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You may well be right about the influence of German manufacturers and developments in this ‘ICE control’ domain, Marty, most notably Bosch in particular with I/K-Bus over a range of different vehicles:

http://ibus.stuge.se/IBus_Compatible_Cars

There is also a whole web. group dedicated to cracking/hacking/deciphering the I-bus, to interpret/use all those various bursts of data communications between modules on the bus and over a wide range of applications…. just google 'NavCoder'.. [So, in theory you could indeed then also use the LR HK DSP amp. on another (compatible) HU/rig for example - or vice-versa ?]

For anyone wondering about it I-Bus an K-Bus are essentially identical.

Incidentally, and still on the German theme, that rather misleading information from WIKI about the (blue) HU CD-changer connector designations was apparently oriented towards VAG, and particularly VW ICE, and I have now made a note to that effect on the relevant WIKI page…..
 

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.......As a response to the poster about the DSP info... (garvin I think - I'm on my phone so don't have previous posts to scroll back to whilst typing a reply!). I believe the DSP control line on the Alpine units controls EVERYTHING about the audio output... DSP setting, volume, front/back fade, L/R balance, Subwoofer level etc...
Thanks Marty - this makes more sense than having a bus for just three discrete settings. I rather like the HK DSP set up so I'll have to keep the existing HU in any upgrade just for the bus control!
 

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Hi Marty,

Did you find a solution to bypass the DSP amp? I have a car that is on it's third DSP amp.
Time for a solution.

Thanks

Florent
 

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Discussion Starter #44
Hi Florent,

I had a case of missing DSP amp syndrome when I bought the car - the stereo didn't work, and upon investigation, found that to be the reason...

I have wired in an aftermarket head unit, which uses the amplified outputs from the head unit to drive the door speakers. I've also build a 4 channel passive crossover, which crosses over about 650Hz, so the bass speakers don't get any of the HF, and the mid/hi's done get LF - seems to work ok... goes plenty loud enough!!

I have pictures of the crossover unit I built, and bought a connector, which I wired into the speaker lines on the car, so it's unpluggable, should the need arise.

I also ran a couple of extra cables from the radio to the boot, for the Rear L/R audio outputs from head unit - as the DSP system only uses the Front L/R signal lines, and I actually got some of the ISO pins for the connector block in the car, and wired the Rear L/R into that, so once again - plug and play to an aftermarket ISO connector.

http://www.rangerovers.net/forum/7-range-rover-mark-ii-p38/39332-2001-p38-stereo-qs.html

That's the link to the thread I had on my stereo issues, and the story that evolved... It also has a couple of pictures of the crossover/connector which is now in the area where the DSP amp used to lurk...

I'm still planning of using the factory subwoofer/amp - but have a whine on my signal line - which I think it originating from the head unit (probably because it's cheap and made in china...) but so far, everything else other than steering wheel controls work (which I'm planning on getting a PAC SWI-JACK at some point to get them going)

I'll need to have the dash apart again to put a GPS antenna in, and can take any extra pictures of you want!

Hope this helps!

Cheers,
Marty
 

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First of all, well done to Marty for documenting this. I could have done with his help last year when I replaced the stereo in my P38 - it would have saved me a lot of time. There is very little (if anything at all) wrong with his documentation that I can see.

I replaced my DSP amp and stereo with a 4 channel class AB and a Blaupunkt DAB stereo with a separate USB/bluetooth interface. The Sub is internally amplified, so I connected it to the sub line out on the stereo. This gave good results on the premium HK speakers, so I left them alone. The only things that don't work are the wheel controls and the satnav audio.

I have made an interface for the Blaupunkt stereo and Jaguar wheel controls using a micro controller and handful of passive components, and plan to make a second and adjust this for the Range Rover when I get a few minutes spare. There's a good chance it can be modified for other stereos too without too much trouble.

The main problem is the satnav audio. The mute wire works, and I know the unit makes noise because I can see the waveform on a scope and can record it on my laptop line in. However I can't get the audio to play on the stereo when I connect it to the Nav/Tel input. Clearly I'm doing something wrong, but I can't see it yet. Has anyone got it working yet?

Thanks
 

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Discussion Starter #46
Hi dnb,

Thank for that! Glad it's been helpful for you.

