I brought the JVC KD-LHX501 head unit from a mainstream motor accesories store (Halfords) and had it fitted in the price. Now I've checked the wiring but am not sure if it's been done correctly as I've read in other posts that the RCA preouts should be used. Are these on the left of the diagram if so they have not be used. Does this matter as the sound from the unit is much better then the stock unit.

The only connections used was the big main block of wiring and the antanna wiring which will be done when I go back and pick up the adapter which is needed.

 

The main wiring block should be all that you need to hook directly to the factory amp. That's how my head usnit was installed also (Alpine). I believe the RCA pre-outs would be used with an additional amp and additional speakers to go with it, like bigger subs in the back.

There are people on here that know more about this than I do. If I'm wrong, I'm sure they'll correct me.

 

I installed my Sony CDX-F7700 the same way too. The sound is much improved.

However to get the "cleanest" sound into an AMP you'd want to use the RCA pre-amp outputs from your head unit.

I doubt that I'll rewire mine, I'm very satisfied with its performance using the stock wiring.

 

Hope this will clear some things up.

The factory head unit does not have an amplifier in it. All it has is rca pre-outs. At the factory instead of using rca cables, which most people are familiar with, they wired it straight to the preamp using the wiring harness behind the stereo. People have been connecting the amplified leads from after market stereos to the stock rca wires going to the amp. I would not suggest this. While it may work for some time there are severe problems with this. One the amplified signal from the after market head unit is very dirty. Audio signals that have gone through a gain stage take on massive distortions. Second the signal has far too gain to properly integrate to the stock amplifiers.



What should be done is that the stock left and right channel leads should be cut from the wiring harness and terminated with rca plugs. Then these can be safely plugged into the pre outs on an after market head unit.

I hope i explained this well enough for you to understand. If not let me know and I will try to explain it better.

 

Doh! Now that's a darn good idea and you can rewire the adapter required to install any aftermarket head unit and not mess up your OEM connection if you ever wanted to return the stock head unit. Now this is something I might do over the weekend... SWEET! thanks

 

That does sound really cool. I might do that soon as well. Let me get this straight though. I need to unplug the adapter that is currently in my Alpine head unit, cut the front left and front/right connections on that adapter and then rewire those to end with RCA jacks. Then plug the adapter back into the head unit and plug the RCA jacks into the head unit as well.

Does all that sound correct? If so, that should be pretty easy to do.

 

On the stock/car wire harness are four wires. Yellow, yellow and purple, blue, and blue and brown. I can't remeber for sure but I think I remember yellow being the left side (don't shoot me if I'm wrong). The solid colors are positive, the striped are negative.

You can either cut those wires, or the wires that correspond to them on an after market harness. Just make sure that you get the positive and negative right. If you switch them you can blow stuff up.

For those that might nt know the center pin of a rca cable is pos and the shielding is neg.

 

Thanks for the info I've just taken the headunit back cos they can't get hold of the antenna adapter so I got a refund.

I'm going to get it cheaper of the internet and install it myself now that I know it is easy to do. I've just got to find the adapters needed. Does anyone know what adapters I should ask for when buying the headunit.

 

I was going to go cheaper too but then decided to get the "right" parts from Crutchfield when Sound Domain wasn't gonna ship my order because they were out of stock on their antenna adapter. Crutchfield now gives you the DIN removal tool (plus the wiring harness and antenna adapter) with any head unit so you don't really save all that much going somewhere else. Plus I can get you $20.00 off if you want.

Anyhow here's the info from DFWSBR:
Universal OEM DIN Tool Pair (Crutchfield P/N 120869001)
Scosche VW01B Wiring Harness (Best Buy)
Metra Antenna Works 40-EU10 Antenna Adapter Cable (Best Buy

From my Crutchfield order:
P/N 120869001 Universal OEM DIN Tool Pair
P/N 12040EU10 Euro antenna adapter
P/N 120701784 VW Wire harness (switch the red and yellow wires when connecting the VW harness to the new head unit harness)

If you're going to buy them somewhere else, go to Crutchfield and print out the pictures of each item or just shop for head units that fit your Crossfire and add one to your cart and the other items will be added automatically.

 

Greg you may of noticed I live in the UK

 

Sorry...

Update:

I just rewired my Sony CDX-F7700 to use its 4 volt pre-amp outputs. While it did indeed sound clear and sharp it was a lot quieter. To make it semi-loud I had to turn the volume up to about 50% to 60%. To go very loud it was almost full volume. In contrast when I switched back to the speaker wires out from the Sony, to make it semi-loud the volume needs to only go to 25%. It is very loud at 50%. After I switched back to use the speaker wires I did not notice any differnece in clarity or quality, it still sounds damn good and a lot louder.

