Aftermarket Stereo Fitment - Keeping the Sub

[jim_m_kidd]

Hi Folks,

So I have been researching fitting my Sony Headunit to my RR and I'm pretty much there. I have currently the clarion head unit with the harmon kardon door amps/speakers

I am going to use the Audiolead PC3-09 to connect spekers to the preouts on my headunit.

This lead connects the front speakers to the front pre-out and the rear speakers to the rear pre-out. It mentions in the kit that it doesn't connect the exsisting sub to the system.

I was wondering if if anybody had gotton around this. What I am thinking of is using a Y phono lead to split the output for the rear pre out and running a seperate amp/woofers.

Or could I just add preout connectors to the exsisting woofer wiring and plug that into my Y lead?

Hope that makes sense - just looking for peoples experience that have used the PC3-09 connector really..!

Cheers

[desertdude]

I swapped my old clarion headunit for a new clarion mp3 n cd enabled headunit and didnt bother with preouts junt wired the audio out to the speaker lines and since it didnt have a sub out just spliced the sub to the one of the rear outs.

Mind you I did a lot of research b4 doing this about how the dooramps are gonna cause a problems and yes I have an real autobiography with the door amps ,But I tried the preouts but something didnt sound right ,only prob I have with this setup is when the volume is between 1-3 on the HU there is very low but audible noise like surface noise on old casstte tape players when u play a blank tape .But once the volume crosses 4 it just isnt there anymore ,and trust me I'm a ex-musician and sound quality is a big issue with me also my sub's were blown I just put in an aftermarket sub,with a sperate amp

Now I hardly turn up the volume above 13 and its loud and clear enough it goes al the way to 30.Also the door amps dont have to work as hard as they are already getting a amplified signal from the HU

And by just changing the headunit makes a very big Diffrence in the sound quality.I have the same HK speaker setup as you and was amazed how poorly the speakers were matched with the Headunit.

You can eaisly Y the sub into any rear channel and things will be fine ,only u wont have any sound level control on the subs .I over came this with volume control with the seperate amp for the sub .Or alternately u can try the fade setting on your HU by increasing the volume on the Front speakers .

Hope this helps

[hildstrom]

If you want to retain separate control of the subwoofer volume...

The factory sub amp runs on high speaker-level voltage. Pre-amplifier outputs from an aftermarket head unit will probably not have enough voltage to drive it at the correct level. The remote turn-on wire works just like any aftermarket amplifier.

That being said, you could amplify the preout using some sort of small wattage amplifier, then connect that to the existing subwoofer signal input. You could also replace the factory amplifier with a small equivalent wattage amplifier that can be driven directly with the low preout voltage from the head unit.

You could also run the front and rear amplifiers in parallel from the head unit front speaker-level outputs and use the head unit rear speaker-level output for the subwoofer. But then you would lose front-rear control and using front-rear control to control the suboofer volume would change the system volume as well.

Now I hardly turn up the volume above 13 and its loud and clear enough it goes al the way to 30. Also the door amps dont have to work as hard as they are already getting a amplified signal from the HU

It does not quite work like that, the door amplifiers still have to work the same amount. The input voltage from the HU drives transistors in the amplifier that drive the speakers. The head unit is isolated from the speakers by the amplifier and its circuitry, the power is not additave. This just means that your head unit is giving the factory amplifiers plenty of voltage when its volume is half way up. Your HU/amp gain mismatch is probably the reason for the audio noise at lower volume levels. The HU is operating at a very low S/N ratio internally and expecting to be driving a speaker directly at speaker-level, which normally might bareley be audible at level 1-3.

If you don't feel like trying to match the voltage output of your aftermarket HU to the factory HU, you can improve the SN ratio by installing a power smoothing capacitor in parallel with the battery or aftermarket amplifier. The DC power produced by the alternator/rectifier/regulator is not pure DC. There is usually a ripple on top of the DC average voltage that can be audible when trying to amplify a small signal. If the noise you hear changes with engine RPM, this is exactly what I am talking about. A large power capacitor of 1F or bigger, will smooth these power fluctuations and result in cleaner amplification. I ran a 20F power capacitor to help eliminate engine whine and smooth amplifier power draw in my last two vehicles and it worked great. The power cap can react faster than a second battery. A battery also does not do much of anything to smooth voltage ripples at its charging voltage because it cannot provide any power at 13.8 or 14.4V, it can only take it.

