E30 Audio Overhaul - My Project Details

[bmwman91]

This will be updated as the project progresses (so, it will be slow).

I rarely post on r3v, but I lurk frequently since there is a lot of decent information here. Since a member here gave me a lot of help via PM, I suppose that I should try to add what I can here through the course of my project. Here it goes...

Well, it all began with me making an uninformed purchase on eBay of a CD43 head unit. For those who don't know what the CD43 is, it is basically the last (and best) DIN-sized head unit produced for BMW by Blaupunkt. It is also called the "BMW Business CD" head unit. Anyway, I say that it was an uninformed decision because I planned to just run the speakers directly from it. I wanted stock equipment in the dash again, and supposedly the unit has better distortion specs than most after-market HU's.

While one CAN run the speakers from it directly, it is apparently not entirely recommended. The CD43 was always used in conjunction with an amplifier in factory installations, and was meant to supply low-power audio signals to that rather than to speakers. So, I looked at amplifiers. Then decided to see what would be required for a "proper" setup, combining things I have wanted for a long time and knowledge I have acquired from my home audio projects.

The cost of the equipment comes in a bit above what I want to spend, so I am still considering a passively crossed over system. That would take almost 40% off of the price (no need for the 6XS or dedicated sub amp). The diagrams below show what I WANT to install. I suppose that I should do it now, because a year from now I will have mortgage payments to make & a lot less cash for fun projects!

11/5/2010
I have put in new, accurate diagrams of the system. Click the images to see the full-sized versions.


Power wire to the amp is 8ga, and LC/XO power wires/remote are 14ga.


Speaker wire is 14ga. I switched to CAT6 cable for the signal running from the HU to the LC6i. It has better noise-rejection properties than the multi-conductor car-audio junk I tried at first. Note that this will ONLY make a difference if you are running differential signals into a device that has differential inputs!

Subwoofer = SB Acoustics SW26DAC76-4, mounted in the ski-pass hole.
Front woofers = SB Acoustics SB17NRXC35-4 7" drivers
Front tweeters = Seas Prestige 27TAFNC/G 1" tweeters
LC6i = Audio Control line level converter, model LC6i
6XS = Audio Control active crossover, model 6XS
MB Quart ONX4.80/500 = 5 Channel amp to drive everything (my "space saver" solution)

I will not be running rear speakers, other than the sub. Rear signal lines will be LPF'ed, summed in the amp & fed to the sub. Some people like having rears, I don't. Personal preference, there.

One big trick will be getting 75mm deep woofers mounted up front. The existing cavities are only 69-71mm deep. I might try some hammering, as well as a few mm of Damplifier stacked for spacing under the driver frame.

Anyone have any comments or critiques? Thanks!

[quickervicar]

Change the negative leads on all the amp/EQ units to a chassis ground as close to the units as possible. DON'T run them back to the battery.

[Mless5]

I'd love to hear some feedback on those SBAs, I've been eyeing them myself. Would also be curious how would you go about mounting them.

[bmwman91]

Change the negative leads on all the amp/EQ units to a chassis ground as close to the units as possible. DON'T run them back to the battery.

I have read a lot of debate on this very subject. Certainly, every run of wire that I can eliminate is one less thing to break. However, I am weary of scraping paint & installing ground lugs (really, I would weld them in, bolting isn't good enough IMO). Since the amps/XO & battery are all in the trunk, the wiring distances are minimal. I cannot imagine that the resistance of 3' of 8ga copper wire is any greater than the steel between the rear bulkhead & battery lug.

From your experience, what has been the negative side to running grounds back? I am certainly open to considering alternate points of view on this.

I'd love to hear some feedback on those SBAs, I've been eyeing them myself. Would also be curious how would you go about mounting them.

Yeah, I have read many good things about them. My experience up until this point has been with indoor audio. Zaph (www.zaphaudio.com) tested out some SBA 15NRXC30-8 drivers & they had some of the lowest distortion figures in the group. They performed great against drivers that were 4x their price! I have confidence that the 7" drivers are also good. I have been working out plans for my next set of multi-way home speakers, and I will be running 15NRXC30-8 woofers & SB29RDC-C000-4 in a MTM setup.

Mounting will be the trick. I enlarged the front speaker holes in my car to fit 6.75" drivers last year. Depth is where I am a little concerned...75mm is pushing it. I will probably have to combine the use of a mallet & wood with some sort of spacer, and then figure out something with the kick panels.

