distribution block near the amps. Similarly a 4AGW ground distribution block is attached to a bare metal chassis ground at the other end of the rack (0Ω to battery terminal).









It seems that the only remote turn on wire is PIN 13 at the back of the CCC head unit (as a Logic7 car the only connection between the CCC HU and trunk mounted amp is a MOST fiber Optic bus, and amp power on is sensed from activity on the MOST bus).









The Zapco's are programmed via a mini USB connector. To make life a bit easier I made up a male mini USB to female mini-USB socker and mounted it in the rear of the center console. Damn those pins are close together.









Next was the center channel, the Morel Integra Ovation 4" is on the left, the BMW stock on the right. Why BMW pushed high frequencies into this mid range driver, or did not use a coxial, is beyond me.









Center channel getting installed. Ken's tip of using four core cable made routing the new speaker wire much easier.









I used Jehnert shallow 8" woofers (from www.musicarnw.com) to replace the underseat subs. Not as much LF as the SWS8, but more musical. I used the jtsherri spacers to fit these into the stock locations and a little butyl rope from Dan at Sound Deadener Showdown - Your Source for Sound Deadening Products and Information to make an airtight seal.









I used Morel HO 4" for the front doors, with Ken's rings to mate with the BMW three screw mounting.









Again the butyl rope ensured an airtight seal between the driver and the baffle (I love this stuff, well all except the lump that I tied tried to pull off a fleece sweater). I had a little Dynamat lying around so put some around the speaker opening.


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## Voisin777 (Dec 27, 2010)

*BMW M6 (the dangers of scope creep) Part 2*

The HO tweeters mounted into the stock sails with just a little heat on the sail's plastic retaining clips (I was frightened about snapping the clips by just forcing in the slightly larger HO tweeter without heat).

















I bought a bassforms sub enclosure for the E63/4 very cheaply and through that I would give it a try. If it does not work out I can always try to make one later. Its about 0.75ft3, stuffed it with poly fill and managed to get two bolts to hold it solidly using existing holes in the chassis.









Tapping into the Logic7 amp outputs was fun. I found a good diagram online which was correct with the exception of the front right channel which is actually yellow/brown and not blue (I reconnected the blue cables that I severed in this photo).

















The speaker level outputs were fed to Zapco BTLs, and then to the amps.

I finally got to hear sound out of each of the drivers a couple of days ago. I've set basic crossover points, and non-dangeous levels although thsi systems has yet to be properly tuned.

Now to the PIA: I have mild alternator whine coming from the center channel and right front tweeter. I've check the amp ground and there is 0Ω between it and the battery terminal. I need to investigate this further and am hoping that I will not have to rerun the speaker cables to the right hand side of the car (the center channel and right door cable take the same path with is along the existing wiring loom). I need to set the levels properly for the amp (but I don’t think that they are too far off). I connected the signal ground from the BTLs to the ground line going into the Logic7 amp, I’ll try running this to the Zapco amp ground point (although this does no explain the right side only noise). Using the remote turn on the HU (without a relay) may have an impact (although I think it unlikely). Anyway looks like I need to test from the speakers back a component at a time over the weekend.

One general questions, I understand that BTLs allow you to partially reverse the ~35Hz subsonic filter BMW implements on the sub channel, but I have found no instructions anywhere (e.g. in the box, on Zapco's website) on how to use the jumpers. Any help greatly appreciated.


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## ohiodish (Jul 6, 2010)

M6 is one of my favorite cars. Just bought my wife an 08 650i convertible and they basically have the same (lame) sound system. She thinks it sounds good, but I know how you feel. The OEM system needs help. Looks great so far and once its all done I'm sure you will be glad you put in all the hours. Some cars take a lot of time just to do the simplest things. Subscribed


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## tlow98 (Oct 8, 2009)

WOW nice equipment and you are not kidding about a time consuming install. My last BMW was so much harder to work on than my current saab. I'm not sure why but I was terrible at removing plastic clips on that car. they always seemed to break.

can't wait to hear your final thoughts on the system. love that morel 10.

here's to me hoping bassforms makes an appropriate box for my car


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## Voisin777 (Dec 27, 2010)

I hear you on the clips. Of course being BMW they have white ones, red ones and gray ones: all with different properties. I bought 5 of each before I started and used a bunch of them. I just need to get over the alternator whine and then can start enjoying the sound. From what I have heard so far it has great potential, although the tweeters are a little bright (remember no tuning yet).


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## tlow98 (Oct 8, 2009)

you could always back off on the tweet gains, too. even if you end up hating them that's a qucik swap.

yea, thanks bmw, rollseyes. i loved mine overall, tho


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## Voisin777 (Dec 27, 2010)

*Re: BMW M6 (the dangers of scope creep) Part 3*

Spent some time on Saturday trying to get the bottom of the alternator whine. First the easy part: center channel whine was just me being sloppy with the install. Center channel is still being driven by the stock Logic7 amp so no ground issues, this was pure induction from parallel power cables. 
Three part fix:
1. Use fully shielded 4 core twisted pair cable between the Logic7 amp and the Morel passive crossover (purple wire in the pictures).









