This cable makes adding an amp to your car while keeping the Volvo head
unit really simple (if you can’t find the proper wiring harness at the
junkyard). If you got a Volvo amplifier, then you still need the Volvo DIN
Amp cable (or wire your own!). If you are adding an aftermarket amplifier,
then you need to make a DIN-RCA breakout cable. Write-ups for this exist
and I can’t do any better than this one…
Now, really, really astute readers will look at the first picture and say, “Hey! There’s a loose wire there!” That’s right, there is. I actually ADDED that wire in by cracking open another factory wire harness and pulling that wire out with its little metal connector intact and then I inserted it into this harness. Everything I read tells me that this wire will allow me to send the head unit a signal to go into TELEPHONE mode. I never tested this, but I had grand plans to purchase a Parrot bluetooth phone interface and wire it directly into the system so that call audio was routed over the speakers and the head unit would mute and display “TELEPHONE” on the display whenever the Parrot unit was active.
800artfreed » I am installing an SC-901 and external amplifier from C70 donor cars into a 1999 S70-GLT. Thanks for all the information in this thread.
Though I pulled a 4 x 100 watt C70 amplifier I decided to use a smaller 4 x 75 watt amp from a S60. This is an under the passenger seat model. In the case of each of the amplifiers used in more modern cars (mid 2000’s) it appears that Volvo started wiring the amp output to speaker wiring directly. This is different than the design when I pulled a Dolby, external amp, SC-900 from a 1998 S70 donor and installed it in my V70 that passed amp output back to the SC-900 via factory cables.
I was concerned about the speaker impedance in this new “bastardized” system using a SC-901 & Dolby processor & external amp. However the good news is that the front dash pad tweeters are 8 ohms. I suspect that IF the car came with 8 speakers each of the speakers is 8 ohms. Volvo pairs 2 speakers for each of the 4 output channels. Left Front, Left Rear, Right Front & Right Rear. This then creates a nominal load of 4 ohms impedance on each of the output channels. If by chance the door speakers are only 4 ohms the pair of 8 & 4 ohm loads would create 6 ohms at the amplifier. I feel this is safe enough. If I need more power I can always swap in the 400 watt amplifier.
I have already created an extended 6 pin DIN cable (SC-901 to Amplifier) from the pieces I hacked out of the C70 donor cars and will extend the amplifier speaker cables to reach a METRA adapter cable connector hooked into the SC-901. This is similar to the picture above in this thread. This allows the retention of the original wiring / connectors if I want to sell the car with only a SC-816. While I saw at least one online picture of the 4 x 100 watt C70 amplifier under the seat in a x70 I am going to see how the smaller amp configuration sounds.
Some interesting observations on cables used in the OEM environment. The C70 used a shielded data transmission cable with 6 conductors. This braided shield is known a a tight braid, meaning there are no gaps in the braid. The individual conductors are just insulated, multi strand 22 gauge wire. The older DIN cable uses UNSHIELDED 6 conductor cable with each conductor having and external “ground” wire running in parallel to the conductor, also 22 gauge multi strand. In any case all these external copper wires must be connected together because they are connected to the DIN connector’s metal sleeves that touches the chassis when inserted. It is actually a 7th connection. The other interesting observation is that each PAIR of the output wires are twisted together as a separate pair. Since these cables are bundled next to each other in an electrically noisy environment I assume this is for noise reduction or to prevent cross talk between the left and right channels.
Will post some picture when I get to the task at hand after the local heat wave passes and the temperatures drop to the md 80’s.
Breakout cable to add an Amp to P80 cars – audio centipede
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Last Updated on August 9, 2022
