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Audio/Navigation :: Front/Rear Channel Swap

Audio/Navigation :: Front/Rear Channel Swap

  #76  
Old 08-22-2008, 11:18 AM
xgarza
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Originally Posted by schatzy62 View Post
According to the wiring diagrams this is how the channels of the amps are wired

1. 40W - rear left woofer
2. 40W - rear right woofer
3. 25W - rear left tweeter
4. 25W - rear right tweeter
5. 25W - front left woofer
6. 25W - front right woofer
7. 25W - front left mid and tweeter
8. 25W - front right mid and tweeter

From doing some listening tests with a signal test disk (20 hz to 1000hz in 20hz increments) it seems the HiFi system has something else going on. This change my not affect the HiFI system as it does the standard system. There have also been reports that the HiFi system may also do volume shaping. I.E. at higher volumes it shapes the frequency response differently.

I will hopefully be doing some independent testing this weekend. look for results on Sunday sometime.

schatzy, this is the Harman Kardon system right? Hi-Fi system = HK system? Very interested and eager for your results. TIA

Regards,
Xavier
 
  #77  
Old 08-22-2008, 11:48 AM
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Originally Posted by xgarza View Post
schatzy, this is the Harman Kardon system right? Hi-Fi system = HK system? Very interested and eager for your results. TIA

Regards,
Xavier
No, he's talking about the HIFI system, which is only on the new R56 models. Your convertible (and mine) are still first-generation cars (R52, specifically).

The upgraded audio system in the first-gen cars (the Harman-Kardon option) is unrelated to the HIFI upgrade option in the second-gen cars, so none of this information about the wiring harness/connectors applies to us.

Fortunately, I don't believe the H/K system even has the rear channel low-frequency rolloff problem in the first place, so none of this channel-switching should even be necessary if you want to add an amplifier with speaker-level inputs to your car. Just tap into the rear speaker wires to feed the amp, and you should be fine.
 
  #78  
Old 08-22-2008, 08:01 PM
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k6rtm: You are awesome!!!!!

I just need to do this mod. I wish someone can help me in case I screw up badly.... Ive never done an speaker exchange or adding an amp myself... always paid someone to do it... and yes.. probably over paid.

So bottom line, with the F and R channel swap, can anyone give me links to website where I can get all the wires to extend to my JL 300.4 amp... and all the wires needed to powerup the amp and back to the speakers?

I still need to shop around for rear speakers as I have my BA SL65.. not great but works well for my ear.
 
  #79  
Old 08-23-2008, 11:40 AM
zach999
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I am currently in the process of doing this mod and I'm having some trouble getting the connectors out.
I bought a 5/32 brass tube from the hobby shop and I made a slit down the side in order to expand it to fit a #27 drill. This dosn't work at depressing all of the pins when inserted because the slot is too large and it doesn't cover/depress all of the pins.
I then tried to bore out the i.d. of the tube out. I was able to successfully remove one pin but it is super difficult to do and I haven't been able to get any others
anyone have any advice?
would a stainless steel tube work better because it would be stronger?
 
  #80  
Old 08-23-2008, 11:48 AM
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Zach--

the real bmw tool uses a piece of thin-wall stainless: 4.4mm od, 4mm id, 0.20 wall thickness (or thereabouts using my cheepie calipers).

One of the secrets to success (for us anyway) was making the slit in the tubing as thin as possible. Too wide a slit and particularly when you expand the thing to the needed diameter, you'll miss one of the 6 barbs on the connector.

If you don't mind paying $8 for an inch long piece of stainless, Mini got it for me in three days.

And we found working on the male pins far easier than the female ones. I struggled for quite a while on the female pins, popping two loose, and when I took a break, my son popped out all the male pins in short order.
 
  #81  
Old 08-23-2008, 01:17 PM
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Originally Posted by zach999 View Post
I bought a 5/32 brass tube from the hobby shop and I made a slit down the side in order to expand it to fit a #27 drill. This dosn't work at depressing all of the pins when inserted because the slot is too large and it doesn't cover/depress all of the pins.
k6rtm may have it -- the tube (and slit) may be a little TOO big now from opening it up with the drillbit ... try closing up the slit a little with a needlenose pliers and retrying -- and if you think it's a writeoff, cut off that inch of tube and try again. Another possibility: skip the drillbit step and try it with just the slit; it may be close to working without stretching the tube out.

I found that steady pressure with a 'twist-back-and-forth' motion to get it to slide up into the connector body (and past those barbs) worked best. Also, you may want to try holding the wire at the back of the pin you're working on (left hand) while pushing/twisting the tube (with the right hand); this may help you to get the tube-end up past the barbs (rather than see the pin rotating back and forth inside the body).
 
