Amplifier, DSP And Power Distribution

One of the first things I made was power distribution relay for MP3 player. Let's face it, Trax (the manufacturer) is not a traditional car audio equipment manufacturer and it shows in their product. Instead of having constant +12 V and separate remote lead, they only have remote lead, which powers the player! I made a simple circuit with a transistor, diode, resistor and relay, which loads headunit's remote lead as little as possible and feeds mStation with fused +12 V.

All the car audio gear was bolted on the back of the enclosure. I fitted the amplifier in the middle so that power terminals are on the drivers side and signals leads on the passengers side. There was actually a point in this, because 0 AWG power wire is located on the driver's side and all the signals are on the opposite side.

I had plenty of wiring stuff from my previous installations: power distribution blocks, capasitor, fuse holders, wires, terminals, looming tube... Wiring the whole thing took only one evening.

I managed to place the equipment quite well to reduce wire lengths. DSP was mounted upside down to make the RCAs face amplifier's RCAs. As you can see from the picture on the right, RCA wires are quite short between the two.

This is a very simple way of mounting the car audio equipment. Yet the final result looks quite nice when the mask panel is on.

Update:

Alpine's DSP was replaced with Sony XDP-4000X which offers up to 72 dB/octave crossover slopes. By removing the plate in the center of the unit, you can connect a laptop into it for adjustments. Actually this is the only way to adjust XDP-4000X. I have serial cable running under the carpeting all the way to glove compartment to ease the adjustment job.

The system in the trunk was grounded in the motor antenna grounding point. It is a thin sheet of metal on the passenger's side of the trunk, but it turned out to be noise free and works very well in this system.

Front Speakers

The Diamond M3 series speakers fit perfectly to replace the stock speakers. Even the attachment points match. I removed the sockets from the original speakers in order to use stock speaker wires.

Dropped in. The tweeter can aligned and at first they were aligned towards the front seats, but after listening awhile they were adjusted towards the windshield. Now stereo image works better. I stuffed cotton foam behind the speakers as much I could to kill the backwaves.

Stock door speakers are 6x9" and Diamond's midbasses 6,5". I made 16 mm MDF rings to fit the Diamonds in.

Original speakers were equipped with foam insulators to protect the speakers from water. I moved those to the MDF rings.

As before, I used the original wire sockets and wrapped them inside a sheet of form to avoid resonances.

Voila! New midbass drivers fit nicely behind the door panel and even the window mechanism works perfectly.

The 2-way passive crossover lowpasses <300 Hz @ 12 dB/oct. for midbass and highpasses >300 Hz @ 6 dB/oct. for midrange/tweeter coaxials.

The crossover is build on a piece of MDF board, which is covered with gray mat. It is located under the passenger's side seat in the place where factory installed amplifier used to be.

Subwoofer Enclosure

The enclosure contains two sealed 38 l boxes. The walls are made of 22 mm MDF and all the seams are sealed with elastic urethane.

The first test fitting. The front wall is made of two 16 mm MDF pieces glued and screwed together. I don't have a router so I have to flush mount woofers this way.

The front wall was then finished with factory like gray mat and boxes were filled with cotton foam. Because 38 l per driver is a bit too small, a lot of foam was used.

Drivers in place. The enclosure is attached to car from the top and there's a 4x50 mm metal bar on the bottom (under the carpet) which is attached to the trunk opening frame and the enclosure.