My Z3 Coupe Build - Part 2: Stereo

[s8ilver]

Now we're cooking.

Almost doused the car and lit a match last night. Had everything wired properly, and couldn't get sound for about an hour. All of a sudden I noticed a red light on the Alpine amp. Internal fault. Swapped with the good one from the M and it fired right up. Everything worked and each signal went where I hoped it would.

I hopped on eBay to give a sob story to the seller, figuring I'd be out a nice chunk of change. Turns out they accept returns for full refund until April 9. I bought the amp February 2. SCORE!

Never really looked at the amp closely while running, so it didn't dawn on me for a while.



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[IndianaRoadster]

Looking mighty fine, I can tell your having fun!

[z3forlife]

So how does it sound? I’m sure a big improvement. You can test that sub by playing Tab Benoit “nice & warm”. The bass is lovely at the beginning. Nice and warm.

[s8ilver]

So how does it sound? I’m sure a big improvement. You can test that sub by playing Tab Benoit “nice & warm”. The bass is lovely at the beginning. Nice and warm.

Sub's OK, but I still have the 10" to add. You can tell it's a shallow design. It'll serve a purpose.

I will certainly check that out. My go to bass test track is Waiting for my Ruca by Sublime.

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[s8ilver]

Looking mighty fine, I can tell your having fun!

Beyond. I'm in my element.

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[s8ilver]

Alright, next challenge: New system has exposed some alternator whine. I know this is quite common on E36 chassis cars, but where to start?

1. Run fresh fat fused power to CD43?
2. Add noise filters to OE power wiring?
3. Test new RCAs (only RCAs are between DSP and amp)?
4. Check battery ground?
5. New alternator (it's original with 164k miles)?
6. Ground amps to battery ground point to try and eliminate a loop? I always try to keep ground runs as short as possible. Right now I'm grounded to one of the lugs that holds up the OE Coupe sub/amp covers.

All of the above?

It's not terrible, but it's there. I'm sure it always was to some extent, but amplifying OE signals has accentuated it. All the extra equipment is grounded at the same point or to OE ground pins (both amps to same lug, DSP/LOC are grounded to OE 12-pin harness).

[ProductUser]

I don't know if it's the same, but my AutoCom (motorcycle) system had a ground loop issue that cause an alternator whine. It was common to use a ground loop isolator.

[s8ilver]

I don't know if it's the same, but my AutoCom (motorcycle) system had a ground loop issue that cause an alternator whine. It was common to use a ground loop isolator.

For sure. In theory, ground loops should be able to be eliminated without isolators, unless the underlying problem is the vehicle design itself. I'll mess around.

[z3forlife]

I would make sure the amp and any other signal processing equipment is powered and grounded at the battery. The head hopefully will be ok powered through the harness. If you still hear it then use isolators on the inputs. You’ll probably want to put rca’s on the ends of you new harness but you can probably find isolators either with rca or screw terminal input/output.

[s8ilver]

I would make sure the amp and any other signal processing equipment is powered and grounded at the battery. The head hopefully will be ok powered through the harness. If you still hear it then use isolators on the inputs. You’ll probably want to put rca’s on the ends of you new harness but you can probably find isolators either with rca or screw terminal input/output.

No RCAs off the harness. The inputs are high level and go right into the DSP. Two pairs spilt and go off to the powered LOC to run the other sub. From the DSP, 3 RCA outs to the main amp, and one from LOC to sub amp.

I'll try a reground, as that's easy enough to test without routing any new cable, yet. The new Knipex strippers cut 4 gauge like butter.

One odd thing was that my Mediabridge was located near the amp power route and moving it to the opposite side eliminated quite a bit of noise. It must not be very well shielded.

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[BimmerBreaker]

I wouldn't be surprised if it's just "how it is" with Z3/E36's that they naturally have some interference. I think audio quality was just about at the bottom of their list of priorities when designing these cars and Z3's weren't given a big R&D budget to begin with.

When I was younger, I was a bit of an audiophile, but for whatever reason as I've gotten older I just stopped caring as much about that sort of stuff. Regardless, this is a cool thread to read.