Hope this helps. -Greg

[jim_m_kidd]

If I can't usefully use the exsisting sub without aplification I may as well replace it with my aftermarket amp & sub - installed in the stock location.

Any additional thought on splitting the pre-out feed from the rear of the headunit to power the rear speakers and amp. Is splitting the 'feed' going to halve the output?

Cheers

[hildstrom]

You can split off the speaker-level output from one of the rear door speakers to drive the sub amp, you just won't have separate volume control of it without installing some other sort of resistors or volume control knob in-line before the sub amp. The factory sub and amp can still be used, it's just not quite plug&play.

Splitting a pre-amplifier output will generally not cut the voltage significantly. Most devices with preouts can drive several amplifiers in parallel with no problems. That being said, splitting the rear preout to get signal to the rear amp and a sub amp accomplishes basically the same thing as splitting a rear speaker-level output and sending it to the factory amp; you would still not have individual volume control of the subwoofer if it is in parallel with the rears.

If your head unit has a separate preout for the subwoofer (3 sets total) then you can have individual control of the subwoofer volume from the head unit, which is the most convenient.

[jim_m_kidd]

Great - thanks for the info - IIRC on my amp there is a seperate 'volume' dial, so I can reasonably 'fine tune' it with the volume!

Again thanks for the insight!

[hildstrom]

I can reasonably 'fine tune' it with the volume

Are you referring to the gain of the amplifier? You can certainly use that to set the volume relative to the other speakers.

What I was talking about before is if you wanted more bass from just the subwoofer for some songs and less bass for others; something you might want to change while driving. If you can only set the gain/volume on the amp itself, you're left with the head unit's global bass and treble controls, which affect all speakers. This is probably fine for 98% of people 98% of the time, but I prefer to have the extra control.

Post again as you make progress. Good luck. -Greg

[dave3d]

I replaced my factory (Alpine) head unit a while ago with a more modern Alpine head unit and I also fitted an Alpine CD changer in the boot. I then fitted a s/h Harmon Kardon subwoofer. This has its own built in amp. The head unit had a separate connection lead for the subwoofer. However I had to run a cable to the back. Later model p38's had the speaker connector already built into the harness. Mine is 2000 model year.
The new head unit has separate settings for the subwoofer including whether to amplify the output or not. This wasn't neccessary as the subwoofer has its own amp.
Very pleased with the result. Enough power to blow your head off.

[jsp]

The factory sub amp runs on high speaker-level voltage. Pre-amplifier outputs from an aftermarket head unit will probably not have enough voltage to drive it at the correct level. The remote turn-on wire works just like any aftermarket amplifier.

Hmmmm the half a dozen P38 stereo upgrades I have been involved with have all kept factory subs and they are a standard line level input simply run from the sub out on a standard head unit....they have a built in 12 watt AMP.

I have blown the subs in mine twice now from a standard line level.

Just an observation.

[hildstrom]

It is also possible that the factory sub amplifiers are different from year to year; I know they switched from Clarion to Alpine head units at some point. On my 2000 HSE, the previous bloke who owned it cut the signal wires going to the amp and used the signal to drive an aftermarket amplifier and subwoofer, but he used a speaker-level to line-level converter in between.

Standard line level is usually 1V RMS, or about 1.414V peak to peak

I don't have time this week, but I will try to throw an oscilloscope on it next week to check.

[paul.adshead]

Hi Folks,

So I have been researching fitting my Sony Headunit to my RR and I'm pretty much there. I have currently the clarion head unit with the harmon kardon door amps/speakers

I am going to use the Audiolead PC3-09 to connect spekers to the preouts on my headunit.

This lead connects the front speakers to the front pre-out and the rear speakers to the rear pre-out. It mentions in the kit that it doesn't connect the exsisting sub to the system.

I was wondering if if anybody had gotton around this. What I am thinking of is using a Y phono lead to split the output for the rear pre out and running a seperate amp/woofers.

Or could I just add preout connectors to the exsisting woofer wiring and plug that into my Y lead?

Hope that makes sense - just looking for peoples experience that have used the PC3-09 connector really..!

Cheers

Forget any pre-made lead. You need to build a special lead, to interface the headunit outputs to match the input needed by the HK amps (- which are non-standard specs, but high-quality). It should only cost a few quid in parts. I've been through this process about 6 months ago. I also used a Sony headunit and 10-stack changer in the boot. The sound is ohhhh so crisp and pure afterwards.

