Nexxia radio fitting kits for P38A

[p38arover]

I'm about to order one of these aftermarket radio fitting kits for the P38A - see Range Rover Fitting Kits | Nexxia UK (http://www.nexxia.co.uk/products.asp?category=Range%20Rover%20Fitting%20Ki ts&section=Car%20Audio).

https://www.aulro.com/afvb/

Anyone who has looked at fitting another radio in an early P38A (fitted with a Clarion radio) knows of the hassles. This looks to be a way around it albeit not a cheap way. Unfortunately, the steering wheel controls will no longer work but the new radio has a remote....

This option is for the Clarion as, apparently, the P38A with the Alpine radio (post-1999) doesn't need any kit. See Range Rover P38 Radio Harmon Kardon | Nexxia UK (http://www.nexxia.co.uk/products.asp?category=Range%20Rover%20P38%20Radio% 20Harmon%20Kardon&section=Car%20Audio)

Why I'm posting this info is that postage is quite high so if anyone wants me to get one for them (or something else from Nexxia) at the same time, speak now.

[996TURBO]

I'm looking for your feedback about that harness. My Clarion makes lots of whine.

[p38arover]

OK, Fran. I hope it works.

No one else seems to want one so I'll place the order today or tomorrow.

[Remy]

Hi Ron,

Did you get this and fit it yet? looking for some feedback
Cheers,
Remy

[p38arover]

Yes, I have, Remy. I'll fit it when I get back from the USA in September.

[996TURBO]

Looks like i'll order it too very soon and fit a modern headunit like the Pioneer 7200 BT

[Remy]

Being impatient i made one using the instructions from RRnet and parts from Jaycar.

Aftermarket Head Unit Adaptation for Range Rover 4.0/4.6 (http://www.rangerovers.net/rrupgrades/entertainment/headunitadapt.html)

RangeRovers.net • View topic - Radio Wiring Diagram (http://www.rangerovers.net/forum/viewtopic.php?f=3&t=43119&hilit=p38+stereo+wiring)

Also download the exel file link to Paul Adshead Wiring Adaptor from this link.

My attenuator finished is here
http://www.aulro.com/afvb/p38a-range-rover/132507-big-thanks-andy-paul-hard-range-2.html

[p38arover]

I'm back so I'll get onto it this week.

[Remy]

Welcome back!

[p38arover]

Thanks Remy.

I fitted the new radio today using the Nexxia kit. Basically it was plug'n'play. I had to shift one pin in a connector on the radio (not the Nexxia kit) to get 12v to tell the P38A's amps to power up. If Nexxia had provided a spare pin, I wouldn't have needed to do that.

All went well except for some low level buzz in all speakers. I'm not sure how I'll find that.

Unfortunately, I no longer have steering wheel controls.

The radio I'm using has a slot for an iPod inside it. One controls the iPod from the head unit knobs. We had a spare iPod that wasn't being used so I'm now filling it up with music.

[996TURBO]

All went well except for some low level buzz in all speakers. I'm not sure how I'll find that.


I'm still waiting for the Nexxia parcel to arrive but received the radio Clarion CZ501E.

BTW, Nexxia says that level buzz in all speaker can be a ground issue on door amps.

[p38arover]

Yes, I saw that, Flo. It also mentions that if the amps are Nokia the problem may not be solved that way but one might need isolation transformers.

My car is a very early build so I suspect it may have Nokia amps.

[996TURBO]

Yes, I saw that, Flo. It also mentions that if the amps are Nokia the problem may not be solved that way but one might need isolation transformers.

My car is a very early build so I suspect it may have Nokia amps.

Received the nexxia kit, everything was wired since i choose the kit PC3-09-Kit with radio surrounds, antenna adapter

Sounds good except an amp noise that you hear at low level or during mute/aux/phone mode.

Sent a mail to nexxia for advice.

[p38arover]

Hi Florent,

It seems like you bought the same kit as me and are having the same problems.

I'll pull the radio out today and try disconnecting each RCA plug in turn to see if that make any difference to the buzz. Then I'll pull the door cards off to cehck the amp earthing.