2. Re-route cable further away from the power cable (I can’t move the power cable any further to the right or the trunk hinges will hit it when it closes (potentially exciting, but really not good).

















3. Just to be sure I also rerouted the center channel and passenger door speaker cables. Previously they we raouted through the main conduit on the passenger side. I noticed a fairly sizable power line in the factory bundle and decided proximity was not a good idea. I puller the cable and routed them over the passenger seat to see if that was the problem.









Sure enough problem solved with center channel. To keep some distance from the factor cables I used some self-adhesive closed cell foam I had from another project, and cut a series of strips ans stuck them just above the factory strips to make a channel for the cables. I wrapped the cables in BMW foam tape which had just enough friction to prevent then from moving.









Continued running the cable block above and away from the main wiring back to the trunk.









Feeling quite pleased with myself (I can pull the interior apart very fast now) I started the car and no noise from the center channel. However the right tweeter is has alternator whine.

Here is where I am:
1.	I know that this is not induction through the cable as the center channel runs parallel.
2.	I know that I have a good ground for the Zapcos, ground distribution block, 0AWG to bare metal, 0Ω from amp ground input to battery.
3.	I moved the signal ground for the 3 BTLs from the amp ground input to the amp chassis (0.1Ω to battery ground).
4.	Removing ALL connectors other than power and speakers from the amp, and hardwiring the remote on still produced whine in the speakers.
5.	No whine from the left front tweeter, just the right, so I moved the left front tweeter and mid to the right outputs from the 360.4 driving them, and the alternator whine moved to the left front.
6.	I was using output ch2 and ch4 for the tweeters, I switched to ch1 and ch3 (with mids on ch2 and ch4), whine still there.
I may try grounding the amp chassis (which Zapco says you can do), although as it is only output ch3 and ch4 I’m starting to think that it may be the amp. Another option might be to install an MSD 8830 Noise Filter under the hood between the chassis and jump power connector (alternator is not easy to get to). I’m assuming the small amount of a.c. creating the problem would just be shorted to ground leaving just the d.c. current from the alternator. Has anyone on the forum tried this?


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## Onyx1136 (Mar 15, 2009)

Try putting a 1/4 farad capacitor on the positive lead between the alternator and the battery. Obviously, ground the negative post of the capacitor. Fixes alot of weird noise issues in Beemers.


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## Voisin777 (Dec 27, 2010)

Thanks, capacitor is now the next step.


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## 3cyltrbo (Apr 11, 2011)

sorry to go a bit off topic

I really like the system diagram you drew - what software did you use? 
I'm floundering with one now

subscribed for more updates as well. 

Cheers

Will


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## Voisin777 (Dec 27, 2010)

I made the diagram in Microsoft Visio. It works well for this type of diagram, you can add connection points to the objects so the lines move with the objects.


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## RBeachTL (Jul 21, 2008)

Sure seems like you have the correct troubleshooting approach. Did I understand you correctly that you observed these results with the amp's symbilink input disconnected but all other connections in place?

Ch1 - left mid => no noise
Ch2 - left tweet => no noise

Ch3 - right mid => no noise
Ch4 - right tweet => noise 

Moved wiring

Ch1 - right mid => no noise
Ch2 - right tweet => no noise

Ch3 - left mid => no noise
Ch4 - left tweet => noise

This is where I wasn't sure what you observed when you switched the mids and tweets; is this what you observed?

Ch1 - left tweet => no noise
Ch2 - left mid => no noise

Ch3 - right tweet => no noise
Ch4 - right mid => noise

if this is what you got then it sure seems like you have isolated the problem to amp channel 4 and you should try another amp.


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## Voisin777 (Dec 27, 2010)

Basically yes. I did two discrete tests changing the channels:

1. Swapping the left and right speaker cable connections to the DC360.4, the noise moved from the right tweeter to the left tweeter, with in both cases was output ch4. I switched the cables back when this did not solve the problem (made the wiring neater).

2. I changed the config on the DC360.4 so that the mids moved from output ch2 and ch4, to ch1 and ch3. The right tweeter noise remained coming out of the right tweeter.

Remember the amp has four input channels with ch1/2 on one Symbilink input on ch3/4 on another. I am only using input ch1/2 and mapping input ch1 to output ch1+2, and input ch2 to output ch2+4 (I could not see a way to use input ch2/3 and map it to all out put channels).

If this is an amp issue then it seems to me that the noise problem is on input ch2. With an 1,800Hz XO point it is easy to detect on the tweeter, although I believe that the same noise is being delivered to the woofer (it’s just ~800-1,800Hz that would be audible). The noise is loud enough to be annoying with the sound muted (the amps are always on with the engine running), but inaudible with the system cranked up. My current hope is that a cap close to the alternator grounding the a.c. will be enough to kill the noise. Failing that there is always the straight through exhaust option .


