How to install an Amp on a Stock Infinity System. With pics!

[Dave57]

Prerequisite:
Mitsu infinity systems were introduced in 1994 after 10 years they are still in use in 2004. Don't know about 05's. The 95 RT/TT has a 2003 Mitsu Infinity System with a 6 disc in-dash changer and Diamond 661 component speakers with crossovers. The Diamond tweeters are mounted in the factory location and are a great improvement over factory in that you can hear them loud and clear. Note that my hearing is not so good anymore and even I can hear them. Factory infinity rears (6x9) but can they take the 50w RMS? I am happy with the existing system but... more power would be nice.

A Diamond D3400.4 (50watts x 4 RMS @ 4 ohms) amp was chosen for the task. http://www.diamondaudio.com/products...&line=3&model=

The idea here is to:
1. Put an aftermarket amp in an infinity system using the PERIPHRIAL MITAH a plug and play infinity to line out adaptor for Mitsu Infinity headunits (HU), that adaptor then plugs in to your upgraded amp.

2.Take some helpful installation pics.

3. Give a few pointers. Check out the under the seat amp fitment issues.

4. Also to investigate the infinity Hu amp turn on issue. A PERIPHRIAL LVT2 (low voltage amp turn on) was purchased to use if needed.

5. Checking into the factory HU power issue after removing an infinity amp is on tap.

6. Setting the gains on the amp via the digital multimeter to avoid clipping and speaker damage.

7. Later research will include the use of a PERIPHRIAL VEN4 that can be used to hook up stock or other radios to the line ins for the amp. This is for radios that don't have line outs. Great if you want that stock look (we shall see).


Tools:
Soldering Iron
Professional wire strippers. (You don't want to loose even a strand of the already thin factory wires).
14mm socket and ratchet
coat hanger
Electrical Tape
Drill
wire ties
screw drivers
Digital Multimeter
Flashlight
Water Then Cold Beer as a reward


The first order of business was to buy the amp, 8 Gauge Phoenix amp install kit, PERIPHRIAL MITAH and PERIPHRIAL LVT2. Ebay helped with all of the above for less than $200 for new parts! The Diamond Amp was chosen to compliment the Diamond Component speakers already in the car. I’m not trying to go more deaf than I already am, so I went for a modest increase in power over the factory 30w rating with probably 10x (?) less distortion. The Specs are:

Model # D3400.4
Type: Full Range
Channels: 4
RMS @ 4 Ohm: 50 x 4
RMS Mono: 200 x 2 @ 4 Ohm
THD: 0.05%
Crossovers: Low Pass, High Pass

Amplifier Life-Time Warranty

Immediately I took notice when I picked the amp up It weighed 18.4 lbs vs the 2.7 lbs wow!
The first order of business was to pull the passenger seat and match them up. This is the factory location of all 3000GT - Dodge… Infinity Amps. Once I got past the excitement of the whole size comparison, I knew this wasn’t the place to start. Add to the tool list a vacuum cleaner too!

Pics the 03 infinity system, 95 factory amp and Diamond amp comparison.

[Dave57]

I think the 101 degree heat 113 heat index and excitement got to me. It was time to start at a logical place running the power wires. The first task was to mount the fuse some 1/8 “ holes were drilled and some pop rivets were used. Next the battery ring terminal was crimped and soldered and the two ends of the wire that go into the fuse were tinned too. These were done inside too! There is a removable nut on the positive battery post to attach the positive to. It is good enough for a 40 amp max draw from the amp.

[Dave57]

The heat was so oppressive the final goal was to route the wire to an under the dash location and finish the ground wire. This turned into a project as the boost gauge line, boost controller line, boost controller wires, ARC 2 wires, and finally temp sensor wires for the compass, temperature, homelink with maplights mirror were there too. This was a real cluster F… . The wire loom had to be replaced too for the wiring under the hood. So some new 300 degree wire loom was installed. The C F was then cleaned up too.

The best way to run the amp wire was via the old coat hanger trick so I pushed the coat hanger thru the already crowded firewall grommet from the inside taped the wire and pulled it back thru the firewall. Works every time! Finally the amp wire power wire was encased with the loom too.
Pics

[Dave57]

Finally the days end was within sight all that was left to do was hook up the ground wire and put wire ties on the wires. I’m sure this cars chassis can support a 40 amp ground as everything is in great shape including the ground wire to it but it may not handle much more with out a separate ground wire to the power source. So a spot was cleaned for the connection with an air grinder. Then a non corroding self tapping screw was used. This connection is important so a clean tight connection is a must. Finally done for the Day!

