It says in my manual that there is speed dependent volume to compensate for road noise although never noticed this while driving - how smart is that! It doesnt say anything about overiding this feature though.

thanx, i thought it was a power fault, more expense!!
 
It would appear that the Clarion unit runs on the C-Bus system. At least that was the protocol that Clarion were using when the P38 was being made.

If ours are C-Bus then....

Pin 6 = Signal Ground
Pin7 = CD L Ch Input
Pin 8 - CD R Ch Input.

There is a picture of the C-Bus pinouts here...

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I found this from a Saab forum earlier, a guy has done a similar mod, and I'm just copying and pasting.....

"We are only concerned with pins 5,6,7,8 and 9.

This is what i did.

I bought a small box, a male 13 pin DIN connector (has 3 rows of 4 pins and 1 at the bottom as the 4th row,) some 6 core cable (you only need 5 core) an rca input mount (for left and right) and a switch. (I also bought a cable gland to stop any unwanted tugging on the cabel pulling out the solder joints)

Simply connect the switch across pins 5 and 9. (Upon closing the switch while the unit is running, it will automatically enter slave mode thinking a CD changer magazine has just become active, and therefore accept audio inputs from the CBUS socket instead)

Next connect your RIGHT auido RCA to PIN 8.

Connect your LEFT audio RCA to PIN 7

Connect GND of both RCA sockets together, and then solder this wire to PIN 6.

Seal up your box and plug in. Plug in your ipod, turn the ignition and flick the switch, the unit will enter (accs) mode on the screen, and you'll hear your music loud and crystal clear thru your factory setup."



Could be a good place to start. Especially if switching pin 5 and 9 causes the HU to switch to accessory mode and just amplify whatever is coming down pins 7 and 8. The only other thing I'd like to have would be a way of connecting up to the power and dropping the voltage to 5.5v so you can charge the ipod too.

If you check out the rangerovers.net link I posted up, you'll see a completely different pinout - not surprising, as most of the stereo kit fitted to P38s was made bespoke, with bespoke pinouts... real arse-chafe!

In addition, there doesnt appear to be a signal ground... it seems like the whole system runs on balanced inputs / outputs, hence its quality when set up right and given a decent input... AND the symptoms of buzz / interference if you try to connect any audio signal -ive to a 'common' ground! The guys who tried this at rangerovers.net also noted background buzz / interference - although they seemed to think it was at levels they could live with. I'm going to investigate a possible A-level solution for this... but I don't expect it to be straightforward... or cheap!!
 
Update to above... first website I went to gave me a possible solution to avoid or minimise the 'buzz' with an aux-in... need to confirm it by experiment on an actual system though...
 
I'm starting to feel like I work at Bletchley Park, and we've just been handed an Enigma Machine!
 
I'm starting to feel like I work at Bletchley Park, and we've just been handed an Enigma Machine!

You're not far wrong! The H /K system is a pain in the t*ts to deal with, but IMO it's worth it. I've been tinkering with car audio for years, and have had high-end systems in pretty much every car I've owned. This H/K setup is second to none - except perhaps Bose. The soundstage is simply incredible, and the way the amps are set up and wired in means if you give it a decent, balanced, impedance-matched input, there won't be a hint of noise, interference or distortion - at any volume. I can't think of ANYTHING, in the sub-£1000 bracket at least, that I'd want to replace those amps with.

The key here is the input. Sh*te in, sh*te out - and trust me, those stock HUs are sh*te. I was bad-mouthing the system, and all set to rip the lot out... until I replaced my HU with a decent aftermarket one. The difference just stunned me. I've also, however, replaced the stock sub with my own Rockford Fosgate unit and amp... I like my bass to shake the ground! The stock H /K sub is, however, more than adequate for the job for 99% of people.

Don't just take my word for it though - there are 2 other LZ members I've built leads for, and they seem very happy with the result! And the 3rd is going in the post tomorrow.

Now, to find a solution for those who, for inexplicable reasons, want to keep the stock s***ty HUs but have ipod input....
 
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You're not far wrong! The H /K system is a pain in the t*ts to deal with, but IMO it's worth it. I've been tinkering with car audio for years, and have had high-end systems in pretty much every car I've owned. This H/K setup is second to none - except perhaps Bose. The soundstage is simply incredible, and the way the amps are set up and wired in means if you give it a decent, balanced, impedance-matched input, there won't be a hint of noise, interference or distortion - at any volume. I can't think of ANYTHING, in the sub-£1000 bracket at least, that I'd want to replace those amps with.

The key here is the input. Sh*te in, sh*te out - and trust me, those stock HUs are sh*te. I was bad-mouthing the system, and all set to rip the lot out... until I replaced my HU with a decent aftermarket one. The difference just stunned me. I've also, however, replaced the stock sub with my own Rockford Fosgate unit and amp... I like my bass to shake the ground! The stock H /K sub is, however, more than adequate for the job for 99% of people.

