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Yeah it weird, I’ve installed several headunit never had an issue like this before. Also I get a slight tump , not loud when the system powers on. Has to be something with the blue/white remote wire or ground. All black wires are grounded together.
Can you not disable the preamp on the head unit? You didn't mention if you tried that
 

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Discussion Starter #66
Its been a bit, so I had to go back to my old install thread, but even the incartec setup had some initial feedback issues, but since the harness has the ability to modify the amp gain, it was easily resolved. I think, to swedespeed7's point its likely headunit specific.

Some folks had great feedback on the Connects2 harness, others had what you describe (hissing, buzzing, etc.) I was worried because the factory amp does not have gain adjustment, and on previous car's I've run into similar audio issues not being able to adjust the gain. I felt it better safe than sorry and went with the InCarTech harness.

For the OP, I would suggest disabling the built in amp on the head unit and see if that helps.

Below is my feedback from my original install:

- Adjusting Amp Gain
Before fully mounting the radio I tested it. When I first plugged it in the audio was overly loud on the lowest setting and there was hissing. My heart sank... but then I adjusted the gain on the amp harness and it sounds perfect. Zero hiss, no humming, not overly loud. The speakers are hooked up to the amp side of my head unit (not the pre-outs). I get the benefit of using the radio's built in amp, as well as the car's. It sounds awesome.
 

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Its been a bit, so I had to go back to my old install thread, but even the incartec setup had some initial feedback issues, but since the harness has the ability to modify the amp gain, it was easily resolved. I think, to swedespeed7's point its likely headunit specific.

Some folks had great feedback on the Connects2 harness, others had what you describe (hissing, buzzing, etc.) I was worried because the factory amp does not have gain adjustment, and on previous car's I've run into similar audio issues not being able to adjust the gain. I felt it better safe than sorry and went with the InCarTech harness.

For the OP, I would suggest disabling the built in amp on the head unit and see if that helps.

Below is my feedback from my original install:

- Adjusting Amp Gain
Before fully mounting the radio I tested it. When I first plugged it in the audio was overly loud on the lowest setting and there was hissing. My heart sank... but then I adjusted the gain on the amp harness and it sounds perfect. Zero hiss, no humming, not overly loud. The speakers are hooked up to the amp side of my head unit (not the pre-outs). I get the benefit of using the radio's built in amp, as well as the car's. It sounds awesome.

Yeah to me sounds more like feedback issues rather then volume issues. It is louder then say a normal headunit install I would do. But you can lower the source gain for each( cd, fm, usb ect). I will check the manual to see if I can turn off preouts.
 

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I think I would be able to solder on rca leads to the speaker wires of the connect2 harness and plug them into the preout front and rear. That would work and still allow me to use the factory amp. Hooking directly to the high level of the headunit is having two amp power the system.
 

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Discussion Starter #70
I think I would be able to solder on rca leads to the speaker wires of the connect2 harness and plug them into the preout front and rear. That would work and still allow me to use the factory amp. Hooking directly to the high level of the headunit is having two amp power the system.
Hey guys since I already have money and time invested in this harness and install. To simplify this, could I just add the pac audio 4ch lineout converter? It has a gain control on the unit like the other wire harness others recommend.
https://pac-audio.com/catalog/audio-interfacing/lp3-4
I would start with connecting to the RCA leads and running them to the pre-outs and see if that helps. I think your issues are because you are using both the amp on your aftermarket unit, and the car - and with no adjustment physically in the Connects2 harness or via software on the headunit (some radios allow lowering or disabling the internal amp output - I guess yours doesn't?), you are getting that feedback.

If you connect to the PRE-OUTs on your headunit, then you should be by-passing the radio's internal amp altogether and only using the factory one. This would be a good starting point.

If that doesn't work, I would then try an RCA ground loop isolator on your new RCA connections. Some folks on this board have reported success with the PAC SNI-1. And they can usually be had for under $5. (Research this, from what I recall the PAC is better with alternator whine and the like, and less with constant feedback as you describe, but I'm not entirely sure.)

