Step 1

Remove trim panels from the unit and set them aside.

Step 2

Take off the top cover to the unit by removing the screws found at each corner.

Step 3

Remove the large screws holding the CD player unit in place. There should be two on each side. These screws are larger than others so remember what they look like for when you reassemble the unit later..

Step 4

Lift the CD player out of the unit's chassis. You may need to use a flat blade screw driver to get it started.

Step 5

To take off the face plate you need to remove a screw on each side. These are diffent screws from the others so remember where they go and what they look like.

Step 6

Take off the plastic piece which is hiding the clips from the bottom of the face plate. It is just glued on. Using a flat blade screw driver gently pry off the top and bottom until it comes loose.

Step 7

Take off the front plate by loosening the three screws in the center and one in each corner. The bolts in the center require a smaller phillips head screwdriver. Put them aside so you remember where they go.

Step 8

Your unit should now look like this. Next we have to remove the plate shown in the photo.This one took me the longest to figure out.

Step 9

Take off the right side clip by removing the two screws. Thes screws are flush mount. Put them aside so that you remember where they go.

Step 10

Remove the hidden screw shown in the photo.

Step 11

Take off the heat sink by removing all the screws on the back side. One is smaller than the others so remember where it goes. Watch out for the white thermal compound used between the heat sink and amplifier chip. It can be real slimy if you touch it. If you accidentally wipe it off you may need to reapply some.

Step 12

Now that the heat sink is off, you should be able to lift off the metal plate, remove the side pieces, and lift the circuit board out.

Step 13

Next we will create our pre-out cables. Take an RCA extension cord and cut off about 12-14" from the female side.

Step 14

The RCA cord I have is a coaxial where the ground wire is wrapped around an insulated signal wire in the center. Remove about 4" of the outer sheath but be careful not to damage the wiring inside. Separate the ground wire from the signal wire for each channel.

Step 15

Repeat steps 13 and 14 with the second RCA extension cord then twist all of the ground wires together.

Step 16

Clip off about 2" of the ground wire since it will only have to travel a short distance inside the unit. Solder a pin (just use the end of a capacitor or resistor) onto the end so we will be able to connect it to the circuit board.

Step 17

Place heat-shrink-tubing around the ground wire and leave about a 1/2" exposed. Use a heat gun or lighter to shrink the tubing. Now is also a good time to label both sides of your signal wires. I just numbered them 1, 2, 3, and 4 but you can do FL, FR, RL, and RR to be more specific.

Step 18

Add a large piece of heat-shrink-tubing around all the wires to group them together. This will be an added layer of protection for when they pass through the heat-sink later and it protects the end of the ground wires.

Step 19

Strip about 1/2" off each signal wire. Take four .47 uf 50v capacitors and clip one side to about 1/2". Solder a capacitor to the end of each signal wire. Be sure to put heat-shrink-tubing on the wire before you solder the capacitor but don't heat it up until after you are finished soldering.

Step 20

If you haven't already, you need to feed your new wires through the heat sink. Use the hole below the antenna jack.

Step 21

Solder the ground wire to one of the ground holes by the amplifier chip.

Step 22

Any one of the three holes that are linked to the pins on top row, second and third from the left in this photo will work.

Step 23

The signal wires will be soldered to holes near the volume control chip. This chip is located in the center of the board. All soldering should be done on the bottom of the circuit board but it is much easier to find the holes in relation to the top of the board. Be sure to leave plenty of slack on the wire so the chassis can be placed back on. Before you solder anything to the circuit board you might want to do a test fit.

Step 24

In this series of photos, the heat sink is towards the top. Solder channel 1 (front left) to the first hole directly above the chip.

Step 25

Solder channel 2 (front right) to the hole off to the lower left of the chip.

Step 26

Solder channel 3 (rear left) to the second hole above the chip. Be careful with your soldering. You don't want to short out the two channels when you power the unit up.

Step 27

Solder channel 4 (rear right) to the hole off to the upper left of the chip.

Step 28

Here is a shot of the leads coming through the bottom of the circuit board. After you solder, clip off the extra lead so it does not short out on the chassis when you reassemble everything.

Step 29

Place the bottom of the unit back on and test fit everything. Make sure the wires do not snag on anything. Reassemble the unit by following the disassembly instructions backwards. I ended up putting on and removing the heat sink several times before I got everything back together.

Testing the Unit

I was unsure about the results I was going to get with this modification so I made a point to perform some thorough tests. Unfortunately I don't have the greatest test equipment. I used a 10a 12v power supply and an RCA-to-1/8" jack converter to connect everything to my computer's Sound Blaster 16 card. I dropped in a CD with a pink noise track and loaded up TrueRTA.

I couldn't get anything remotely resembling a flat signal so I ran some tests on my Clarion DRX9575rz head unit. I know the unit has a fairly flat response curve but it wasn't displaying well through my system either. After hours of tweaking and calibrating I decided to simply compare the factory head unit's response relative to the response provided by the Clarion unit. This turned out well and gave me some curves that made a little sense.

Test 1 - David Navone LOC

The David Navone LOC is a pretty good unit for converting speaker level outputs to high-voltage line outputs. The factory amplifier chip picked up a 60Hz spike from the power supply so ignore that. The three curves shown are the factory head unit at 1/4 volume, 1/2 volume, and 3/4 volume. As you can see the response curve is absolutely horrible at 1/4 volume almost as if there was some sort of loudness affect. At 3/4 volume the response curve smooths out but the bass response plummets below 100Hz. Without some sort of bass boost using a LOC will not give you desirable results.

Test 2 - New Pre-outs

In this graph you can see that the frequency response at 1/4 and 1/2 volume still sucks. However, we see a great improvement at 3/4 volume. We have a flat response down to 40Hz and a reasonable roll off after that.

Test 3 - Direct comparison between Pre-Outs and LOC

Here are the 3/4 volume results placed side by side for comparison. Clearly the pre-outs take the cake with bass response.

Conclusion

Although this mod addresses the bass response issues with using a LOC connected to the speaker level outputs, it has one flaw. The signal strength obtained directly from the volume control chip is not strong enough to power aftermarket amplifiers. A line driver would be required to make the most out of your system. During my in-car tests, the factory rear speakers were just as loud as my front speakers being powered by an 85w x 2 amplifier and the bass was barely audible. Even when I turned the gains up all the way the amplifier could not produce enough sound to drown out the rear speakers being powered off 10w from the factory head unit.

The best solution to fix this and the response changes at different volumes would be to get a 1/2-din eq and mount it below the ashtray. You could set the factory head at 3/4 volume and use the eq volume instead.

As far as sound quality is concerned, the mod provides a much cleaner signal that is better suited for amplification. I listened to a few high-fi recordings and the mix was very transparent and the highs were much more detailed than with the LOC. The staging and imaging is not comparable to my Clarion unit with it's 20-bit DAC but I would put it on par with most entry-level aftermarket head units. I used to get noticeable hissing from my LOC but the line-outs do not produce any hissing even at full volume with my amplifier gain at 100%.