Premium sound option and an aftermarket radio.

[fujioko]

This is a new thread.. based on another thread I started. My radio install has taken a turn and I seek new advice.

First of all, my OE radio has never worked… well sort of.

I took the OE unit apart and discovered the output amps were blown. I replaced chips and put the unit back in the car… still no sound. This really didn’t disturb me, I thought I might have missed something when I had the unit apart.

Fast forward a few months and now I’m putting in an aftermarket radio. Sure enough after I install the new radio… still no sound….. So I check the Bently… ahhh perhaps my car has an amp… So I go looking in the trunk and Yep there is a secondary amp. Damm.

I pull the amp and notice the fuse is blown… I wonder…Hmmm… I pop in a fuse and connect the original OE unit and fire it up… SOUND!

OK, so the original sound system is good.

This new Sony radio has RCA line outs and amplifier enable control wire. So its compatible with the BMW amplifier.

Currently the new radio wired wrong because I was not aware of the power amp in the trunk. My current configuration is utilizing the built in 17 Watt amp in the Sony unit. I’m aware that this would overdrive the BMW trunk amplifier… just for giggles I tried it and sure enough it all works at low volume. I didn’t try to bump up the volume for fear of blowing the BMW amp.

Anyway here is my question:

Is the BMW amplifier worth keeping? It appears to work and I can rewire my Sony to provide line level input to the amp.

Or I could just bypass the amp and have the Sony provide the power.

I’m inclined to keep the BMW amp if its worth keeping.

Comments?

[gmannino]

easy fix, your sony deck also has low level outputs in the form of rca plugs on the back of it. We will use these to feed signal to your factory amp. Take 2 sets of rca wires and cut off the ends, leaving enough room to solder or splice the ends of the wire.

Remove your aftermarket wiring harness that plugs into your factory radio harness behind the radio. Instead of connecting speaker wire outputs from the deck to this harness, you want to use your cut rca's. Wire each channel, front left and right and rear left and right. The plug each rca into each corresponding channel to get low level output to your factory amp. This will yield the best sound output from your system. Email me or PM if you need more help.

[Dr. evil]

it would be cleaner if you used a universal interface, you can find them at crutchfield.com. these are use to switch factory Front/Rear Signal to RCA's. This is if you don't already have Front/Rear RCA ouput's on your sterio.Also i'm assuming that you are going to be runing highs with your amp.

If it were me I would get a better amp that has more power and options. Save the old one for a rainy day.

[gmannino]

Replace the radio first, he might be happy with his factory amp. Besides replacing the amp would involve re-wire each speaker with a new crossover.

[TheMissile]

keep the bmw amp if it has more or less the same output than the sony. If you absolutely want to use the sony the followig applies:

1) rewiring is an extensive job - crossovers need to be included, shared ground for the front speakers are confusing -
2) research research research....this site was my haven for stereo wiring
diagrams. http://www.bmwe34.net dont know if this here site has the same.
3) big balls needed - cutting them there wires commits you.
4) Count on some $$$ if you get an auto shop to do it - make sure they know what they are getting into as its not straightforward and if they havent done it before...well, you've been warned :D
5) Stock up the cooler....you'll be at it a while if you do it yourself.
6) Add a nice big removable subwoofer whilst you are at it - what a difference !!!

My own setup after about 8 hours work:
- Alpine 9850RI head unit (4 x 50 watts)
- rear speakers : JBL GTO - 2 way
- Front speakers - withe jbl crossover - combination of : tweeters-jbl component, mid range-stock, woofers-Stock; I cant fit my JBL woofers due to an inverted mounting system in the front kick panels...havent found the patience to figure it out yet)
- Crunch 300w subwoofer amp - mounted in the car jack compartent
- Crunch 500w subwoofer : A removable box which sits really nicely under the rear seat rim in the trunk - I just un-plug the speaker wires and make sure they dont ground out !!
LOUD and AMAZINGLY CRISP - my kids particularly love the body shaking bass booms my system now makes !!!:D

[fujioko]

Experiment #1…
I rewired the sony with line level output to the BMW amp… this proves to be NFG.

Back to the drawing board…

A little research on the Bimmer amp indicates that the amp is expecting a speaker level input with a maximum of 5 watts. The line level input is simply not enough.