I wonder if some of the whine is because of how they distribute the power throughout the car. The alternator goes to the positive post under hood (which runs from the battery positive), which is also where the fuse panel (radio/speakers) grabs it's power from. Maybe you need to run a direct line from the battery to the radio and speakers. It's been a long time since I dabbled in this stuff so I may be way off base

[s8ilver]

No BB, I think you're onto something. If a reground nor isolators do the trick, I'll look at power options. I have a direct line to my internal fuse block I added, so that would be a cake walk to repower the HU. I can run switched and unswitched lines depending on fuse placement.

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[z3forlife]

I believe the cd43 is a line level output not a high level.

[s8ilver]

I believe the cd43 is a line level output not a high level.

Indeed. Slip of the tongue. That JL software measures input voltage, and I was shocked to see over 4 volts from that HU on each channel. If course I still boosted it.

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[s8ilver]

Alright, messed around a bit. A re-grounding didn't really change anything. Moving that Bluetooth box has proven most effective. I would say the alternator whine is all but gone. What's remaining is a bit of white noise that I attribute to purely signal. I can unplug ONE RCA from the 6 into the main amp and the static vanishes. Let's hope the isolators can take out the rest of the noise.

Again, it could still be goofy power running into the CD43, giving the noise on output to the DSP. What I am not certain of is the OE routing of amp power with relationship to signal wires. If they parallel back to the OE amp, that could certainly be a cause as well. All the factory wiring daylights in the hatch at the same point, so they certainly cross paths, at least there. I believe the OE amp power originates at the distribution block under the dash, but not certain. I could pull its fuse and repower everything in the hatch from the battery.

[s8ilver]

With all the extra equipment, I'll have to raise the hatch floor about 1 inch. Playing with hardware and spacers (and waiting on some longer machine screws to stick with my fully reversible theme), but looks like I can raise the forward panel fully, and just shim the leading edge of the rear panel. That gives me a gradual slope to the rear of the floor, but I won't have a step and can more or less use the hatch as before.

I don't think any but the most trained eye will be able to tell. The tie down points (that I've never used) are still fully retractable. I could shim the rear as well, but it just lies on carpet covered plastic lips that hold it up and there seems to be no good way to do that edge cleanly.

Don't worry about the rogue wiring. I'm just playing with trigger wires and the reground test. For some reason my DSP will not trigger on its signal sensing capability but when I add a remote wire, fire up the stereo, and switch it back to signal sensing it'll just keep going if I unplug the trigger. Interestingly, the powered LOC that is downstream of the DSP works just fine on signal alone. Both are JL units with similar circuitry.



I could hurt myself and tuck everything behind interior panels, but then I couldn't access them again without a headache.

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[s8ilver]

Well this is great. Got all the filters in and noise persisted. Had a brain wave and swapped RCAs. Noise followed. WTH?!! Crap, brand new "premium" cables. Tested an ancient set from probably the 70s and the noise went down a good 90%. Premium. OK. Premium garbage.

I can kill just about the rest with a gain reduction, but I'll keep at it.

Got back on it today and knocked out the floor raise. I used 6 shims to space the black plastic brackets on the underside of the two hatch panels. Replaced the 10mm M4 machine screws with 35mm versions, and no trim was modified permanently. I also installed two floating shims where the panels bear on the raised part of the floor.

I had a pet emergency Wednesday and the little dude now just doesn't want to eat on his own. It's a royal mess getting him to eat. He's probably still sore from the tube that went that place designed as exit only.


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[BimmerBreaker]

I really hope your cat is ok! It's always heartwrenching when our beloved pets have any kind of emergency and certainly very hard when they aren't eating

[ProductUser]

Did your cat stop eating around the time you started your stereo upgrade?

All kidding aside, I hope your cat gets better.

[s8ilver]

Did your cat stop eating around the time you started your stereo upgrade?

All kidding aside, I hope your cat gets better.

Ha! He had a stuck #2 last Wednesday (scary), and after the $$$$$ emergency vet evac he basically didn't leave his bed for 2 whole days. He's now showing some interest in being a cat again, and will eat a bit on his own with some extreme coaxing. It's frustrating though; usually he just chews and spits out whatever I offer him and turns his head away from wherever I place the food.

