Sub-woofer wiring advice ?

Mikele82 · Post by **Mikele82** » 17 Feb 2020, 15:15

Hello,
trying to "simply" add a subwoofer to my xc70 2004.
so i got a 12inch woofer and enclousure box + amp + hi to low level converter
( https://catalog.pac-audio.com/catalog/a ... cing/lp7-2 )

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was thinking connecting it to the speaker wire = tweeter in the D-piller, just up from the trunk left fuse box.
but now im understanding that this line for The tweeter wires are crossed over too high of a frequency.

so what would be the simplest path to connect the hi-to-low converter for the sub amp with a full spectrum audio/speaker wire ?
would it be routing a speaker wire from rear door speaker ,
or
is there a simpler path from full spectrum speaker wire to route all the way to the trunk ?

also, is there audio out on this rear fuse box?

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the v70 has a REM diagram for subwoofer, is that somewere on the rear fusebox?

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EngineeringBloke · Post by **EngineeringBloke** » 25 Jun 2020, 16:33

Hi, have you added your sub woofer yet?

While the diagram is for a 2007 model and yours is a 2004, it shows the unit at 16/79 is a subwoofer plus amp module.

That module gets power via 12v from the REM on B-17 and B-18, and ground via 16/79 lines 9 and 10. Those provide the power to run an amp to drive the sub. It looks like the amp is turned on via REM O-7.

The audio signal comes from the rear bass/mid speakers. I do not think there is audio in the REM itself.

Due to the dual 12v and grounds, it appears this is a dual mono (or stereo) sub system - it may have two speakers.

vincenz · Post by **vincenz** » 03 May 2021, 22:19

I've changed the hu850 for an Alpine UTE93 Dab head unit in my Volvo XC70 (Premium Sound system).
I've connected the pre out of the Alpine to the amplifier under the passenger seat.
I can finally listen to the radio as the original one was dead.
I've lost, for the moment, the parking aid sensors: I'm waiting for an Incartec retention module.
My question: how can I turn on the Volvo subwoofer?
Can I use the cable that come from REM D-7 and connect it to the white/blue cable of the Alpine that turn on the amplifier?
Please help.
Sorry for my English.
Vincenzo

Stu70 · Post by **Stu70** » 04 May 2021, 03:36

My understanding is that D7 goes low on turn on. It goes to ground (zero volts) - you would need a relay to turn this into a positive feed for your amps turn on blue /white wire.
The rear d pillar speakers have a capacitor on the actual speaker that blocks the low frequencies, so you can get a ‘high level ‘ out from the wires going to the speaker to your line level converter at any point before the speaker itself. Hope this makes sense.
I’ve done this myself just recently.

vincenz · Post by **vincenz** » 04 May 2021, 15:49

Thanks.
I will try this weekend.

vincenz · Post by **vincenz** » 08 May 2021, 23:35

I've tried to connect the blue/white wire of the Alpine hu to the socket of the Volvo subwoofer (once cut the wire that come from the REM). When I turn on the Alpine I have +12V on that wire but the subwoofer doesn't turn on.
What do I need to turn it on?

vincenz · Post by **vincenz** » 08 May 2021, 23:45

Stu70 wrote: ↑04 May 2021, 03:36 My understanding is that D7 goes low on turn on. It goes to ground (zero volts) - you would need a relay to turn this into a positive feed for your amps turn on blue /white wire.
The rear d pillar speakers have a capacitor on the actual speaker that blocks the low frequencies, so you can get a ‘high level ‘ out from the wires going to the speaker to your line level converter at any point before the speaker itself. Hope this makes sense.
I’ve done this myself just recently.

I still have the original Volvo cable for the subwoofer: two +12V wires, two ground wires and the four wires coming from the rear d pillar speakers. I only need to turn on the subwofer amp connecting "something" to the pos 2 of the diagram above.

vincenz · Post by **vincenz** » 09 May 2021, 00:10

Hi Stu70,
what do you mean with "My understanding is that D7 goes low on turn on"?
I thought that without the original Volvo radio Hu850 the wire D7 coming from the REM was "dead".

Stu70 · Post by **Stu70** » 09 May 2021, 00:32

So you have the Volvo subwoofer or your own subwoofer/ amp set up?
D7 goes to 0v when the key goes to position 1 Not when the radio remote is powered.(That’s what the ‘x’ means)

If you connected the blue/white wire from the alpine to the Volvo subwoofer it won’t turn on. But a usual aftermarket amp should.If you have a test lamp or multi meter (if you haven’t get one, it’s essential for these types of issues), put one lead on the violet wire and one of the red wires. You should have no power with key off and a light/12v present with key on ‘accessory’
I got different answers when asking similar questions to you.Some suggesting the violet wire had to be ‘turned on’ via dealer programming.

If the blue /white wire goes to 12v when the hu is turned on and your aftermarket amp requires a 12v remote on signal it may require running a new wire to the amp. Or it will work using the relay diagram above
Or take it to a car audio place and pay your way out of the problem…
Good luck

vincenz · Post by **vincenz** » 09 May 2021, 00:52

I have the original Volvo subwoofer.
I've tried to connect to the pos 2 of the Volvo subwoofer the blue/white cable coming from the Alpine hu. I made this way for the Volvo amp under the passenger seat and it works. I thought it was the same for the subwoofer amp.
Thanks Stu70.