Mach 460 Question ...

mustang90

Founding Member
Feb 8, 2001
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I installed a pioneer head unit inplace of the factory mach stereo. Although im using the factory amplifiers the stereo sounds AWESOME! My PROBLEM is when i turn the stereo on it makes a quick crackle or popping through the speakers for a quick second. What could be causing this? I was told its just the way its gonna be?
 
It is doing this because your amp turn on from your new head unit is too high of amps. You have to get resistors (radio shack sells them a few pennies) and wire them into the line to lower the amps or the popping will continue. I know because mine was the same way, I don't remember what size of resistor I used. This is what has to be done to stop the popping, or wire in a remote turn on switch, but you'll have to always turn the amps on after the headunit comes on.
 
I recently installed a Pioneer DEH-P7700MP in my 2000 GT with Mach 460. The Pioneer head unit is a 12 volt system while the stock head unit is a 5 volt system. The voltage mismatch is causing the popping sound. You need to wire in a voltage regulator. Radio Shack part number 276-1770 will do the trick. It is a small square with three prongs (input, ground, output). The blue/white wire from the Pioneer head unit will be the input into the regulator. The output will go to the power antenna/amp remote turn-on wire of your adapter. Make sure you ground it as well. Soldering can be tricky because the prongs are delicate and close to each other. The voltage regulators are cheap, so buy 2 in case you make a mistake the first time (because I did)! I hope this makes sense. Let me know if you need some tips.
 

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If this is correct and it is just the remote turn on voltage it is a very easy fix. I would not just throw a resistor in line though. volage drop with a resister varies over curtent draw so it is not as static of a number if the current varies. I would use a 5v zener diode or voltage regulator.
 
I used a 1kohm resistor in my amp signal wire, and it works like a champ.

Some of the newer amps out there don't even use a remote wire anymore. They just power on when they detect signal.

Here's a harness that you need to wire the new aftermarket radio in without subs. If you plan on running subs, then you'll need to make sure either your new head unit has a low-pass crossover built in, or the amp has the option. Most newer amps have a switch that lets you select high ass, low pass, or full signal. If neither your radio or amplifier has a built in x-over, then you're running some old stuff, and need to get some in-line RCA low-pass crossovers. I saw them at Best Buy a while back.

Last thing you might need is bass blockers. If your new head unit doesn't have a built in crossover, then your tweeters will be getting full signal, and that sounds like butt. Get some of these and splice them in mid-line with the horns, and everything should sound awesome. You can choose whatever frequency you feel suits you best. Make sure you're blocking the bass to those tweeters! Good luck!
 
I have to agree with hognutz on this one. Ohm's law is V=IR (Voltage = Current * Resistance). If you put in a resistor, and the current changes, the voltage will change as well. You have a slight chance of still getting a popping sound. I tried my setup without a voltage regulator, and I had a popping sound. I then wired the voltage regulator, and the popping was gone.

Shiroelex, did you only put bass blockers on the tweeters? My head unit has a built in cross over, but it will block bass to all four front speakers. I still want some bass out of the bottom fronts.
 
ok so i installed the 1 kohm inbetween the amp turn on for the factory amplifier. When i turn the key on i hear no sound but then when i start the car i hear a slight scratch sound not nearly as bad as before. Im going to try the other suggestion. any other ideas?