The normal output of the sony is 17 watts at speaker level… that is too much power for the BMW amp.

Option #2 …I have the tools and facilities to build a plug in harness to bypass the BMW amp. I may do this today. Yep your right, the front speaker configuration appears a bit confusing . I’m certainly up to the job… I’m normally build robots and other industrial equipment.

OR.. perhaps I’ll try an experiment by inserting some resistors in line to reduce the effective power of the Sony. I’ll need to calculate the wattage.

Stay tuned

[genphreak]

This new Sony radio has RCA line outs and amplifier enable control wire. So its compatible with the BMW amplifier.

No, (as you now know) the RCA outputs will not drive the stock amp's inputs.

The stock amp however is more than an amp. (well actually it is a booster amp which prevents any benefit from the fitment of a high powered head unit)

High powered head units are **** anyway, so it doesn't matter.

To get good sound you need to use the low level outputs (RCA connectors) to connect the head unit to a decent (so long as it is reasonably heavy) amplifier. Why BMW didn't do this in the first place is a complete mystery, they got so much right about this car (espeically the amazing 10-speaker sound system) it is amazing that they went and used high-level connections and a booster amp to power it. But hey, maybe Engineering had to give in to Marketing somewhere...

The BMW Booster amp is more than a booster amp. It is also a crossover which is why it connects to each of the 10 speakers individually through one of its connectors. It even has a special tuning module to adjust it to suit the accoustic characterisitics of each different interior. This is the part worth keeping.

First thing to do is remove the amp and check to see if it is possible to retain the crossover section: If so, the upper section (incorporating the heat sink) will obviously unscrew from the box- when you open it up you will be able to see that it will as the booster amp is a separate PCB at 90 degrees to the main PCB which is the crossover section. If it isn't possible all the booster and crossover components are mounted on the one circuit board with the power transistors screwed to the one-piece casing... so there is no unplugging of the booster module itself.

Now the point of doing this would be to install your new, additional amp using the low level inputs from the head unit- wiring this new amp's outputs to the cars crossover (booster removed) and thus simply retaining all speakers, wiring and the perfect crossover points for your car's cabin.

If your amp is not this and you are handy enough to replace power transistors, it is easily possible to retrofit an old 535 amp (which you can definatley remove the booster from) and chuck the old amp. You just have to check the connectors as some pins are slightly different (the remote on connection) between your model and the 535 one, but the connectors are physically the same.

Oh yes, and as a bonus you can even use the wiring in the car (what the head unit's speaker level connections used to use to run to the old amp) instead of routing a new shielded RCA lead. The remote on can come from the stock wiring to the crossover as will no longer be necessary to power the crossover unit. The only new wires you need to run will be the power and ground for the new amp and enough speaker wire to run from the new amp to the crossover inputs witinin the trunk.

And before you ask the stock crossover and speaker system can handle ooodles of power. It will sound 3x as good with a decent power amp and 10x as good if you add a subwoofer. (Hint- get a cheap 5-channel amp and mount it under the parcel shelf). It will be much louder (without distortion) than you would possibly imagine before doing it. I can easily deafen myself if I start driving my car regularly. :) Nick

By now you must be feeling that this is pretty hard work... but stick with the program, you can make this really worth doing.

[zhandax]

Either the factory head unit or the factory amp is too bass-enhanced for my taste. I intend to replace both and have the compenents on the bench, but I want to connect an XM tuner to my Eclipse HU, and the HU is "Sirius ready". Will require a little re-engineering. I already have the I2C protocols, winter is coming, I will get the time.

[Anthony (M5 in Calgary)]

This new Sony radio has RCA line outs and amplifier enable control wire. So its compatible with the BMW amplifier.

No, (as you now know) the RCA outputs will not drive the stock amp's inputs.

The stock amp however is more than an amp. (well actually it is a booster amp which prevents any benefit from the fitment of a high powered head unit)

High powered head units are **** anyway, so it doesn't matter.

To get good sound you need to use the low level outputs (RCA connectors) to connect the head unit to a decent (so long as it is reasonably heavy) amplifier. Why BMW didn't do this in the first place is a complete mystery, they got so much right about this car (espeically the amazing 10-speaker sound system) it is amazing that they went and used high-level connections and a booster amp to power it. But hey, maybe Engineering had to give in to Marketing somewhere...

