A/M headunit Mach 460 98 Cobra, no bass.

Chris98Cobra

Member
Apr 18, 2018
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SoFla
I searched and found many threads, too many as it became confusing. I went through many of them and seemed to cross most of the problems other people had off my list. Yet I'm still having, what appears to be a common issue.

98 Cobra with the Mach 460, with slave CD player. I am replacing just the headunit. I like the system but I want bluetooth streaming. I bought the 70-5510 Metra harness and a Boss HU with front and rear RCA outputs.

The radio only has blue (ant), yellow (mem/bat), red (power), and black (ground). It doesn't have a separate amp power out the guy I talked to at Crutchfield said to use the blue (ant) for amp because the Boss unit has power there all the time and works as an amp signal as well. Seemed strange, but ok. The other RC harness is pretty straight forward, rr, rl, fr, fl. No problems there as far as I can tell.

Radio powers up but it sounds like it's only coming out of the tweeters and the balance doesn't work. The sound sort of changes, but does not cut off one side or the other. Fade seems to work fine, but again only sound from the tweeters. Gets loud, but doesn't sound full obviously.

I tossed a few ideas out in my head but I don't know if I'm on the right track. Everything worked fine with the stock radio and cd player. Sounded great actually. I'm a punk/metal guy so I'm not looking to blow doors off. Just hear my music full and loud with good bass and highs.

I am wondering if the ant wire to signal the amp is the problem. Also I see the connector shows amp ground, which I don't have anything for. Also I didn't reconnect the two black chassis wires. One went to the frame of the radio the other to the frame of the CD player. Not sure if that's an issue.

Also when I switched around the RCA wires to the back of the radio, just for craps and giggles, I get the same results. I can mix them around and get the same sound no matter which ones are connected to which jack.

I think I covered most of it, any ideas would help.

Sorry for asking a question that's been asked a million times, but after searching and reading I didn't come across any solutions that I hadn't already corrected or tried. Except the ones I noted, lack of amp ground and using the ant wire to signal the amp.
 
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Does your new head unit have an adjustable 5 Band or more equalizer? You need one to set the frequencies manually since you lost that when the OEM head unit was replaced.
 
Going back to my ground questions.

Looking at the factory connectors I see the factory connector on the radio shows two grounds, one black and one bk/LG. When I look at the primary amps, both front and rear, they both also show ground pins bk/LG.

I assumed each amp was grounded to chassis at it's location, which I'm sure is still true. But I'm also wondering if the harness needs to have a completed ground signal from the radio to the amps. Which I would think I could just jump off the radio ground.
 
Mods, feel free to delete this thread. I figured out my problem.

If anybody has similar issues, check your rca pigtail in the Metra kit. It's a total pos. The pins are loose, I think they are installed upside down, but whatever. Ditch that thing. Either make your own rca connectors or pull the pins out of the shell on this kit and make your own connector.

I pulled the pins out and stuck them in the correct locations in the factory harness and everything came to life. Balance works, all the speakers work. Now it's just a matter of making my own connector.
 
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ill haven't found a
I searched and found many threads, too many as it became confusing. I went through many of them and seemed to cross most of the problems other people had off my list. Yet I'm still having, what appears to be a common issue.

98 Cobra with the Mach 460, with slave CD player. I am replacing just the headunit. I like the system but I want bluetooth streaming. I bought the 70-5510 Metra harness and a Boss HU with front and rear RCA outputs.

The radio only has blue (ant), yellow (mem/bat), red (power), and black (ground). It doesn't have a separate amp power out the guy I talked to at Crutchfield said to use the blue (ant) for amp because the Boss unit has power there all the time and works as an amp signal as well. Seemed strange, but ok. The other RC harness is pretty straight forward, rr, rl, fr, fl. No problems there as far as I can tell.

Radio powers up but it sounds like it's only coming out of the tweeters and the balance doesn't work. The sound sort of changes, but does not cut off one side or the other. Fade seems to work fine, but again only sound from the tweeters. Gets loud, but doesn't sound full obviously.

I tossed a few ideas out in my head but I don't know if I'm on the right track. Everything worked fine with the stock radio and cd player. Sounded great actually. I'm a punk/metal guy so I'm not looking to blow doors off. Just hear my music full and loud with good bass and highs.

I am wondering if the ant wire to signal the amp is the problem. Also I see the connector shows amp ground, which I don't have anything for. Also I didn't reconnect the two black chassis wires. One went to the frame of the radio the other to the frame of the CD player. Not sure if that's an issue.

Also when I switched around the RCA wires to the back of the radio, just for craps and giggles, I get the same results. I can mix them around and get the same sound no matter which ones are connected to which jack.

I think I covered most of it, any ideas would help.

Sorry for asking a question that's been asked a million times, but after searching and reading I didn't come across any solutions that I hadn't already corrected or tried. Except the ones I noted, lack of amp ground and using the ant wire to signal the amp.
I'm experiencing the same issues with a kenwood receiver. Everything seems to work but not like it should. It's like I've bypassed the amps completely. I've found a few solutions on you tube and other sites but there wire are a different color or they're saying to use ground wires in the rca harness which would require splicing into that harness. I'm still looking for a definitive solution. will let you know if I have any luck. Please do the same if you come up with something.
 
I would focus on your RCA jumper. The factory connector has small female pins and recesses around those pins that allow the male pins in the aftermarket jumper to go into the recesses and not in the female part of the pins, yet you can still put the two connectors together making you think they are connected. I ended up removing the pins from the aftermarket connector and sticking them in the factory connector, one by one, and everything worked. My final fix was to just cut the factory connector off and hard wire the rca cables. I didn't want to cut up the factory harness, but there was no way to make the two connect properly.