C70: Audio: Rear seat subs

[mikealder]

In the diagram I have coloured the parts you need to look at to get what you need, the pair of subs have purple ellipses around them. 12V is fed from fuse 11C/32 down the wire coloured red to the rear sub switch (component ID 3/146) the switched output is the green coloured wire, the actual wire in the car will be coloured Yellow/ Green, if you connect your second sub remote on/ off to this wire it will switch on/ off along with the built in SUB.

The line I have coloured BLUE is the DIN plug lead going between the head unit and the main amplifier, this contains the pre-amp outputs and the amp remote on/ off switch, this shouldn't be touched for what you are trying to achieve.

The Filters (Component ID 16/51 & 16/52) are what switch the actual rear subs on/ off depending upon the position of switch 3/146 - Mike

[Thanatos]

Mike if your going to run power from the battery for the 2nd amp go down the left hand side of the car for the wiring and you might need to add a power cap to stop interference

Also what amp were you thinking of using as you will need to match the power to the Volvo/alpine amp otherwise you will find one amp turning off when you turn the volume up.

As I had issues with that with my jbl amp and the alpine amp doing this.

[MikeS100]

Wow, thanks for the detailed reply, that's perfect! I really appreciate you taking the time to do this!

It's a stand alone unit so doesn't have a seperate amp. I must admit to not really knowing what I'm doing with this, lol, but I've had it in cars with amps before and just wired the power straight into the battery with a switch and then just tapped into the audio feed from the rear speakers. It's pretty basic, it just has 4 wires on, black and red for the power and the 2 audio cables. In this case I'm hoping it will work connected to the rear subs rather than rear speakers.

Am I right in thinking I can put a relay in line in the wire from the rear sub switch and then the other terminals on the relay in line with the direct power feed from the battery for the extra sub?

I'll see if I can find some details for it online and post a link sp you can see what I'm talking about. I bought it about 10 years ago from a car show and never seen another one like it.

[MikeS100]

This is it, apparently it's a spark-o-matic bass cannon
http://www.focusfanatics.com/forum/s...d.php?t=201146

I know it's not the best looking thing, but it's a perfect fit underneath the roof storage in the boot of the C70 and most importantly it's free as I 'borrowed' it from my project car I think I only paid about £30 for it at the time so it's not that powerful, but I always liked the little extra kick that it gave.

I've also found that I need to wire the audio leads to the negative speaker lead on both sides, so can someone identify from the wiring diagram which colour wires that would be on the car?

[Thanatos]

The wire with the white line is negative IIRC but to be honest the speaker tube you have I would connect to the subs in the rear side compartment where the speakers are already as then the crossover will take care of everything else.

[MikeS100]

Originally Posted by Thanatos

The wire with the white line is negative IIRC but to be honest the speaker tube you have I would connect to the subs in the rear side compartment where the speakers are already as then the crossover will take care of everything else.

I just want to make sure I understand properly, are you saying tap into the speakers in the side panels or still tap into the sub wiring but in the side panels by the speakers?

It's a bit of a pain to get those panels off from what I understand...

[Thanatos]

Yeah tap into the speaker feed to get the low down base as the subs and midrange will possibly blow the tube

[mikealder]

Here you go:



It is a small portion of the earlier diagram and I wiped out some of the drawing to make was for the second sub and power switching relay.

I have taken the power for the new sub from the existing amp pos cable, in reality you should run that back to the fusebox but make sure you fit an inline fuse.

The green wire from the power relay goes to the green wire from the sub enable switch.

The left input to the sub is coloured blue in the above diagram, it is connected to the Brown/ Black wire on pin 4 of the left cross over. You can also get at this wire at the output connector of the main amp Plug B pin 6.

The right input to the sub is coloured purple in the above diagram, it is connected to the White/ Black wire on pin 4 of the right cross over. You can also get at this wire at the output connector of the main amp Plug B pin 8.

The two wires I have annotated as 0V simply connect to the cars bodywork - Mike

[MikeS100]

Thanks for your help on this guys, and I really appreciate the modified wiring diagram! Having that to hand will make it so much easier!

I've just looked at the weather for Saturday which is when I would like to have a go and apparently it's going to be raining! If it is I'll have to put it off but not sure when I'll get a chance then as I'm busy the following weekends I need a nice day though because I think it will be much easier with better access if I can put the roof down and take the rear seats out. I will keep you updated but it may be a couple of weeks until I get a chance to look at it

[mikealder]

Having the top down will make it rather difficult to get access to the components and wiring which is mostly in the boot, if the boot is full of roof you won't get at much - Mike