The BMW Booster amp is more than a booster amp. It is also a crossover which is why it connects to each of the 10 speakers individually through one of its connectors. It even has a special tuning module to adjust it to suit the accoustic characterisitics of each different interior. This is the part worth keeping.

First thing to do is remove the amp and check to see if it is possible to retain the crossover section: If so, the upper section (incorporating the heat sink) will obviously unscrew from the box- when you open it up you will be able to see that it will as the booster amp is a separate PCB at 90 degrees to the main PCB which is the crossover section. If it isn't possible all the booster and crossover components are mounted on the one circuit board with the power transistors screwed to the one-piece casing... so there is no unplugging of the booster module itself.

Now the point of doing this would be to install your new, additional amp using the low level inputs from the head unit- wiring this new amp's outputs to the cars crossover (booster removed) and thus simply retaining all speakers, wiring and the perfect crossover points for your car's cabin.

If your amp is not this and you are handy enough to replace power transistors, it is easily possible to retrofit an old 535 amp (which you can definatley remove the booster from) and chuck the old amp. You just have to check the connectors as some pins are slightly different (the remote on connection) between your model and the 535 one, but the connectors are physically the same.

Oh yes, and as a bonus you can even use the wiring in the car (what the head unit's speaker level connections used to use to run to the old amp) instead of routing a new shielded RCA lead. The remote on can come from the stock wiring to the crossover as will no longer be necessary to power the crossover unit. The only new wires you need to run will be the power and ground for the new amp and enough speaker wire to run from the new amp to the crossover inputs witinin the trunk.

And before you ask the stock crossover and speaker system can handle ooodles of power. It will sound 3x as good with a decent power amp and 10x as good if you add a subwoofer. (Hint- get a cheap 5-channel amp and mount it under the parcel shelf). It will be much louder (without distortion) than you would possibly imagine before doing it. I can easily deafen myself if I start driving my car regularly. :) Nick

By now you must be feeling that this is pretty hard work... but stick with the program, you can make this really worth doing.


What he said:D

[mkaareng]

Do the American E34's have 10 speakers? I can only count 8.

[genphreak]

Do the American E34's have 10 speakers? I can only count 8.
I believe so, but have never seen a US 535 :(
ie it should be
4 rear (tweeters+woofers)
6 front (tweetersin door, mids in dash +woofers in kick panels)

[fujioko]

Hmmm..

Nice write up! I have seen you respond to other members in the past…You defiantly have an excellent technical background and great writing skills!

Electronics is my occupation, however audio stuff is something I never paid attention too. Passive filters are universal apply to more than audio.. so thankfully I do understand what I’m looking at.

Anyway It occurred to me today that the crossover section is too important to loose. After reading your post, I think I’ll toss the idea of building a bypass harness and try and salvage the crossover section.

I like your idea of pitching the OE power section and utilizing the crossover with a high power amp.

My OE amp has the power transistors and the crossover components mounted to the main circuit board. There are two little circuit boards mounted at right angle to the main circuit board. Each board has a single 20 pin DIP M5243P12. A quick check on the net says this chip is a tone control three- element EQ. No data sheet were found. Perhaps these little boards are tuned to the particular cabin?? Hard to say at this point.

The amp has two 12 pin connectors. One black and one white. The part number is 65.12-8 350 407.

It sounds like you have experience in hacking the BMW OE amps. It sounds like mine is closer to the 535 description you gave.. or did I misread that?

Am I in the right direction or did I miss something?

[everlast]

Can you guys check this out? I posted this, didn't want to repeat myself here.

http://www.bimmer.info/forum/showthread.php?p=207351#post207351

[fujioko]

I gave up on trying to salvage the OEM trunk amp because of the grounding issues. BMW combines the speaker level output grounds prior to conecting to the amp. This is not acceptable with a modern headunit.

its time to rewire the car and install aftermarket crossovers and amps. More $$.....

As a minimalist, this is certanly not something I would do.... however i really want the stupid ipod controls built in to the HU.

BTW... my keyboard has been busted for a few days now. been using the silly microsoft "on screen" keyboard. really sucks.