head unit hiss (sync3)

[Emilbadal]

i don't claim to be an expert on it, but the main difference is that in a balanced setup there are 2 cables carrying a signal, unbalanced there is only 1. In our cars both the + and - cables at the factory amp carry a signal. Remember there is no RCA cable in the factory setup so the 3 wires vs 2 wires is not how it was designed to be transmitted.

SpArKy, how many unbalanced outputs does the JL CL-RLC provide?

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[SpArKy]

SpArKy, how many unbalanced outputs does the JL CL-RLC provide?

It has one pair of inputs, and 2 pairs of outputs, 1 fixed, and 1 controlled by the volume control which is the units primary purpose.

 

[Racemaster]

I want you guys to read this.
https://www.rane.com/note110.html
There are numerous pages on the RANE website that are filled with great information.
It will help you understand what is happening when you connect different pieces of equipment.
I use a rane deq60 in my high end home stereo setup to shape the sound,as my preamp has no tone controls.
It took me a bunch of tries of making cables to get rid of all the noise.
The same is with the mustang system.It is very sensitive to noise and ground loops.
I am glad the JL worked for you,but all you did was use it to "Break" the ground loop.Nothing really was fixed,just a work around.
RCA cables are unbalanced...period

 

[Emilbadal]

I want you guys to read this.
https://www.rane.com/note110.html
There are numerous pages on the RANE website that are filled with great information.
It will help you understand what is happening when you connect different pieces of equipment.
I use a rane deq60 in my high end home stereo setup to shape the sound,as my preamp has no tone controls.
It took me a bunch of tries of making cables to get rid of all the noise.
The same is with the mustang system.It is very sensitive to noise and ground loops.
I am glad the JL worked for you,but all you did was use it to "Break" the ground loop.Nothing really was fixed,just a work around.
RCA cables are unbalanced...period

Racemaster, I don’t have a DSP, just plain 4ch amplifier connected through RCAs to the ACM with RCA harness. I’m desperate to get the noise reduced because I cannot increase the gain above minimum before the noise becomes annoying and if I stay with the minimum gain, the input signal is not strong enough to get the speakers sound optimal. My amp ground resistance is literally 0.0( ground 4AWG wire is 2 inch in length). Even my brother’s GT350 with everything stock has this damn hissing noise. What would be your suggestion for me to get rid of this ground loop hiss?

 

[Racemaster]

Emilbadal..I know you have been chasing this for some time now.I wish I had a concrete answer to your problem.
Unshielded/poor quality cables could pick up noise.You could try that JL unit like sparky did.For $65 it is not going to break the bank.

 

[SpArKy]

I want you guys to read this.
https://www.rane.com/note110.html
There are numerous pages on the RANE website that are filled with great information.
It will help you understand what is happening when you connect different pieces of equipment.
I use a rane deq60 in my high end home stereo setup to shape the sound,as my preamp has no tone controls.
It took me a bunch of tries of making cables to get rid of all the noise.
The same is with the mustang system.It is very sensitive to noise and ground loops.
I am glad the JL worked for you,but all you did was use it to "Break" the ground loop.Nothing really was fixed,just a work around.
RCA cables are unbalanced...period

yeah sure, was aware it wasn't the correct solution. still not sure what that is though. am unsure how or if it's even possible to get a balanced signal into an RCA connector. bottom line is, i'm not going to waste any more time on it. i have minimal hiss now, like virtually unnoticeable at lowest volume and completely inaudible with music playing so i'm happy with it it's just the perfectionist in me wanting to resolve it. have also read here and elsewhere that there is always a slight hiss from the ford oem unit so the best solution if it really bothers me is to replace it.

 

[Emilbadal]

Has anyone with electronics background tore apart an ACM to figure out where is this defect coming from? I'm pretty sure it's internal, because during my search to find the source of the hiss, I literraly shorted the chassis of the ACM to the negative of the battery with a longA$$ aligator clip wire and still the hiss was coming through. Mind you I have two ACMs(one base and one HD|SAT) and both of them have the same hissing noise.

