low-level output on stock system

[UKenGB]

Originally Posted by Brian-bmw

The system is pretty sophisticated.

That being a euphamism for overly complex

[DouglasABaker]

Originally Posted by willtwilson

I recently had a Parrot bluetooth kit fitted and the installer couldn't get the telephone mute pin to work on my system.

Am thinking I will try testing the corresponding pin from your pin guide. Any idea when the change over for radios was during 2002? (I will count the number also.)

For testing: presumably the radio needs a 12V positivie signal pulse to activate the mute function. Can anybody confirm this? And what is the telephone ON pin for? Stupid question probably.

Thanks a million!

Old radio has round pins, the new one has flat blades. You cannot mistake the 2.

d-

[DouglasABaker]

Originally Posted by Brian-bmw

Yes, the radio changes behavior, depending on the amp connected to it. If DSP, then the signals are low level, but full volume. If standard HiFi amp, then I believe that they are "normal" low level. If no amp (only offered in Europe), then the radio puts out speaker level, but low wattage outputs.

Let's clarify - the signal is not capable of driving a speaker since it is low wattage, but it is not "normal low level".

A normal low level is an unbalanced output that is typically in the 0.1-1V range.

The BMW radio unit will revert to +/- 5V balanced outputs (ie. 10V inputs). These are NOT compatible with most aftermarket amplifiers unless that amp accepts high level inputs.

d-

[DouglasABaker]

Originally Posted by Brian-bmw

I don't know if the balanced signal behavior changes with the amp connected. For all I know, it probably does. The system is pretty sophisticated.

They do not become unbalanced, they simply begin to change volume with the head unit controls.

d-

[Brian-bmw]

Originally Posted by DouglasABaker

Let's clarify - the signal is not capable of driving a speaker since it is low wattage, but it is not "normal low level".

This is incorrect. There are three versions of the E38/E39/X5 audio system. There is the standard stereo, the HiFi system, and the Top HiFi (DSP) system. The standard stereo system was never available in the US market, but it was very common in other global markets. In the standard stereo system, the radio drives the speakers directly, and there is no separate amp in the car. Read the technical details in the WDS and study the wiring diagrams for the standard audio for more details.

[DouglasABaker]

Originally Posted by Brian-bmw

This is incorrect. There are three versions of the E38/E39/X5 audio system. There is the standard stereo, the HiFi system, and the Top HiFi (DSP) system. The standard stereo system was never available in the US market, but it was very common in other global markets. In the standard stereo system, the radio drives the speakers directly, and there is no separate amp in the car. Read the technical details in the WDS and study the wiring diagrams for the standard audio for more details.

I was referring only to the ones with an amplifier - otherwise there is nothing to "revert" from. Sorry, I should have been more specific.

d-

[UKenGB]

Here's an interesting take on this matter-

Originally Posted by RichardP1

Just a normal characteristic based on the load that the amp is driving. Speaker loads are relatively low impedance (usually 2 or 3 ohms on BMW's) whereas amp inputs are higher impedance, if the amp is designed with this in mind then it will drive both types of load.

In which case the radio module could drive a third party amp without having to fool it into believing the OEM amp is connected.

There is still the issue regarding the output varying with volume depending on whether it's a DSP amp or other, but if this is true there's no need for any Speaker->LineOut converter. There would just be the DC bias to take care of. Not sure if that's better or not.

Could do with the experts offering their insight on this one.

[DouglasABaker]

Originally Posted by UKenGB

In which case the radio module could drive a third party amp without having to fool it into believing the OEM amp is connected.

There is still the issue regarding the output varying with volume depending on whether it's a DSP amp or other, but if this is true there's no need for any Speaker->LineOut converter. There would just be the DC bias to take care of. Not sure if that's better or not.

Could do with the experts offering their insight on this one.

There is no question that the factory radio unit will drive any aftermarket amplifier - it will do so with no issue. The only question in this case is whether or not the amplifier can handle the signal being provided to it. When there is no DSP amplifier attached to the factory radio it will provide a balanced +- 5V signal (note that this is the same as a 10V signal). This is a considerably higher voltage than most "low level" inputs are designed to accept, so you may need LOC's. If you amp also has "high level" or "speaker level" inputs, then you can just provide the signal directly to those instead of LOC's.

There is a question as to whether the factory radio module can drive a speaker load. I would say the answer is "Not for very long" since speaker impedance is so much lower than amplifier impedance (and therefore higher current which will fry the radio unit circuit). Having said that, I've never tried. And for clarity, I am referring specifically to the radio unit mounted in the trunk. You, apparently, have a headunit that drives speakers without an amp. By definition then, your headunit is capable of driving both amplifiers and speakers.

d-

[Brian-bmw]

Originally Posted by DouglasABaker

There is a question as to whether the factory radio module can drive a speaker load. I would say the answer is "Not for very long" since speaker impedance is so much lower than amplifier impedance (and therefore higher current which will fry the radio unit circuit). Having said that, I've never tried. And for clarity, I am referring specifically to the radio unit mounted in the trunk.

Both the in-dash radio and the navigation board monitor radio are designed to drive the speakers directly. BMW uses the same radio in all three configurations of the audio system. That is probably the reason for the high voltage output. The radio is designed to serve a low impedance, high current load.

[DouglasABaker]

So there are no systems that have just a head unit without the additional radio box in the trunk?

That is interesting only because I helped someone (via phone) with an install who said he only had a head unit w/ no box in the back...

d-