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Stereo Information (Wiring, Upgrades, etc...)

Racemaster

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You did not connect the canbus lines to anything,did you?
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DAZZA

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I went back and read your post where you first mentioned the hiss. The fact that the hiss doesn't get louder with an increase in volume sounds like a "ground-loop" hiss. To verify this, I would remove your hand built cable and connect your headphones or a multimeter set to a low AC volts setting directly to the factory plug... if the hiss is gone, your cable may need to add a ground wire to the black or brown plug of your cable.

Although the diagram doesn't show a ground pin, I would suspect that the ACM is getting it's ground from the amp and now that the amp is not connected, the ground may be floating. Typically, a shield is a ground point, and the original diagram on page 1 shows pin 19 of the black plug as a shield. I'd connect a wire to pin 19 and while monitoring the hiss, touch the other end of the wire to the amp chassis which is still grounded and see if the hiss goes away.
Ok I did some more tests. The grey and brown plugs plugged into the factory DSP/Amp

The Black plug unplugged and connected to my mouser socket with my own rca cables on pin 8&7 and Pins 4&3. I have a noticeable hiss, as reported before.

I made a new connector just in case.

I tried a number of grounding tests chassis on the negative of the RCA etc - no sound

I unplugged left channel no sound at all coming out of right channel - that makes no sense.

I checked and rechecked my wiring and it is correct. I hope this diagram is correct.

eventually I used a ground wire disconnected the negatives on my RCA plugs and connected the ground to one channel RCA and the hiss went very quiet but still there a little?? i faded to the front and balance set to left and then right to confirm wiring is correct - confirmed it faded left and right.

all this makes no sense.

Can someone confirm this drawing is correct? how do run preamp outputs without this grounding issue?

Mumbles there is no pin 19 on the black? should I use pin 16?

Also want to note its a clean loud hiss not a buzz or hum which would normally indicate a poor ground or ground loop.

Is there anyone who has simply unplugged the factory amp plugged in their own wiring loom preamp cables on the black socket and run it directly to a power amplifier bypassing the factory amplifier completely - successfully?

Thanks
ACM Black Socket.png
 

mumbles

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Ok I did some more tests. The grey and brown plugs plugged into the factory DSP/Amp

The Black plug unplugged and connected to my mouser socket with my own rca cables on pin 8&7 and Pins 4&3. I have a noticeable hiss, as reported before.

I made a new connector just in case. Did you test the new connector?

I tried a number of grounding tests chassis on the negative of the RCA etc - no sound

I unplugged left channel no sound at all coming out of right channel - that makes no sense.

I checked and rechecked my wiring and it is correct. I hope this diagram is correct.

eventually I used a ground wire disconnected the negatives on my RCA plugs and connected the ground to one channel RCA and the hiss went very quiet but still there a little?? i faded to the front and balance set to left and then right to confirm wiring is correct - confirmed it faded left and right.

all this makes no sense.

Can someone confirm this drawing is correct? how do run preamp outputs without this grounding issue?

Mumbles there is no pin 19 on the black? should I use pin 16? Sorry, I should have been more specific... I was referring to pin 19 (or 16) coming out of the ACM in the diagrame below;

5.png

Also want to note its a clean loud hiss not a buzz or hum which would normally indicate a poor ground or ground loop.

Is there anyone who has simply unplugged the factory amp plugged in their own wiring loom preamp cables on the black socket and run it directly to a power amplifier bypassing the factory amplifier completely - successfully?

Thanks
I plugged earphones into both front and rear RCA outputs from the wiring loom so no factory amp or aftermarket amp and I hear a hiss through the earphones???
Are you using your self-made cable at this point or how are you plugging earphones into the factory plug?
 

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DAZZA

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Are you using your self-made cable at this point or how are you plugging earphones into the factory plug?
I have all the mouser plugs. Simply soldered a RCA Cable to Pins 8/7 and 4/3 with the correct polarity.