I'm on my phone at the moment, so typing is a pain! But.. does your nav/tel system expect a line level signal, or a direct speaker output?
The navigation unit output is actually amplified - driven by a 8ohm, 1w amplifier. So if you put it into a system expecting a lower signal level, then it will probably do nothing..

I thought it wasn't amplified, so put it through an amp and to a speaker, and got nothing. Connected it straight to speaker (after researching and finding out that it was amplified) and worked fine...

May not be of any use... But maybe you need to drop the nav output level to a line level signal?

Hope this is of use...

Cheers,
Marty
 

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Thanks. I worked it out tonight - the USB/blutooth thingy doesn't like to share the tel input with the satnav. If it is disconnected then the satnav speaks to the stereo nicely. I think I need to come up with a solution involving an analog mux IC to switch the inputs according to the satnav mute signal state integrated with the microcontroller for the wheel controls. How hard can it be? ;-)
 

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Discussion Starter #48
Ah - hah... That's always useful to know!
If you manage to build something to get the steering wheel controls to.work, then let me know... I haven't got.to that bit yet, but think a PAC audio SWI-Jack is the bit of kit to use... The autoleads piece of cr*p I got was just a waste of money, mainly as their tech support was unresponsive in trying to help me get it working!

Hope you get the system sorted how you want it!

Out of interest, what unit are you using for the nav audio integration?

Cheers,
Marty
 

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I have already got something to make the wheel controls work. It turns out that the Jag controls and Range Rover controls are similar in that they are resistive ladders. I had to change the constants in my microcontroller and it works. However the unit suffers from the same problem as the Satnav audio - the USB/Bluetooth thingy is fighting it...

My system is based on a Blaupunkt Woodstock DAB54. It has a satnav/tel mono input with radio mute, and an input for a Blaupunkt remote. These are shared (very reluctantly) by the external USB/bluetooth device I use for mass storage for some features, hence the need for an additional interface module.

I reverse engineered the Blaupunkt remote signals and found it was quite easy to make the car to stereo interface - an A to D to sample the button presses and then a timer unit to control sending pulses of set length to the stereo. I will need to extend the interface to have an analog switch (something like a DG403DJ-E3) to cope with switching between the Bluetooth phone and satnav audio feeds. I just hope the remote input is a "wired or" type arrangement. It would seem that most of the problems left now are of my making...

I too didn't like the Autoleads solution. It seemed like I had to buy loads of bits and then not have anywhere to put them, plus it was an awful lot of cash for something I could do in a £1.59 bit of silicon. Do you know what your stereo requires for a remote?
 

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Discussion Starter #50
Hi dnb

I'm not sure what the exact values I require for the stereo are, but its a JVC KD-R432 unit, with the one wire control. I'm not sure if that helps!

I'll have a look when I get back home and see if i can find out any information on what it expects to see... the A to D idea sounds good, and is effectively what the autoleads unit tries to do, but it's not very user friendly, or customisable! I wouldn't have a clue how to build a unit if i did find the values, would you be willing to lend some expertise?

Cheers,

Marty
 

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Wow what a find. I have a p38 2002 that someone has tried to fit a Halfords radio to and hacked the wiring about. I have been trying to do exactly what you have done but from the RAV diagrams. Gee they sure make things complex!
Now I'll try to sort the mess but with your tables it will be much easier. Many thanks
Ken
 

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Marty

Thanks so much for this pdf. I'm restoring the stereo in my 2000 Vogue and this diagram will no doubt be invaluable.

Greetings from Melbourne Australia.
 

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Discussion Starter #53
Thanks! I'm glad it's still helping other owners all these years later!!
 

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Recently found an interesting idea for steering controls using an LM3914 or LM3915 LED driver chip. Needs to be the linear version, and cannot remember which is which !!

Will hunt out the details, but the concept was to simply use the LR steering resistive ladder to serve as Input Voltage to the LM3914. This would then trigger specific LED outputs in Bar or Dot mode. Replacing the LEDs with a 2nd resistive ladder to match the stereo remote input requirements. The chip outputs are simply open collector drivers, so effectively short each point in the output resistive chain to 0V.

There are some multi-comparator style versions out there, but the LM3914 simply does it all in one.

BTW, I also found the Resistance & Voltage from the steering wheel seems to vary depending whether the ignition is on or off. I suspect this is actually differences between the Radio & Steering earth points, or just a bad earth behind the dash.