Don't just take my word for it though - there are 2 other LZ members I've built leads for, and they seem very happy with the result! And the 3rd is going in the post tomorrow.

Now, to find a solution for those who, for inexplicable reasons, want to keep the stock s***ty HUs but have ipod input....

Clarky, do you have pics of your sub and amp ? Is it made into a decent box? My non hk system is reasonable but lacks bass so was gonna add something , but not sure on whether to custom make a box or buy one
 
It's just a thought, but if you were to plug a radio transmitter into the boot 12V socket, so that it was right next to the aerials for the radio, would that provide decent quality?
 
take it from me Clarky know EXACTLY what he's talking about. I was asking myself the same question for weeks about different ways to connect my Iphone to the HK System. Decided to buy a Alpine head unit from Halfords that was reduced from £299.00 down to £130.00. It's supplied with a proper Iphone lead not a USB lead so I get full access to all my music and it also enables me to use my phone hands free utilizing the vehicles speakers and a seperate micro phone plugged into the back of the head unit and fitted to the dash. Can also control the Iphone phone book through the stereo.

I bought one of Clarky leads which is so easy to fit even I couldn't get it wrong and fitted the new stereo within 10 minutes.
Wow, what a transformation, its like sitting in a different car. I cannot recommend it enough.
If you like listening to music don't bother P##sing around with a 10 year + old head unit. Buy one of Clarky's leads which in my opinion he could double the price of and they would still be good value, buy a decent head unit and enjoy.

Dave
 
Hmm, I'm becoming more and more tempted, but I would really miss my steering wheel controls. I have a temporary solution en route, but hmmm....

Clarky, haven't you come up with a solution for them yet?
 
There IS a commercially-available solution out there... but it ain't cheap. It requires two seperate units - one that is a universal 'programmable' device that reads your steering wheel controls and outputs a data stream, and another unit that is compatible with the remote control input on your new HU. It was from the US and total cost, for me (it's HU-specific), including postage, would have run to well over £100. In my view, not worth it.

Frankly, I don't really miss the steering wheel controls... but I guess it's a personal thing. My own experience with OEM steering controls and aftermarket HUs (I've trod this path many times before!) is that it almost never gives 'full' fuctionality - there is always ONE function that simply won't work... and sod's law says it's going to be the one you find most useful.

TBH, if you're going to be using an iPod as your music source, it's highly unlikely that any interface will give you much useful functionality anyway... The best you could hope for is to have the volume controls working.

As an aside, I have just completed the full 'how-to' I have been promising for a while... it's quite long and contains alot of background info, so I've put it in PDF format and can email it to anyone who is interested - just PM me an address.
 
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TBH, volume controls would be most useful for me - mainly because I run playlists on my ipod and all the individual tracks have very different volume levels.

Be very interested in your document Paul.

Guy
 
Suitably encouraged by Clarky's assertion that the Head Unit is the weak link in the HK system, I dug out a spare Pioneer HU that I'd pulled out one of my other cars a while back just to see how it worked.

Plugged it straight in, and it sounded perfect first time. Can't believe the difference!

I used the same loom which I pulled out of my old Audi with the head unit, so I'm curious now if I ought to do anything about attenuation, or if the head unit somehow already matches the correct impedence (I bought it to plug my iPod in to the Bose system on my old A4, so maybe I bought a HU with the right impedence for an amped system? I'll have a look for the manual over the weekend). It finally sounds the way I'd have expected it to sound, just about.

The unit I've put in for now is just to prove the concept, as I don't like plugging my iPhone in to the USB on the front of the HU, but now I'm happy that it'll work properly, my next task will be to find a decent HU as a permanent fixture.

The lack of steering wheel controls will annoy me, so this might give me an excuse to dust off the oscilloscope and disappear in to the workshop for a while! RS Components is my friend at times like these :D

Clarky - all of this means I have a spare Alpine HU knocking around for experimentation, and I'm unlikely to use the CD changer again, so happy to do a bit of trial and error to try to bodge an interface in to the original HU. I'll never go back to the original HU myself though - now I've heard what the system is capable of sounding like given a decent input!
 
Suitably encouraged by Clarky's assertion that the Head Unit is the weak link in the HK system, I dug out a spare Pioneer HU that I'd pulled out one of my other cars a while back just to see how it worked.

Plugged it straight in, and it sounded perfect first time. Can't believe the difference!

I used the same loom which I pulled out of my old Audi with the head unit, so I'm curious now if I ought to do anything about attenuation, or if the head unit somehow already matches the correct impedence (I bought it to plug my iPod in to the Bose system on my old A4, so maybe I bought a HU with the right impedence for an amped system? I'll have a look for the manual over the weekend). It finally sounds the way I'd have expected it to sound, just about.

The unit I've put in for now is just to prove the concept, as I don't like plugging my iPhone in to the USB on the front of the HU, but now I'm happy that it'll work properly, my next task will be to find a decent HU as a permanent fixture.

