[bluelake]

So far I've talked to four so-called hi-end installers in the Bay Area. I get a different story from every one about what to do with the car to install an amp and speakers.

So here's my basic question. Is the feed out of the head unit into the stock amp digital or analog in my non-L7 2007 US-spec 328i? I'm really confused by the forum threads.

One installer guy said there is a plug in the back of the HU to get an unprocessed analog signal. One guy said the stock HU needed to be replaced by something better to get good sound. One guy swore the HU powered the front door speakers. Another said it's all digital and you need major processing before the aftermarket amp to undo the factory equalization. The list goes on and on. Okay, I'm counting on you guys to help me! Thanks.

[Technic]

Originally Posted by bluelake

So far I've talked to four so-called hi-end installers in the Bay Area. I get a different story from every one about what to do with the car to install an amp and speakers.

So here's my basic question. Is the feed out of the head unit into the stock amp digital or analog in my non-L7 2007 US-spec 328i? I'm really confused by the forum threads.

One installer guy said there is a plug in the back of the HU to get an unprocessed analog signal. One guy said the stock HU needed to be replaced by something better to get good sound. One guy swore the HU powered the front door speakers. Another said it's all digital and you need major processing before the aftermarket amp to undo the factory equalization. The list goes on and on. Okay, I'm counting on you guys to help me! Thanks.

Your HiFi system (Logic7 is Top HiFi) OEM HU has analog outputs using Differential/balanced topology. So you will need either a balanced inputs line output converter, a balanced inputs capable processor or just a balanced inputs capable aftermarket amp to interface aftermarket audio components to your OEM HU.

That's very important to consider before connecting anything to the OEM HU outputs.

[tintivilus]

Originally Posted by bluelake

So far I've talked to four so-called hi-end installers in the Bay Area. I get a different story from every one about what to do with the car to install an amp and speakers.

So here's my basic question. Is the feed out of the head unit into the stock amp digital or analog in my non-L7 2007 US-spec 328i? I'm really confused by the forum threads.

One installer guy said there is a plug in the back of the HU to get an unprocessed analog signal. One guy said the stock HU needed to be replaced by something better to get good sound. One guy swore the HU powered the front door speakers. Another said it's all digital and you need major processing before the aftermarket amp to undo the factory equalization. The list goes on and on. Okay, I'm counting on you guys to help me! Thanks.

Your HU has a differential analog output to an outboard amp in the trunk. I have no idea how much processing is done to those signals, though.

edit: damn, Technic beat me to it

[gIzzE]

[Technic]

Thanks...

[gIzzE]

I never knew that the radios were a balanced output.
A lot of the guys were moaning on the 1 series forum that when they bought a used head unit of ebay, swapping business to professional they lost volume, like more than twice as quiet, do you think that the head unit is programmed to be regular high level or balanced when installed??
This would answer the volume change.

Also some have lost all bass off the rear channels, this is probably because bass is cut off from the main channels when in an L7 car as it is told to go to the sub channel, because there is no sub channel on the analogue side you are stuffed.

[tintivilus]

I *think* the 1er is more like the E46: business has speaker-level outs, where professional uses an outboard amp. Both should be differential.

[gIzzE]

The 1 series and 3 series are exactly the same, same part numbers for everything radio/nav/phone related.

[hkkuf]

I thought Logic 7 came with 13 speakers?
Isn't Top Hifi Logic 7?

[Technic]

Originally Posted by gIzzE

The 1 series and 3 series are exactly the same, same part numbers for everything radio/nav/phone related.

I think that depending of the audio system configuration the radio has to be programmed/switched to the proper output: speaker level/preamp level (either Business or Professional) or digital output (only Professional).

How that programming/switching is done, I don't know yet...

[Technic]

Originally Posted by hkkuf

I thought Logic 7 came with 13 speakers?
Isn't Top Hifi Logic 7?

That Top HiFi in the illustration is the Logic 7 system of the 1 Series.

[bluelake]

Thanks for the clarification. I wish, just once, that an installer I talk to would simply admit they don't know, instead of filling me up with BS.

