Home Forums Articles How To's FAQ Register
Go Back   Xoutpost.com > Electronics > Mobile Electronics Forum
Arnott
User Name
Password
Member List Premier Membership Search Today's Posts Mark Forums Read

Xoutpost server transfer and maintenance is occurring....
Xoutpost is currently undergoing a planned server migration.... stay tuned for new developments.... sincerely, the management


Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 07-31-2005, 02:09 AM
Vendor
 
Join Date: Jul 2005
Location: Portland OR
Posts: 499
el_duderino is on a distinguished road
In-depth analysis of 2005 X5 "DSP" Nav audio system

Hi there. My name's Ken, and I own a car audio shop in Portland, Oregon (avincar auto sound, we're at www.avincar.com ). A forum member just had us upgrade his X5 audio system. I'll let him tell you about the factory system and his experience of our upgrade to it (hopefully that's all positive, but I hope that if anything comes up, he tells you and us: )

This post is intended to tell you about how the OEM audio system works, and what's complicated about it, and how we worked with it. THIS IS NOT A DIY POST. One, I didn't do the wiring personally (our installation manager did) and can't tell you wire colors anyway. Two, I know there's a lot of variation from system type to system type, so I might not describe the car you're working with anyway. Three, I do this for a living, and while I don't mind helping as much as I can over the internet (I advise many people on an Acura forum about A/V questions), this is a very complicated process, and - no offense meant - I frankly don't want to take reponsibility for your results.

OEM system basics


So first off, this system is a Nav system with a changer and Sirius, and there is a menu line for "DSP". HOWEVER, there is no digital cable out of the changer. Apparently that means that it's some sort of "quasi" DSP system.

The signal that comes out of the HU to the OEM amp is two-channel, and fixed in level. That means that when we manipulate the Volume, Fader, and Balance controls, nothing changes on this signal. Apparently there are also data lines from the HU to the amp, and these control the tone controls inside the amp. (We did not test these preamp signal wires for frequency response, nor did we test to see if the seven-band EQ in the HU affected the signal on these wires. More on this later.)

The amplifier has either twelve or fourteen channels of output. That's right - fourteen.

Front tweets in the mirror sails (2). Front mids in the front top of the dash (2). Front mid-bass in the doors (2). Rear mids in the rear doors (2). Rear midbass in the rear doors (2). And two dual-voice coil "subs" in the right rear corner (2 or 4 - didn't take the amp apart to find out).

Frequency distribution and equalization

The front tweeters play from 5000 Hz and up. There is a slight amount of EQ "bump" at about 16K, but not a lot.

The front mids play from 5K down to 800 Hz. They have a slight EQ bump at about 1K.

The front midbass play from 800 Hz down to about 80 Hz. Lot of midbass EQ boost.

The rear midrange plays from 5K down to 800. The rear midbass plays from 400 to around 50 (it *seemed* to play lower than the front midbass according to our analyzer, an NT Instruments Acoustilyzer). There is a one-octave hole from 400 to 800, and since there are no rear tweeters, there is no significant output above 5K in the rear doors.

The subs play from 80 and down. While there doesn't seem to be much in the way of obvious subsonic filtering, there does seem to be an EQ "bump" around 65.

Design flaws

The audio system bears all the marks of having been designed by a committee of electrical engineers - in that it's a very complex and highly engineered train wreck : ) The speakers look expensively made (although in Hungary, not Germany) and the amp must have cost a small fortune. However, sound quality was horrid in both my opinion and the customer's.

The 6" midbass in the doors have a mechanical resonant frequency of 50 Hz. This allows them to play pretty low - in the front doors, lower than they are allowed to play.

The "subs, on the other hand, are not only trying to play through 3mm of ABS panel and 20mm of felt noise-padding (as has been pointed out here by many, many posters) - they also have a mechanical resonant frequency of 80 Hz! They mechanically start rolling off at 12dB/octave AT THE LOWPASS CROSSOVER FREQUENCY! (Translation - weak and thin bass.) The woofers look well made, but poorly designed for this application.

