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Thread: E36 Vert : Aftermarket Headunit -AMP Bypass the easy way ?

  1. #1
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    Wink E36 Vert : Aftermarket Headunit -AMP Bypass the easy way ?

    Thanks in advance, I love this forum as it has been a great source of information for me (as a BMW Newbie).

    I have a 96 E36 vert. When I purchased it there was a aftermarket (Sony) Head unit installed. Luckily the harness was not hacked, however the Amp wire was hooked up wrong.

    Now that I resolved that problem, I found that my sound is highly distorted. I believe this is due to the factory amp being overdriven and want to 'bypass' this amp or remove it. The options I seem to have are .

    1-Run new wire
    2-Somehow splice the amp wires bypassing the input and output sections. [was hoping there was a plug and play solution to this.]

    Hopefully there is a plug and play solution that will allow me to just remove the factory amp, insert a converter plug of some sort, and be done with it.

    Is this available, or does anyone have a 'DIY' of some sort for this? I really hate splicing wires and hacking things up, thats why I figured I would post here before I break out the tone generator and 9volt batteries (and I really hate tracing speaker wires ...yikes).

  2. #2
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    The same thing happened to me when I bought my car. The factory amp can't be bypassed because it also serves as the crossovers for the front and rear component speakers. Tear out the factory amp, replace the front speakers with a nice set of components and mount their passive crossovers where the factory amp went. Replace the rear speakers with a pair of 6 X 9's using an adapter that can be purchased. Make all your speaker connections in the trunk and your done.

    Edit: Sorry, I don't know what kind of speakers are in a vert. I got the adapters for my coupe.
    Last edited by 15flounder; 04-16-2013 at 08:54 PM.

  3. #3
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    Ok I put some Coaxial 5/14 's in the rear (the fit) .. Haven't taken apart the front setup yet, but likely will go with 6.25 (I hear they fit the lower kick) .

    Bummer, but I guess there will be no 'easy way'..

  4. #4
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    Update :

    I found a PIC that shows the wiring of the speakers./ For the Vert the amp is behind the passenger side rear seat (right). There are two harnesses a big one with about 15 wires, and a smaller one with about 8 wires. The woofers are 'wired' to the smaller harness [amp1 in the diagram] , and the tweeters / mids wired to the larger one [amp2 in the diagram].


    Basically take the wires from [AMP2] -From the Radio and splice/merge them to the wires for the 'woofers' [AMP1]. Or if you're 'fancy' you can wire 'From the Radio' to your crossover and from the crossover go to the harnesses [AMP-1/2].

    [AMP2] has Power, ground, and the amp on wire for your sub, and on the Vert its located in a good place to pass the wireing to the trunk.

    My last 'task' is to remove the radio 'again' , send a rca pair to the sub, and drill a hole so I can pass my Ipod cable into the glovebox (hidden Ipod ftw).


    Took about an hour, a 9 volt battery, a tone generator, and crimp kit to get the wiring correct. My only issue now is reconnecting the factory tweeters to the harness on the driver side. I think I'm missing some electrical hardware in the door panel on my driver door, so currently I have my 'new' 2 way speakers in the rear and front kick, and my tweeter (passenger door) connected. It is not too hard and the wiring pic is spot on.

    e36radiowiringdiagram.gif

    I hope this helps someone else out. NO way that Ive found to avoid cutting the harness, but since I intend on keeping this car until it dies I dont feel that bad about it. Make it yours I always said.

    Ase!
    Last edited by Turbohugh; 04-26-2013 at 04:45 PM.

  5. #5
    Stereoinstaller1 is offline Senior Member Supporting Vendor
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    Oh man, wish I had caught this in time.

    There is a very easy way to properly integrate an aftermarket deck with that stock amp and get nice clean sound.

    No stupid interface boxes either!

    http://forums.bimmerforums.com/forum...it-with-SOEM-4


    Closing SOON!
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    Thanks for 10 years of fun!

  6. #6
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    Man I didnt understand what you meant:

    Connect the HeadUnits Positive wires to the **** Harness and do not connect the ground (-) wires?

    I hated to butcher it but After posting and waiting there seemed to be no common solution.. IF you could write up a detailed method that works that may help the next person avoid taking the scalpel to the harness.

    ~Thanks in advance.