Okay, next question - I guess there is a bunch of EQ or other processing done to the signal, somewhere before it reaches the speakers. Would this be done in the HU or the amp? I'm looking for the cleanest signal, obviously. Since the HU output is analog (yaay!), I should be able to just bypass the OEM amp and tap the wires before they enter the amp, right? then deal with the balanced/differential issue at or before the new amp. Sorry if I seem so dense- but I'm learning, with everyone's help. Thanks again for your time and expertise.

[tintivilus]

Originally Posted by gIzzE

The 1 series and 3 series are exactly the same, same part numbers for everything radio/nav/phone related.

Assuming by "3 series" you mean E9x, then never mind

Originally Posted by Technic

I think that depending of the audio system configuration the radio has to be programmed/switched to the proper output: speaker level/preamp level (either Business or Professional) or digital output (only Professional).

How that programming/switching is done, I don't know yet...

You think all the head units have both analog and MOST ports and are just coded for one or the other? Why would they bother -- just in case they want to use a 1-line HU with the Logic7 amp?

[hkkuf]

Originally Posted by Technic

That Top HiFi in the illustration is the Logic 7 system of the 1 Series.

Thanks for clarifying that.

[Technic]

Originally Posted by tintivilus

You think all the head units have both analog and MOST ports and are just coded for one or the other? Why would they bother -- just in case they want to use a 1-line HU with the Logic7 amp?

As gIzzE stated, the P/N among Professional and Business OEM HU respectively are the same, regardless of the audio system that they are connected to (stereo, HiFi or Top HiFi).

In Europe the Professional OEM HU is optional and available from the base stereo system (speaker level) all the way to the 16 speaker Individual system (digital); the Business OEM HU is standard in Europe and available across the board only with analog outputs (speaker level and preamp). In the USA only the Professional is available and standard from the HiFi (preamp) to the same 16 speaker Individual system.

So their respective outputs must be configurable somehow to those audio systems (speaker level, preamp, digital) for this to work with a single OEM HU platform.

[Technic]

Originally Posted by bluelake

Thanks for the clarification. I wish, just once, that an installer I talk to would simply admit they don't know, instead of filling me up with BS.

Okay, next question - I guess there is a bunch of EQ or other processing done to the signal, somewhere before it reaches the speakers. Would this be done in the HU or the amp? I'm looking for the cleanest signal, obviously. Since the HU output is analog (yaay!), I should be able to just bypass the OEM amp and tap the wires before they enter the amp, right? then deal with the balanced/differential issue at or before the new amp. Sorry if I seem so dense- but I'm learning, with everyone's help. Thanks again for your time and expertise.

According to http://wds.west.lv/ :

The HiFi amplifier does not have speed-dependent volume adjustment or speed-dependent equalizing. The function of the HiFi amplifier is only to amplify the low-frequency output.

So -as it was in the E46 OEM HU- we can assume that the E9x OEM HU outputs should be fairly flat all across the full frequency response. Also, notice that the OEM amp has low pass crossovers for the subs, so tapping the OEM amp outputs is not that great of an idea if you are looking for a clean, full frequency response output to feed processors or amps without a summing feature.

[gIzzE]

This is what I was saying in the sub upgrade thread, the installer I spoke with said they take the signal direct from the head unit bypassing the amps completely when adding new amps.
Maybe all that happens is the speaker level is dropped from around 8v to around 4v when coded from a stereo that drives the speakers directly to one that drives them via an amp?

But others have said that when putting a unit from an L7 (top hi-fi) car into a car with no amp at all the frequencies are limited as well as the volume being low.

[tintivilus]

Originally Posted by Technic

As gIzzE stated, the P/N among Professional and Business OEM HU respectively are the same, regardless of the audio system that they are connected to (stereo, HiFi or Top HiFi).

In Europe the Professional OEM HU is optional and available from the base stereo system (speaker level) all the way to the 16 speaker Individual system (digital); the Business OEM HU is standard in Europe and available across the board with all outputs. In the USA only the Professional is available and standard from the HiFi (preamp) to the same 16 speaker Individual system.

