2002 Mustang GT Vert Dual XDVDN9131 aftermarket head unit installation notes - Ford Mustang Forum
 
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post #1 of 3 (permalink) Old 02-23-2013 Thread Starter
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2002 Mustang GT Vert Dual XDVDN9131 aftermarket head unit installation notes

I know there is a ton of information about using aftermarket head units and components with the Mach 460 system in various years of Mustangs. I have in my head a plan of what I need to test and decide based on what I have done. I just did all of this work in the past 10 days or so, so I am putting this experience down into words on a post so that someone else might find it later and maybe it helps them. Maybe it's not a panacea of information, but there may be tidbits in here that help someone else understand what is going on with their system. That said, I'm not opposed to any feedback about my situation from anyone knowledgeable, in case some stuff I have said and/or assumed is wrong. Here goes:


Car: 2002 Mustang GT Vert
Stock with 6 Disc CD Changer Mach 460 system

New head unit: Dual XDVDN9131 (this was a Christmas gift). Based on reviews I have seen, this head unit would not be my first choice for multiple reasons (motorized screen, lackluster reviews, longevity, etc.). It was a nice gift though, so I installed it.

Installed the new head unit using a Metra 99-5026 dash adapter. I will note that the XDVDN9131 is a motorized fold-out display unit. It is adjustable for how far and at what angle the screen comes out to. With my 2002 GT Vert using the above referenced Metra dash adapter the screen has to be set at the farthest "out" position and also the most forward angle setting (the screen actually points down a little bit). With these settings the screen contacts the heater control/dash bezel frame but is within the "freeplay" range. If the screen is set to be in any farther or angled any farther back it will bind, the head unit will complain and it won't slide back into the head unit until a deep power cycle or long wait with no power. The trick is that you have to set the head unit screen controls when the unit is not installed because it binds on the default settings. Because the head unit retains the "forward/backward" and "tilt" settings for the display, this isn't really a problem unless you have to disconnect the battery or lose power for some reason. The head unit will internally reset to the default screen depth and angle. The screen will bind and complain if you try to open it unless you disassemble the dash and get the head unit into a position where it will open without binding so that you can adjust the depth and angle. This is not in any way Metra's fault. Their dash adapter works perfectly for adapting a single DIN unit into the stock Mach 460 radio space. The mechanized geometry of the XDVDN9131 just doesn't match well with the installation.

I also will comment on the parking brake lockout feature of the DVD display. Many people have heard of this lockout which prevents the DVD screen from displaying if the parking brake is not set. On many older and other units, this could easily be bypassed by running the parking brake signal wire (which comes from the head unit) straight to ground. With this XDVDN9131, this is not possible. Due to what may have been pressure from government agencies (or not), the XDVDN9131 requires you to cycle the parking brake if it detects that it is grounded when DVD is activated. I worked around this by wiring a push button switch into the center panel right next to the cigarette lighter/power port. The parking brake trigger line from the XDVDN9131 goes to one leg of the switch. The other leg of the switch is connected to ground. Now I can cycle the "parking brake" using the push button switch. One second on, one second off, one second back on and the screen activates. DISCLAIMER: I only did this installation in this way to verify that a bypass exists. I currently have the system properly hooked to the parking brake signal line as it is legally intended to be installed. I am not liable for anything that happens if you choose to bypass the parking brake lockout in the method described above, or any other method.

For the wiring, I started by using the Scosche FDK13B harness adapter (apparently compatible with the Metra 70-5519 harness adapter) and the new harness that comes with the XDVDN9131. Using a guide posted by mixedbreed02gt, I soldered and heat shrink wrapped various connections, starting by connecting all eight speaker wires (FL, FR, RL, RR + & -) to their appropriate leads on the Scosche harness and the new harness that comes with the XDVDN9131.

From my understanding of the Mach 460 system in my 2002 GT Vert, this system had a Digital Signal Processor integrated head unit that sends internally amplified speaker-level output signals to four tweeters, two in the door pods and two in the rear side panel speaker enclosures (this is a convertible). The system sends preamp outputs over a harness data bus line to the two rear amplifiers which actually drive all four "woofers" (two in the door kick panels and two in the rear convertible side panel speaker enclosures). The tweeters in all four locations are 2.5" (the same all around). The woofers are some type of shallow 5"x8" (haven't inspected them or bothered with them yet). I will differentiate this from my 1998 Mustang GT convertible which also has a Mach 460 sound system. In my 1998 there is another amp in the stereo/dash area that actually feeds all of the tweeters. My 2002 GT convertible does not have this and I suspect that Ford somehow integrated the tweeter amplifier into the head unit or the 2002 head unit is powerful enough to drive the four tweeters without an amp, although I question whether there is internal Digital Signal Processing filtering going on with the 2002 stock system (more info later).