If it makes no difference, I may need the isolation transformers - another 30 pounds plus post.

Buy PC8-101 Car Stereo RCA Noise Filter (http://www.nexxia.co.uk/product.asp?product_code=PC8-101&category=Noise%20Suppression&section=Car%20Audio)

I'm starting to wonder if it's worth it.

[996TURBO]

Hi Florent,

It seems like you bought the same kit as me and are having the same problems.

I'll pull the radio out today and try disconnecting each RCA plug in turn to see if that make any difference to the buzz. Then I'll pull the door cards off to cehck the amp earthing.

If it makes no difference, I may need the isolation transformers - another 30 pounds plus post.

Buy PC8-101 Car Stereo RCA Noise Filter (http://www.nexxia.co.uk/product.asp?product_code=PC8-101&category=Noise%20Suppression&section=Car%20Audio)

I'm starting to wonder if it's worth it.

Hi Ron,

Yes, same kit so same solutions given by nexxia.

"
You will need to add new wires from the car door to the chassis amplifier.

More common problem is interference in which case you will need PC8-101 to stop the interference."

PC8-101 is a standard RCA filter.

I tried running the headunit without RCAs and i have the dzzzz noise from the door amps. Plugged old HU and it stops, i think it's more a ground problem of the headunit. I'll try to add some wires from the chassis of the new HU to a good known ground.

So i don't think RCA filter will make any difference but will buy one and try in front of the caraudio accessories shop.

Since i had a matchmute box to wire in the Parrot kit with the Clarion Diversity, i'll trash that thing first.

Anyway, beside that the sound of that new Clarion is perfect with much more power (no more saturation at high levels).

Downside is the blue illumination of the HU that makes the P38 looks like a ricer :cool: since it doesn't match the green factory lights.

I may try to change color the HU later... for a more neutral white

[p38arover]

G'day Flo,

I pulled the new HU today and unplugged the adaptors. The buzz mostly disappeared but I noticed that I could get it to come and go by movement of the wires on the RCA leads. I stripped off the heatshrink tubing and found faulty wiring. I've fixed that but the overall buzz is still there. As you say, plugging the original Clarion back in gets rid of all the buzz.

The next job is to try an earth wire back from the amps to a common point with the HU.

I think the RCA noise filter is actually an isolation transformer. I tried buying some today but none in stock at my local auto or electronics shops. One auto parts store will have one in for me by Monday. I'll try it out. I could make one tomorrow as I think I have some small isolating transformers in my boxes of electronic parts.

My Fusion CA-IP500 HU also has blue illumination. I can change the lighting around the knobs from blue to white (done that) but the blue screen doesn't look too good. I could use more drive out of the HU RCA line level outputs.

I may have to pull the HEVAC out to be able to put all the cables and connectors down out of the way of the HU.

[996TURBO]

G'day Flo,

I pulled the new HU today and unplugged the adaptors. The buzz mostly disappeared but I noticed that I could get it to come and go by movement of the wires on the RCA leads. I stripped off the heatshrink tubing and found faulty wiring. I've fixed that but the overall buzz is still there. As you say, plugging the original Clarion back in gets rid of all the buzz.

The next job is to try an earth wire back from the amps to a common point with the HU.

I think the RCA noise filter is actually an isolation transformer. I tried buying some today but none in stock at my local auto or electronics shops. One auto parts store will have one in for me by Monday. I'll try it out. I could make one tomorrow as I think I have some small isolating transformers in my boxes of electronic parts.

My Fusion CA-IP500 HU also has blue illumination. I can change the lighting around the knobs from blue to white (done that) but the blue screen doesn't look too good. I could use more drive out of the HU RCA line level outputs.

I may have to pull the HEVAC out to be able to put all the cables and connectors down out of the way of the HU.

Lots of work and testing this afternoon for me.

1)Tried the RCA noise filter and...as expected it doesn't work. That kind of thing is used when you have buzzing noise with RCA but not without those.
Since we have buzzing noise even without RCA, those can filter what they want but we get no good result.

2)
Found many things during my tests :
-buzzfrom the medium and tweeter only. Bass speaker do not produce any buzzing.

