Factory Amp Question

[UtahWright]

I have read through all the threads, and they were helpful, but...

My amp doesn't look like any of the others posted, and I have replaced the HU and now want to just use the crossover in the amp. Does anyone have any idea of where I would need to modify my amp to do this?

Thanks for the help,

Bob

[gmannino]

I would be best to buy a new electronic crossover unit. Using the factory amp as a crossover would surely add noise that you dont need and it will be the weak link in your system. You can add capacitors or coils to each speaker to crossover your speakers but a electronic crossover is adjustable, which is the way to go.
Out with the old stuff, in with the new.

[UtahWright]

I just read the many comments from people who had been able to use the crossovers in their amps and wanted to try doing the same. But found that my amp is different from the one in the pictures showing how to do it. My amp is not on a removable board, but I can see the inductors and caps from the crossover. Just trying to figure out where to tap in and what needs to be removed.

Please help, anyone who has done this.

Thanks,

Bob

[genphreak]

Just sell that one and buy an old one from a 535 at a dismantler. Remove the amp and presto! Check your pin outs on the cables from the trunk's loom, if worst comes to the worst you will have to swap some connectors around inside the connectors. I doubt you'd have to, but check jic. The old x-over is great, handles shitloads of power with no distortion or degradation. No Buzz whatsoever, and is a heck of a lot simpler than having to wire new crossovers in to 10 individual speaker outputs that are already wired...

[Anthony (M5 in Calgary)]

I just read the many comments from people who had been able to use the crossovers in their amps and wanted to try doing the same. But found that my amp is different from the one in the pictures showing how to do it. My amp is not on a removable board, but I can see the inductors and caps from the crossover. Just trying to figure out where to tap in and what needs to be removed.

Please help, anyone who has done this.

Thanks,

Bob

Chances are you can apply your new HU speaker leads directly to the PCB where the amp ICs are mounted - they're the ones clipped to the heatsink. If you feel adventurous and don't care about the factory amp anymore, tear into it and post the device part numbers. You can probably find a datasheet for the parts online - it'll show how to apply the speaker leads.

Genphreak is right about the quality of the factory crossover bits - very good and properly tuned for the OE speakers and the car itself.

[UtahWright]

I did as you suggested (I think). I went to the salvage yard this morning, and after going through about 20, found a 735 with an amp that looked like it had the amp board as in the photos. It is a Blaupunkt though. I opened it up and removed the amp board, and hooked up leads to the pins shown in the photos on this board. When I hooked it up in the car, the front speakers distort and don't even sound as good as the HU going through the amp originally in my car. It seems that either: the crossovers are different in this amp (being Blaupunkt), there is something else different I missed, or my speakers are the problem. I didn't rewire the output lines, and can't find any reference to it being any different than my original amp, but maybe. They both had two 12 pin connectors (one black and one white), and sound did come out of the speakers, just low in level and distorted if I turned it up even half way on my HU.

Thanks,

Bob

[genphreak]

I did as you suggested (I think). I went to the salvage yard this morning, and after going through about 20, found a 735 with an amp that looked like it had the amp board as in the photos. It is a Blaupunkt though. I opened it up and removed the amp board, and hooked up leads to the pins shown in the photos on this board. When I hooked it up in the car, the front speakers distort and don't even sound as good as the HU going through the amp originally in my car. It seems that either: the crossovers are different in this amp (being Blaupunkt), there is something else different I missed, or my speakers are the problem. I didn't rewire the output lines, and can't find any reference to it being any different than my original amp, but maybe. They both had two 12 pin connectors (one black and one white), and sound did come out of the speakers, just low in level and distorted if I turned it up even half way on my HU. Thanks, Bob The stock BMW system is a booster amp and so the trunk amp takes the high power outputs from your stereo (post dash-mounted fader if you have one) and boosts the power by 2x or more and then sends the signal off to the crossover, as you have.

Are you only using the head unit to power the speakers? No power amp? If so what wires are you using? Are you are using the car's wiring?

Perhaps run a piece of speaker wire direct from the head unit to the input pins you have soldered to on your new amp and see if this helps.

