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      02-17-2010, 11:18 AM   #1
VP Electricity
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Drives: E91 XDrive
Join Date: Jan 2008
Location: portland oregon


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E9X audio systems defined

The E9X as of this date has three main levels of audio system, plus another only found in the E92 in M3 trim.

Please note that the in-dash "head unit" does not define the audio system connected to it. There is not a "Professional" audio system - just a Professional head unit. Ditto iDrive.

Any external audio sources - sat radio, iPod, AUX, nav, or Bluetooth - all come into the head unit and then come out the head unit to the amps. When the OEM amp is bypassed, all these functions continue to work just as they did before.

Speaker provisions

The E9x cars have the following speaker provisions:

Front door 100mm midranges (with limited depth and magnet diameter, ESPECIALLY in the E92). The speakers attach via threaded studs on the backside of the door panel. Theses do not correspond to any standard speaker screw patters (there are only three of them) but adapters can be used. I put 50mm as a good rule of thumb for E90/E91. I need someone else to supply E92/E93 data.

Front door tweeter in mirror sail, with interesting mounting. The opposite side tweeter is on axis to the listener, and the same-side tweeter is only about 30 degrees off axis, so many auto-intended tweeters with rising frequency responses on-axis (in an attempt to have a flat response off-axis) can have raspy or tinny sound. Some aftermarket tweeters snap into the BMW mounting tabs, and a 45mm outside diameter tweeter housing seems to be the absolute widest that can do this.

Wiring - the mid and tweeter are connected in parallel with only a single set of speaker wires going into the door.

Positioning - the front mid and tweeter are equidistant from the listener's ear.


Base audio

The "base" audio system has been around since the early days, although it only made it to the US in 2010.

It uses four channels of deck power (yes, that's right, good old 50Wx4 when lightning strikes, 18Wx4 if you're charitable, and 12Wx4 if you do the actual 12V math into 4 ohms and 1% THD).

The front channels drive:

- 6.5" woofers underseat in 8" frames and molded plastic enclosures. The underseat enclosures are identical for all systems. There is uncertainty regarding whether the duct connecting the enclosure to another chamber in the frame is actually a tuned port, or simply a funny-shaped sealed box. The woofer is not crossover-filtered. The only things taking mids and highs out of the audible output are the driver's own mechanical rolloff, and the acoustic filter formed by the seat and your rear end.

-4" mids in the door. These have a capacitor on them, acting as a high-pass crossover filter and also making the two-speakers-in-parallel a load the deck can handle.

The signal is heavily equalized to the front speakers, and has a subsonic filter around 40 hertz.

The rear channels drive only a pair of 4" mids in the back. This channel is high-pass crossover filtered around 160 Hertz, so connecting a subwoofer to it is a disappointing experience. It is also heavily equalized.

There is a low-current-output remote turn-on present with base audio systems, but it's not controlled by the radio play state. It turns on when the doors are unlocked and stays on for a while after ignition is turned off.



HiFi or Premium system

Some US folks call this the "base" system since it was the entry-level audio offered in the states until MY2010. This is a US-centric POV, though, and for clarity, let's call it the HiFI system.(It's HiFi in the service docs and Premium in the marketing lit).

This system is the easiest to perform performance-minded upgrades with, since it has flat, full-range analog outputs (two pair, front and rear). The processing and crossover-filtering happens in the HiFi amplifier (in the trunk, L rear corner, under the plastic snap-off plate in sedans and coupes, behind the cargo door and under a plastic bolt-on guard in wagons. There is a remote turn-on wire present at the amplifier, similar to the base audio system in operation.

Speakers

Front door mids and tweeters (highpassed between 100 and 160)

R door or deck mids and tweeters (ditto)

Underseat 8" flat woofers (low-passed around 100 to 160 with significant stopband output)

There is no center channel, and no rear effects speakers.



Logic 7

Logic 7 is a Harman-owned technology which was supposed to be marketing to record companies for them to use when recording stereo recordings to make them sound like surround sound. In the Logic 7 information online, there is about a paragraph about using the technology to play stereo recordings and make them sound like surround sound, even if they haven't had Logic 7 technology used in their production.

To many of us, two-channel stereo works great, and music is usually recorded to reproduce the effect of the performers being in front of you, not surrounding you, so the effectiveness of Logic 7 is debatable. BMW has announced that in 2011, L7 is being replaced by the good old "harman/kardon" badge from the E36/E46 days. (No word on hardware changes).

The Logic 7 amplifier is a 7.1 or 7.2 channel amplifier:

- front mids and highs

- rear mids and highs

- rear effects mids and highs

- center channel

- one or two channels for the underseat woofers

Early versions of the Logic 7 system used metal-piston drivers. Supposedly various production dates sound better and worse.

The Logic 7 amplifier is supplied a digital signal via a fiber-optic cable using the Multimedia Optical System Transport protocol, or MOST. No analog inputs.


There are three options for those wishing to upgrade the amplification in a Logic 7 system:

1) Use a summing and -de-equalizing device.

2) Use some not-yet-commercially-available in the States MOST audio gateways.

3) Recode the HU to non-Logic 7, activating its analog outputs, repin the HU connector, and ta da. (Your graphic equalizer in the HU will disappear and be replaced by good old bass and treble controls).


I'd like someone else to cover the M3 system, as I'm unfamiliar - and please supply suggestions for this, thanks.