Just finished installing my new system last night. This is in a '95 M3. I know that even the factory had problems with alternator whine on the '95, so they just clipped the signal above 10kHz.

System consists of a Nakamich MB-75 in-dash 6-disc changer, MB Quart 6.5" separates with MusiComp crossovers, JL Stealthboxes all being run by a Rockford Fosgate 600a4 amp.

Amp is mounted in stock position, power is run directly from the battery, ground is to chassis. Both with 8 gauge cable. There is no question of the integrity of the connections.

Interconnects are Monster Cable MicroXLN 4-channel units. Run away from the power wires, through the trunk pass-thru on the drivers side, then across to the center tunnel and up to the head unit.

Any suggestions on eliminating the whine? Thanks in advance.

Mark

I have a little whine in my system too. Hardley noticeable unless the volume is way down. You can try a source ground. Disconnect the ground from the deck to the factory wiring. Run an 18ga ground wire from the deck to the amp. Tie the deck ground directly to the ground terminal on the amp. That way both the deck and the amp have the same ground potential. If you use multiple amps, loop the 18ga ground to each amp, in addition to the amps normal 8ga ground. Keep the amp ground as short as possible. Hope that helps. Jay

That seems to be a common E36 problem...
I have a very slight whine similar to what Jay describes. Granted I have a pile of spaghetti for speaker wires in my trunk (at the current moment). It is an interesting problem because I have tried using muting plugs (these short the RCA's center pin to the outer connector ring) which garuntee 0Volts (ie. no signal at the input of the amp)...and I still have whine. If I shut my deck off...I still get whine. I think there is something in that trunk that is inducing noise...and damint'all I'm gonna find it.

If you used the muting plugs and you still have whine, that means you are picking up the noise in your amp, crossovers, or speakers and wires.

You still haven't ruled out the headunit and interconnect cables either, but you won't be able to do that until you get rid of the noise from the other components.

I used the muting plugs, and the system was completely silent, so I've ruled out the amp, crossover networks, speaker wire and speakers. My noise is being picked up somewhere upstream of the amp, which in my case is limited to the headunit and interconnects, since I don't have an EQ or anything else inline.

From the research that I've done, I think it's unlikely the headunit is picking up the noise, so it must be from the interconnects. THis is still pretty hard to believe, however, since the MicroXLN cables that I used are alread unshielded twisted pairs, which is the best for noise rejection.

I need to get it worked out though, because my whine is VERY audible even at higher volume settings.

Mark

I hear ya Mark...

My next step is to cluge together a pair of stereo head phones to a set of female RCA jacks. Than I can listen via the head phones to the signal coming from the deck...thus determine if I have other noise coming from the deck and or cable. I also have UTP...my guess is it's the pile of spaghetti in my trunk ( I have not yet had time to clean things up back there so it's a friggin' mess). I'm sure that may help some. Keep us updated on your findings , sounds like we are all fighting a similar battle here. I'll post my findings as well.

Later,
Mark

I believe that the problem we all seem to have could be due to the fact that the battery is mounted in the trunk, which is where all of are amps, signal processors, and the like are, and the alternator has a direct line to the battery so instead of having it all located under the head far away from everything, we have it all in the trunk where all the equipment that is highly sensitive to exterior sounds are located.

Just an idea....

From an electronic standpoint, BMW's are some of the "noisiest" cars around. The battery in the trunk is certainly a contributor to this condition.

Mark

I also got a whine when I installed my after market system. From what I know, one of the reasons you hear the whine is because aftermarket amps are just so much better and more sensitive than the factory amp, they pick up more noise. One thing you could do is ground the amp at the same location as the factory amp or try a ground loop isolator (from Radio Shack) between the amp and head unit. But unfortunately, even after you do all that and use premium aftermarket cables, connectors, etc., you will probably always have some type of noise.

Originally posted by jmciver
I also got a whine when I installed my after market system. From what I know, one of the reasons you hear the whine is because aftermarket amps are just so much better and more sensitive than the factory amp, they pick up more noise. One thing you could do is ground the amp at the same location as the factory amp or try a ground loop isolator (from Radio Shack) between the amp and head unit. But unfortunately, even after you do all that and use premium aftermarket cables, connectors, etc., you will probably always have some type of noise.

Ground loop isolaters work, but they have a tendency to adversely affect the sound you *want* to hear, too...

