For some reason, the right and left channels are mixed for the front speaker channels. The rear signal is fine.

The Image Dynamics Q 450.4 amp has four input RCA jacks. I've made a cable that plugs into the X9331 connector with audio channels going to a 4 channel RCA cable, and the RCA cable connects to the Q 450.4. The other wires in the X9331 connector go to the half of the X9331 connector that connects to the HIFI amp.

Large Brown, Large White, Small Brown, and Brown/White are passed on to the HIFI amp. At least one of these is required, or the car wont start. I did notice that the ohm meter indicates the Small Brown and Large White are connected somewhere. No resistance between them. Don't recall about the others.


I know that the problem isn't with the Image Dynamics amp or speaker install because connecting the rear channel RCA plugs to the front channels on the Q 450.4 gives good channel separation.

Doesn't matter whether the front channel RCAs are plugged into the front or rear channels on the Q 450.4, they play both right and left channel signals in both right and left speakers. A test mp3 track that tests left, right, phase, and balance plays in both speakers. The out of phase test is barely audible.

Since the rear channel RCAs play correctly in eaither front or rear speakers, and the front channel RCAs play incorrectly in front or rear speakers, I assume the problem occurs before it gets to the Q 450.4 amp.

I've tested the cable from my X9331 plug to the RCA plugs with an ohm meter and it all seems to be correct. No polarity problems, no shorts from one channel to another.

I can't figure out what is going on. Anyone have any ideas about how to fix it?

 

My x9331 connector is completely disconnected and i have not problem starting the car so why you would have a problem with any of the above wires disconnected I have no idea as they are data lines and are not required unless you need a software upgrade to any part of the car.

Switch only the following pins around ad see if that clears teh problem.

Swap the location of the black violet - front left and the yellow black - front right. DO NOT move the front positive wires.

Try this and let me know what happens.

If this works and the channels are now separated (i.e. play only on one channel) but are backwards then you will need to swap these pins back and swap the positives.

As the signals are what are called balanced outputs the negatives are not connected together so if one of those is swapped (accidentally, or the positives are swapped accidentally) then this would cause your problem.

If you do not understand PM me.

 

The difference between our cars may have to do with my having the HIFI amp (after the X9331 connector) and your having the standard audio with no amp after the X9331 connector. It is a mystery to me why having the HIFI amp completely disconnected would prevent the car from starting, but it did.

I will give this a try. Does it matter that the negative on the input RCA jacks on the Q 450.4 amp are all connected? I checked this because of what k6rtm said about the Bass600 amp. I also check my home audio systems and found that this seems to be standard to all of them. I tested a Denon receiver, and a rather expensive Pre-processor from Outlaw Audio. They all had RCA input negatives connected.

 

Your situation is unusual. Others have completely disconnected their HiFi amp without an issue -- after all, that's how it was discovered that the amp had to be reconnected during software upgrades.

When you say that channels are reversed, were they correct while playing through the factory HiFi? The physical wiring upstream from X9331 should be the same for HiFi or not.

 

The wirinig up stream toward the head unit is the same for both the Hi-Fi and Non Hi-FI cars. That is why this is somewhat confusing. Although the headunit outputs depending on the type and design of the circuity can make a difference here even if the other end (amps) have common grounds for the inputs.

BTW Robin my car does have the HiFi system in it and I have the X9331 connector completely disconnected. so why yours will not start I am not sure.

 

Just verified it. Engine wont start if nothing connected to the amp. I did figure out that it isn't the Small Brown nor the Brwon/White. Car starts with just the Large Brown and Large white are passed to the amp. Didn't go further with testing to isolate whether both are required.

No joy. Swapping the front channel grounds made no difference.

It seems strange, but I just verified it.

Channels are not reversed. That could be easily remedied. They are merged. I have a test track where a man says "Left channel" on the left channel, then "Right channel" on the right channel. For the rear speakers it plays as it should. For the front speakers "Left channel" plays through both speakers, as does "Right channel".

If I plug the front input RCA plugs into the Q 450.4's rear inputs, then the merged signals play through the rear speakers. The rear speaker signals play correctly when connected to the front speakers. So, it isn't a problem with the Q 450.4 setup.

This is driving me crazy.

 

And I assume you have ruled out the disk itself as being he culprit? If you play this disk in other systems it works as it should? ONce i ruled that out as a possibilty..i would suspect the cable itself? Have you tried running 2 separate pairs of RCA cables?

 

Yes, plays fine through the rear speakers, and on my home theater system.

That would require making a new X9331 connector to RCA cable. As I said earlier, I checked the cable with an ohm meter and there were no shorts between wires. So, I don't see how the cable could be the cause.

 

Robin,

As switching the channel grounds did not work there is one last thing to try.

Take a speaker and find a way to hook it directly to the X9331 connector side that goes to the head unit. There is enough power out of the head unit to drive speakers as we know from the base system. Both the HiFi and the base system use the same head unit. And then play the CD. If there is a merge of the signals still then the problem is in the head unit itself.

Let us know how that comes out.