 

[krishelnino]

Thank you, It sounds incredible.

Low level signal just before factory amp.

Where do you stop? Probably somewhere between what you and I have done would please all but the most hard core golden ears. I initially fretted about the hiss until I realized I don’t just sit in the car while it’s off and no music is playing but the acm is still active. By the time the car is running and the seat coolers kick on with the ac, that hiss is a distant memory.

I plan on upgrading the Mustang’s Helix DSP to a Helix DSP Pro MK3 when it comes out and recycle the Helix DSP into my 30 Plymouth to make that rumble seat rumble in a way that was never intended.

yeah sure, was aware it wasn't the correct solution. still not sure what that is though. am unsure how or if it's even possible to get a balanced signal into an RCA connector. bottom line is, i'm not going to waste any more time on it. i have minimal hiss now, like virtually unnoticeable at lowest volume and completely inaudible with music playing so i'm happy with it it's just the perfectionist in me wanting to resolve it. have also read here and elsewhere that there is always a slight hiss from the ford oem unit so the best solution if it really bothers me is to replace it.

So does the Ford OEM unit have a slight hiss ? I have the same behavior as @UserName. The installer says it's the ACM but i've been trying to convince him it's an issue with the install itself. Basically there's a hiss when the ACM turns on and volume is 0. You can hear it when the car is stationary, once i turn up the volume i don't notice it. If i turn down the gains on the amp to very low (like 1/4th of max), i can barely notice it though.

 

[StangTime]

So does the Ford OEM unit have a slight hiss ? I have the same behavior as @UserName. The installer says it's the ACM but i've been trying to convince him it's an issue with the install itself. Basically there's a hiss when the ACM turns on and volume is 0. You can hear it when the car is stationary, once i turn up the volume i don't notice it. If i turn down the gains on the amp to very low (like 1/4th of max), i can barely notice it though.

Yes there is some hiss present in the ACM. I commented on setting gains. Here is the quote from page 1.

Have you adjusted the gain on your amplifier too high? You want maximum signal out of the head unit and minimal gain at the amplifiers to avoid amplifying noise. Start by turning your DSP volume down to get rid of as much hiss as possible. Then set your amplifier gains to zero and head unit volume to 80%. Then bring up the gains slowly on the amps to the loudest, cleanest point at which you would listen. Hopefully the noise floor is now reduced when listening at the lower end of the volume control. Forgot to add: You might need to go back and tweak the DSP volume again to reduce any amplification it might be doing to the noise floor.

 

[19-kilo]

Im getting the same static. Constant and does not change with volume changes on the head unit.

Im running JL C5653 speakers, JL 4 channel amp, and I have tried DSR1 and LC7i line out converter. Same issue persists even when I bypass the stock amp. So the sound is being generated by the head unit.

(no its not a bad ground on my aftermarket amp, the sound goes away when I try a new RCA source. )

I’m getting so much static out of the radio when it’s at 0 volume. It sounds like an AM radio at 25% volume all the time. I’ve tried almost every aftermarket part to fix this. No luck.

how do you get ford to assess the head unit? This can’t be right. It’s offensive unless I tune the amp to be at minimum gain (and the stereo is very quiet).

Is this something that can be fixed with settings or do I have a defective head unit?

 

[Emilbadal]

Unfortunately it's an issue that you have to use settings to balance between how much hiss you can tolerate and how much volume you want. On my setup I can increase the gain roughly to 5-7% before the hiss takes life of its own and become prominent. There is something really wrong with the ACM's engineering that causes this type of issue, or they really designed it like this to prevent people from changing speakers and amplifier(As if they had done such a marvelous job!!!) I heard stories that some were able to take their cars in and the dealerships changed their ACM and the issue was resolved(in some cases temporarily). I personally have thrown the towel long time ago and just try to ignore it

 

[krishelnino]

Im getting the same static. Constant and does not change with volume changes on the head unit.