  7. #7
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    Quote Originally Posted by 15flounder View Post
    The same thing happened to me when I bought my car. The factory amp can't be bypassed because it also serves as the crossovers for the front and rear component speakers. Tear out the factory amp, replace the front speakers with a nice set of components and mount their passive crossovers where the factory amp went. Replace the rear speakers with a pair of 6 X 9's using an adapter that can be purchased. Make all your speaker connections in the trunk and your done.

    Edit: Sorry, I don't know what kind of speakers are in a vert. I got the adapters for my coupe.
    Ok, finally something about the speaker set up makes sense to me. I have polk audio components that I've wanted to install, but couldn't figure out where to put the crossovers. You've done me a real service here.

  8. #8
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    you can remove the oem amp. desolder the connectors internally or cut the board so that you can mount it in a project box. put spring loaded terminal strips and rca bulkheads on the project box. now you have a permanent convertor box and you didnt cut the harness.

    as far as taking all of the - signal leads to ground. not something I would do. its a crap shoot that you wont pick up noise from fans and differences in resistance from one ground point to another. it might work for some but it wont work for all.

    the signal leads out of the head unit to the amp are balanced signals, not conventional signals.

    let me simplify. your front right channel has 2 wires going to the amp. 1 would be considered positive and one would be considered negative but they arent what you think. conventional systems the - would be ground and the positive would be the signal wire. most of the bmw systems are based on a potential between the 2 wires not 1 wire and ground. so ground is at 0 and + is at 1 on a conventional to generate whatever frequency is in that 1volt.

    line balanced or potential based systems are different. to generate 1 volt the head unit puts -.5 on the - and +.5 on the positive. bmw amps are setup for this because if you run your wire across some noise it the amp wont care. the amp is looking for plus half and minus half. you have a noise source that generates a +1. both wires are offset to +1.5 and +.5 by this noise. the only thing the amp will reproduce is the potential or difference between the 2 wires which is still 1. the noise does not get amplified by the amp.

    if you drop the - wire in a line balanced system to ground (to make it conventional) the amp will only see the difference between the +.5 and 0. it will reproduce it at half of the volume and I think you can see why. but now you run your wire by a 1v noise source. one side is grounded so that wire stays at 0. however the other wire is now at 1.5. the amp will reproduce the noise because of the potential voltage between + and -. now you have an antenna for amplifying noise.

    you need 2 things really. the replacement amp should be capable of taking high level inputs and line balanced signals. sometimes they are called differential inputs. I didnt research all mfg's who build amps this way but I know most of the JL stuff does.

    good luck and sorry for the length but its a difficult subject to communicate in simple terms. so the oem amp is incompatible with the conventional signals from the sony. other units can run line balanced. and now that you have removed the noise immunity by using the conventional method you might find some bad wire routing in the factory system because they used line balancing so they didnt have to.
    Last edited by bry195; 05-01-2013 at 10:34 PM.

  9. #9
    Stereoinstaller1 is offline Senior Member Supporting Vendor
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    Quote Originally Posted by bry195 View Post

    as far as taking all of the - signal leads to ground. not something I would do. its a crap shoot that you wont pick up noise from fans and differences in resistance from one ground point to another. it might work for some but it wont work for all.

    the signal leads out of the head unit to the amp are balanced signals, not conventional signals.
    This is incorrect.

    BMW does not use differential inputs. Ford and GM/Bose, Nissan/Bose and a couple of other cars do, but not BMW.

    Simple common ground on the decks. The amps outputs are NOT common ground, of course, but the output of the deck is.

    If you don't believe it (32 years as a pro car audio installer, specializing in BMW since 1984) grab a DMM and meter the stock speaker leads, you will see all 4 "negatives" are common to each other, and maybe .01ohms above ground.

    You can simply connect all the speaker negatives from the car to ground, leaving the aftermarket decks speaker negatives disconnected.

    I have done this to literally hundreds of BMWs. None have had any issues at all.

    Luke


    Closing SOON!
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    Luke AT germanaudiospecialties DOT com or text 425-761-6450, or for quickest answers, call me at the shop 360-669-0398
    Thanks for 10 years of fun!

  10. #10
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    Quote Originally Posted by M20E34 View Post
    This is incorrect.

    BMW does not use differential inputs. Ford and GM/Bose, Nissan/Bose and a couple of other cars do, but not BMW.

    Simple common ground on the decks. The amps outputs are NOT common ground, of course, but the output of the deck is.

    If you don't believe it (32 years as a pro car audio installer, specializing in BMW since 1984) grab a DMM and meter the stock speaker leads, you will see all 4 "negatives" are common to each other, and maybe .01ohms above ground.