You results may be different...

 

A 4v pre-out will certainly be quieter than an amplified signal. A signal from a car amp should be approx 12.5v. The problem is that it is also carrying 25-50watts depending on the amp in the head unit. Amplifiers don't like to have large amount's of watts input into them. Normally the signal stage of an amp will only tolerate an amplified signal for a relatively short time before something gives and it blows up. The resistors and capacitors in a signal stage are not normally rated to take the additional strain/heat. It is possible that the stock amps can take the beating of a 25watt 12.5v input, but I doubt it. I would say that it is just a matter of time before it blows up.

Think of it this way, would you ever take the speaker wires coming out of you home theater amp and plug them into the rca inputs of another home theater amp to make it louder.

 

Yup, you make perfect sense... glad I have a 3 year 36,000 mile warranty...

When I have a problem I'll just slap the Chrysler head unit back in there.



Edit: actually I'm wondering now if the Chrysler HU isn't louder than the sony using its RAC outputs. Does anyone know what the number max volume on the Chrysler HU is? I seem to recall that is was quite loud around 28 to 30 volume setting but I don't know what that equates too. If the volume maxes out at 36 then it too was almost at full volume to be loud but if it maxes out at 45 then it was around 75%. Just wondering...

 

Update:

I jusr rewired my head unit to use the RCA pre-outs rather than the speaker level outs on the wiring harness. This was all pretty easy. I modified the after-market harness so I can still use the original if I ever decide to put the factory head unit back in.

Here's what I've noticed so far. It now takes more volume on the head unit get get loud. For example, what used to be the volume listening level on 4 now needs to be set at about 15. This is fine by me because the normal listening level used to be 3 (out of 40) and 7-8 was very very loud. I never even attempted to go above 15. Now the normal listening level will probably be around 15 and it will get very loud at around 30+. CyberGreg, this is probably what you noticed as well.

Second, when listening to music at lower volume levels (cd and mp3 discs) there is MUCH less hiss/noise than there used to be. It used to be like listening to a cassette tape without dolby noise reduction. Now it's barely noticable.

Third, I can now turn the internal amp off in my head unit. (this may not be a feature of all head units). This makes the head unit use less power and according to the manual, produces better sound quality as a side affect. I didn't really notice this right away, but on some sub-sonic level it's probably true.

Anyway, I'm going to leave it the way it is now. I have much more control over the volume and the lack of noise/hiss is a reason within itself. Overall I'm very happy that I did this. Thanks for the advice everybody.

 

Very cool, thanks for the update. Maybe I'll give the pre-amp outputs another try and see if my Sony can drive the Infinity amp loud enough (for me).

After checking the specs on your head unit I see that your pre-amp outs are 5 volts where mine are only 4 volts.

Oh well.... I'm still

 

You can get line drivers that are relatively cheap. Will bump the line voltage up to 8-12v without the danger of the gain stage amplified sgnal. Can usaly find audiocontrol drivers on ebay for ~50.

 

Mark or Scott,

If I purchase a european head unit will I be able to set it for US FM radio stations. Ours are all on the odd sequence like 93.3, 94.1 or 96.5. You radio's can tune to those stations, right? They can also tune to the even stations too, right like 93.2, 94.4 or 96.6?

I'm about to purchase a european Becker head unit and I want to make sure it will work on FM. I'm pretty sure that the AM won't but I don't care about the AM band, never listen.

Thanks!

 

Just an update on my rewiring. It's been a few weeks since I bypassed the internal amp on my head unit and wired the RCA pre-outs directly to the stock amp and I couldn't be happier. For some reason before I made the change, I could just never get the sound the way I wanted. There was always something a bit...off... and I could never really figure it out. Well now the sound is great! Less noise, more definition, less bass distortion. There is less volume but it's still plenty loud enough when I get above 30 (the max is 35 on my HU).

Thanks to everybody for suggesting this. I'm really picky about how my music sounds and I'm finally able to just listen without messing with the internet EQ all the time now.

 

If you jonesing for some more volume just throw a line driver in there. A line driver will boost your output voltage thus giving you more volume.

 

Where is the stock amp and how do I run RCA cables to it? I just put in an aftermarket head unit using the scosche harness, and there's a lot of noise. The volume is way too sensitive as well. The lowest setting is loud. I'm pretty sure running RCAs to the amp will help. Any ideas?