My first couple of projects:
First 2-Way - 4" Woofer & Titanium Tweeter
The Monster Subwoofer (156L, 130lbs)

[StereoInstaller1]

This is such a nice plan. How the hell do you do those diagrams? I wish I had those skills, I could raise my prices about 200X.

1. Deck power: I feel it is just fine to use the stock wiring. Not only "just fine", I actually feel it best...and I do mean best, not "best for the money", just best. I have never had any issue with the stock wiring...no popped fuses, no abraded wires, nothing...ever....in literally hundreds of BMWs.

If you wanna do better, fine, but first, show me a 20 year old example of whatever wire you use that is still in good shape...you can't, basically, because BMW wire is some of the best in the whole damn world!

Let me make something else clear: that is ONLY my opinion, YMMV. It is also one of the reasons I love Classic BMWs so much, the wiring rocks!

Now, switched power: use a relay. Simple enough, huh? You might wanna add a switch for antenna remote, since it will likely be down often. Why BMW didn't split antenna remote vs amp remote back in '94 or whatever is still beyond me.

I use the stupid window cut out switch for mine. Easy and fits nice.

2. Speaker wire: the stock BMW wire will sound better, fit better, last longer and just in general kick the shit out of whatever 14 ga you are gonna find.

Let me tell you, I have pulled many miles of 5 year old "monster" or whatever (even supposedly high end stuff, OFC, linear crystal, whatever) out of cars. I have pulled crap I put in myself 10 years before...ALWAYS nasty looking. High dollar wire is a complete sham IMO, except ONE brand: Kimber. I have pulled 20 year old Kimber and it still looked great. I have never heard a wire sound SO much better, and nothing rejects noise better, nothing. I have done 5 or 6 cars with it over the years. When mine gets redone this summer, I am gonna run 1 run of 8TC up each side, then split the conductors before the drivers, using 6 conductors for midrange and 2 conductors for tweets, since my system is active, too.

For the record, I have never put in serious high end speaker wire in a car. No Monster T1000, no Bruce Brysson stuff, nothing over $25/ft ever. No clue how MIT Shotgun would sound or last in a car.

3. Zobel network on the mid! A pile of inductors/caps and wire would resistors, a decent DVM and a test CD or signal generator. Flatten the response of your mid "mecahnically" by electronically filtering the effects of its envoronment. Might be a HUGE improvement in your plan, but it would also be interesting to hear the difference!

If the amp sees a flatter impedance curve, it will make power with better linearity, thus inherently a flatter, more accurate response...but as it something that is affected by the environment, it needs to be done installed in your car, with all drivers in. This is something that should be done on all drivers, but the mids are easily the most important, and are easiest/cheapest to do. It is best if you are in the car, and the doors must be shut.

Grounding: the only issue with a battery ground is the length of wire involved. If your amp needed 4 GA with a 15' run, it is gonna need 0 ga if that runs is 30', basically.

Power is a loop. You gotta get power from hot to ground, that is the trick. We all know that, right? Makes installing in a boat an absolute bitch, though!

In the case of the E30, a battery ground is just fine as long as the battery is in the trunk already...those amps aren't gonna need THAT much power, right? Just keep in mind that the largest wire in a car IS the car!

I do as I see fit on BMWs. Sometimes a battery ground, sometimes body, both are fine as long as specs work out.

This is gonna be one damn hot sounding car. You get the sub half as right as you are doing everything else, this will be an amazing sound quality car.

[bmwman91]

This is such a nice plan. How the hell do you do those diagrams? I wish I had those skills, I could raise my prices about 200X.

Haha well, you are in luck. The program is free & open-source.

http://www.inkscape.org/

The tutorials are pretty good, and everywhere. If you dedicate an hour a day to them, you will be making diagrams like that in a week easy. Everything was drawn, there weren't any built-in blocks or anything. You can make your own blocks though, which helps. The diagram only took a few hours.
I am the kind of person that hates buying stuff online because I have to wait to get the merchandise, but I also hate wasting $ so I always go with cheap shipping. I want to have every part that I can't get at Radio Shack/Home Depot ordered up & arriving at once! Being a visual learner type, diagrams help with figuring out what I need.

