I've seen a lot of requests for information on the Volvo OEM amplifiers and how to interface with them.
I've got a '98 V70 R that also includes the Dolby ProLogic Surround, so that's what I'm basing this on.
The thing to remember here is that the amp is just an option in an assembly line process.
It costs Volvo time and money at the factory to add an amp option, so they Keep It Simple Sound.
Every car comes prewired for at least a deck and 4, and in the Gen 1 870's case, that's really 8 speakers.
By using 8 ohm speakers with two for each corner, they can just wire the 8 ohm voice coils in parallel.
Ohm's law tells us that the stereo will see a 4 ohm load at each corner using this method.
With the basic HU's, like say an SC-816, the 4 x whatever amp in the deck just drives the speakers directly.
But people wanna Rock da Volvo, so pretty much every HU they've made in the last 15 years or so has an
AMP connector. It's a circular, 6 pin DIN connector that provides a preamp level signal for all 4 corners,
a signal ground for them and a 12 volt remote turn-on signal whenever the HU is turned on. Pretty basic stuff.
(I downloaded this pic somewhere... Thanks to Whoever!
In fact, since almost all this stuff is made by Alpine for Volvo, they stick to the same levels found in car audio
everywhere. The thing that throws most people is that they use a single 6 pin DIN, where aftermarket car audio
would normally use 4 separate RCA connections and a stand alone remote turn-on lead. (Ya know, the blue wire ).
When Volvo adds the amp, they’ve come up with a nifty cable assembly that has the DIN from HU to amp,
the speaker return leads from the amp back up to the HU location and then amp power all in one tidy package.
So adding an amp or making any changes or upgrades is Plug and Play!
Fortunately, all it takes is a simple adapter to connect the DIN to RCA and it’s very easy to build or buy.
You can get them as New HU to OEM amp, OEM HU to new amp and “Add a Sub” to an OEM HU/amp.
( Search eBay for "Volvo Amp" if you don't care to solder up your own ).
There are two common amps, a 4 x 40w that mounts on the tunnel behind the HU :
And a 4 x 50w that gets installed under the passenger seat:
If you’ve got an SC-900 or the newer SC-901, you’ll have the 4 x 50 (I’m NOT going into C70’s here…)
And you may also be lucky enough to have the Dolby ProLogic Surround option with a center channel.
This covers only a limited segment of the available audio configurations that the 870’s may have.
Keep your eyes open for the big amps in C70’s, changer interfaces for iPods / aux inputs and the
Excellent optional Dynaudio speakers that were delivered with a very small number of these cars.
I hope it helps with whatever project you may be undertaking and helps you Drive Happy!
PS - PLEASE, think of the next guy and Always Use a Wiring Harness Adapter !