All the speaker voice coils are 8 Ohm impedance (nominal, measured with an impedance meter, not an ohmmeter). Why use 8 Ohm speakers in a 12V electrical system in this design is beyond me. It means you have 1/2 as many watts with the same electrical parts in the amplifier. If you upgraded the speakers to 4 ohm, you *should* get twice the power - IF you can figure out what speakers to use.

Upgrade issues

Well, the first issue is that VERY few manufacturers, if any, make speakers that correspond to the OEM speakers in size and function. 2" cone mids are almost unheard of (at least by me). If you wanted to bolt in new speakers and have them play off of the OEM amplifier, you would have a tough time covering all the frequencies. This is why some of the posters here have put in new tweeters and new midbass, but have continued to use the OEM midranges.

The second issue is that the signal to the rear doors is NOT full-range - it has two huge holes in it (400-800 Hz, and 5kHz and up).

The third is that the "preamp" balanced signal from the HU to the OEM amp does not change with volume - it's more like the output on the back of a home CD player than it is the output of an aftermarket car CD player. So you can't run this signal straight into an aftermarket amp.

Also, there ain't much room for amps.

Options

Well, the first option I'm going to mention is a JL Audio Clean Sweep - tap it into the fixed line out from the HU to the OEM amp. This has pluses and minuses. A plus is simplicity (compared to what we did below). A minus is that your fader and your steering wheel volume controls are all useless afterwards, and I believe that your OEM 7-band EQ is as well (but I did not verify this). If you are working with a shop that's not too good with theory, this might not be a bad choice (if you can stand losing all that functionality) because the second option may kick their butts.

The second option is to take the various channels of output and run them into certain high-voltage Line Output Converters and then sum their outputs together to get a full-range response (as SIM did with janix). We did this. This approach has pluses and minuses too.

The pluses include retaining the OEM EQ and the steering wheel controls (but probably not the fader). The minuses include requiring some skilled troubleshooting of RPM-associated "alternator whine", addressing the resulting frequency response curve (which looks like the roller coaster at Coney Island, and NOT just because of the BMW equalization, no matter what anyone says), and probably purposely losing the OEM fader.

Why lose the fader? Because IF you go with rear speakers (some of us believe that rear speakers are a Commie plot, but many of you will ignore me on that one), then the OEM amp's output to the rear speakers is unsuitable - it has those two huge holes in it. Any speaker connected to those output signals would suffer from the same problem. Garbage in, garbage out.

So our approach to this car is to interface with the outputs of the OEM amp, re-combine the audio signals so that we can use midrange-tweeter components instead of the three-way setup that BMW uses, then address the frequency response issues with a parametric EQ, and THEN install new amps and speakers (and we take the front output and split it to both front and rear, and put a fader knob in the ashtray).

The OEM graphic EQ in the HU just doesn't give us enough flexibility to correct the response, which is screwed up when you "sum" the signals back together. In the stopbands of the outputs of the crossover, the signals are out of phase with each other to some degree, and the result is dips and peaks in the response around the crossover points that do not correspond to the predicted response from looking at individual response curves. We also use the EQ as a line driver because the LOC outputs aren't as strong as we'd like, and we don't want to gain up the amps in order to avoid noise (a bugaboo which we finally have eliminated with this car (knock on wood)).

So what we did was put silk-dome tweets with a low resonant frequency in the OEM midrange dash locations, kill the mirror-sail tweets, and install 6.5 mids in the midbass spots. Since the tweets play down to 2500 Hz with authority (and play more in the stopband of the passive crossover), the vocalist is firmly and solidly elevated into the windshield. With metal-dome or harder dome tweeters, which are crossed over an octave higher (usually 4500), this effect is lost. I want a good strong center-forward image over metal-dome tinkliness everytime. We then put a 10 in the back corner and some amps under the load floor (kept the spare, no visual mods).

Anyway, I hope this made sense - my apologies if it doesn't - and I hope that I can answer anybody's questions, which I also hope you feel free to ask. Use the e-mail feature - I probably won't check PM's too often.