-buzz can be stopped by grounding those 2 speakers (medium and tweet) BUT this stops the sound too.

-tried to ground the amps using black cable number 6 to bare steel : no change

-black wires from nexxia kit and not wired to anything can be wired to a negative speaker wire from 10 iso pink plug and provide a much clearer sound (voice) and attenuate the buzz slightly.

3)Bought a line output converter high level to low level (level attenuator).
http://www.davidnavone.com/images/products/NE7V/NE7VB.jpg

Looks like i should wire this into front speakers wires on 10ISO plug then find a male-male RCA adapter to wire that converter to the HU.

:angel: i thought the nexxia kit did that job.

Then if that doesn't work, i trash everything and bypass door amps using crossovers like i read on landyzone.co.uk

[996TURBO]

G'day Flo,

I pulled the new HU today and unplugged the adaptors. The buzz mostly disappeared but I noticed that I could get it to come and go by movement of the wires on the RCA leads. I stripped off the heatshrink tubing and found faulty wiring. I've fixed that but the overall buzz is still there. As you say, plugging the original Clarion back in gets rid of all the buzz.


Ron,

Since your stripped off the heatshrik tubing, did you find any attenuator circuit like Ray Ambler advice

Aftermarket Head Unit Adaptation for Range Rover 4.0/4.6 (http://www.rangerovers.net/rrupgrades/entertainment/headunitadapt.html)

I think this what we need mate

Flo

[Remy]

Ron,

Since your stripped off the heatshrik tubing, did you find any attenuator circuit like Ray Ambler advice

Aftermarket Head Unit Adaptation for Range Rover 4.0/4.6 (http://www.rangerovers.net/rrupgrades/entertainment/headunitadapt.html)

I think this what we need mate

Flo

That all i am running and it seems pretty good to me - see earlier post for picture of the attenuator i built.

[p38arover]

Did you have an Alpine or Clarion radio, Remy?

[Remy]

Hi Ron,
Clarion in a 95 model. About $30 for resistors, wire blocks and board from Jaycar.
Cheers,
Remy

[p38arover]

Thanks Remy. I'd have all the parts in my electronics workshop. I'm just getting to lazy to build stuff any more.

[p38arover]

Ron,

Since your stripped off the heatshrik tubing, did you find any attenuator circuit like Ray Ambler advice


Not really. When I first sketched it I thought it was an L-pad - then I realised I had drawn it the wrong way about. The revised sketch is attached.

At first glance it doesn't make sense unless the negative lead into the door amps is grounded (it probably is).

https://www.aulro.com/afvb/

The Clarion's output spec is 0,125v at 660 ohm impedance. My new HU has a 4 volt line output level.

[996TURBO]

That thread is awesome. It's a team project ;)

I'll wire Ray's attenuator this evening. Already have everything except one missing resistance.

[p38arover]

Revised diagram (correct way around) now uploaded.

I'm no design engineer so I'm thinking out loud here.....

It looks to me that it's not a true attentuator. It's not an L-pad (voltage divider) nor a T-attenuator (I'd expect the 1 uF cap to have low impedance to AF). I think the 750 ohm resistor is just a load resistor to match the output impedance of the head unit.

Of course, the two resistors could form part of a Pi network if the inputs of the door amps have a resistor to ground.

I wonder what would happen if I changed the values of the resistors?

What I find interesting on mine is that if I plug all RCA plugs except the front left, the buzz isn't too bad. It's still there but at much lower level. As soon as i plug in the FL channel, the buzz is very annoying.

[p38arover]

I wonder what would happen if I changed the values of the resistors?

I haven't had a chance to play today except for trialling a 4K7 resistor directly from the HU RCA to the output lead to the door amp.

That significantly reduced the buzz to an almost inaudible level. I think I need to experiment a bit here. It also reduced the audio level but not a lot.

[996TURBO]

I wired the Ray's attenuator and i have excellent results :p, no more buzz noise and lot of power but i may have miss the wiring of the plugs since i get sounds only on left hand front speaker...

I'll do it again more neatly.