[Dave57]

Damn Should have finished it on Saturday it’s even hotter today (104)!

The first order of business today was to check on the blue wires in the amp plug. There have been reported instances of the stock radio not working after the amp was pulled. So both wires were checked with the ignition off. Both had 12.3 volts a jewelers screw driver was uses to contact the pin as the probe was too big. So this car was not going to have a radio issue as there is always power here. I can’t see why the issue exists as these are a constant feed VS the switched power the radio gets?? Anyway the cure is to jumper the two blue wires. I suspect the battery voltage was down slightly due to the door being open with the interior lights on for hours on Saturday. I was working under the dash on Saturday and needed all the light down there I could get. Other wise I would remove the screw on the door switch. This also eliminates the key in the ignition noise. Thanks to my son for this idea. Also this car has a maplight mirror for an additional drain. But at my age the additional light is starting to become welcome.

Then the amp plug was cut in an area to make any possible re-connection easier. The wires here were then tinned with solder.
Pics:

[Dave57]

The coat hanger trick works again as the power wire was fished under the rug. The wire was then tucked on the side of the rug where it wouldn’t encounter abrasion or foot pressure. Then I had an idea. How the heck was I to see the little adjustments with the amp after it was installed without problems so pictures were taken if needed.

[Dave57]

The factory infinity systems have the dash speakers on separate wires from the doors unlike the other 3S cars which are jumpered. So the dash speakers were jumpered at the amp so that a 4 channel amp could be used instead of a 6 channel like the stock infinity amp is. Since the Factory Infinity radios have only line outs the connection to an amp is made easy with the addition of the PERIPHERAL MITAH. This also supplies the aftermarket amp turn on power that exists in the infinity system.

Some amps use just relays to turn them on and some amps have a solid state turn on that uses very little current. The available amp turn on voltage is 11.19 (see pic)volts but because the output is from a low current type of solid state circuit it will not turn on a normal 12v relay. The easiest work around is to use a PERIPHERAL LVT2. It eliminates the hassle of using a separate relay you have to wire, it’s all done for you. Also may be used to sense audio signals to create an amplifier turn-on. I will check that feature out at a later date when I use the Peripheral VEN4 line output converter with a stock radio with an amplified output to feed the Diamond amp.

The PERIPHERAL LVT2 isn’t needed! The output is 10 volts (See Pic) with the amp in circuit. This amp has a built in delay circuit that is solid state and not a current hungry relay circuit. Although I’m sure it does eventually use a relay just not in the turn on input.

[Dave57]

Now that the amp was fired up and actually works great. It’s time to set the gains. Diamond adds a twist to setting gains in their instructions by telling you how to use a multi meter to detect clipping as not many people have an o scope. This is a cut and paste:

SETTING THE GAIN
The best way to set the gains on any amplifier is with an oscilloscope and test tone. Using
the scope will ensure the amplifier is not clipping and protect your system from being damaged
from being overdriven. If you have an oscilloscope and need help using it, feel free to call DAT
Technical Support for help.
Another way is with a multi-meter and test tone. Set the multi-meter to DC voltage, play
the test tone at 75% volume. Tune gains up until DC voltage is present, then back the gains back
down a little.
If an oscilloscope, multi-meter, or test tone is not available, find out the output signal
voltage of the head unit. Match the gain knob with that amount of voltage. It should be
between 500 mV and 5 V. If it is above 5 V, the head unit has too much signal and the amp will
clip even with the gain set at minimum. Turn system on and volume to 75%, if there is
noticeable distortion, gains should be tuned down some.

Its time to wire tie the wiring mount the amp and put the seat back in. For seat clearance issues and amp size specs. See this thread http://www.3si.org/forum/showthread....96#post3022596 Check out the before and after pics too The wires in the before pic are for the active aero spoiler. It looks like the stock infinity 6x9's will make it! Only time will tell.

Pics

[Dave57]

Thanks for letting me finish too!

Now it's time to edit two digital olympus cameras with the same pic #'s go figure!

[lamar69]

question...since you jumpered the dash speaker with the door speakers, would the wattage be split in two between the dash and the door speaker? causing the door to recieve 25 watts and the dash speaker to recieve the same to make up the 50 watt per channel?