1. Deck power: I feel it is just fine to use the stock wiring. Not only "just fine", I actually feel it best...and I do mean best, not "best for the money", just best. I have never had any issue with the stock wiring...no popped fuses, no abraded wires, nothing...ever....in literally hundreds of BMWs.

If you wanna do better, fine, but first, show me a 20 year old example of whatever wire you use that is still in good shape...you can't, basically, because BMW wire is some of the best in the whole damn world!

Let me make something else clear: that is ONLY my opinion, YMMV. It is also one of the reasons I love Classic BMWs so much, the wiring rocks!

This is good to know. Since I won't be driving the speakers from the CD43, it probably won't eat much power, so I suppose the stock wiring/fuses will suffice. You would know, so I will take your word for it!

Now, switched power: use a relay. Simple enough, huh? You might wanna add a switch for antenna remote, since it will likely be down often. Why BMW didn't split antenna remote vs amp remote back in '94 or whatever is still beyond me.

I use the stupid window cut out switch for mine. Easy and fits nice.

That is a good idea, using the window lock switch. I have some extra switches & blank spaces on my HVAC panel...maybe I will put an antenna switch there.
What did you mean by "use a relay?" Were you thinking something like using the existing switched 12V line to run the coil, and running a new 12V line to the relay/HU? It sounds like I should just stick with the stock hot/switched wires & not complicate things with relays & new wire?

2. Speaker wire: the stock BMW wire will sound better, fit better, last longer and just in general kick the shit out of whatever 14 ga you are gonna find.

Let me tell you, I have pulled many miles of 5 year old "monster" or whatever (even supposedly high end stuff, OFC, linear crystal, whatever) out of cars. I have pulled crap I put in myself 10 years before...ALWAYS nasty looking. High dollar wire is a complete sham IMO, except ONE brand: Kimber. I have pulled 20 year old Kimber and it still looked great. I have never heard a wire sound SO much better, and nothing rejects noise better, nothing. I have done 5 or 6 cars with it over the years. When mine gets redone this summer, I am gonna run 1 run of 8TC up each side, then split the conductors before the drivers, using 6 conductors for midrange and 2 conductors for tweets, since my system is active, too.

For the record, I have never put in serious high end speaker wire in a car. No Monster T1000, no Bruce Brysson stuff, nothing over $25/ft ever. No clue how MIT Shotgun would sound or last in a car.

In that case I might have to see what Kimber cable is available. There aren't enough wires in there right now to support a multi-amped setup, so new runs are required at this point.

3. Zobel network on the mid! A pile of inductors/caps and wire would resistors, a decent DVM and a test CD or signal generator. Flatten the response of your mid "mecahnically" by electronically filtering the effects of its envoronment. Might be a HUGE improvement in your plan, but it would also be interesting to hear the difference!

If the amp sees a flatter impedance curve, it will make power with better linearity, thus inherently a flatter, more accurate response...but as it something that is affected by the environment, it needs to be done installed in your car, with all drivers in. This is something that should be done on all drivers, but the mids are easily the most important, and are easiest/cheapest to do. It is best if you are in the car, and the doors must be shut.

Interesting. I have always preferred active XO setups because they let me avoid passive components. I suppose that the fact that the driver has complex impedance might still warrant some compensation though. I think it would be fun to work out some passive compensation to correct for cabin gain & resonance though, so I will have to play with that!

Grounding: the only issue with a battery ground is the length of wire involved. If your amp needed 4 GA with a 15' run, it is gonna need 0 ga if that runs is 30', basically.

Power is a loop. You gotta get power from hot to ground, that is the trick. We all know that, right? Makes installing in a boat an absolute bitch, though!

In the case of the E30, a battery ground is just fine as long as the battery is in the trunk already...those amps aren't gonna need THAT much power, right? Just keep in mind that the largest wire in a car IS the car!

I do as I see fit on BMWs. Sometimes a battery ground, sometimes body, both are fine as long as specs work out.

The battery is in the trunk, and the equipment will be too. Maybe I will weld a lug onto the shock tower to keep the wiring a little simpler. I just hate scraping off the nice factory electrostatic primer. It prevents rust better than anything in a can. I figured that a 3-4' run of 8ga would probably be fine. Wire sizing is based upon maintaining 300 circular mils of copper per amp, which seems to be a fairly standard, conservative rule in chassis wiring.