I have multiple spares so I made a new one and with neat short wires. I tested it with my meter its correct no shorts and the polarity is correct. I am stumbled.

I took a ground from pin 11 of the brown connector and used that as a negative for the preamp RCA's it works but very little volume and a little unclear, not sure it's correct.

I have a RCA to 3.5mm adapter connected to earphones - this is how I conduct the test.
I have checked this and its also correct, besides I also have run it to my power amp and I have same problem anyway.

Pin16 is a Canbus negative so I nervous to use this one.

Its so frustrating now I am of the mindset to change the head-unit out for aftermarket or connect a DSP after the factory amplifier.

I think I have a ACM issue, why it works with the factory amplifier has got me stumbled. It has to be a grounding issue but leaving all the connectors plugged in except the black connector should sort out any grounding issues with the ACM but it doesnt.

Do you think I should cut into the black plug with the pre-amplifier wires from the ACM with it plugged into the factory amplifier? This may be my answer. Take the signal with it all connected. This black plug does not have a earth connection point but something must be causing it to hiss when its unplugged.
 

Racemaster

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2 rca cables or 4 ? Are you using the rear channels?

Pin 8 is left front + / Pin 6 is left rear +
Pin 7 is left front - / Pin 5 is left rear -
Pin 4 is right front + / Pin 2 is right rear +
Pin 3 is right front - / Pin 1 is right rear -

Do not use the chassis ground for the rca connections.

RCAadaptor (Custom).jpg

RCAadaptor3 (Custom).jpg
 

DAZZA

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2 rca cables or 4 ? Are you using the rear channels?

Pin 8 is left front + / Pin 6 is left rear +
Pin 7 is left front - / Pin 5 is left rear -
Pin 4 is right front + / Pin 2 is right rear +
Pin 3 is right front - / Pin 1 is right rear -

Do not use the chassis ground for the rca connections.

RCAadaptor (Custom).jpg

RCAadaptor3 (Custom).jpg
Only 2 RCA, exactly as per your picture I have done the same. I only use Pin8/7 and 4/3

Should be simple and it is - cannot get more straight forward than that - so this tells me my issue is a problem with the ACM or you guys in the USA have something different in your wiring looms to the Aussie spec mustangs.

The Aussie spec has the factory amplifier in the passenger foot well compartment not drivers side. There has to be a difference.

I am going to cut into the preamp cable with it connected to the factory amplifier and tap off a pair of RCA cables leaving everything connected to the factory amplifier and see what happens as something in this black plug must be eliminating the hiss as the factory amplifier is not picking it up.
 

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2 rca cables or 4 ? Are you using the rear channels?

Pin 8 is left front + / Pin 6 is left rear +
Pin 7 is left front - / Pin 5 is left rear -
Pin 4 is right front + / Pin 2 is right rear +
Pin 3 is right front - / Pin 1 is right rear -

Do not use the chassis ground for the rca connections.

RCAadaptor (Custom).jpg

RCAadaptor3 (Custom).jpg
Given up on this... if I unplug 1 channel at a time the hiss goes awy and its a clean signal. having both rca plugged in the hiss is there.

I am going to install a DSP and connect it to the low level signal from the ACM and see if the output has a hiss. If not I can remove the factory amplifier and keep my DSP in its place this solves all my issues.
 

mumbles

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Given up on this... if I unplug 1 channel at a time the hiss goes awy and its a clean signal. having both rca plugged in the hiss is there.

I am going to install a DSP and connect it to the low level signal from the ACM and see if the output has a hiss. If not I can remove the factory amplifier and keep my DSP in its place this solves all my issues.
I'm glad you didn't cut into anything! It still seems like this is a ground issue... when you have everything plugged into the amp, the hiss goes away, correct? I think that is because when all the plugs are connected, you are picking up the appropriate ground on one of the pins... question is, which one? A semi-quick way to test this would be to unbolt the factory amp and pull it away from the chassis which should mean it's not grounded. If the hiss returns, then the amp is providing the ground to the ACM through one of the plugs.