By hooking up the four speaker wire pairs of the Scosche harness to the same four speaker wire pairs of the XDVDN9131 harness, these signals route to the 2.5 inch tweeters in the door pods and in the rear convertible speaker assemblies. These are head-unit driven speaker-level outputs.

The XDVDN9131 has five preamp RCA connection points. Two are for the Front RCA preamp outputs, two more for the Rear RCA preamp outputs. There is also a single subwoofer RCA preamp output.

I currently have the four speaker-level outputs on the head unit hooked straight to the four tweeter speaker pairs on the Ford harness via the Scosche adapter. The two RCA plugs from the Scosche adapter that hook to and provide signal to the rear Ford amplifiers (which power all four woofers, one in each door panel and one in each rear convertible speaker assembly) are hooked to the Front RCA preamp outputs on the XDVDN9131.

I noticed that, to me, the sound when running the new head unit sounds “flat” or “stale” in that there is not enough clear, high volume treble to match the bass and mids coming through the rear amps which power the four woofers.

I thought I might have blown the tweeters without using bass-blockers or other high pass capacitance filters on the speaker-level outputs on the head unit. That may still be true for the front tweeter door pods. For shits and giggles, I turned the fader all the way to the rear. This effectively eliminated the rear amps and all four woofers since they are driven from the RCA plugs which I have connected to the Front RCA preamp outputs. I didn't expect much sound, if any. Well, there was sound. It was coming from the rear 2.5 inch tweeters. It was quiet but once I turned the volume up on the head unit they sounded pretty good. I didn't really hear any popping or scratchiness that might indicate the tweeters were receiving bass that wasn't filtered out somewhere else (not 100% positive on the filtering of the factory Mach 460 head unit and speakers, but I suspect that a Digital Signal Processor inside the factory Mach 460 head unit does some filtering before sending outputs through the harness. In this case that would mean the tweeters are probably getting undue amounts of bass signal from my new head unit's speaker-level output lines).

I faded the signal gently from the rear toward the front, just a bit, until the bass was kicking through the woofers in an approximately appropriate proportion and balance to what was coming out of the rear tweeters (I couldn't hear the front tweeters because they would require as much power as the rear tweeters but would also cause all of the woofers to overdrive because the woofers are running off of the Front RCA preamp outputs on the head unit). The rear Mach 460 amps, to my knowledge, do not have adjustable gain. I can't use a potentiometer on them to adjust their gain to balance with the head unit speaker-level output.

TO DO:

Disconnect RCA plugs from head unit leaving all four speaker-level outputs connected.

Test for:
1) Fader/balance to each corner to verify that each tweeter is working and sounds like the others;

2) Sound quality from the tweeters in general, running together while playing various mixes of music styles to determine if the tweeters suffer from distortion caused by unfiltered bass passing to them.

Connect one of the RCA plugs from the Metra harness into the subwoofer output on the head unit.

Test for:
1) Is there an internal low pass filter in the head unit which only puts out certain frequencies to the subwoofer output RCA line? <100Hz? <80Hz? If so, it won't serve my purpose. The “woofers” in the Mustang are mid-range drivers as well.


Hypothesis:

The subwoofer RCA output on the head unit will be unusable for my situation because it will filter frequencies that I need to be passed to those woofers (which operate as mid-range drivers as well, from what I gather from my very basic and piecemeal knowledge about this sound system).

Anticipated possible solutions:

1) Re-solder the Scosche harness adapter to the XDVDN9131 harness so that all four tweeters are driven from either the Front or Rear speaker-level output connections. Then connect the RCA plugs on the Scosche harness to whichever (Front or Rear) RCA preamp outputs correspond to the speaker-level outputs that I'm not using. If using speaker-level Front to drive all four tweeters, hook RCA plugs into Rear RCA preamp outputs. This would allow me to use the Fader as a gain control to balance the tweeters and the woofers, IF the head unit will be okay driving four tweeters from either Front or Rear speaker-level outputs. Even with this option, depending on how the tweeters respond to being driven at usable power from the head unit, I am guessing I will probably need a high pass filter on the speaker-level lines to provide the best clarity from the tweeters.