Some details of what's needed:
http://rangerovers.net/forum/viewtop...=162573#162573
Read the whole thread - not just that post.

So to summarise:
- run each corner, from the speaker-level outputs (- not line-level), through the attenuator (- one attenuator circuit needed per corner), into the existing amp wiring.
- for the sub, run this from a pre-out output (- on my Sony unit, one of the pre-out circuits can be configured for sub output), directly into the sub-amp. I wired mine up in a 'Y' fashion, whereby both the L & R side of the pre-out feed the sub amp.
The frequencies that the sub responds to are very low, so 'high frequency hiss' is not a problem on the sub circuit. Also a lot of headunits have adjustable volumes for the pre-out/sub circuits. Net result, is that the issues reported as problems on the four corners (- when pre-outs feed the amps), are not issues for the sub circuit.



Attenuator details:

Ray has been extremely helpful and kind enough to share his solution to using the built in amps on a standard high level output from basically any stereo head unit!


Below with his consent:



Purchase an ISO male to ISO female head unit lead from a motor factor or car audio stockist.

Construct 4 off the circuit shown. Parts from Maplin or similar.

Cut each speaker pair of wires in turn and connect in the circuit.

Repeat for the other 3 channels.

Insulate the components so as not to short onto anything when installed.

You now have an inline adaptor lead that will attenuate the speaker level to the correct value and provide impedence matching for the head unit and HK door amplifiers.

Plug and Play!

Quoted from: http://rangerovers.net/forum/viewtop...?p=65513#65513

[paul.adshead]

For those wanting to make one of these adaptor cables, I've put togethor all of the information needed into one place. It is contained in an Excel spreadsheet and is available for download from:

http://jimsrover.afraid.org/rover/pa...ng.Adaptor.xls
(It is probably best to right-click the above link and use 'save as' to get a copy on your machine, before opening it.)

There are five 'tabs' in the spreadsheet - don't forget to look at the other 'tabs'!

The spreadsheet contains, information about:
- how to identify which leads connect to where;
- which leads need the attenuator;
- specs of the attenuator;
- details of the sockets needed, to connect onto the existing loom; and
- some photos of how my adaptor cable ended up.
Hopefully this will be of use to someone, or will give someone the confidence to do the same.


Cheers,
Paul.

[hildstrom]

Okay, I stand corrected. I played a 35Hz full-amplitude test tone on my IPod through my factory head unit with the sub amp disconnected. I turned it up until the remaining bass from the door speakers was rattling things sufficiently, which would have been very loud with the sub still connected.

The voltage on my oscilloscope read about 0.85V RMS on the signal input wires to the subwoofer amplifier. So I conclude that jsp is correct and the signal input to the subwoofer amplifier is standard line level at about 1VRMS. It seems the signal input to the subwoofer amplifier is not speaker level voltage. The previous owner of my rover had been running the head unit output through a speaker to line level converter to an after market amplifier, which was obviously unnecessary; this lead to my previous incorrect conclusion.

If you decide to drive the factory subwoofer amplifier with an after market head unit, make sure the subwoofer preout is a 1V RMS standard line level output. If the head unit has 2V, 4V, 5V, or 7V preouts, it is too much voltage for the subwoofer amplifier and some sort of attenuator should be used to get back down to 1VRMS standard line level.

I hope this clears things up. Thanks. -Greg

[jim_m_kidd]

For those wanting to make one of these adaptor cables, I've put togethor all of the information needed into one place.

Excellent Excel speadsheet - very comprehensive and useful.

More to follow re my install

[jim_m_kidd]

So far - I have brought the audiolead pc3-09 lead (the lead from nexxia) and used this to power the speakers from the pre-outs on my radio

Having installed it I get a whine when playing Radio/CD's

I did find another recent post asking most of the questions I was interested in and having read through this and looked at the spreadsheet linked I'm now thinking that I need to create this attenuator lead.

It sounds like there are many different components/system specification for radios and this made picking the right solution quite difficult

I now know that my 1995 has the clarion headunit with the 10 speaker +amp HK system, as opposed to a non amplified system as opposed to a later alpine stereo

I think that the exsisting lead that I have that the pre-outs are in someway not providing a suitable feed to the door amps. There are a lot of technically minded folk who talk about ampage, impedance and all that and I just have a gut that one of these figures is screwing with using the preout

So... Looks like I'll be paying a visit to Maplins for some bits tomorrow.