 

Started to rig something up to try this and realized that the spare speakers I have are 2 ohm. Doesn't the HU amp require 4 ohm?

 

Disconnected all the pass-through wires except the Large White. That was the only one required for the car to start. With the Large Brown disconnected, the front channels have proper separation.

 

Strange but interesting. I will have to look closer at the wiring diagrams as to what would cause this.

 

Robin--

I'm not sure from a quick read of this thread just what's going on. I'll re-read it when I have more time in a couple of days (have a musical to close out and strike tomorrow). I'm leaning toward what I think are shatzy's thoughts of a crossed line between channels.

One approach would be to put an oscilloscope on the pins while feeding the front end test signals...

--bob

 

Oh ya - you definitely need the large "weiss" (white) wire connected at X9331 - it runs directly to the starter. If you don't pass this signal through you are definitely not going anywhere. See below:

 

Thanks very much for the explanation and diagram. Running the starter motor signal though the connector for the audo channels seems very bizzar to me. Sort of like running the reproduction system through the same apparatus as waste disposal...

Can you tell me what these other wires are for--Small Brown, Brown/White, Large Brown Ground? I wouldn't want to disable DCS, air bags, or something like that.

Any idea why the Large Brown Ground would cause the front channels to get mixed?

Thanks again.

 

Bizarre to me too, and I'm an EE. I often shake my head at the mysteries of BMW wiring design. Be grateful they are at least reigned in by adhering to DIN standards - I shudder to think how confusing it would be otherwise.

Here is a complete listing of the contents of X9331. The "large brown" is the heater blower motor ground (again, who knows why it is here). The "small brown" appears to be very important and is the ground for many, many devices. I'm surprised that the car would work at all with this wire disconnected (I suspect there is another - possibly inadvertent - ground somewhere). Note that what you refer to as "brown/white" is shown as another small solid brown in the MINI WDS. Could be a change between model years.

There are no "data lines" on this connector (as referenced by Schatzy earlier in the thread).

I'll be honest in that I don't exactly understand what you did and didn't have connected when you were trying this. My suspicion is that you wound up connecting the front right and front left channels in series, without a common reference for either one. This resulted in each input getting the sum of the two channels. Difficult to explain without a picture.

 

This is very strange. The heater blower motor ground being connected caused the front audio channels to mix?

All I've done is take the audio channels and connect them to the four RCA inputs on the Q 450.4 amp. I ran my own wires from the amp to the speakers. The left front speaker wires from the amp go to the Image Dynamic X-over board in the armrest of the left door. The X-over has a pair of wires to the tweeter, and another pair to the woofer. The right door is wired in a similar way. Rear speakers are mounted on custom wooden shelves in the rear (rear seat delete of my own design). I've run wires directly from the amp to the rear speakers. Nothing is in series.

The amp turn on signal comes from an add-a-circuit on fuse location F31 5A 15 X11008 11 0.5 GN/RT AUC sensor. Could this have anything to do with it?

I've run a 4 gauge wire from the battery + to the amp, and a 4 gauge wire from the amp to a seatbelt bolt (not being used for a seatbelt) under where the rear seat used to be.

A Boss Bass600 powered subwoofer also gets power and ground from the 4 gauge wires. It gets its turn-on signal from the same wire as the Q 450.4 amp. The RCA imputs to the Bass600 were disconnected while troubleshooting this problem.

 

Executive Summary --

I'm seeing a lot of reports of wild things in Mini audio systems. I believe many of the problems people are experiencing are a side effect of the circuit topology Mini uses.

Accidentally swapping similar looking (yel/brn, yel/red for example) wires can lead to fascinating sonic effects! And it's particularly easy to do with old eyes and not too good lighting! Guess how I know this!

An important part of the test/repair cycle -- when you think you've found a problem, take that problem and think it forward -- does the problem you think you found produce the symptoms you're observing? If it does, you may have found the right one. If it doesn't, keep looking!

Circuit Topology - the Bridge Amp

Audio power amp designers are in a real pickle when it comes to cars. A "standard" single-ended power amplifier can only swing to half the supply voltage, and to do that over a wide frequency range, particularly at low frequencies, you need a big (electrically as well as physically) blocking capacitor between the power amp output and the speaker. On the good side, one side of the speaker is referenced to ground. Aside from the big cap, life is simple.

(Technically, with zero input, the output of the power amp is around Vcc/2. As the amplifier's input goes positive, the output approaches Vcc, and as the amplifier's input goes negative, the amplifier's output approaches 0. A blocking capacitor removes this Vcc/2 bias while allowing audio signals to pass through. The low frequency limit is a function of capacitor size and load resistance.)

A really common automotive design is to use two power amps in a bridge configuration. The inputs to the two power amps are driven by the same signal, with one important change -- the input to one of the amps is inverted. Each amplifier can still only swing half the supply voltage, but by connecting the speaker between the amplifiers, the combined voltage swing available approaches the supply voltage -- we can deliver twice the output voltage to the speaker and since p=e^2 * r, doubling e increases p by a factor of four! And that big output cap? We don't need it any more!