2) Buy a 2-channel amplifier. Disconnect the rear Mach 460 amps completely. Adapt the Ford harness at the Mach 460 amps to feed the line-level signals from the RCA plugs at the head unit into the line-level inputs on the new amp. Steal the power and ground wires from the Mach 460 rear amp harness and use them for the new amp. Connect the Mach 460 trigger/remote line from the Mach 460 harness to the new amp's trigger/remote line. Then I should have an adjustable gain for all of the woofers and will be able to balance that loudness with the volume required on the head unit to effectively drive all four tweeters. This way I would still have quadraphonic sound through the speaker-level outputs to the tweeters but would also have the woofers pumping bass and mid-range. (I know this is a lot of "adapting" the Ford harness, but it would be easier to adapt then string new line as long as I know the color schemes for all of the harness wires and how they relate to the RCA plugs on the Scosche harness and the voltage, ground and trigger supplies on the Ford harness).


1998 Triple Black GT Convertible ("Mr. Mustang")
2002 Triple Black GT Convertible ("Number Two")

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post #2 of 3 (permalink) Old 02-23-2013
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Great write up

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post #3 of 3 (permalink) Old 02-23-2013 Thread Starter
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Update...

I did some more investigating tonight and I am posting my findings (for others to see and also for me to have this written down somewhere that I can refer to later).

I disconnected the RCA plugs (the ones in the Scosche harness) from the head unit. This left just the four speaker level outputs from the head unit connected. These four speaker level outputs drive the four 2.5" tweeters (one in each door pod and one in each rear convertible speaker enclosure).

I used the fade/balance on the head unit to verify that all four of my tweeters are working fine. There does not seem to be any inline filter near the tweeters, I'm guessing, because the bass adjustments on the head unit causes a noticeable change in the way the tweeters sounded (less bass giving, obviously, better clarity output from the tweeters).

I then connected the white RCA plug on the Scosche harness to the single subwoofer RCA output on the head unit. To my surprise, there is apparently not a sharp low pass cutoff on that subwoofer output, which I expected there to be. It sounded pretty good (to me, I'm not super picky). There does seem to be some lackluster mid-range performance, but I'm not concerned much. I was pretty happy with the results. There is a separate subwoofer gain control in the head unit software which I adjusted to blend the woofers into the tweeters. I couldn't really tell real well if all four woofers were firing (I had only connected one of the RCA plugs on the Scosche harness to the subwoofer output). The fronts definitely were working. I couldn't really tell if the rears were. I had guessed that the red and white RCA plugs on the Scosche harness would be a Right and Left output to the rear amps. I was apparently wrong.

Just to be thorough, I hooked the subwoofer output to the other Scosche RCA plug (the red one). It still sounded good, but the door woofers weren't firing now. I could tell that the rears definitely were though.

It appears that the Red RCA plug on the Scosche harness is not for a Right channel, but a REAR channel. The Red RCA plug leads to the system that fires the rear woofers. The White RCA plug is for the front woofers.

I will get a Y-RCA adapter so that I can plug both Red and White RCA plugs into the subwoofer output on the head unit. This should give me all four woofers firing. There is apparently another advantage to this hookup in that the bass and treble adjustments on the head unit didn't seem to affect the subwoofer output much, if at all. This is good news because I can turn the treble up and the bass all the way down on the head unit since the head unit is just driving the tweeters. It's a half-assed way of not using inline capacitance high-pass filters on the outputs, but if it sounds okay to me and the tweeters sound happy, I'm good with it.

I was definitely a bit pessimistic and discouraged last night with the extra stuff that I might have to do/buy to get this aftermarket head unit to work well with the factory Mach 460 speakers and woofers/amplifiers. I'm feeling much more optimistic now. It sounded pretty good to me running all four tweeters and only two woofers at a time. Once I get the Y-RCA adapter to get all four woofers firing I expect that it will sound fuller and richer.

1998 Triple Black GT Convertible ("Mr. Mustang")
2002 Triple Black GT Convertible ("Number Two")

Yes, I know it is snowing.
No, we are not putting the top up.
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