Stereo help; new headunit and speakers

[bondheli]

I'm going to be doing a complete stereo up grade on my '90 525i, and need to know how much of the original wireing I can use. I'm going with a 45w x 4 deck and plan to run new cable to the front two kickers. I want to cut out the rear deck speakers and use the existing wireing but I have a couple of Q's
Where is the amp for the rear decklid speakers located?
Can a couple of the tweeter wires be used to carry the signal for a rear amp and subwoofer?
I am going to be using a high end head unit; do I need to use filters with the stock wireing?
And what is the purpose for the large capacitors I see in alot of stereos?
thanks

[bimmerd00d]

Use RCA cables from the head unit to the amp, you will produce much better quality sound that way. Capacitors are used to take the load off of the alternator/battery of the car when the amp draws a large load when listening at a loud volume. It's just a filter to keep the voltage consistent. The stock wiring is great, but you need to find out how the car is wired before getting into this, it's not like any other car. The speaker wires all junction in the trunk, where the amp should be located if you have one (driver's side behind the carpet on the side) There are wires running from the amp to the head unit area, and sets running to each individual speaker (on my '93 525i at least). I had to find out what wires were coming from the head unit, and cut them off the harness to splice them into the speaker wires. There are wiring diagrams on www.bmwe34.net, and

http://bmwe34m5.com/articles/E34_91_535_wiring.zip

unzip it and read the text file to find the acrobat file regarding radio wiring.

PS: If you use RCA cables and an external amp for the speakers, you dont have to worry about the stock wiring behind the head unit, only finding power for the head unit.

[Incantation]

what kind of head unit did you get

[bondheli]

It will either be an Alpine or Eclipse head unit. I like the layout of the Eclipse better but a lot of high end car manufactures seem to go with Alpine (better sound quality?) so its still a little up in the air.


what kind of head unit did you get

[emw525E34]

Bondhell,

The amp is located in the trunk driveside, just behind the tail lights. Remove the side panel and you can see it and its associated wiring there. The rear deck speakers are tricky to take out, it takes longer.
For the front kick panel, you can only fit 5-1/4 inch cones there. Depending on the type of speakers you want/have, the magnet size may get in the way becuase the space clearence is not great in there.
If you are willing to cut the kickpanel, you can fit 6.5 inch speakers that will sound great. But caution, the depth of the speakers due to magnet clearence. I got kicker 5.25in ones with a huge magnet, I had only about 2mm clearence from the magnet to the metal. It works. I stick black electrical insultation tape in the space to prevent any possible clunking noise in case there is contact there.

Best of luck.

[bondheli]

Yah, Ive heard that was a problem. What I plan to do is cut out a circle of mdf and adhere it to the kick panel, then use a grill to cover it all.

[Incantation]

there is a ton of space behind the kickpanel.. the issue is not the depth of the panel, it is the placement of the speaker because the outer rim of the speaker has only so much lateral room to fit within.. you have to make sure you cut it out in the right spot so that the panel doesn't close the speaker back against the metal frame.

this is not an issue on passenger side; on drivers' side, place the speaker as far forward into the dead pedal and it will fit fine.

[Incantation]

ok well you mentioned high-end. that is a relative term.. depending on who you talk to.

i would suggest that if you are going to spend big money on a deck, don't bother installing anything until you can rip out all the old shxt and replace everything.. the stock wires are a pain in the ass the way they're set up and you're far better off running new everything than using the old setup.

might be a better idea to spend less on a deck and buy some good wiring.. so that when you want to put in a real amp and a sub, etc.. you will be set up properly.

[bondheli]

Im thinking of a $150 used alpine or eclipse hu as opposed to a jvc or sony. I'm going to be installing it my self and I will be running new wire to the front 2 speakers. I would rather not rip apart the interior to run new cable if i can help it. I wonder if there is a way to run cable under the center console...? Even with using the stock cable for the rear speakers, I still have an issue with getting a signal back to the subs....?

[Incantation]

well..
#1 it would be silly to try to run a sub (or subs) with deck power
#2 it would be more silly to try to run a sub (or subs) with deck power in the trunk of an e34.. you wouldn't even hear it.

you can run the wires through the center console.. it's a big pain in the ass. it's easier to run them left, under the steering column.. down the left front kickpanel and run it under the carpet at the edge of the door sill to the back. it's actually quite easy to set it up this way.

i suggest you list your goals for the car.. there are a lot of us in the forum who have spent a lot of time (and money) setting things up differently in the car and can make a lot of suggestions that will prevent you from wasting your own time and money. and of course we'd all be happy to help you out..

[bondheli]

Who said anything about running the subs off deck power? I said I still have an issue with getting a signal back to the subs.
Anyone know if + 12V constant power and Ground are run from the head unit directally to the back? If so, I will just clip those and use them to carry the sub signal. Taking up the carpet and interior panels is a deal breaker for me.
I have the deck unit, amp, front and rear speakers figured out, I just need to find 2 extra wires.