  #82  
Old 08-23-2008, 01:24 PM
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update: I was able to finish the mod using the bored out brass tube. I had used the other half of the tube and bored it out with the #27 bit.
The key turning point was when I found that the white connector was actually two pieces. I unclipped the top part of the male connector and it somehow made it easier for the clips to be released if that makes sense
 
  #83  
Old 08-23-2008, 02:22 PM
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COMPLETE sense. Glad you figured it out.
And welcome to the land of THUMPA-THUMPA!
(PS: updated the photo in my gallery to convey your method)
 

Last edited by basil49; 08-23-2008 at 02:32 PM.
  #84  
Old 08-23-2008, 02:56 PM
clnconcpts
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The only thing I've notice with the HiFi system is the bass isnt good on the 6".I feel just adding a cap to cut off low feqs would fix that.

By swapping speakers you loose your imagining.I prefer more of a frontal sound stage.
 
  #85  
Old 08-23-2008, 05:34 PM
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FYI: I just used one of my test CD's that has a 0dB level sine sweep from 20-20kHz and it's clear there is no high-pass on either the front or rear channels of my Hi-Fi system.

That means the front/rear channel swap is only for stock "boost" stereos and NOT Hi-Fi systems.
 
  #86  
Old 08-23-2008, 05:36 PM
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Well that puts me out. Thanks for the info
 
  #87  
Old 08-23-2008, 05:44 PM
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Originally Posted by TWISTER View Post
Well that puts me out. Thanks for the info
x2 Thanks ryephile
 
  #88  
Old 08-23-2008, 08:39 PM
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I drove up to Silicon Valley today and Bob (k6rtm) did some analysis on the signal for front and rear at the connector, and signal at the rear speakers. Hopefully, he will post graphs. Anyway, it seems to be bad news for HIFI owners. The pin swap doesn't help. Both front and back speaker signals are full range at the connector. Signal at the rear speakers is missing the deep bass before and after pin switch.

Here are a couple photos of the connectors:




 
  #89  
Old 08-23-2008, 09:08 PM
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Originally Posted by Robin Casady View Post
Anyway, it seems to be bad news for HIFI owners. The pin swap doesn't help. Both front and back speaker signals are full range at the connector. Signal at the rear speakers is missing the deep bass before and after pin switch.
So are you saying that with HiFi, the amp (instead of the headunit) is blocking low frequencies? Did you have a chance to test the HiFi amp's output?
 
  #90  
Old 08-23-2008, 09:44 PM
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Originally Posted by rkw View Post
So are you saying that with HiFi, the amp (instead of the headunit) is blocking low frequencies? Did you have a chance to test the HiFi amp's output?
Bob did the actual testing. Hopefully, he will post soon.

My understanding is that the low blocking is happening somewhere between the connector and the speakers. It could be in the amp.

Bob tested the amp output at rear speakers. He didn't test it at the front speakers. That would have required pulling more panels. We could hear that the front had more bass than the rear.

I guess that the good news is that if you wanted to add your own amp, the HIFI option gives you good signals front & rear at the connector. So, perhaps you could connect it there and not have to use a CleanSweep to straighten it out. Probably a good idea to leave the HIFI amp in place so the OBC still sees it and doesn't get grumpy about it missing.

Someone with more knowledge than me should comment on this.
 
  #91  
Old 08-24-2008, 12:47 AM
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Something is not making sense; if the non hi-fi head unit clips the rear, and if the head units are the same, then the head is the clipping source.

Has anyone done the swap in a hi-fi car and heard a difference? Seems odd that these would all be stock radios. Is everyone adding amps between the head unit and the amp then getting full range to both front and rear? I thought no one was pulling sub taps from the rear because they were clipped.

Some clarification would be nice because this is somethimg I would like to do.
 
  #92  
Old 08-24-2008, 05:28 AM
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I gotta ask a favor....

When all this is worked out, would someone PLEASE post a summary for those of us who are completely lost in this thread?? PLEASE!

I am an audio-idiot, so everytime I try to re-read this thread, my bean hurts.

Take your time. Make sure it works first. I am so afraid I'm gonna get all ambitious and rip up my car to do one of these mods and then read something like the last few posts: IT DOESN'T DO ANYTHING!

Thanks, all. And remember: take your time!
 