What year is your GT? There have been differences noted between 15-16 years and 17 years, plus, yours is an Aussie version, so there is no guarantee the diagrams I used for my drawing match the wiring in your GT. The only way to be sure would be to measure the signals on each pin of the C2470 plug (blk).

Something else I noticed, in your post #539, there is a picture of a plug pin-out with highlighter markings labelled as pre-outs from the ACM, which should be on plug 2470. In the picture, the plug is labelled as C2385A, so something seems off there...?
 

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DAZZA

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I'm glad you didn't cut into anything! It still seems like this is a ground issue... when you have everything plugged into the amp, the hiss goes away, correct? I think that is because when all the plugs are connected, you are picking up the appropriate ground on one of the pins... question is, which one? A semi-quick way to test this would be to unbolt the factory amp and pull it away from the chassis which should mean it's not grounded. If the hiss returns, then the amp is providing the ground to the ACM through one of the plugs.

What year is your GT? There have been differences noted between 15-16 years and 17 years, plus, yours is an Aussie version, so there is no guarantee the diagrams I used for my drawing match the wiring in your GT. The only way to be sure would be to measure the signals on each pin of the C2470 plug (blk).

Something else I noticed, in your post #539, there is a picture of a plug pin-out with highlighter markings labelled as pre-outs from the ACM, which should be on plug 2470. In the picture, the plug is labelled as C2385A, so something seems off there...?
Hi Mumbles - Sad to say I did cut into the loom and had to resolder with heat shrink each wire, fortunately..I am a soldering pro having worked on a production line in my early days.

To answer your comment about when I plug it into the amplifier the hiss goes away - if this was the case there wouldn't be an issue - my issue is if only 1 channel is plugged into the amplifier there is no hiss as soon as I plug the other channel in the hiss is introduced other than the hiss the audio is clear and I can fade left and right. The polarities are correct with my wiring. I also tried to disconnect one channels negative etc to see if it creating a ground loop etc but nothing seems to fix it.

Since the hiss is not present when the factory amplifier is connected in the system it does tell me that one of the wires in the ACM to the factory amp is eliminating the hiss. (grounding)

My next move is to install my DSP in place of the factory amplifier using the factory amplifiers power source from the Brown connector and the low level signal from the black connector in the DSP and from the DSP to my power amplifier. My DSP has balanced differential inputs and takes anything from low level to high level signal. If this works my problems are solved and I can get on with building the rest of my system.

I have a 2017 Aussie spec mustang GT premium package. Getting to the wiring harness is so easy and accessible as its on the passenger side. I noticed when peeling back the black cloth of the wiring loom (black plug) there were some braided earth wire unconnected running through unconnected to anything. I checked with my meter and this earth wire is grounded...I take it that this to reduce interference pickup?
 

mumbles

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My next move is to install my DSP in place of the factory amplifier using the factory amplifiers power source from the Brown connector and the low level signal from the black connector in the DSP and from the DSP to my power amplifier. My DSP has balanced differential inputs and takes anything from low level to high level signal. If this works my problems are solved and I can get on with building the rest of my system.
I'll keep my fingers crossed for you!

I have a 2017 Aussie spec mustang GT premium package. Getting to the wiring harness is so easy and accessible as its on the passenger side. I noticed when peeling back the black cloth of the wiring loom (black plug) there were some braided earth wire unconnected running through unconnected to anything. I checked with my meter and this earth wire is grounded...I take it that this to reduce interference pickup?
That sounds like a shield loom, like you said, to reduce interference.
 

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I'll keep my fingers crossed for you!

That sounds like a shield loom, like you said, to reduce interference.
Update time.

I installed my DSP (JL-Fix-82) I had one lying around I would not have picked that product if I were to start from scratch but I had it anyway.