    You can simply connect all the speaker negatives from the car to ground, leaving the aftermarket decks speaker negatives disconnected.

    I have done this to literally hundreds of BMWs. None have had any issues at all.

    Luke
    I respect your right to disagree and its great that you are accomplished in audio installation.

    I hate listing qualifications because there are allot of people with no qualifications that should not have their opinions short sold but here goes.

    I was an installer while I was going to school to get my EE
    I learned most of what I know from Steve Wenger, one of my heroes and took pro sq+ more times than I can count including being number one multiple years at iasca
    not to mention the cars he built for others that did the same.
    I took many regionals myself
    I managed an engineering team at one of the largest electronic manufacturers in the world that patented an average of 2000 patents per year
    I have designed and sold no less than 40million in networked mechatronic manufacturing. I even installed and debugged all of my own stuff on prototypes
    my greatest achievement is when i figured out how to get my moms home speakers into the backseat of my dodge colt.
    qualifications probably work in court but when it comes to a forum......I dont put much weight on mine so its hard to just accept an opinion without some logic behind it so lets disregard qualifications. You have a right to disagree and I really dont have a need to take away from your opinion, but my point is that to say im incorrect is an opinion of yours not a fact.

    so if we read the link to the other installation mentioned earlier it says if you drop your negatives to chassis ground and plug your positive into the amp, the amp no longer clips. the circuit gets attenuated. why? because you dropped half the potential voltage to ground. the amp only sees half the input voltage it was designed for. this would not happen if it was conventional becasue you purposely drop 1 leg to ground and according to you that is how bms's are so why would dropping one leg to ground have any effect at all if it was oem'd like that. thats cuz its not oem's convetional.

    a dmm is a great tool but not for high speed measuring of discrete components. you need a scope with differential probes and watch the signal live while its driving, if you want to see a signal representative of what the amp experiences. I have done it and seen what I claim. speaking of claims just do a search on the internet for bmw and line balanced signals. Allot of people have my opinion and came to the same conclusion on most of the bmw's from early 90 and up.

    then there is the wires themselves. you ever notice they are twisted pairs? no shielding, you ever notice that rca's are shielded? twisted pair is a requirement and has a specific amount of turns per inch. simply so that any noise that gets on 1 wire gets on both in the same amount. why, because noise on both wires is cancelled in an amp designed for differential inputs sees the same voltage on both wires. if you get a voltage with the same polarity on both wires its not reproduced, only opposite polarities of equal amplitude are reproduced. no shielding on bmw these wires to keep noise from getting into your signal. it keeps the cost down and does a better job than conventional to chassis ground with shielding wires.

    Im sure its just as hard for you with 30 years of history to accept what I have learned as it is for me to accept what you have learned because it has worked for both of us for so long and everyone knows how most of these disagreements end on the board. Im sure what you know will serve you well far into the future and about the best someone can get from 2 guys going back and forth about something that will never really end in a clear answer like m20 you were right but I'm open to it. and if nothing else we get to add to the chaos on the board.

    maybe we can stick to technical facts that even after everyone else gets tired of reading our techno babbling that is uninteresting to most people, you and I can disagree or agree but know that the guy on the other side of the keyboard might have something there. now where is my dog so I can kick him. kidding, he wont come near me after the time I got in an argument about pouring water in your intake to make your car run better.
    Last edited by bry195; 05-03-2013 at 03:16 PM.

  11. #11
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    sooo whats the word on a simple deck install and wiring it to work correctly with the factory amp (non-hk)?

  12. #12
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    Quote Originally Posted by cooler breeze View Post
    sooo whats the word on a simple deck install and wiring it to work correctly with the factory amp (non-hk)?
    Get the adapter that comes with a head unit install kit (crutchfield, for example), and plug it in. Difficulty arises when trying to delete the factory amp with stock speakers
    '93 325is: ZF swap, Borla Type X muffler, cat delete, X Pipe, Tune, Powerflex bushings (subframe, diff, RTAB, LCAB), Apex ARC8's, Raceland Ultimos, Corbeau seat, Renown steering wheel, M3 front and rear bumpers, BMW motorsports moulding, Euro tails, Depo headlights (soon to be retrofitted)




  13. #13
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    You have no idea how much you just helped me lol. I have a double din I just got in and it has a built in amp in it and blew my factory amp. Now I can just bypass it. Your a hero man. 100000 thanks!!!!!!

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