  #93  
Old 08-24-2008, 08:31 AM
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Originally Posted by mteahan View Post
Something is not making sense;
Yes, there are a few things that are puzzling. I forgot to mention that there was a February 2007 build R56 MCS Coupe there that Bob did not take apart (the car is on a lease) but did listen to a test CD in it. It had the HIFI and stock speakers. The impression was that it had bass in the rear. My R56 MCS was built in March 2007. The test CD did not produce bass in the rear in mine. My car has a NAV. I don't think the other MCS did, but I'm not sure.

if the non hi-fi head unit clips the rear, and if the head units are the same, then the head is the clipping source.
Do we know that they are the same?

Take a look at real OEM. I can't really make sense of this, but there seem to be two radio/CD units -- the "RADIO WAVE CD" and the "BOOST CD RADIO"

http://www.realoem.com/bmw/partgrp.d...31&hg=65&fg=05
 
  #94  
Old 08-24-2008, 08:39 AM
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Originally Posted by richs10 View Post
I gotta ask a favor....

When all this is worked out, would someone PLEASE post a summary for those of us who are completely lost in this thread?? PLEASE!
So far, I think it boils down to this: If you have the standard non-HIFI system then:
Originally Posted by k6rtm View Post
Swapping the front and rear channel connections at the X9331 connector makes a huge improvement in bass response.
If you have the HIFI system, the jury is still out. It may not be the same for all HIFI equipped cars. It looks like the clipping is done at the amp in the rear (after the X9331 connector) on my MCS, although it could be anywhere between the connector and the rear speakers.
 
  #95  
Old 08-24-2008, 09:01 AM
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For all HiFI owners following this thread.

I did some independant testing on the X9931 connector yesterday.

Results were that they X9931 Connector has full range for both front and back speakers. Th problem is that the Amp does some strange things with the sound including phase shifting. So IF, (i have not checked this yet as i need a better piece of test equipment) the front and rear channels are out of phase at a particular frequency. lets say 40HZ then there will be a great reduction in th sound volume at that frequency. This is not a good thing.

Unfortunately my scope only has two channels on it. This only allowed me to look at the input signal and one output signal at a time. What i found was that the 20 HZ signal for the right rear woofer was about 30 degrees out of phase to the input.

When i can get my hands on another scope and be able to look at the input and output of two channels simultaniously I will be able to check the phase variance between channels and see if that has anything to do with the poor bass response.

I also noticed a bout a 12dB spike from about 30 Hz to 70Hz compared to 2000 Hz.

So again for those watching this thread please stay tuned. There will be more information coming but if may take a few days to get it out here.
 
  #96  
Old 08-24-2008, 09:50 AM
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basil49: thanks for the credit in your gallery
just to be perfectly clear: I bored out the tube gradually by using the smaller drill bits and eventually ended up with the number 27 size. It gets a little hairy once you get up to size 29 and then 28 because you can see the tube deforming as you drill into it, ill have to grab a picture of my tube a little later.

I have the hi-fi system with the stock speakers, and I must admit that after I switched the F-R channels I didn't notice a huge change. I am not a true audiophyle so I cant comment on the quality of the sound but I just wasn't all that impressed after switching the channels.
 
  #97  
Old 08-24-2008, 10:32 AM
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Take your time, guys.
We will quietly sit here while you work it all out for us.

(In fact, I'm so sure of your talents, I'm transfering my 'deep bass' cds to my iPod now)

 
  #98  
Old 08-24-2008, 10:44 AM
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schatzy62: Is there any differences with the HiFi units from when you received your Mini and the current release(R56)?
I just picked up my Mini and have had one day to listen to the HiFi and it sounded good (Taken into the fact of less them 1 hour with it).
I connected my SKYFI3 to AUX and its good.
Time will tell on satisfaction. I am going to test using my CD's from Chesky and TELARC for CD/HeadUnit sound.
 
  #99  
Old 08-24-2008, 11:15 AM
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Originally Posted by mteahan View Post
Something is not making sense; if the non hi-fi head unit clips the rear, and if the head units are the same, then the head is the clipping source.
The headunits may very well be the same, but programmed for different output depending on standard or hi-fi speakers in the car (speaker level vs. line level outputs).
 
  #100  
Old 08-24-2008, 01:11 PM
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Originally Posted by Robin Casady View Post
Take a look at real OEM. I can't really make sense of this, but there seem to be two radio/CD units -- the "RADIO WAVE CD" and the "BOOST CD RADIO"
In the US, all headunits are the "Boost" model as standard. In other parts of the world, an even lower grade unit (if you can believe it) called "Wave" is offered on some models such as MINI One.
 

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