2010 S5 amp and sub install write-up
 

I thought I would consolidate all the other scattered info that is out there, and share some pics to help anyone else who choose to do this. I've seen the writeups about replacing the factory subwoofer with a 10" free-air sub, but I personally like A LOT of bass, and I had a feeling that was just not going to cut it. I chose Kenwood products because I've had god luck with them in the past, and they are a decent value. I'm not trying to win any sound comps here - and Kenwood is pretty good stuff for a pretty good price. I paid $60 for the sub, $130 for the amp, $30 for a box, and $20 for a 4 gauge install kit. A few hours of work and you're there. Let me start off by saying that my main goal was not to alter the car in any way. I wanted to be able to completely remove the sub and amp and leave no trace that it was ever there. You understand if you've ever gotten into wiring on an old car that someone hacked up the factory harness to install sweet street glow lights or some crap like that... Ugh.

1 - first thing is to remove the tie down anchor on the pass side towards the front of the car. This will be used to ground the amp and mount the speaker box. It uses a torx bit, fyi. Keep the anchor and screws in a safe place so you can put it back when you sell the car, or whatever...

2 - remove the spare tire and the styrofoam tool tray thingy that sits under it.

3 - disconnect the ground wire from the battery (safety first, heh)

4 - make your power wire for the amp. Install kit comes in handy here. I found that the easiest location to fit the in-line fuse they provided was as shown below. Kits and fuses vary so just do whatever works.

5 - Make your ground wire for the amp, piece of cake.

6 - Disconnect the speaker leads to the factory sub - this is tough to do from inside the trunk, but I was able to lay on my back completely inside the trunk and reach up into the rear deck and get it unplugged. To extend the speaker leads, I used a couple of red blade terminals that fit inside the factory connector. Wrap some electrical tape around to keep them in place, and this way you can undo it all and reconnect the factory sub very easily. I didn't get a pic of this, sorry :(

7 - The 12v switched signal was the only thing that gave me some trouble. There was 0 info out there about finding a 12v switched power source to use to turn on the amp. Let me digress for a moment though ...

... AMPS THAT AUTO-POWER-ON FROM SPEAKER LEVEL INPUTS WILL NOT WORK ...
One of the reasons I chose this amp was that it has an auto power-on feature, so I thought YAY I won't need a 12v switched source. WRONG!
When you connect the signal for the factory sub, to the amp - the signal strength is only strong enough during hard bass hits. I hooked it up this way first, and the amp would pulse on and off with the kick drum in the song that was playing. Of course, it takes the amp a second or two to actually produce sound, so even though the power lights were flashing on and off, there was no sound produced... :(

OK, back on track - since I couldn't find any info about a 12v switched source I just had to go hunting. I busted out the voltmeter and tested every wire coming into the factory amp and nav system, nada. I was about to give up when I started thinking, jeez - maybe I will just use the taillight (daytime running lights, right?) so I stumbled onto the fusebox behind the little cubby hole on the pass side of the trunk. A small consult with the owners manual, and I found several 12v switched sources. I chose the aux power outlet in the center console. I know that they way I connected it is pretty cheesy, but again - I wanted to keep this all simple to uninstall. I just removed the fuse, stripped some 14g wire and shoved the wire into the right side of the fuse holder (hot side, so amp will still work if fuse blows). Then I just pushed the fuse back in place, smashing the wire down securely... I know, I know - there are more professional ways to do it... But now we have a nice, short 12v switched lead to run to the amp.

8 - build a bracket for the speaker box. I know not everyone has a welder laying around, but this is what I did. Some strap steel, some trick tabs, and I needed to buy some 6mm by about 50mm bolts to replace the screws that came out of the anchor, which was removed earlier. I used the anchor as a guide to drill the holes in the strap steel after I welded on the tabs. I used #10 wood screws to attach the box to the tabs. I found it was necessary to place some larger nuts underneath the metal bracket. The factory nutsert things are weak, and will not take any side-loading. Adding some nuts created a shelf of sorts for the bracket to clamp down against. Definitely more solid that way.

9 - attach the amp to the sub box - pretty self-explanatory. Again, I know this is "bad practice" since the vibes from the box can hurt the amp, but my main goal is to not put any holes in the car, and this was the easiest way I could think of.

10 - slide the box in place and measure your wires to make sure they are the right length. Cover up the end of the hot wire from the battery, so it doesn't short out during the next step.

11 - pull the box back out, open the floor again and reconnect the ground wire to the battery. Position the in-line fuse, and then put the tools and spare tire back in place.

12 - final stretch - put the box back in, get it in position and bolt it down, including the ground wire. Connect the hot lead from the battery CAREFULLY, and then connect the 12v switched lead and the speaker leads from the factory sub.

Warp-up - the sound is killer. Could be a little tighter, but I think that is due to the low-end speaker quality which is easy to change if I decide to. The sound more than keeps up with the rest of the B&O system. I have the gain at about 2/3, no 40 hz "bass boost" and the crossover set to 150 Hz. With the Bass setting on the B&O at half, it transitions nicely from the sub to the mids in the doors. The sub is 4 ohm, and this amp makes 500w at that load. If I decide to replace the sub I will be looking at a dual voice coil so I can run 2 ohms. But hey, this is no audio competition winner.

On with the pics...

...

Still need to zip-tie the wires up, I'll try to get to that this afternoon...

So how does it sound. i feel the same way. the B and O ius nice but could use more bass. Kenwood Exelon would have been a better choice. Pro series woofers are reasonable and rock. Thanks for the info.

Well - I'd be lying if I said it was the best system I've ever heard, but I did used to frequent the car audio shows - been in kenwood, JL, Orion, R/F competition vans that put out >150 db. This is not an ear-bleeding system by any means, but - in my experience, you want an equal number of watts going to your sub as the rest of the system - especially with 13 other speakers... 500w to a single 12 rounds out the B&O system very well and gives you the right adjustments to tune it to your liking...

Might just use my kenwood excelon and use a 12 inch in the deck. ill let you know hoew it sounds. does need some bass for sure.

how did you get the source signal to the new amp?

its very simple, just tap into the stock woofer audio feed.

I'm not a car audio installer but a little confused. Don't you need RCA's running to the amp to get the signal?

Also, I'm kind of interested in adding a sub but I'd rather just find a better sub to replace the factory sub and just add a little amp to give it a little more power.

What do ya think?