Lastly, I'd then look to implement a gain adjuster like the LocPRO you linked to. But the RCA pre-out connections on your head unit... they should already be no or low wattage, in which case adjusting the gain probably won't make a huge difference...

You could look into a unit that connects on the high (speaker) side of the radio and can act as a gain adjustment between the radio and the Connects2. Plus that way you would get to use both amps. That's how the incartech unit works.
 

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I would start with connecting to the RCA leads and running them to the pre-outs and see if that helps. I think your issues are because you are using both the amp on your aftermarket unit, and the car - and with no adjustment physically in the Connects2 harness or via software on the headunit (some radios allow lowering or disabling the internal amp output - I guess yours doesn't?), you are getting that feedback.

If you connect to the PRE-OUTs on your headunit, then you should be by-passing the radio's internal amp altogether and only using the factory one. This would be a good starting point.

If that doesn't work, I would then try an RCA ground loop isolator on your new RCA connections. Some folks on this board have reported success with the PAC SNI-1. And they can usually be had for under $5. (Research this, from what I recall the PAC is better with alternator whine and the like, and less with constant feedback as you describe, but I'm not entirely sure.)

Lastly, I'd then look to implement a gain adjuster like the LocPRO you linked to. But the RCA pre-out connections on your head unit... they should already be no or low wattage, in which case adjusting the gain probably won't make a huge difference...

You could look into a unit that connects on the high (speaker) side of the radio and can act as a gain adjustment between the radio and the Connects2. Plus that way you would get to use both amps. That's how the incartech unit works.
Yeah I, going to start with soldering on rca to the harness speaker wires and hook to headunit rca preouts.

I went on and ordered the pac Audio 4ch high level unit just in case since I was ordering other parts.

I think I have a groun loop isolator somewhere, I will try that also.
 

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So I soldered 2set of rca on the wire harness and plugged them into the headunits rca preouts Front and Rear. All the buzzing and hiss is now gone. The volume level is pretty low since I’m only using the factory amp power alone. Seems like when you have this sound issue when using this harness, you have to add on the CTAMPPASSTHROUGH. Which reduces the gain level when connecting to high levels. But I think I’m going to hook up a aftermarket amplifier down the road anyways rather then buy that harness. Thanks again for your help guys.
 

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So I soldered 2set of rca on the wire harness and plugged them into the headunits rca preouts Front and Rear. All the buzzing and hiss is now gone. The volume level is pretty low since I’m only using the factory amp power alone. Seems like when you have this sound issue when using this harness, you have to add on the CTAMPPASSTHROUGH. Which reduces the gain level when connecting to high levels. But I think I’m going to hook up a aftermarket amplifier down the road anyways rather then buy that harness. Thanks again for your help guys.
Really cool, thanks for reporting back. Maybe the suspect was the hi-level outputs on your aftermarket head unit?
 

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Guys, I just saw this thread. I'll offer a basic word of advice that may save you some headaches.

You NEVER, EVER want to run the output of a power amp into the input of another, unless your life literally depends on it. Not only will you have level issues, but even with a level control it's a lousy idea.

If your head unit has built in power amps, you either use those (connect the head unit directly to the speakers and ignore the factory amp) OR use the pre outs (connect them to the factory amp).

Here is what happens if you run the high level ouputs of the head unit to the factory amp: The head unit preamp gets the signal to about 2-4V, depending on the unit. Then the built in power amp boosts it up to speaker levels. Now to properly feed that into the input of the factory amp you need to attenuate it back down to the 2-4V level. You have just pissed away all the gain of the first amp and added all the noise from it. So when you're done you have used 2 amps to obtain the same gain as a single amp but twice the noise.
 

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Hi guys, i have just installed it on my 08 9-3 works like a charm i am using the oem amps. honestly i can say the sound quality is great no noise or anything like that, i am having issues with the stalk adapter, it is not giving me the reverse output on the purple wire, it's driving me crazy as i have a convertable i dont really want to dismantle the whole care to get the reverse signal from the tail lights, i have also installed a wireless video transmitter so as not to pass the new cable. Can any on help?
 
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