**INFO** P38 Alpine/DSP Amp Connections and wiring - Page 4
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Thread: **INFO** P38 Alpine/DSP Amp Connections and wiring

  1. #46
    LEGACY VENDOR marty_nz's Avatar
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    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
    ------------------------------------------------
    '01 4.6 Vogue Black/Lightstone "Snog" -- Bought Jan 2012
    '99 4.6 HSE Cobar Blue/Lightstone -- Sold March 2009
    '95 4.6 HSE Epsom Green/Tan -- Traded June 2008
    http://p38webshop.co.uk

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  3. #47
    dnb
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    Re: **INFO** P38 Alpine/DSP Amp Connections and wiring

    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?

  4. #48
    LEGACY VENDOR marty_nz's Avatar
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    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
    ------------------------------------------------
    '01 4.6 Vogue Black/Lightstone "Snog" -- Bought Jan 2012
    '99 4.6 HSE Cobar Blue/Lightstone -- Sold March 2009
    '95 4.6 HSE Epsom Green/Tan -- Traded June 2008
    http://p38webshop.co.uk

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  6. #49
    dnb
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    Re: **INFO** P38 Alpine/DSP Amp Connections and wiring

    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?

  7. #50
    LEGACY VENDOR marty_nz's Avatar
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    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
    ------------------------------------------------
    '01 4.6 Vogue Black/Lightstone "Snog" -- Bought Jan 2012
    '99 4.6 HSE Cobar Blue/Lightstone -- Sold March 2009
    '95 4.6 HSE Epsom Green/Tan -- Traded June 2008
    http://p38webshop.co.uk

  8. #51
    NEWBIE
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    Re: **INFO** P38 Alpine/DSP Amp Connections and wiring

    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

  9. #52
    FRESHMAN ROVER Atticus's Avatar
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    Re: **INFO** P38 Alpine/DSP Amp Connections and wiring

    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.

  10. #53
    LEGACY VENDOR marty_nz's Avatar
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    Re: **INFO** P38 Alpine/DSP Amp Connections and wiring

    Thanks! I'm glad it's still helping other owners all these years later!!
    ------------------------------------------------
    '01 4.6 Vogue Black/Lightstone "Snog" -- Bought Jan 2012
    '99 4.6 HSE Cobar Blue/Lightstone -- Sold March 2009
    '95 4.6 HSE Epsom Green/Tan -- Traded June 2008
    http://p38webshop.co.uk

  11. #54
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    Re: **INFO** P38 Alpine/DSP Amp Connections and wiring

    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/t....140501/page-2

  12. #55
    LEGACY VENDOR marty_nz's Avatar
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    Re: **INFO** P38 Alpine/DSP Amp Connections and wiring

    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!
    ------------------------------------------------
    '01 4.6 Vogue Black/Lightstone "Snog" -- Bought Jan 2012
    '99 4.6 HSE Cobar Blue/Lightstone -- Sold March 2009
    '95 4.6 HSE Epsom Green/Tan -- Traded June 2008
    http://p38webshop.co.uk

  13. #56
    FRESHMAN ROVER
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    Re: **INFO** P38 Alpine/DSP Amp Connections and wiring

    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

  14. #57
    LEGACY VENDOR marty_nz's Avatar
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    Re: **INFO** P38 Alpine/DSP Amp Connections and wiring

    No problem! I'm glad it is still helping other owners out!

    Marty
    ------------------------------------------------
    '01 4.6 Vogue Black/Lightstone "Snog" -- Bought Jan 2012
    '99 4.6 HSE Cobar Blue/Lightstone -- Sold March 2009
    '95 4.6 HSE Epsom Green/Tan -- Traded June 2008
    http://p38webshop.co.uk

  15. #58
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    Re: **INFO** P38 Alpine/DSP Amp Connections and wiring

    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

  16. #59
    LEGACY VENDOR marty_nz's Avatar
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    Re: **INFO** P38 Alpine/DSP Amp Connections and wiring

    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
    ------------------------------------------------
    '01 4.6 Vogue Black/Lightstone "Snog" -- Bought Jan 2012
    '99 4.6 HSE Cobar Blue/Lightstone -- Sold March 2009
    '95 4.6 HSE Epsom Green/Tan -- Traded June 2008
    http://p38webshop.co.uk

  17. #60
    FRESHMAN ROVER
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    Re: **INFO** P38 Alpine/DSP Amp Connections and wiring

    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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