Im running JL C5653 speakers, JL 4 channel amp, and I have tried DSR1 and LC7i line out converter. Same issue persists even when I bypass the stock amp. So the sound is being generated by the head unit.

(no its not a bad ground on my aftermarket amp, the sound goes away when I try a new RCA source. )

I’m getting so much static out of the radio when it’s at 0 volume. It sounds like an AM radio at 25% volume all the time. I’ve tried almost every aftermarket part to fix this. No luck.

how do you get ford to assess the head unit? This can’t be right. It’s offensive unless I tune the amp to be at minimum gain (and the stereo is very quiet).

Is this something that can be fixed with settings or do I have a defective head unit?

Unfortunately it's an issue that you have to use settings to balance between how much hiss you can tolerate and how much volume you want. On my setup I can increase the gain roughly to 5-7% before the hiss takes life of its own and become prominent. There is something really wrong with the ACM's engineering that causes this type of issue, or they really designed it like this to prevent people from changing speakers and amplifier(As if they had done such a marvelous job!!!) I heard stories that some were able to take their cars in and the dealerships changed their ACM and the issue was resolved(in some cases temporarily). I personally have thrown the towel long time ago and just try to ignore it

After switching to fully active setup, there's enough power for each speaker (channel) so I've found a balance between tolerable hiss and volume level by adjusting gain levels in the Helix DSP. But yes constant background noise is still there no matter what

 

[NotMarc]

I believe I'm chasing this same problem. I purchased the JL converter that @SpArKy mentioned but need to try adjusting the input/output levels and amp gain somehow. I still am foggy on the balanced vs unbalanced problem and why it didn't improve immediately after connecting the JL adapter, but I'll continue to research.

I'm willing to paypal someone pizza/beer money in exchange for a working Dayton 408 tune in an S550. I can adjust crossovers and deal with EQ later. I'm beyond frustrated with it at this point.

@StangTime @Emilbadal

 

[Emilbadal]

I don't think the balanced or unbalanced theory is very accurate, my amplifier is capable of receiving high output/ speaker level signal and low level as well, but yet the hiss is there either with low level or high level signal, and also there has been way too many people with all kinds of processors and line output converters and Amp DSPs who all have the issue at different levels. So basically what I'm trying to say is that the ACMs are trash and there's no other way than adjusting the gain levels to balance the noise and signal ( I just got so frustrated that I set my amp gains to minimum and left it there). I have 2 ACMs, one from factory and one when I upgraded to Sync3 with HD Radio and SAT radio and both have exactly same issue. As I have mentioned before somewhere here, I tried even grounding the ACM to chassis and Battery even to no avail. Just be patient and lower your expectations(I know it's sad!)

 

[19-kilo]

I don't think the balanced or unbalanced theory is very accurate, my amplifier is capable of receiving high output/ speaker level signal and low level as well, but yet the hiss is there either with low level or high level signal, and also there has been way too many people with all kinds of processors and line output converters and Amp DSPs who all have the issue at different levels. So basically what I'm trying to say is that the ACMs are trash and there's no other way than adjusting the gain levels to balance the noise and signal ( I just got so frustrated that I set my amp gains to minimum and left it there). I have 2 ACMs, one from factory and one when I upgraded to Sync3 with HD Radio and SAT radio and both have exactly same issue. As I have mentioned before somewhere here, I tried even grounding the ACM to chassis and Battery even to no avail. Just be patient and lower your expectations(I know it's sad!)

Did you try a Mustang GT head unit (ACM) that does not have the engine noise module? Or use Forscan to turn off the signal coming out of the head unit?

I talked to a guy who makes custom harnesses and has been making sound systems for Mustangs for years. Hextall said there should not be static coming from the head unit if it has been configured correctly. He said the ACM is actually quite good and just needs to be setup correctly to turn off the Ford OEM engine noise and EQ.

https://www.harnessbyhextall.com

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