So in a bridge design, we add more silicon (cheap and small since it's in an integrated circuit), lose the output cap, and increase the power available to the speaker by a factor of four. The downside? You have to run two wires to each speaker, and none of them are grounded or can be grounded.

No wonder the bridge output topology is so widely used!

As an aside involving symptoms some folks are seeing, a higher-end manufacturer will design current sensing into the output stages, and if a power amp draws more than a preset amount of current, shut down that amplifier, or maybe all amplifiers in that integrated circuit package, or all the power amps in the radio. This protects the radio in the event a power amp output is shorted to ground, or power amp outputs are shorted together. More on this later.

As I said, bridge amps are a good thing in cars. Four times the power for the same voltage at an increase in silicon, and you lose the big output caps. Winner.

Additionally, since the output signal is essentially a differential signal (the + and - parts), not tied to ground, it's free from most electrical noise, particularly all the crud you get flowing in a vehicle's ground system.

This means you can use those same outputs to drive a 4 or 8 ohm speaker, or you can use them as differential drivers to drive the input of a larger power amp.

I'm pretty damn certain that's what Mini does.

Problems--

Robin (and others) have reported funky sounding audio, using terms such as "merged." I'll sweep all of them into the highly abstruse technical term "funky."

Was ist das, "funky?"

Let's look at those bridge outputs again. How would I get a "merged" signal across channels? How about by using the + signal from one side (left or right) and the - signal from the other side?

That's going to give me (more or less) L+R on the speaker, or going into the amplifier. I can get this, for example, by mixing up (switching) the yellow/brown and the yellow/red wires!

If I use the same (+ or -) leg from both sides to a speaker (or the amp), for example two + wires, I'm going to get the difference of right and left channels, which is going to sound pretty thin for most signal sources!

Aside -- the test disc I did (Robin, you have one), the first two tracks are from the Denon Audio Technical CD and are sonically not very impressive -- a dude saying "Right Channel" and "Left Channel" and for the second track "In Phase" and "Out of Phase." Those two tracks help uncover many sins!

Confession

When I did the channel swap on another Mini owner's car on Saturday, I came damn close to mixing up two wires (don't remember which). Double checked all of them, swapping a pair. And yes, I did have my glasses on at the time, and we had a nice bright sunny day (such is late November on the Left Coast).

Once I had the connector restuffed, we played those first two tracks and I listened very carefully! Sound should be all or nothing from each speaker during the channel (R, L) check. Sound should go between full and thin on the phase check.

Miswiring will do things such as spreading the (R,L) channel check across both channels. Phasing may also be messed up. Things may not sound the same between front and rear speakers -- since this is a simple male voice, it should sound more or less the same in both front and rear speakers.

Using the Low-Level Inputs on the Bass600...

Contemplate with me for a moment on the topology of a protected bridge amplifier once more...

Now let's take that bridge amp and tie the "-" outputs of the left and right channels together.

With a lot of "real" music, a lot of the information is the same in both channels. so those tied-together "-" outputs are going to more or less swing together, and the output protection circuitry isn't going to care.

It's only when we have a LOUD signal that's DOMINANT in one channel or the other that one of those "-" outputs heads for zero while the other one (the quiet channel) wants to stay at Vcc/2, and the protection circuitry complains, shutting things down.

I suggest this is exactly what happens when you use the low level (RCA) inputs on the Bass600. The negative signals get shorted out at the Bass600 RCA inputs. But the radio's self-protection circuitry doesn't complain unless and until you get something that's both loud and single channel dominant. When that happens, the radio goes quiet and sulks until you power cycle it.

Respectfully submitted--

Bob

 

Checked the wires on the HU side of the X9331 connector and all were in the correct locations.

Reconnected all four pass-through wires (browns and white).

Moved the Add-A-Circuit tap from: F31 5A 15 X11008 11 0.5 GN/RT AUC sensor
to: F30 5A 15 X11001 6 0.5 GN/WS Park distance control (PDC)

All seems good now. Channels are separate, phase is correct. PDC still works.

There seemed to be some strange interaction between the Auto Climate Control system and audio when the AUC sensor fuse was used as the source for the amp on signal.

Update: The PDC alert beeps are not playing thought the correct speakers, they should be coming from the right or lelft rear speakers, depending on where the object is. However, I'm hearing some beeps through the front left speaker. At some point, I'll try using the cig lighter circuit for amp on.

 

Hey guys, I just got a Boss Bass600 in the mail. Which signal wires do I want to use for the subwoofer's input signal?

 

There are two ways to go about it:
the first is described in great detail all over these forums, and thats to jump into the wires at the X9331 connector by either tapping in to the wires directly or by building a harness and plugging it in (see here: https://www.northamericanmotoring.co...te/1251552553).

The way that I did it was to jump into the wires at the stock amp (if you have the HiFi system).
I have the pinout and diagrams of how I tapped into the wiring at the amp itself.
As a matter of fact I guess I should post pics of my Infinity Basslink install...