[p38arover]

I wired the Ray's attenuator and i have excellent results :p, no more buzz noise and lot of power but i may have miss the wiring of the plugs since i get sounds only on left hand front speaker...

Ray's circuit is based on using the speaker outputs from the HU not the line level (RCA) outputs. Is that where you connected it?

https://www.aulro.com/afvb/images/imported/2011/09/734.jpg

[996TURBO]

Ray's circuit is based on using the speaker outputs from the HU not the line level (RCA) outputs. Is that where you connected it?



Rewired it neater and it works perfectly. Sound on all speakers (except my rear left door that has green wires), no buzz at all. My HU is awesome with it's built in phone kit.

I did respect all Ray's infos ie i used the speakers output from the HU no RCA at all, except for the Subwoofer (SW).

I didn't use at all the Nexxia thing since i'll send it back:mad:.
I didn't count how many hours i spent on that project. Are those guys professional or what?

But now, i really think about factory making some kits and offer those on the market for people who don't want to worry about soldering.

I used a set of ISO8 (male and female), i shaped the female connector to work with the factory ISO10 pink plug. Couldn't wait for a true ISO10 female connector.

Didn't connect the S/W since i need to find a RCA connector with 2 wires to connect to the S/W RCA output on my HU.

[996TURBO]

Not really. When I first sketched it I thought it was an L-pad - then I realised I had drawn it the wrong way about. The revised sketch is attached.

At first glance it doesn't make sense unless the negative lead into the door amps is grounded (it probably is).

https://www.aulro.com/afvb/

The Clarion's output spec is 0,125v at 660 ohm impedance. My new HU has a 4 volt line output level.

Hi Ron,

Does the RCA sub out has a the same circuit as the others?

BTW, had nexxia on phone today and they're ok for refund so i need to find a solution to make that sub work. Not that it is really necessary with the grunt the new headunit has but i don't want to carry a sub that doesn't knock:p

Good day

Flo

[Remy]

I didn't think the sub was amplified on most stereo's so it can just tap straight into the sub line of the car. If it is amplified then the same principal that Ray has used to attenuate signal will work for the sub just need to add another circuit (resistance might differ depending on output of sub)
Cheers,
Remy

[p38arover]

Not really. When I first sketched it I thought it was an L-pad - then I realised I had drawn it the wrong way about. The revised sketch is attached.

At first glance it doesn't make sense unless the negative lead into the door amps is grounded (it probably is).


I pulled a front door amp out today. It is labelled Harmon Motive so i assume Harmon Kardon. The speakers only have LR labelling, not the HK labels I've seen in other forums.

The speaker feeds from the HU are capacitively coupled via 4.7uF caps on both the + and - leads. I wonder if it uses balanced inputs. I guess I'll need to trace the diagram out.

I cannot find any info on the 'net relating to the amps, e.g., specs or circuit schematics.

[p38arover]

I've looked at the circuit for the Clarion head unit (I am only referring to the PU9836A) and the output stages are balanced, i.e., the output stages for the +ve and -ve lines are the same (mirror imaged) and neither the + or - leads are earthed.

I have traced a small section of the Harmon Motive front door amplifier and it appears that the inputs go to the + and - inputs of an op amp (part of a quad op amp BA14741F) wired as a differential amp. The inputs are also balanced. I suspect (but, as I'm not an electronics engineer, I'm not sure) that any buzz and hum coming in on both inputs will be cancelled assuming they are in phase (Common Mode Rejection?).

I need to trace a bit more - I shouldn't drink red wine whilst doing it!

Unless I'm wildly wrong, the design of the attenuator interface from Nexxia cannot work to properly interface a new head unit to the door amps. Also, the Nexxia unit has capacitors in circuit but for reasons unknown. Both the output of the Clarion HU and the inputs of the Harmon door amps are capacitor coupled.

Instead of earthing (grounding) the negative input, I have decided to try a resistor (value to be determined) to ground on the negative wire at the head unit end (pseudo-balancing).

In theory, that should still leave it capable of picking up the same interference as on the +ve line and, hopefully, they should cancel out in the differential input amp of the door amplifier.