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## RBeachTL (Jul 21, 2008)

I'm not sure what version of DPN you are using but in V1.41 you should be able to check the Ch 1/2 channel select box at the top of the screen; then pull down the input channel select pull-down menu in the lower left part of the menu and select Ch1. Then check the 3/4 channel select box at the top and pull down the input select and choose Ch2. Try this and see if the noise is still there.


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## Voisin777 (Dec 27, 2010)

Last night I moved the input from ch1/2 to ch3/4. Using DPN 1.4.0 I could direct ch3 to the right tweeter and ch4 to the right woofer, alternator whine is still there, actually a bit lounder. Waiting for the cap to arrive. If that does not fix it I think I'll take the amp to Zapco to have them test it.


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## quality_sound (Dec 25, 2005)

If the noise moved to the left when you swapped the speaker leads at the amp then the problem is the amp or something ahead of it, not the tweeter or speaker cables going to them. I'm thinking your custom input is at fault. Try swapping input cables and see if the noise moves to the other amp. That'll confirm if it's the input cable or the amp itself.

I wouldn't even use the cap. We want to fix the problem, not hide it.


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## emoon3 (Apr 16, 2011)

subscribed


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## Voisin777 (Dec 27, 2010)

OK, time for an update. The crutch of installing a capacitor to eliminate the alternator whine was clearly wimping out so I sent it back unopened. I bought a DC200.2 and installed it so the center channel is active. Now there is absolutely no alternator whine from the center channel, so I’m pretty confident that the noise was being induced in the coils of the passive crossover. All that is left is alternator whine from the front right tweeter. Just to recap:


Engine running no power to amp no noise.
Swapping left and right speaker cables the noise moves from right to left.
Swapping Symbilink inputs for 200.2 and 360.4 noise stays with CH3/4 outputs on 360.4.
So I know:


The noise is not being induced in the speaker cable as: (i) the center channel cable runs next the right channel, and (ii) the noise disappears with the amp power off.
The noise is not on the input side as: (i) it is still present with no input, and (ii) moving the input to the 200.2 there is no noise from the 200.2.
It is not a ground loop as only CH3/4 on the 360.4 are noisy.

So now I’m thinking it’s the amp. I live pretty close to Zapco so I call them up and speak to Mike the service manager. *At this stage I need to say that Mike has been unbelievable helpful, going well above and beyond what anyone could reasonable expect of a manufacturer, I have nothing but respect for Zapco and thanks to Mike.* With Mike’s approval I take the car to Zapco. We then connect another 360.4, no noise, I naively think 'YES it’s the amp'. Mike scratches his head and says that makes no sense as the power supply is common across the channels and if the amp were at fault you would hear noise on all channels. Mike tests the amp and finds no fault.

I mount the test amp under the rear shelf, noise comes back. So now we know it’s not the amp, instead of throwing me out (which I fully expected and would be completely reasonable), Mike is intrigued enough to humor me a little more. I swap my amp back in and give him his test amp back, noise returns without the amp mounted, noise gets worse with the amp mounted.

Here’s the current theory: 1-8 kHz noise being induced by some hidden device in the rear shelf that is located directly above the CH3/4 section of the 360.4. (Why my amp made some noise when left on the floor of the trunk is that there is a factor power distribution/fuse unit under where I had the amp located.)

I pulled a diagram of the rear parcel shelf from the service manual, and sure enough there is a “backup antenna amplifier” located above CH3/4 side of the amp. After a little reading up on VLF noise: it seems my options are trying to create some form of Faraday cage around the antenna amp and/or installing a flat grounded shield between the 360.4 and antenna amp. Searching the Internet I came up with using the Magnetic Shielding Foil from this site Magnetic Field Shielding Materials. Before I go ahead and buy the foil does anyone here have a (probably more educated) opinion the best way of tacking this problem (material and shield design/location).


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## quality_sound (Dec 25, 2005)

I'd agree with that. It's likely the amp.


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## SSCustoms (Oct 16, 2008)

Voisin777 said:


> Before I go ahead and buy the foil does anyone here have a (probably more educated) opinion the best way of tacking this problem (material and shield design/location).


Could you just pull the fuse for the antenna? If not fused, just disconnect it?


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## jpeezy (Feb 5, 2012)

Find some of that dynamat floor stuff,it has a thin layer foam and a lead septum layer,try the lead layer in between the amp and deck,I've used the foil it only worked maybe once out of 6 times.make sure the chassis of the amp is not touching any metal, good luck.the mobridge piece won't work in that car?Can you relocate the ant. Amp?


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## boltcd (Sep 26, 2011)

I had a similar problem in my e39 bmw, and the problem was in the crossover for the tweeters, i switched to running actiive and it solved the problem.


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