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Yes, you are right. The connectors are keyed and thus that I I ordered will not work. Based on Mopar connector database, the same connector is in use with many Chrysler and Dodge models - e.g. Chrysler 300 MY2017 Premium 2 audio has the exact same connectors. I need to dig this a little further, since I'm sure that someone has made necessary connectors for at least some Chrysler / Dodge models.


About the ETM output modes, one thing is for sure: Base Hifi manages the volume control within the ETM unit itself. By forcing the HK Hifi into Base Hifi mode, the volume control will work correctly. It might be that in this case the ETM will be in amplifier mode, but it is still better than nothing.

When I get necessary connectors and JL Audio amplifier, I will dig deeper into this.

The picture shows the Giulia Premium audio 2 (= HK) connectors. Premium 1 (= Intermediate) has only the two larger ones.

After some googling:
I believe I found the both connectors:
I have them both now on order and will report when having tested these.

Also this harness has both 22-pin connectors (but not the small one also required with HK Amplifier). The harness itself is intended for other purposes, but it does not matter as long as it has the connectors required for the purpose.

 

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Is the ETM physically identical for the base model and HK? I assumed they were different i.e. one had built in amplification and the other didn't hence why I thought the HK might possibly not have any form of attenuating the line outputs.

The HK amp only has 4 audio inputs: Left, Right, Navi & Handsfree; or in brackets for the same inputs: Left Front, Right Front, Left Rear and Right Rear. Not sure which of these 2 combinations is correct but one would imply volume, fade etc is carried out at the amp and the other would imply volume, fade etc is carried out in the ETM.
 

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Also worth noting; my scope on the HK outputs shows no clipping even at full volume with 0dB test tones. It shows what looks like a slightly distorted waveform at all volume levels at the top of the sine wave peak but I get this when playing the same test tones through other systems at all volumes so may just be a scope resolution issue.

Also, if anyone is interested, the front door woofers have a high pass filter at about 40-50hz.
 

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Is the ETM physically identical for the base model and HK? I assumed they were different i.e. one had built in amplification and the other didn't hence why I thought the HK might possibly not have any form of attenuating the line outputs.

The HK amp only has 4 audio inputs: Left, Right, Navi & Handsfree; or in brackets for the same inputs: Left Front, Right Front, Left Rear and Right Rear. Not sure which of these 2 combinations is correct but one would imply volume, fade etc is carried out at the amp and the other would imply volume, fade etc is carried out in the ETM.
ETM is physically the same on base model and HK. It's just running on different mode and I believe proxi alignment byte 112 controls it. Also, the datasheet of amplifier IC used in ETM also implies there is an amplifier and line driver mode built into it.

Byte 112: ETM Line driver mode / amplifier mode toggle. Value 0x00 = Amplifier Mode. Value 0x20 = Line Driver Mode

Based on Alfa Romeo documents, HK Amplifier has four audio inputs:
  • Right front speaker
  • Left front speaker
  • Right rear speaker
  • Left rear speaker
Since all channels are separately fed from ETM, Fade etc. can be done on ETM itself.
 

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Interesting, that confirms they wired my amplifier up wrong and got the wires on terminal 7 & 18 the wrong way round making my right hand woofer out of phase.
 

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Interesting, that confirms they wired my amplifier up wrong and got the wires on terminal 7 & 18 the wrong way round making my right hand woofer out of phase.
If so how do you fix it and do you reckon if they made the same mistake on all the HK systems? I have very minimal knowledge of audio and associated electronics. I am more of a mechanical guy!
 

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Interesting, that confirms they wired my amplifier up wrong and got the wires on terminal 7 & 18 the wrong way round making my right hand woofer out of phase.
You are from UK and you have RHD car, I suppose? Maybe they changed also the wiring to "right hand" wiring... :)
 

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If so how do you fix it and do you reckon if they made the same mistake on all the HK systems? I have very minimal knowledge of audio and associated electronics. I am more of a mechanical guy!
For me it is very simple to fix I could swap the wiring anywhere along the chain between the HK amplifier and my aftermarket DSP / processor, amplifiers, speakers or just click the invert button on my laptop when connected to my DSP. Before making changes to the OEM wiring I'd need to confirm if it is wired out of phase or whether the error was corrected somehwere else along the chain or perhaps it was a deliberate change to the wiring to correct an issue elsewhere. I don't recall a lack of bass from the front door speakers when my system was still stock which suggests they were wired 'correctly' (i.e. in phase with each other) so I suspect it doesn't matter other than the wiring colours are wrong.
If you are not aware, if the woofers are wired out of phase with each other one will be going out while the other will be going in, effectively cancelling each other out causing a lack of bass when playing together (against each other). Easy to tell by changing the balance to the left completely, noting how much bass is heard, then start fading towards the right; if as soon as the right hand speaker is introduced you start losing bass then they are out of phase. Hard to tell with the rear subwoofer working at the same time though.
Sometimes you can deliberately wire a speaker out of phase as some crossovers will introduce a phase shift. Perhaps they noticed this after producing all the wiring diagrams and introduced the change at the amplifier outputs to make it sound better?
 

