Ive decided on a Head Unit, need some help

[bondheli]

I have already looked at bmwe34.net
So with powered headunits, the rca jacks are the preamp outputs, and the harness is the powered output correct?

Since I'm using the stock speakers and amp, if I use the HU harness connection, won't the speakers already be recieving power, and won't more power just distort the amp or the speakers
?
I have the older style stereo, pre universal harness besides hooking up - to - and positive (I have the diagram) is there anything not discribed at bmwe34.net that I should know?

Do I still need a harness for the oem wires or can I just soilder to the alpine harness?

TIA

[bondheli]

bump

[Kalevera]

Have to do a hardwiring on the pre-uni harness...no way around it.

I don't know about the distortion; just make sure you're aware of the fact that the stock AMP gets turned on with the POWER ANTENNA on the BMW side of things (see the wiring diagram)...I think the alpine has a dedicated AMP POWER line in addition to a POWER ANTENNA line that should get connected so that you get sound when using other inputs besides the radio, but Jon K. knows more about that than I do.

best, whit

[pmlmotorsports]

to engage the stock amp would be a bad idea as it has much less power than any aftermarket in-dash receiver. The best remedy is to make custom crossovers ($45-$50) and hardwire everyspeaker to the radio's amplifier outputs. Why would anyone want "reduce" wattage by 60% thus eliminating the true benefits of an "upgrade"? Hope this helps.

[Jon K]

to engage the stock amp would be a bad idea as it has much less power than any aftermarket in-dash receiver. The best remedy is to make custom crossovers ($45-$50) and hardwire everyspeaker to the radio's amplifier outputs. Why would anyone want "reduce" wattage by 60% thus eliminating the true benefits of an "upgrade"? Hope this helps.


Thats not exactly how it works. The stock head unit does put out a powered signal... it's been refered to 5w or so. The factory amp merely amplifies that signal. It's not a TRUE pre-amp and amp system. To make custom cross overs wouldn't mean just spending $50 per channel or total even. You'd have to cross over each and every speaker, at the speakers. You can't just cross the radios 4 channels of output because you have 10 speakers. The front channels need to route the front 2 channels out to a total of 6 channels and the rear 2 to a total of 4... unless you're REAL advanced in making cross overs (which i doubt he is else he'd know what he has to do, and then wouldn't be where he is right now) the best way is to run an aftermarket headunit thru the harness and into the stock amp, it won't distort until the head unit it turned up considerably. But, obviously the correct way to do it is run a head unit and use pre-amp out RCAs to a an amplifier then out from the amp to the aftermarket cross overs and then out from cross overs to appropriate speaker... but i think he is trying to keep cost down.

[bondheli]

The stock sound quality is fine with me, I just want a nice cd player and Sub.
Do I hook up the stock amp to my headunit with the RCA's or the harness?
Do the Rca's put out 5 volts too?
If I hook it up with the harness, won't the 40w x 4 be to much for the amp to handle and end up distorting the sound quality?
thanks for your help guys, Ive obviously never done a stereo upgrade before.

[bondheli]

Also, the center pin of an rca conector is positive right?

[pundit]

Thats not exactly how it works. The stock head unit does put out a powered signal... it's been refered to 5w or so. The factory amp merely amplifies that signal. It's not a TRUE pre-amp and amp system. To make custom cross overs wouldn't mean just spending $50 per channel or total even. You'd have to cross over each and every speaker, at the speakers. You can't just cross the radios 4 channels of output because you have 10 speakers. The front channels need to route the front 2 channels out to a total of 6 channels and the rear 2 to a total of 4... unless you're REAL advanced in making cross overs (which i doubt he is else he'd know what he has to do, and then wouldn't be where he is right now) the best way is to run an aftermarket headunit thru the harness and into the stock amp, it won't distort until the head unit it turned up considerably. But, obviously the correct way to do it is run a head unit and use pre-amp out RCAs to a an amplifier then out from the amp to the aftermarket cross overs and then out from cross overs to appropriate speaker... but i think he is trying to keep cost down.

I'm beginning to think in would be worth investigating a modification that would allow line level (pre outs) of an aftermarker head unit to drive the factory amp directly. Most amps that use an existing head units amplified speaker outs for their input signal simply attenuate the input signal using resistors to bring in back to basically line level anyway... and then re-amplify the whole shebang once again. To allow for pre-out signal levels it would be a case of either removing those resistors and either replacing them with wire links or different value resistors depending on the circuit. Another option could possibly the inclusion of a switch that allows selection between line level or 'amplified' level. Many aftermarket car power amps have input level selection to allow specifically for this. I'll see if I can come up with something - providing that most are using the same factory Blaupunkt amp as mine. ;)