{UPDATE} . . . here's the link http://www.electro-tech-online.com/threads/hacking-steering-wheel-controls-to-radio.140501/page-2
 

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Discussion Starter #55
Very interesting...

Another possible line of enquiry - if you have a head unit which accepts a wired remote input, is to make an adapter to feed into that, unlike the forum post where he was talking about trying to use the chip to manually 'press' the buttons (though there's no reason that shouldn't work either).

I was talking to another member on there - codecruncher - awhile ago and he was mentioning that the control protocol from most head units on the steering wheel control line are a wired version of an IR code if you were using a wireless remote (granted no every head unit has an IR remote - but I guess that input on ones which don't is connected to the Steering Wheel Control wire in the ISO loom (if present).

Also, apparently a fair number (again, thanks codecruncher for the info!) of head units use the Kenwood (I think) IR control codes, which are available online. With that in mind, it should in theory be fairly easy to program a microcontroller to read the input from the P38 steering wheel control line (with the resistor ladder) and filter out what button has been pressed and then match the to the correct IR code, and then transmit that on an output wire to the head unit for control.

I haven't tried it myself, as I am using a pre-built solution - but the idea is interesting... As is the one you've mentioned which would be especially useful if a stereo didn't have a SWC input line that expects to see IR codes transmitted to it!
 

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Would just like to say your hard work in producing such a detailed wiring document is very much appreciated and has made my fault finding nightmare alot more bearable. Thank you
 

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Discussion Starter #57
No problem! I'm glad it is still helping other owners out!

Marty
 

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Orangebean has just pointed me at this thread to answer a question I had so thanks for all the effort. I'm still a little confused though. If, as I and others suspect, the DSP does all the tone, balance, fade etc (it has to do the fade because there are only two audio input channels used), why does it have separate analogue inputs for the subwoofer? As I said in my post, it seems to use a significant number of op-amps and a DA converter to modify the gain / frequency response of the inputs to the power amps and has a similar design driving the sub output - but no power amp of course. I have no output to the sub amp so I will check whats on pins 1 &4 of C0921 tomorrow
 

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Discussion Starter #59
I'm not sure why they went with a separate output for the subwoofer, rather than deriving it from the left/right feeds already implemented.
It could be that it is a 'mono sum' of Left/Right, being as the subwoofer is just a mono unit, and I'm not sure if the head unit filters the bass frequencies on the sub output internally, or whether it is a full-range output, and the filtering is done in the DSP amp/subwoofer amp..

I'll be interested to see what you find out though...

Marty
 

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I think I understand how it all works now. It seems that the Alpine head unit was originally designed to work with a conventional amplifier - as used on the Discos and BMW E46s. It has five outputs Front Left, Front Right, Rear Left, Rear Right and subwoofer.

On Discos and BMWs the four head output channels go to the power amp and each amp channel has two power amps - Bass and Mid Range plus tweeter - giving eight output channels. I'm pretty certain the subwoofer output from the head unit is simply connected straight from the sub input to the sub output pins on the power amp i.e. there is no amplification / frequency control in the power amp. the sub amp is, in effect driven direct from the head unit. (I've tried connecting the sub output from the head straight to the sub amp and it works fine). I believe the power amp and the sub amp have a fixed gain so the head unit controls the volume to both the door speakers and the sub.

The DSP amp does things a bit differently. It only uses the front two head output channels, each of which goes to a DSP that then generates the front and rear outputs for each channel. This allows the DSPs to modify the spatial content of the output channels to give the DSP effects. One of the DSPs also generates the (mono) sub output via a D/A converter. So the rear output channels and the sub output from the head are not used in the DSP setup.

Where it gets a bit confusing is the gain control. I have proved that the head unit output is varied by the volume knob (by connecting one output channel of the head unit directly into the sub) but I (and others) have connected an aux input directly into the power amp inputs. The head unit still controls the volume when using this input so the head unit must be controlling the power amp gain as well.

I've heard of people using Disco / E46 amps to replace the DSP amp (much cheaper on eBay) but reporting that only the font speakers and the sub work. That experience fits with my description above but it should be possible to get the rear speakers working by connecting the rear outputs from the head unit to the appropriate inputs on the power amp (bit of pain to wire though). The drawback of this setup would be that providing an Aux input would be much harder - using the CD changer might be the best bet.
 
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