The lack of steering wheel controls will annoy me, so this might give me an excuse to dust off the oscilloscope and disappear in to the workshop for a while! RS Components is my friend at times like these :D

Clarky - all of this means I have a spare Alpine HU knocking around for experimentation, and I'm unlikely to use the CD changer again, so happy to do a bit of trial and error to try to bodge an interface in to the original HU. I'll never go back to the original HU myself though - now I've heard what the system is capable of sounding like given a decent input!

Excellent news! 'Free' is always the best solution! It must've been, as you suggested, a low-output unit... or perhaps the harness has some attenuation built-in? If it sounds good as it is, no distortion or buzz, even at high volume, then I'd leave well alone.

Good that you now have an Alpine HU we can experiment with - all I need now is the pinouts for the C3 connector, which unfortunately are proving very tricky to track down. Somebody, somewhere, must have them? All I really need to find out is where the audio signal input is, and I can bodge something 'quick 'n dirty' just as a proof-of-concept.

What I envisage as a more mature solution is something with a switch, perhaps mounted in a spare switch blank, to select the input source (CD / iPod) and an aux-in jack.
 
As an aside, the steering wheel controls are a simple, single-wire, resistive-ladder type. Pain in the jacksie to try and interface with almost any modern aftermarket HU!
 
As an aside, the steering wheel controls are a simple, single-wire, resistive-ladder type. Pain in the jacksie to try and interface with almost any modern aftermarket HU!

I reckon something like this ought to do the job:

PAC SWI-PS Steering wheel control interface for Dual, Jensen, Pioneer, and Sony at Crutchfield.com

Given the fact it is translating a resistance ladder to a pulse signal, I wonder if it might be possible to program some of the additional functions by holding two buttons down at a time (eg. answer phone by pressing seek down and volume down together)... just a thought :)
 
I reckon something like this ought to do the job:

PAC SWI-PS Steering wheel control interface for Dual, Jensen, Pioneer, and Sony at Crutchfield.com

Given the fact it is translating a resistance ladder to a pulse signal, I wonder if it might be possible to program some of the additional functions by holding two buttons down at a time (eg. answer phone by pressing seek down and volume down together)... just a thought :)

I think that's the one I looked at myself. Dismissed it as too much of an arse-pain in the end, but for those REALLY attached to their steering wheel controls, it may fit the bill.

I don't see why what you suggest wouldn't work - it listens to whatever it gets sent, and then asks you to assign something to send to the unit that works with your HU - may be an almighty faff, but some I think would consider it worth it!
 
Incidentally, I'm making progress with my iPod-to-OEM HU research. I now believe I've identified the pins that carry the audio signal from the CD changer in the C3 connector. I just found something on Landroversonly where somebody identified the wire colours that carried the signals - although this was from a 2003 disco with an Alpine HU, I matched up the quoted colours with pin numbers from a piccy somebody took for me of the plugs in the back of his P38 Alpine HU, and then compared that to my 'suspicions' of where the audio inputs lie, based on where the extra shielding in the loom is, according to RAVE. They match up perfectly - it seems like the L audio is on C3 pin 13 (+, red) and pin 16 (-, grey) and the R on pins 14 (+, white) and 17 (-, black).

The BAD news is, this arrangement can only mean it's a balanced signal... meaning you couldn't just splice an iPod connection into it raw, without causing buzz and interference. I'm currently delving into a way round that, though, using a centre-tapped autotransformer designed for audio applications as a 'balun' - which will take the iPod output (unbalanced) and convert it into a balanced signal. Not sure if that would kill the 'buzz' though, as autotransformers don't provide isolation. It depends on how much isolation the audio source (iPod) has between it's audio and power grounds. We may find that it works just fine, but buzzes like a good'un as soon as you plug a charger into it... the infamous 'ground loop' effect!

Theory all done, and already have a circuit design in my head - just need to protoype and experiment now (difficult without an Alpine setup in front of me to play with) - but if it all works out like I think it will, I should be able to produce an iPod-input adaptor for around the £20 mark.

I may even be able to work a USB charging port into the mix for about an extra tenner... but I'm getting a little ahead of myself there!!
 
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I use a cassette adaptor in mine and it sounds great.

Ok, I have to thump it every so often to get rid of the buzz that the dodgy soldered joint causes and the display doesn't work, but when it's working, it sounds great.

Perhaps upgrade your casette adaptor? Mine's a Sony.

I will send mine off to be reconned eventually (mine's a Clarion).

Same here. When you are listening to (let's face it) digitised music that is not lossless in 99% of cases, combined with road noise, Range Rover beeps and other noise then how can tell the difference? I would blind test anybody who contests it and that comes from an electronic engineer with lots of audio experience.

Decent cassette adaptor, clean heads, adjust the levels to suit and the sound is pretty amazing really............ My view anyway,,,,,,,,
 
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