Regards,

Ken
Reply With Quote

Sponsored Links

  #2  
Old 07-31-2005, 12:39 PM
SPAMMER
 
Join Date: Jun 2005
Posts: 135
vendettabmw is on a distinguished road
good review..i have an 03 x5 4.6 w/dsp,nav audiopjile system...in my cabrio i sprnd a good 20k on my stereo and i LOVE the x5 stereo! I'mm adding the dension ice-link as i have a changer and want the songs on the obc, but other tyhan that its loud enough, and sounds great..the bass couold be a touch louder, but i'm used to 2 13w6's w/ a jl 1000/1 in a e46 cdabrio.....so its not bad

overall i love it and considering the $ it would take to make it a TINY bit better, IMO its not worth it.

i'm now selling the cabrio as i love the x5 and keeping system stock...bmw has already pimped out the 4.6is IMO.
Reply With Quote
  #3  
Old 07-31-2005, 02:23 PM
Chris F.'s Avatar
Member
 
Join Date: Mar 2005
Location: Northeast
Posts: 1,618
Chris F. is on a distinguished road
Great writeup Ken. Why on earth manufacturers do this is beyond me. How are other brands -- MB, Audi, Lexus, Acura, Volvo, etc? Are they that bad too?

I was really surprised that the rear speakers have such 'holes' in the frequency response and don't even play full range! I though it was a two way system back there -- apparently there are no tweeters.

I have the regular (Non DSP) stereo in my X5 and my shop did the same thing you guys did for a subwoofer -- they just tapped into the low frequency wires with a high to low level converter. We added a Alpine 4313 to adjust the bass and all is well...

Have you guys had a chance to play with the new Logic 7 systems yet? I'm not sure I want to even touch that one, I heard they are using fiber optics and an interface similar to Firewire now? Yeesh....

Chris
Reply With Quote
  #4  
Old 07-31-2005, 04:31 PM
Vendor
 
Join Date: Jul 2005
Location: Portland OR
Posts: 499
el_duderino is on a distinguished road
Quote:
Originally Posted by vendettabmw
good review..i have an 03 x5 4.6 w/dsp,nav audiopjile system...in my cabrio i sprnd a good 20k on my stereo and i LOVE the x5 stereo! I'mm adding the dension ice-link as i have a changer and want the songs on the obc, but other tyhan that its loud enough, and sounds great..the bass couold be a touch louder, but i'm used to 2 13w6's w/ a jl 1000/1 in a e46 cdabrio.....so its not bad

overall i love it and considering the $ it would take to make it a TINY bit better, IMO its not worth it.

i'm now selling the cabrio as i love the x5 and keeping system stock...bmw has already pimped out the 4.6is IMO.
I mean no offense, but you must have a different stereo than this one, or when you were a kid you sat next to same steam whistle that Amar Bose did. This OEM system was horrible.
Reply With Quote
  #5  
Old 07-31-2005, 04:36 PM
Vendor
 
Join Date: Jul 2005
Location: Portland OR
Posts: 499
el_duderino is on a distinguished road
Quote:
Originally Posted by Chris F.
Great writeup Ken. Why on earth manufacturers do this is beyond me. How are other brands -- MB, Audi, Lexus, Acura, Volvo, etc? Are they that bad too?

I was really surprised that the rear speakers have such 'holes' in the frequency response and don't even play full range! I though it was a two way system back there -- apparently there are no tweeters.

I have the regular (Non DSP) stereo in my X5 and my shop did the same thing you guys did for a subwoofer -- they just tapped into the low frequency wires with a high to low level converter. We added a Alpine 4313 to adjust the bass and all is well...

Have you guys had a chance to play with the new Logic 7 systems yet? I'm not sure I want to even touch that one, I heard they are using fiber optics and an interface similar to Firewire now? Yeesh....

Chris
Thanks for the kind words.

Optical MOST buses are becoming very popular. The aftermarket is working on the MOST protocol to make a MOST gateway to allow inputs and outputs, but none have arrived yet. Mercedes and Volvo are two who use the optical - Mercedes on everything, and Volvo on at least the XC90. You address these the same way we did the X5 system.

