98 S70 GLT Stereo Overhaul DIY

Duake · Post by **Duake** » 29 Oct 2013, 15:09

Hey, everyone.

I know a lot of people have been confused and everything about the way the Volvo's stereo is wired and what not, so I'm going to write out everything that I know about the stereo situation and the equipment that I'm going to be putting in my own vehicle. Hopefully this will help others with installing their own.

I have an S70 GLT that has the 8 driver speaker system. This had the SC-816 as the main head unit. From the wiring diagram, the 2" dash tweeters and the front doors both ran straight to the unit itself. The rear 2-way 6.5" door and the 2-way 8" rear deck speakers are wired into each other and then go to the head unit. The tweeters are 8 ohms as well as the rear doors and rear deck. The only speakers that are 4 ohms are the front doors. Not sure why, but they are wired directly to the head unit as well. The rears must be wired in parallel to create a 4 ohm load to the head unit. Technically, using 8 ohm speakers and then wiring that way lowers the resistance so the head unit doesn't have to push out as much power.

What I plan on doing: Right now I have replaced my SC-816 with an old Alpine HU that I used to own in another car of mine - a CDA-9830. I'm not sure if anyone noticed, but if you don't happen to have a really good EQ on your aftermarket headunit, the bass just disappears. Luckily with the 9830, it has a 4-band parametric EQ with different frequency levels for each band. It also has an MX button which helps with MP3 files and regular CDs as well. That's called Media eXpander and it's supposed to help with compression issues and loss of bass. Think of it as a "loudness" button.

I'm going to replace the 9830 with the 9831. Why? It has a dot matrix display and dimmer and also has everything that the 9830 has plus iPersonalize.

Speakers and placement:
Cadence CS2.65K 6.5" Component System
- Woofer going in front door and tweeter being mounted on sail opposite the mirror.
- Will eventually put in a 2"-2.5" midrange in dash to replace tweeters and run off head unit.
- I originally was going to make a 3-way driver for the front off of 1 crossover.

Cadence FS6535 6.5" 3-way Coaxial
- Going in rear door
- The Flash series 6.5" can go down to 45 Hz and handle 50w RMS so bass will be good.

Cadence XS804 8" 4-way Coaxial
- Mounting in rear deck

Cadence FMA750.6 6-Channel Marine Amplifier
- 90 watts RMS per channel @ 4 ohms
- yes a marine amp. Still works in a car. Just mainly built for water applications.
- Used to have a 5-channel Cadence amp (100w x 4 @ 4 ohms, 300 x 1 @ 4 ohms) and worked great.

Why am I using Cadence? Well, I have experience with their amps and thought I'd give their speakers a try. They are one of the only manufacturers of an 8" car speaker that doesn't cost more than $60. And with 100w RMS to boot, can't do any harm in checking them out.

Right now, I don't have all the parts, as I'm still waiting on the 8" and 6.5" coaxials, but I tend to put everything in this thread on how I did everything. I might do videos as I'm installing as that might help people out more than pictures. I'd be using my phone camera, but it can do 720p, so it might not be too bad.

Not sure when I'll be starting the install, but it may not be until this coming weekend when I get all the parts. It gets dark here earlier so I won't really be able to do much after work.

If anyone has any questions on anything relating to this project or anything technical, ask it in this thread. I for one can't wait to get all this into my car!

Duake · Post by **Duake** » 03 Nov 2013, 19:30

I managed to get the component system in the front doors today. Got interrupted so much, that it was the only thing I was able to do.

How it's wired:
- Disconnected the dash tweeters. This doesn't necessarily have to be done as the aftermarket harness combines the door and dash together. Granted, the factory tweeter is 8 ohms, so the load comes out to be something odd to the head unit. For safety and sound quality sake, disconnect.
- The Cadence component system comes with a relatively small passive crossover. Both the tweeter and woofer connect to it simply as the spade connectors are already factory set up so you just push them together. Can't beat that. The crossover was mounted right next to the power mirror wire harness inside the door. There's nothing there to get in the way. You'll see a small gray "pad" that's on the metal of the door where there is space.
- The tweeters are rather large and once I held them up to the sail panel with the door closed, they come close to the dash. They fit and are basically somewhat in the way of the defrost vent, but the air can still flow out and go around them.
- The crossover of the system has the wires to hook into the head unit already, but I wanted to use the factory wiring for the fronts as I had in the past with other cars. I got lucky and the ends of the wires are "tinned" which means they are like straight wires. I pushed the ends into the factory speaker harness and they are pretty tight, so nothing more to do.
- I used foam gasket tape on the factory speaker mounts where the woofer goes. I also put it on the door where it attaches to the metal. There was A LOT of vibrations without it when I cranked it up. Pretty useful stuff and costs like $2.

I'm liking the setup so far, but these really need that amp that I have sitting in a box. The next thing I'll probably do is run the wiring for it in the car. When I get more time, I'll post pictures of the doors and put them into this body since I'm referencing them here.

Any questions, post them here.

clifford06 · Post by **clifford06** » 10 Dec 2013, 17:29

Hello. Man , your post is what I'm thinking of doing in my 2000 S70 T5. I like the fact that you thought, researched and planned.

clifford06 · Post by **clifford06** » 10 Dec 2013, 18:42

I have a few quick questions.
1. Where do you plan to run the power wire for amp thru your firewall? Is there a factory knockout or will you drill and grommet?

2. If the door speakers are 4ohm, could I upgrade my 6.5" door speakers to improve clarity ? I have a set of Alpine SXE-17255 that I could try for a sound check.

3.Where did you get your speakers/components from ? Cadence is a brand I used back in the day, and got my money's worth out of them.

4. Any modification for the 8" deck speaker installation ? If I swap these out, I'll use Ozark Lee's " How To" write up .

I feel your pain to install the amp. I have some stuff from my other cars that I can use.

Duake · Post by **Duake** » 09 Mar 2014, 15:03

I finally managed to install my components in the front and have to get a bandpass crossover for the 2" midranges in the dash. The 8" in the rear deck mounted in the factory brackets, but since the magnets were bigger, I had to cut the bottom off of them.

The amp is installed under the rear deck with really long screws since it is so uneven back there. The power is running on the left and the patch cables/speaker wire on the right side. I ran the power cable through the big grommet/hole for the steering wheel. I just shoved it through there with minimal effort and works fine. It wasn't fun running the wires, but I've done the same thing in my Mazda 3, so it wasn't unknown to me.

Everything sounds great! I can't wait to hook up the mids to the head unit and get the rear doors installed as well.

Post by **marshallh** » 15 Mar 2014, 16:43

I didn't know the fronts were 4ohms and the back/cargo speakers were paralleled 8ohms. That makes sense, and explains why I was confused in VIDA