If you want to minimize the noise, this is what I find that helps. Use a high quality deck that has a high voltage output and set it to use the higher end of the volume control (example if deck goes to an 80 for max volume, use 70 as the loudest you would want to turn your deck up to). Then run it to the next piece, eq, crossover, amp, etc. Turn the gains to the lower end of the spectrum on all pieces in the trunk. By doing this you use the high voltage signal coming from the deck to mask the noise and by using a lower gain setting in the area where I will assume most of the noise is going into the system, ie the trunk, you will not be amplifying the noise in the system and this way you can keep the alternator whine to a minimum.

Another suggestion is having all components, deck, eq, amp, etc all grounded to the same spot, whether it be the chasis or the negative post on the battery. I have seen this eliminate all whine from a system by having a common grounding point.

Ground loop isolaters work, but they have a tendency to adversely affect the sound you *want* to hear, too...

That may be true, but I installed an MP3 player in my car (using a computer as the MP3 player) and used the ground loop isolator. I didn't notice any difference between the MP3 player via my computer or music coming from the CD changer. But then I don't consider myself to a super audiophile either....I don't know.

Well it looks like i'm finally going to get my new Diamond amp in next weekend. We are going to clean stuff up and hopefully that will make for some improvements. One of these days (once I buy a set of probes for my oscope) I my drag the old scope out there and see if I can figure out where the noise is actually coming from.

In my case, the interconnects are definitely picking up the noise. my only course of action is to try a different set of interconnects, use the speaker level inputs on the amp, or get a new deck with a higher S/N ratio and higher preout voltage.

I will be trying the new interconnects. I won't have them for another week or so.

Running speaker level to the amp isn't my favorite option, since it will introduce more distortion.

Mark

Hmmm...Mark...

Have you tried taking your deck out, and getting a set of RCA Female to male adapter to connect the pre-outs directly to the amp? You would have to do a little clugeing with the power, ground, remote etc... in the trunk, but this way you can determine if it is absolutely the interconnects.

BTW...are you the guy posting on Carsound.com about this topic?
it sounds very familiar.

I had the same problem but it is more evident when i turn on the defogger. I narrowed the problem down to the interconnects so i got the zero interconnects from streetwires. I had the same problem but now it is not that noticeable. So i transfered the interconnects instead of traveling at the left side at the back seat i wired it in the middle portion of the back seat. It seems to be working... I installed it last week and haven't heard of the whine since. hope this helps.

I have a 95 M3, with Blaupunkt Malibu C50, Kenwood units in kickpanels and doors, Kenwood 4.5" coaxials in rear deck, and Kenwood 10" subwoofer/amp in the trunk -- very good performance (I'm a longtime home audiophile). For a long time with my original head unit (Blaupunkt Sydney), I had alternator noise -- and tried to eliminate it through multiple filters in subwoofer amp power line, inputs, outputs, thinking it was getting in through battery-to-alternator connection.

Sydney (a very nice color matched display) started to fail less than 2 years after purchase, and replaced with Malibu (changed yellow LED display to orange simply by glazing plastic face with a coat of permanent red marker). Installed by a smart technician who found the noise problem. The unused RCA output jacks from the head unit were grounded, and they shouldn't have been. Since then, noise has been extremely low -- can only here any alternator noise if no CD in and volume up to 50-60.

By the way, factory amp was retained -- powering only the larger tweeters in the doors.

My only problem is very poor AM reception -- 50 miles outside of Atlanta and can't pick any Atlanta AM until within 15-20 miles of Atlanta. Don't know if this is due to the powered multipiece antenna or AM in general. As I recall, the original crappy BMW Alpine unit could pick up AM much clearer --- any insights on this ?

Well...I hacked together my new Daimond Amp (D7056) in my trunk...and low and behold a bunch of the quirks that I had with my original Crossfire amp are gone. Here are the Problems I had and what was fixed.

Turn on Alternator Whine (you could hear the alternator spinning up to idle speed through the whine). - Gone

Turn on pop - Gone

Whine in AM receiver - not alternator whine - didn't change pitch...just a constant high pitched annoying tone (probably from the Crossfire's switching power supply) - Gone

Alternator Whine - Drastically Reduced....But still present. I think this may have more to do with the fact that I don't have my install completed yet (just a temporary hack together until I save the funds for the final install)...So I have alot of excess speaker cabel coiled up under the board I have my amp mounted to. They could be inducing the noise from the amp's power supply or various other sources. I'm relatively sure that my speakerwires are what is inducing the noise.

About the AM receiver problem...aftermarket decks are pretty notorious for having poorer reception than most stock head units. I guess that's the difference in priorities between a stock headunit design and aftermarket headunit design.

Yeah, I did post on Carsound about this too. I did move the deck to the trunk and connect it directly to the amp without interconnects. The noise went away completely, so I'm sure it is the interconnects. Still waiting on the new ones, I'll post again after I've got them installed to let you know what happened.