Re the conectors, on mine one is white and one is blue. I am concerned that the connectors are different through the years as the amps are. The more I think about it the more I think I remember some differences when I was looking at the various pinout information people had posted on the web, Specifically where was a difference with the remote on feed... not sure what else.

BTW; you can remove the fuse from the replacement amp btw, it is no longer necessary as the cross-overs are not powered.

Also, using a separate amplifier will get far better clarity and volume. The amp in your head unit will be nowhere near the same. :( nick

[UtahWright]

Thanks!

After reading and re-reading all the posts, I decided to give it another try, and IT WORKS, and sounds pretty good. It seems the problem was/is two-fold. I failed to remember that this came from a salvage yard car (exposed to more weather than normal), and so I checked the contacts, and they were oxidized and several were even black. I cleaned them with contact cleaner and now the speakers work much better. I still have one odd problem: when I fade front to back the distortion comes back. But I think this has more to do with how the PO hooked up the Hu than anything else. I'll work on that next. The PO had installed a Cool Sony HU and an Eclipse Basslink Sub, but I think I'm going to install an Alpine this week with an Alpine amp, run through the factory crossover and speakers. I'll leave the Eclipse Sub. If that sounds like I hope, I'll be done (at least with this project).

Thanks to everyone.

Bob

[genphreak]

I use a $12 sub in a $40 box, a $150 5-channel amp and a $150 head unit that plays USB sticks and SD cards (and this is Aussie dollars btw!)

With the 10 speaker stock cross-over and system it sounds incredible. At 4 ohms it pushes 70Wrms x4 plus 150Wrms to the sub.

The head unit is shitty but the front comes off to deter the theives and as I said I'm on a budget: I just wanted to play MP3s (but to my astonishment the radio actually works very well). If I had more cash I'd have bought a DVD playing head unit with USB and SD and more usable controls (but they are $500 plus). There is no way I'd spend more on a sub or an amp. In car audio most of what consumers and sellers go on about is crap.

What I've found through the years is:
Decent tuners are worth a difference. Pioneer's Super Tuner III is great example- they were the first to deliver a decent FM tuner that managed multipath reception issues gracefully whilst driving in the city. Kenwood's was nowhere near as good, but Clarion came up with an excellent FM front end also. Nowadays they will all say they have the best radio, but the question is does your model actually have one of these built-in in the right way or is it just a ******** logo pasted into the brochure. Then again, now automotive tuners on the whole are vastly improved.
Amps however just need to be large and heavy- working from a 12VDC power source it is impossible to build an audiophile setup anyway. Big transistors, big heatsinks and a decent PWM supply are all that's needed. Amp distortion specs in the car are almost meaningless.
Speakers need to be decent quality, but not these big magnetted SE Asian wannabies... they make as much difference as that between a 64-bit MP3 and a non-compressed file, or radio to a CD. My $12 12" sub is a heavy cloth/paper cone with an ugly bling paintjob but it didn't include a heavy frame I didn't need to cart around and was solidly made.ATM I'm toying with replacing the 12" sealed sub enclosure with a specially built 8" nicely fitted into a solid plate mounted inside the ski pass-thorugh (a la A/D/S style). This would reduce weight and give me some trunk space back, but the present box sounds really awesome so I am up against it doing this- I don't want to chase rattles in the parcel shelf for the rest of my life and the bass won't be so tight.

I am actually worried that if I drive the car much more I could go deaf... better go back to listening to news on the radio and turn it the **** down... :) Nick

[Airborne001]

I am actually worried that if I drive the car much more I could go deaf... better go back to listening to news on the radio and turn it the **** down...

HUH??? .. WHAT?? I can't hear you from the last time I had Freebird wound out at 120mph.

[Derek A.]

AGREED !

With my new Tri-Amp setup using the factory crossover. I am aamzed how often I drive around with the music way cranked up, and how good it sounds for 16 year old factory speakers.

Next e34 meet ( may actually attend) we should bring a db SPL meter to see who can play the loudest !

http://www.opus45.com/pics/e34_amps.JPG