So their respective outputs must be configurable somehow to those audio systems (speaker level, preamp, digital) for this to work with a single OEM HU platform.

www.bmw.co.uk won't let me configure a vehicle (tried a few 3'ers and 1'ers) with "HiFi Sys Prof DSP" -- which I think is the Logic7 / top-hifi setup -- without also selecting the Professional HU. This is consistent with the detailed head-unit descriptions only listing MOST on the Professional.

You're completely right, though, that the Professional head unit does not require Logic7 or HiFi. It must have analog outputs that can run at either line or speaker level. Aren't the DSP and GEQ functions dependent on Logic7, rather than the HU?

[Technic]

Originally Posted by tintivilus

www.bmw.co.uk won't let me configure a vehicle (tried a few 3'ers and 1'ers) with "HiFi Sys Prof DSP" -- which I think is the Logic7 / top-hifi setup -- without also selecting the Professional HU. This is consistent with the detailed head-unit descriptions only listing MOST on the Professional.

You're completely right, though, that the Professional head unit does not require Logic7 or HiFi. It must have analog outputs that can run at either line or speaker level. Aren't the DSP and GEQ functions dependent on Logic7, rather than the HU?

You are correct, the Professional OEM HU is the only HU with dual output capability (analog/digital outputs), not the Business (corrected above).

All the DSP/EQ functions are done in the OEM Top HiFi amp.

[bluelake]

This is great info. Thanks to everyone who is contributing.

The HU (it appears I have the Professional = std US issue) seems to have four channels going out to the amp: left front, left rear, right front, right rear. Then the amp has 6 channels going to the speakers (like above, but adding underseat mid-bass speakers). The mid-bass channels seem to be derived from the left and right front channels coming from the HU. Am I correct to assume that the amp takes those front channel signals and splits them up into door and sub channels, with both doors and subs equalized separately?

If that is true, I'm not sure how to get a proper sub channel into my aftermarket amp - or do I need an inline EQ device, like one of the Audiocontrol or other brands? Or would the amp (Audison Srx5) take the unequalized signal and create a low-pass sub channel for its fifth (sub) channel configuration. Anyway, I feel like I'm getting close to understanding how this works! Thanks.

[Technic]

Originally Posted by bluelake

This is great info. Thanks to everyone who is contributing.

The HU (it appears I have the Professional = std US issue) seems to have four channels going out to the amp: left front, left rear, right front, right rear. Then the amp has 6 channels going to the speakers (like above, but adding underseat mid-bass speakers). The mid-bass channels seem to be derived from the left and right front channels coming from the HU. Am I correct to assume that the amp takes those front channel signals and splits them up into door and sub channels, with both doors and subs equalized separately?

If that is true, I'm not sure how to get a proper sub channel into my aftermarket amp - or do I need an inline EQ device, like one of the Audiocontrol or other brands? Or would the amp (Audison Srx5) take the unequalized signal and create a low-pass sub channel for its fifth (sub) channel configuration. Anyway, I feel like I'm getting close to understanding how this works! Thanks.

The OEM HU outputs are full range, so that's where you need to tap for the inputs to your aftermarket components. The 4 channel OEM HU outputs are split into the 6 channel outputs of the OEM amp (Front, Rear and Subs), so unless you use a summing device to re-create the full range (adding Rear plus Subs channels together, for example) then there is no point in using the OEM amp outputs for anything. Whatever device you use (amp/processor/EQ) will take that full range signal and apply whatever crossovers are available to give you an adjustable and independent sub output in addition to high pass/band pass if available. The best solution to tune your system to your particular liking.

Again, as long as you use a device that accepts balanced signals you do not need any LOC between the OEM HU and the device. It will connect straight...

[gIzzE]

If you have an SRx5 then I would take out the factory amp compltely, take the 4 incoming channels and put them into the hi-level inputs on the Audison.

Then use the same wires that were going from the factory amp to the speakers and put them into the outputs of the Audison.

Cross over the front speakers at around 200hz, do the same with the rears but also cut out everything above 5000hz so you have just midrange rear fill and add some Earthquake subs. Maybe run new cable to the subs? In fact just use the existing cable.


This will give you a superb sounding system.