I connected the JLFIX power source from the factory amplifier wiring loom using the mouser sockets so it just plugs in. I also placed my 2 way crossovers into this wiring loom using existing speaker cables.

HISS is now gone. 4 Channel amplifier runs the 2 way components in the front and single 12 inch subwoofer in the rear.

Sounds fantastic so much better than the factory amplifier.

I would not have bothered with the JLfix if I did not have a hiss issue. I think that the differential inputs of the JLFIX must have sorted out the grounding issue as my amplifier connects both grounds from each channel together and maybe this is what was causing the issue? Same as when I used my earphones both channel negtives get connected together.

This explains why when I connected each channel on its own there wasn't a hiss and it was clean. but when both channels were connected the hiss was present. Had I had a amplifier that had each channel neagitves independent I would not have had this issue.

Now that I have conquered the problem and removed the factory amplifier. Its time to consider better components as I am not sure the ones I am running are that great.

Current setup is:
Single Channel DSP - JLFIX82
Pioneer GM-D9604 4 Channel amplifier Front 2 channels set as HPF rear set to LPF bridged to Subwoofer.
Subwoofer - ROCKFORD FOSGATE R1-1X12 SINGLE PRIME R1
Component Speakers - PP-CM650 single set installed in doors with dynamat
 

mumbles

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Update time.

I installed my DSP (JL-Fix-82) I had one lying around I would not have picked that product if I were to start from scratch but I had it anyway.

I connected the JLFIX power source from the factory amplifier wiring loom using the mouser sockets so it just plugs in. I also placed my 2 way crossovers into this wiring loom using existing speaker cables.

HISS is now gone. 4 Channel amplifier runs the 2 way components in the front and single 12 inch subwoofer in the rear.

Sounds fantastic so much better than the factory amplifier.

I would not have bothered with the JLfix if I did not have a hiss issue. I think that the differential inputs of the JLFIX must have sorted out the grounding issue as my amplifier connects both grounds from each channel together and maybe this is what was causing the issue? Same as when I used my earphones both channel negtives get connected together.

This explains why when I connected each channel on its own there wasn't a hiss and it was clean. but when both channels were connected the hiss was present. Had I had a amplifier that had each channel neagitves independent I would not have had this issue.

Now that I have conquered the problem and removed the factory amplifier. Its time to consider better components as I am not sure the ones I am running are that great.

Current setup is:
Single Channel DSP - JLFIX82
Pioneer GM-D9604 4 Channel amplifier Front 2 channels set as HPF rear set to LPF bridged to Subwoofer.
Subwoofer - ROCKFORD FOSGATE R1-1X12 SINGLE PRIME R1
Component Speakers - PP-CM650 single set installed in doors with dynamat
That is awesome, glad you overcame the hiss and did not give up!!!

I have a recommendation regarding equipment... DON'T rush into buying anything. If you aren't familiar with the site, check out the forums at Do It Yourself Mobile Audio ( http://www.diymobileaudio.com/forum/ ), read a little bit and find out what equipment fits your listening style and budget. Then you can pick up some good deals in the Classified section.

The VAST majority of the folks at DIYMA are great and don't sell junk... I've purchased my mids, subs & processor from the classifieds and have been more than happy with what I got.

Best of luck moving forward and keep us posted... build thread (hint, hint :))
 

DAZZA

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That is awesome, glad you overcame the hiss and did not give up!!!

I have a recommendation regarding equipment... DON'T rush into buying anything. If you aren't familiar with the site, check out the forums at Do It Yourself Mobile Audio ( http://www.diymobileaudio.com/forum/ ), read a little bit and find out what equipment fits your listening style and budget. Then you can pick up some good deals in the Classified section.

The VAST majority of the folks at DIYMA are great and don't sell junk... I've purchased my mids, subs & processor from the classifieds and have been more than happy with what I got.

Best of luck moving forward and keep us posted... build thread (hint, hint :))
Sounds like a plan Cheers
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