We're just thankful it happened when it did. We had a 4 day trip planned for Thursday, and had it happened a day later I think we'd have come home to a tragedy. He usually fights everything, but I've been able to shower him with the tub hand sprayer, and he's finally got the energy to clean himself again. Slow going, but we're getting there. I did find a miraculous protein gel that's super high calorie and I can get a serving down him without too much trouble.

Stereo is thumping, and I am now deaf. Had a scary moment yesterday. I was running it with the 10" sub hooked up and all of a sudden it quit. Red light on the sub amp, but the main amp just chugged along. It looks like it went into protection mode due to low voltage. Fired the car up, and it came right back. So now I'm considering an alternator upgrade (original is a little grindy anyways) and perhaps adding a small capacitor. I could go nuts and do a 2nd battery with a switching diode to save the main battery to always be able to start the car. Also, no clue where to locate a 2nd covert battery inside the cabin. I think I can fit a cap behind the carpeted panels covering the shock mounts.

Ah, and on the noise issue: The Dice Mediabridge is basically an unshielded POS. Just touching the plugs and moving them around makes all sorts of interesting sounds. I pulled the plugs apart, cleaned them well and reinstalled with dielctric grease. HUGE difference, but still sorting the rest of the noise. When the text scrolls on the HU, it makes a blip concurrent with the text. I'm sure there's a way to turn that off, but haven't figured that out yet. If I press the "M" button and quickly press > or <, it'll pause/play the music. Never heard of that before. If I do it slowly, nothing happens.

[s8ilver]

I really hope your cat is ok! It's always heartwrenching when our beloved pets have any kind of emergency and certainly very hard when they aren't eating

Now it's a game of where I place his food bowl. No interest in his usual spot, but I put it next to his bed and he goes to town. Heated bed too. He's such a diva.

Yes, his name is Stinky. He's earned that name tenfold this week with his lack of interest in cleaning himself. He originally earned the name by passing gas the minute I met him.

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[s8ilver]

What do we think about a beefy alternator?

https://www.powerbastards.com/prodde...3882-250-HD3-3

In theory the system can pull 140A before it blows a fuse. I believe my alternator is stamped 140A.

Of course my concern would be wire gauge. 4AWG up to about 200A feels right, but don't imagine that I'll ever pull over 200.

[BimmerBreaker]

Glad Stinky is doing better overall


Regarding the capacitor - I remember always thinking those were a bandaid solution. They take systems without sufficient voltage supply and store the insufficient voltage to let it out as needed. In most cases, you are better off doing what you are thinking of doing now - a better alternator. As you mention though, bumping the alternator up in size often necessitates larger gauge wiring. I do think BMW went a size or two up from what was required but if you are always going to be at this "upper limit" then it is way safer to upgrade the wire. I know back in the day, particularly in sound/subwoofer competitions (are those even still a thing?) people would run a second alternator and a second battery just for the sound system

Of course that was over a decade ago now. My memory is hazy - and technology may have improved. I was doing this back in the day when "digital" amplifiers were still a new thing

[ProductUser]

Glad Stinky is doing better overall


Of course that was over a decade ago now. My memory is hazy - and technology may have improved. I was doing this back in the day when "digital" amplifiers were still a new thing

What??? I don't have to take my vacuum tubes to the grocery store to test anymore??? When did this happen??

[s8ilver]

Glad Stinky is doing better overall


Regarding the capacitor - I remember always thinking those were a bandaid solution. They take systems without sufficient voltage supply and store the insufficient voltage to let it out as needed. In most cases, you are better off doing what you are thinking of doing now - a better alternator. As you mention though, bumping the alternator up in size often necessitates larger gauge wiring. I do think BMW went a size or two up from what was required but if you are always going to be at this "upper limit" then it is way safer to upgrade the wire. I know back in the day, particularly in sound/subwoofer competitions (are those even still a thing?) people would run a second alternator and a second battery just for the sound system

Of course that was over a decade ago now. My memory is hazy - and technology may have improved. I was doing this back in the day when "digital" amplifiers were still a new thing

I've done the dual battery thing, but never the double alternator. Battery wiring seems like 4AWG, or perhaps slightly larger. That is good to 200, and some will run 250 on it. I ran a 250A alternator in my Bronco for over a decade and it was perfectly good on the 4GA. Then again, it probably never drew 250. I had a tactile transducer under the driver's seat (for sound you can feel but not hear) and it was power hungry.