[Jon K]

For what its worth Bondheli, i rewired my entire car... sorta. I used the factory wires, because they are actually good! Problem is I had to re-config the entire trunk because they use common ground by default. When you start removing the wrapping around the wire harness in the trunk, you will see that the left front 3 speakers are all grounded together, and the right front are grounded together... you get the idea. aftermarket head units use floating ground, so this doesn't work. Since I have MB Quart Q 3-ways, I had to install crossovers anyway, so i cut the harness apart and seperated each channel. Then again, nothing about my stereo is stock... and it gets worse and worse. But yeah, don't be scared to use the stock wiring (physical wiring that is, not the polarity...) because its relatively good.

[bondheli]

I plan to scrap the harness, and just use 4 of the wires going back to the trunk. I will cut out the back 2 speakers and soilder extension wires to the 4 that use to go the amp, to connect them to the new speakers. Where does a crossover come in? Besides the 4 wires for the rear speakers, are there any more stock wires running to the trunk that i could cut off the amp and use to carry a subwoofer signal from front to back? With a floating ground thats only a 2 wire hookup, positive and negative, no 3rd wire correct?
BTW Your Ferrari horn is the coolest idea I've heard yet on this board, and I may just have to steal it. Also, your car pic is the reason I am upgrading to HIDs. Looks great!

[Jon K]

I plan to scrap the harness, and just use 4 of the wires going back to the trunk. I will cut out the back 2 speakers and soilder extension wires to the 4 that use to go the amp, to connect them to the new speakers. Where does a crossover come in? Besides the 4 wires for the rear speakers, are there any more stock wires running to the trunk that i could cut off the amp and use to carry a subwoofer signal from front to back? With a floating ground thats only a 2 wire hookup, positive and negative, no 3rd wire correct?
BTW Your Ferrari horn is the coolest idea I've heard yet on this board,and I may just have to steal. Also, your car pic is the reason I am upgrading to HIDs. Looks great!


What you are planning to do -- the rewire, is a BIG job. You have to run more than 4 wires from the front. You will need to run a pair (two wires) for each component: tweeter, midrange (dash), and kick speaker. Thats 3 pairs (6 wires) per side (12 wires total!). then for the rear its 2 components per side, to pairs per side, 4 wires per side, 8 wires total... So yeah you'll be running 20 wires. Hehe. If you use an aftermarket head, you want to run pre-amp RCAs to the trunk for subs. If you aren't, and you want to tap your stock amp for a sub source (not the best but i did it and it worked), tap any one rear channel PRE-AMP! If you tap post-amp, it will have already been crossed over and your subs will sound like trash because they won't have a full range signal. For instance, use the right rear signal from the headunit, not the signal to the specific speakers (ie. right rear tweeter or right rear woofer). The HIDs are a nice upgrade, not very cheap but worth it. Thanks.

[bondheli]

I'm just planning to do a simple aftermarket 4 speaker setup, all 4 with tweeters built in and an aftermarket Head Unit. They will go from a powered HU 4x45 so I won't be using the the preamps at all. I will run new wire for the front 2 speakers, and use 4 of the existing wires that are currently running to the amp now, cut them off and use them for the back 2 speakers. Besides the 4 wires I will be using for the rear speakers, are there any more wires running from the stock head unit to the stock amp? I saw the wire spreadsheet on bmwe34.net but it is unclear if I can find another 2 wires that are running from front to back already to carry the sub signal.

[Incantation]

running RCAs from a deck to amp isn't an issue.

[Jon K]

I'm just planning to do a simple aftermarket 4 speaker setup, all 4 with tweeters built in and an aftermarket Head Unit. They will go from a powered HU 4x45 so I won't be using the the preamps at all. I will run new wire for the front 2 speakers, and use 4 of the existing wires that are currently running to the amp now, cut them off and use them for the back 2 speakers. Besides the 4 wires I will be using for the rear speakers, are there any more wires running from the stock head unit to the stock amp? I saw the wire spreadsheet on bmwe34.net but it is unclear if I can find another 2 wires that are running from front to back already to carry the sub signal.


Bro that's a really bad idea. Your sound stage will be all sorts of messed up. The stock system would be better than a setup like that. The speakers you are talking about where the tweeter is built into the woofer is called "coaxial" meaning tweeter and woofer are on the same axis.... thats bad for up front. You want the treble to come in clear and the mids as well, the lower frequencies are less directional and so they can be on the floor, ie kick panels. but if everything is coming from down there, it will sound horrid.

[bondheli]

So to avoid that, you would run the 4 preamps to an amp witch would devide the signal into highs mids and lows and send it back out to 8 different speakers?
The stock speakers can not be used as you said so what about an amp up front powering woofers in the kick panels, then a 3 in mid with a tweeter in the middle in place of the dash speakers?