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Have a look what this guy said. Haven't seen any more quality posts from this guy since though.
The quote was found on an old thread:

Originally posted by TwoTimer:
Let me offer a few more thoughts on the new M5 sound system. Like most of the other owners, I was annoyed by the general flabbiness of the bass and the excessive reflections and echoes present in the DSP presets. Having enjoyed an excellent aftermarket system in my E34 M5, I zoomed, as only the M5 can zoom, over to my audio dealer to pursue an upgrade. After dreaming of replacing all the electronics, save the head unit, I was brought to my senses by the head installer who said "no way" would he touch the M5. Apparently, he attempted such an upgrade on a similar (identical?) DSP-based system in a new 7 series vehicle, was utterly defeated, He claimed he was also out of pocket to the tune of about $400 to have it restored to normal operation by the local BMW dealer. He said the system simply shut down and locked up in just one attempt to upgrade the midrange drivers. I haven't checked any other shops, but this one does most of the high-end auto installs in my area and should have a handle on what is and isn't possible. If anyone has succeeded in upgrading the drivers or the amplifiers, please post your results to this thread. I'm all ears, as they say.

Faced with no immediate prospects for an upgrade, I went back to the DSP to see what I could do with the few available controls. I mean few, of course, in a relative sense. It's an abundance of controls compared to most OEM systems and the volume aftermarket upgrades, but for me it looked pretty bleak. My old M5 had a full bore DSP with adjustable delays and amplitudes for early and late reflections, 1/3 octave equalizers for the front speakers and subs, and 1/2 octaves for the rears and center channel, plus active, tunable crossovers for the bi-amplified speaker feeds. Obviously, the new M5 system isn't capable of the near infinite adjustability I had with the old system, but faced with no alternative, I sat down to see what could be done.

For me the biggest problem, other than the flabby and boomy bass, was the lack of a front facing stereo image. This was a major focus in the design of my E34's system. The early DSP unit (vintage 1991) created a true center channel. My installer cleverly placed, with a little help from his heat gun, a small "full-range" 3.5 inch Nakamichi driver under the vent grille located in the center of the dash. With the right time delays, the system created an authentic stereo image with voices and instruments properly placed from left to right and front to back, but always forward of the driver and front passenger positions.

My visit to my audio dealer had made me more aware of speaker placements, which were quite different from my old M5 and much more problematic. The culprits in the new M5 are the small drivers located in the rear doors. Although I'm relatively short (5'8"), my seat was far enough back that the earliest arrival was from unit in the left rear door. A taller person would probably find that speaker just a few inches from his or her left ear. The fix was relatively easy and, IMHO, cleans up the imaging, even for the DSP presets, to a remarkable degree. I simply moved the fader slider to the right between 6 and 8 clockwise steps of the knob. The further back the driver's seat position, the more clicks I recommend. Like a Dolby surround speaker, you should never perceive the rear door speakers as a distinct source. The fader tweak also had a side benefit of reducing the excessive bass boost. I suspect that the subwoofer level is affected by the fader control, but I haven't spent much time trying to measure the degree of the change. If I have some time this weekend, I'll pull out the Radio Shack SPL meter and measure the bass change using the TDK car stereo test disk.

I did not, as one of the other post suggests, turn the bass (or treble) control all the way down. There is a faint vertical mark at the mid-position of all the "tone" controls, and I set the treble, bass, and balance sliders to cover that middle position. I assume (who can stand watching that video?) that the middle setting is the flat setting for both bass and treble. If you're not familar or comfortable with DSPs, you might be tempted to adjust the response curve with these tone controls. After ten years with a DSP in my old M5, I generally avoid tone controls. Only in the rare case, where a poor cassette recording or DX AM broadcast needs a bit of a cut or a boost, do I ever touch them.

Returning to the DSP's equalizer, after adjusting the fader setting, I created a set of my own equalizer settings. For Memo 1, my version of Jazz Club, I arrived at a set of levels that more or less matches those posted earlier:

80 Hz - -5 (db's or something like that)
200 Hz - -2
500 Hz - +1
1000 Hz - +1
2000 Hz - +1
5000 Hz - +2
12000 Hz - +4

Room - +3 and Echo - +4

As far as the rising high end goes, I should first say that I have 50 year old ears. It's quite possible that a younger person would find it overly bright. My 13 year old son, however, did not think it was excessive, but we were both in the car and that does change the reflections and absorptions. Another factor to consider is the interior of the car. For my new M5 the major change from stock upholstery has been a pair of the sheepskin seat vests. They are more absorbent than the bare leather and might contribute to the greater treble lift.

I added a Memo 2, with the same low end equalizer settings as Memo 1, but with 0db settings for the 500 Hz and 1000 Hz sliders, for listening to news and talk. The Room and Echo settings are both at zero, as I find any artificial reflections or reverb distracts from pure spoken voice. I should note that high end DSPs found in home theater surround processors actually detect pure voice and dynamically reduce the reflection and echo amplitudes to keep voices sounding natural, but I have yet to encounter this capability in a car stereo.

Memo 3 is currently a trial setting for classical music. I'm not quite happy with it yet, so I won't comment about the current positions.

If you haven't experienced DSP before, it's fairly typical to want to turn the Room and Echo controls off for everything. My strong recommendation is to use them only for music. I think you'll will come to appreciate the fact that they can and do enhance the listening experience. In fact for me, turning them off makes the system sound like ordinary car stereo, not anything resembling either home stereo or a live performance. It's actually more like listening inside a giant set of headphones.

Relative to my previous DSP environment, the M5's DSP is rather simple. The Room control appears to set the time of the first reflection, with the delayed signal feeding the front speakers. If you were in a small room, sitting close to the combo in a jazz club, the early reflection would probably be the bounce off the room wall or stage wall behind the group. Since there is only one Room control, it may also adjust the late reflection off the rear wall and feed this to the side and rear speakers. It's only a conjecture, as I haven't crawled in the back to verify it. The Echo control appears to adjust the simulated room reverberation. Small, live rooms tend the have a earlier and higher amplitude echo and a longer decay given the hard walls. A movie theater has a later and lower amplitude echo with a more rapid decay due to seat and curtain absorption. Unfortunately, the new M5 sound system doesn't give you much control over the echo timing. The control seems to range from louder and longer at the top end and softer and shorter at the bottom end. Nevertheless, you can achieve something that is better than what even a mid-priced aftermarket system can deliver.

Bottom line for me is this is a system I can now live with. It's by no means as accurate, either in terms of imaging, response, or extension as my old M5's system, but it can be quite enjoyable. I picked up a copy of Linda Eder's recent CD "It's No Secret Anymore" (Atlantic 83236-2), at a charity auction last weekend, and popped it in the changer for the drive home. She's was a big surprise and so was the sound in the M5. The real comparison, however, will come this weekend when I have tickets to hear her and Michael Feinstein live at the local concert hall. If history is any guide, I'll be back to the DSP for a post-concert adjustment...

Here's to good driving and good listening!
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