Rear sub wires at head unit...

Just a quickie..

Been searchin' for ages but no luck.

On the wiring loom at the head unit, i have two ISO plugs and two loose wires that were not connected to anything (rear sub never worked). The iso plugs are self explanatory, but i seem to recall somewhere a thread regarding the sub wiring, something about a brown plug with two wires?????

It looks like my plug has been cut off and i have a red and a black wire.

My guess is that the red is the signal and the black is the ground for the rear sub???

If i touch them to earth, the sub makes a pop or click so i'm confident the amp is live (ignition was on). I have fitted new speakers to it as the old ones were rusted solid hence would never work again.

My head unit has a "pre-out" feature with two phono style sockets so i would go with a 2-into-1 phono adaptor then feed the combined signal into the red wire and the shield to the black wire??

Sound like i'm on the right track??

Thanks all

Dave


BTW, following my water leak saga, i have replaced the buggered rear speakers with ones having nylon cones and rubber surrounds, should last ok, the paper ones were totally destroyed.

My sub is wired as follows. (on my 90)
Big thick red lead to battery
Brown thick lead to earth (body)
Thin wire remote I think its called is connected to one of the wires that comes on when Ignition is on, I think rear wiper
Then the 2 phono's go into the low output on rear of head unit.

You can get these things from Welcome to Trago Mills | Trago, the westcountry's unique family shopping that convert the high output speake wire to low out put for your amp, but they are a bit ****.

Like this


That blue wire is the remote and that turns the amp on/off connect that to the ignition.
The 12v is your battery
Gnd is earth

And with regards to the speakers they have been bridged - speaker cable to - left, +speaker wire to + right.

:nospamhere:

Hi Dave yes you are on the right track a 2 into 1 patch lead is required as you require a mono signal and the red and black wires are the audio into the amp, the amp picks up its 12v supply from the headunit.

I made my lead as I found the purchased ones too bulky to place behind the headunit and get it pushed back fully along with all the wires I had.

Thanks discool, the plug from my sub leads has been chopped off, the leads were stripped bare and just left floating around!

I'll solder a phono pair up and insulate it all, should do the job, looks like the iso plugs will mate straight into my head unit.

I'm fitting an old unit I had in storage because it has pre-out for the sub and also a aux-in so I can plug me iPod in easily. It has a cassette because it also had an 8 disc cd changer before, don't use CDs now and hopefully as it's got a cassette, no scrotes will bother trying to nick it

Just a single phono plug and one of these leads, red is the centre conductor and black is the ground/screen.

Great stuff, thanks

All done, works a treat, had to get a new head unit as the old one would not take aux-in without the cd changer fitted Still its all sorted now, the sub definately puts in a worthwhile effort too.

Thanks for the info.

Easy peesy than Dave. Well done

Yep, plugged straight in, no iso adaptors.

The new head unit was tiny, it was just a tuner/amp, no cd player. This made it really easy to fit all the wires in the dash. I never use CDs now so its ideal.

The new speakers sound ok too, nice to have some sounds again

Hi, I've fitted a new head unit to my car ( disco 1 ), great all Iso to iso do no worries but then came to wiring the sub back in. Easy peasy I thought, two phono leads , and two wires going to the sub. I cut a pare of phono leads I had thinking I can just plug one red phono to the red wire and the white to the black wire. This popped at the sub but no sound. I then realised there is obviously two wires within one phono lead so stripped back the outer and insulated it away. The core of which I connected to a spade and into the Iso block ( red) and done the same with the other if that makes sense. When I plug one phono to the back of the head unit I get the sub, but very faint, when I connect the two ( white phono) it stops working. Where am I going wrong, I've seen the two into one phono lead on here but Doesn't explain how to make it.
Do I take the core of each phono (red and white) and join together and connect to red wire on the iso block and the outer in shrouded wires connect together and connect to the black wire on the ISo block. Sorry no pics as using mobile not computer.

As the bass is mono you need to combine the left and right channel and the screen into a two conductor patch lead from the head unit into the black- and red+ audio lead to the bass amp, the amp requires two 12v supplies both supplied from your head unit, and don't forget to adjust the gain to suit the amp.

The pics of one I made earler and using with out any probs

Cheers discool, I had read ur reply to the other fella with the same problem. But I just couldnt see how to make the lead.

I think I have made the correct lead now but dosent seem to work, I dont here even a pop at the amp. I wonder if ive blown something. Is there a seperate fuse for the SW?

My lead is a chopped twin phono lead. The insulated cores have been soldered together with a wire and a spade wich fits the ISO (red) connector . I stripped the outer wire (earth?) back on each phono lead , soldered them together with a wire going to a spade into the (back, - ve) iso block. But nowt :-(

I wonder if I ve blown the amp or something as I kept switching the spades on the iso block to see if it would help . Also I presumed the outer wire on the phono was earth but seems thicker than the insulated core? But both are really thin and didnt seem upto the job.

The main 12v supply to the amp is the same one as the head unit and the amp switching supply is the aux supply from the head unit, usually a blue wire, it is also used to supply electric aerials etc so not fused with the vehicles fuses. Your unit may have a fused output but maybe not.
If you have matched the head units connector block with that of the discos you will find the two supplies at the amp when the unit is switched on.
What you have done with the lead is correct, the two center conductors twisted and soldered together and the same with the outer screen. The center cores are very thin with the screen much thicker when twisted together.

Cheers again, well i might try making another in case the lead has split inside other than that its a shame as the SW makes a good difference to the sound even if the head unit is good. Couldnt believe how hot the heat sink at the back of the headunit gets also

Well just an update incase anyone ever in the same position. I GOT IT WORKING

I made a single phono lead (2 into 2) as aposed to a double (4 into 2) but at 1st this didnt work either. I decided to check the sub still worked as I wasnt even getting a pop from it, by re connecting the old stereo. Burst to life straight away. Hmmm. So positive my home made cable was ok I reconnected the new stereo connecting the sub first then the power block then the speaker block and turned on. Result. Just had to turn up the SW Level via the menu to 10db (max) and alls well. So not sure why it didnt work the 1st time, perhaps it had to be connected in sequence for the headunit to recognise it or just the usual landy gremlins

what colour wires need the blue or yellow main power supply and what colour wire requires the blue ignition wire many thanks kris