I calculated current from the max anticipated RMS power into 4 Ohm loads, x sqrt(2) to get peak, and then divided by 12V to get worst-case current.

S580.4 max expected output 100W RMS into 4Ohm x 4 drivers x sqrt(2) = 567W. Divided by 12V, that gives 47.1A. 8ga wire is ~16400 circular mils, and divided by 47.1A that leaves 348 circ-mils/A.
The S270.1 will pull even less, and I am using 8ga since it is just easier to buy one size.

This is gonna be one damn hot sounding car. You get the sub half as right as you are doing everything else, this will be an amazing sound quality car.

Thanks! I am hoping to achieve some modest sound quality. My aim is definitely not to be explosively loud, but I would like to be able to crank it up & not have terrible amp distortion like you get from using the amps in HUs.

[george graves]

sub'scribed.

[dinanm3atl]

I will follow along. Looks like quite the setup! Your ears will enjoy!

[StereoInstaller1]

1. I believe the CD43 to have enormous pre-amps, I don't think it has any actual power IC, but I could be wrong. I would love to see my theory proven one way or another...you have brains, I have experience, between us I think there is proof somewhere.

I actually don't wanna say anything else on this install: you clearly have things VERY well in hand, and I don't know that I can be of any real help!

i will DL and install inkscape, seems badass. If I can do half as nice as yours, I will be thrilled. Do you think it will let me make subwoofer box drawings too?

[bmwman91]

1. I believe the CD43 to have enormous pre-amps, I don't think it has any actual power IC, but I could be wrong. I would love to see my theory proven one way or another...you have brains, I have experience, between us I think there is proof somewhere.

I actually don't wanna say anything else on this install: you clearly have things VERY well in hand, and I don't know that I can be of any real help!

i will DL and install inkscape, seems badass. If I can do half as nice as yours, I will be thrilled. Do you think it will let me make subwoofer box drawings too?

I can check the idle current pretty easily with a DMM. There is equipment at my work that I can use to measure peak/RMS current in operation, but that is a lot of work. I might be able to rig something simpler up to get an approximation.

Inkscape can be a pain in the ass until you get comfy with it. It took me like 5 minutes just to find the icon that turns on the stroke settings sidebar! You will be just fine once you try some beginner tutorials. Turning on the grid & snaps is highly recommended for things like this.

You definitely CAN use it for box drawings, although making changes could be time consuming. Personally, if I needed something fast & free for doing enclosures, I would look at using Google SketchUp. You cannot make dimensioned 2D drawings with it, but it is super simple to model with and you can add dimensions onto the model. It is nifty for making 3D drawings, for sure. Of all the CAD programs I know, it is by far the easiest to use, albeit limited in capabilities.

[StereoInstaller1]

gotta be better than this, right?

[bmwman91]

Hey, no shame in that! Paper still gets the job done...and it is faster for brainstorming, for sure. Trust me, I went through a few sheets before committing anything to Inkscape.

Oh, and my CD43 is waiting for me at the post office (wasn't home to sign for it today). Yay.

[Spaz]

Setup looks amazing bmwman91

But i have a question for luke.

2. Speaker wire: the stock BMW wire will sound better, fit better, last longer and just in general kick the shit out of whatever 14 ga you are gonna find.

Let me tell you, I have pulled many miles of 5 year old "monster" or whatever (even supposedly high end stuff, OFC, linear crystal, whatever) out of cars. I have pulled crap I put in myself 10 years before...ALWAYS nasty looking. High dollar wire is a complete sham IMO, except ONE brand: Kimber. I have pulled 20 year old Kimber and it still looked great. I have never heard a wire sound SO much better, and nothing rejects noise better, nothing. I have done 5 or 6 cars with it over the years. When mine gets redone this summer, I am gonna run 1 run of 8TC up each side, then split the conductors before the drivers, using 6 conductors for midrange and 2 conductors for tweets, since my system is active, too.

Let me get this straight...
So when you're installing a new deck to an e30 you reuse the old speaker wiring but in a proper non shared ground setup?

Hmm, i might have to try this myself.

-Cam

[quickervicar]

This is going to be good :)

[BeirBrennerE30]

subscribed.. Take lots of pics of this install!!!

I always thought with the cd43 that you only needed the + speaker wire and you were supposed to ground out the - on the RCA to the CD43s ground???