Breakout cable to add an Amp to P80 cars - audio centipede

[800artfreed]

As you know the output of the 4 x 100w amp is wired directly in some fashion to the c70's 10 speakers . The center dash pad speaker gets plugged directly into the rear of the 901. In the S70 8 speaker system how did you distribute / connect the speakers? There are 2 LF and 2 RF. If they are 4 ohms each that brings the load down to 2 ohms. Same for the rear door and deck speakers. That is a pretty low load. With so much power from the amp I was thinking to hook each pair in series to load the amp channels with an 8 ohm load. What do you think? Thanks.

[matthew1]

Just FYI this thread is from 2011 so the OP is almost certainly not around any longer. But maybe someone else who knows will chime in.

[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.

[Richard99]

Does anyone know if wires 1,2,7, and 8 are actually used in the upper left plug of the picture? I am not sure if they need to be used since they should be accounted for in the two plugs on the right side.

[ojdorson]

Just wondering how you mounted the 400 w amp under the seat. It seems too large to fit. Was it a manual or power adjustment type seat? What did you use for the mounting bracket? I previously installed the 50 watt amp in my v70 with a SC-900. Looking forward to installing the SC-901 and amplifier I just pulled from a C70 into my 1999 S70-GLT.

That car is, very unfortunately, long gone. I may not have used a mounting bracket, but I do remember that it fit totally fine under the passenger seat.

[800artfreed]

The amp I pulled is just the 100 watt unit from the trunk. There are other pictures on the site that show it under the passenger seat. I haven't actually finished the installation yet. I might decide to just use velcro. I hope to finish this project in the spring.