<later>

I had a quick play with pseudo-balancing and the results were very, very encouraging.

I now have more drive into the door amps than I was getting from the Nexxia interface with significantly less buzz. In fact, the buzz is almost inaudible. I have only done one channel.

Next week, when I get back home from the bike races, I'll try trimming the balancing resistor (I'll install a pot and adjust it) and I'll do all channels.

This is the Nexxia interface (posted earlier) which I don't believe can possibly work:

http://www.aulro.com/afvb/attachments/p38a-range-rover/39073d1315978986-nexxia-radio-fitting-kits-p38a-nexxia-attenuator.jpg

What I have done is disconnect the door amp -ve lead from the 750 ohm resistor and connected it to an 8.2Kohm resistor to ground. The only reason I picked an 8.2K was that I made a mistake - I meant to get a 4.7Kohm resistor out of the drawer. I'll reduce it in value for the next test.

[p38arover]

I tried a potentiometer to ground in the -ve line to the door amp and tweaked it for minimum buzz. The good news is that the buzz was completely nulled out. I have more than sufficient drive to the door amps - probably more than from the original Clarion.

Now the bad news.

There is the very slightest trace of a medium pitched whistle. I knew I shouldn't have put the door trim back on. :( I need to pop it off to put a CRO across the mid-range speaker. The whistle is inaudible with the engine running.
To get best nulling of the buzz, the resistor to ground needs to be adjusted. One front door required 10 Kohm and the other 5.6 Kohm.
I feel the system may be distorting so I need to check further.


Those figures are for my car so another may vary.

More experimenting tomorrow. It looks like I'll end up throwing away a fair bit of the Nexxia kit.

I'm annoyed (mild term) that I spent good money (with postage, it wasn't cheap) for the Nexxia kit which patently doesn't work and they should have known that it wouldn't work. Had I been able to buy the 10 pin connector for the radio I certainly wouldn't have bought the Nexxia kit.

[p38arover]

Ok, status as of today.

I took these Nexxia interfaces:
http://www.aulro.com/afvb/attachments/p38a-range-rover/40015d1318326660-nexxia-radio-fitting-kits-p38a-nexxia-1.jpg

http://www.aulro.com/afvb/attachments/p38a-range-rover/40013d1318326487-nexxia-radio-fitting-kits-p38a-snap_2011.10.11_20h30m20s_002.jpg

and modified them to this design (two per PC board):

http://www.aulro.com/afvb/attachments/p38a-range-rover/40014d1318326503-nexxia-radio-fitting-kits-p38a-snap_2011.10.11_20h30m38s_003.jpg

http://www.aulro.com/afvb/attachments/p38a-range-rover/40016d1318326674-nexxia-radio-fitting-kits-p38a-nexxia-3.jpg


I then adjusted each potentiometer (variable resistor) to minimise the buzz in each door. I only modded the front and rear interfaces as there is no audible buzz in the sub-woofer.

Results?

No audible buzz or whistle from the front left speakers.
Extremely low level buzz from the mid-range speaker in the right door but a little more from the tweeter.
Extremely low level buzz from the mids in the rear doors.

All of the variable resistors are set at different points which was expected. If this was to be made for sale, then the installer would need to adjust the pots for best results.

With the engine running, the noise is inaudible and I'll try it like this for a while to see if I feel it's OK. It is certainly far superior to the original Nexxia product.

I also tried the test tones and I was happy that there was no significant distortion in the amps - what I'd been hearing was distortion on the tracks on the iPod I was using for a sound source.

I have ample drive to the door amps, in fact, I think I have higher sound pressure levels from the speakers than I did before. It is much louder than i'd ever want to hear.

[Hoges]

Ron, you never cease to amaze...!!:BigThumb:;)

[p38arover]

This morning I hopped in the Rangie to shift it and could hear the buzz/tone. :(

I moved the car and turned it off and could still hear the buzz/tone. I got out, quite dejected, closed the door and could still hear it.

Then it clicked! :idea:

It was my tinnitus. :D

I can usually tune it out but I must have been listening for noises.

On the road, the system is fine.