I haven't played with the Logic 7 systems yet but I believe the innovation is all in the UI - the output side is about the same as the X5 we did, I suspect. Only so many ways to push around a moving coil, after all : )

In one way I respect what BMW did with the rear speakers - almost. Rear speakers don't help sound quality. Rear vocals and highs confuse the stereo image - but many people want them anyway. What they SHOULD have done IMO is programmed the DPS to essentially do the same thing, but include full-range drivers, and then it's a selectable feature.
Reply With Quote
  #6  
Old 07-31-2005, 08:32 PM
X5 Sport's Avatar
Member
 
Join Date: Apr 2005
Location: London UK
Posts: 689
X5 Sport is on a distinguished road
Well I got lost after the first few lines,But thanks for trying to explain,what can i do to make my stock system better ? Would changing the speakers help?
Reply With Quote
  #7  
Old 08-01-2005, 12:12 AM
Vendor
 
Join Date: Jul 2005
Location: Portland OR
Posts: 499
el_duderino is on a distinguished road
No Reader's Digest version on this one, sorry. You kinda need to know why it's not simple, or you'll just ask "Why don't we do it the simple way?"

First step for you is to decide what flaws you notice the most, and what budget you'd dedicate towards addressing those flaws. Next is figuring out if you have a local shop that seems competent to respond to what you want changed.

Let's give the forum member who owns this 2005 X5 4.8 the chance to tell us about what he had us do... I may have already stolen too much of his thunder by talking about the OEM system ...
Reply With Quote
  #8  
Old 08-01-2005, 01:24 PM
Acezoned's Avatar
Member
 
Join Date: Jul 2005
Location: Hollywood, CA
Posts: 162
Acezoned is on a distinguished road
...and how much is all this?
__________________
Rockin' is my business and business is good!
2005 4.4 X5 Black/Black, the goods
Reply With Quote
  #9  
Old 08-01-2005, 06:24 PM
Vendor
 
Join Date: Jul 2005
Location: Portland OR
Posts: 499
el_duderino is on a distinguished road
You really have two cost components.

One is what it takes to get the OEM source units (Nav, CD/Tape, Bluetooth, AM/FM, Sirius, etc.) up to par with an aftermarket head unit as far as adding amps and speakers is concerned.

The other is what amps and speakers you get, and how you have them installed.

I'd say that you are looking at about $400 in parts to get to a full-range pre-amp signal, and then from $250 to $800 to add that optional EQ to get that signal as flat as possible from a frequency-response point of view.

For installation on that, I'd look at around $500 for the install and tuning, especially if you have a front-mounted fader to install (please note that earlier years may very well have rear signals without the "holes" in the response, which would eliminate the outboard fader but probably add another $150 in parts cost for those additional channels.

All that is just to get you to the point that you can get excellent-sounding speakers and amps and have them getting a good signal that they can use to sound the way they should. Obviously, if you are looking at doing an upgrade with entry-level gear, it's probably not going to pencil out.
Reply With Quote
  #10  
Old 08-02-2005, 12:38 AM
Member
 
Join Date: May 2005
Location: X5world
Posts: 128
silkster is on a distinguished road
analysis of audio system

I have an 01 X5 with DSP and Nav. I am plannning within the next month to do an upgrade similar to what janix did with the exception of a few things.
like going with the audio control LC6 which is a six channel LOC and plan on using Diamond S600s Hex as my components front and rear. in addition an Audio Control EQS six channel equalizer. For the subs I plan on Porting a single Jl audio 12w6v2 in the sub location and powering the system with the Phoenix Gold TI 500.4 and 800.1

I just wanna know if you have any recommendations or suggestions that i may wanna take into consideration.

Thanks
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On





All times are GMT -4. The time now is 01:06 AM.
vBulletin, Copyright 2020, Jelsoft Enterprises Ltd. SEO by vBSEO 3.6.0
2017 Xoutpost.com. All rights reserved. Xoutpost.com is a private enthusiast site not associated with BMW AG.
The BMW name, marks, M stripe logo, and Roundel logo as well as X3, X5 and X6 designations used in the pages of this Web Site are the property of BMW AG.
This web site is not sponsored or affiliated in any way with BMW AG or any of its subsidiaries.