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ETM is physically the same on base model and HK. It's just running on different mode and I believe proxi alignment byte 112 controls it. Also, the datasheet of amplifier IC used in ETM also implies there is an amplifier and line driver mode built into it.

Byte 112: ETM Line driver mode / amplifier mode toggle. Value 0x00 = Amplifier Mode. Value 0x20 = Line Driver Mode

Based on Alfa Romeo documents, HK Amplifier has four audio inputs:
  • Right front speaker
  • Left front speaker
  • Right rear speaker
  • Left rear speaker
Since all channels are separately fed from ETM, Fade etc. can be done on ETM itself.
I've just had a thought; I could probably use the old HK terminal block I have to plug into the B connector and solder some RCA leads onto it then see if it works with the volume control etc. Or even easier, just connect my scope to it with a test tone playing on the head unit.
 

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For me it is very simple to fix I could swap the wiring anywhere along the chain between the HK amplifier and my aftermarket DSP / processor, amplifiers, speakers or just click the invert button on my laptop when connected to my DSP. Before making changes to the OEM wiring I'd need to confirm if it is wired out of phase or whether the error was corrected somehwere else along the chain or perhaps it was a deliberate change to the wiring to correct an issue elsewhere. I don't recall a lack of bass from the front door speakers when my system was still stock which suggests they were wired 'correctly' (i.e. in phase with each other) so I suspect it doesn't matter other than the wiring colours are wrong.
If you are not aware, if the woofers are wired out of phase with each other one will be going out while the other will be going in, effectively cancelling each other out causing a lack of bass when playing together (against each other). Easy to tell by changing the balance to the left completely, noting how much bass is heard, then start fading towards the right; if as soon as the right hand speaker is introduced you start losing bass then they are out of phase. Hard to tell with the rear subwoofer working at the same time though.
Sometimes you can deliberately wire a speaker out of phase as some crossovers will introduce a phase shift. Perhaps they noticed this after producing all the wiring diagrams and introduced the change at the amplifier outputs to make it sound better?
You could test the wiring up to the woofer to determine if the (+) and (-) alignment is correct from the connector up to the woofer element itself. Easy way to do this to use multimeter and extend the cable outside the car back to trunk to determine if (+) cable, for example, makes the loop.
 

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I've just had a thought; I could probably use the old HK terminal block I have to plug into the B connector and solder some RCA leads onto it then see if it works with the volume control etc. Or even easier, just connect my scope to it with a test tone playing on the head unit.
If you have an oscilloscope, you could check the level of audio signal in the wires between ETM and HK amplifier to see if the signal changes there when changing the volume on ETM.
 

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You could test the wiring up to the woofer the determine if the (+) and (-) alignment is correct from the connector up to the woofer element itself. Easy way to do this to use multimeter and extend the cable outside the car back to trunk to determine if (+) cable, for example, makes the loop.
Yes I will do this when my adaptor is ready for fitment and I strip the door down.
 

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If you have an oscilloscope, you could check the level of audio signal in the wires between ETM and HK amplifier to see if the signal changes there when changing the volume on ETM.
Yes, that was my thinking. I just had a look at the pins. I can just about get my scope on there as long as I use some insulation tape on the adjacent pins to ensure I don't short anything out.
 

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So with my scope on pins 6 & 17 (labelled as either Left Front or Navi In) I had no signal when playing a 1kHz test tone at any volume level.
When I moved the scope to pins 4 & 15 (labelled as Left Rear or Left In) I saw a nice clean waveform with about 10v peak to peak. This was consistent from volume 1 through to 38. The only change was when I went down to volume 0 at which point I lost the signal altogether.
So it seems the Alfa multimedia document that I got the pin outs from is correct for the first set of labels and the ones in bracket are not correct i.e. THIS IS CORRECT:
Pin 4: Left in +
Pin 15: Left in -
Pin 5: Right In +
Pin 16: Right In -
Pin 6: Navi In +
Pin 17: Navi In -
Pin 7: HFP In +
Pin 18: HFP In -

And the alternative versions in brackets are incorrect for me. i.e. THIS IS WRONG:
Pin 4: Left Rear +
Pin 15: Left Rear -
Pin 5: Right Rear +
Pin 16: Right Rear -
Pin 6: Left Front +
Pin 17: Left Front -
Pin 7: Right Front +
Pin 18: Right Front -


So this confirms that the HK amp controls the volume and fade to rear etc. And it looks more than likely that the Sat Nav and handsfree Telephone inputs are sent separately to the HK amp too.
 

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Also worth noting; my scope on the HK outputs shows no clipping even at full volume with 0dB test tones. It shows what looks like a slightly distorted waveform at all volume levels at the top of the sine wave peak but I get this when playing the same test tones through other systems at all volumes so may just be a scope resolution issue.

Also, if anyone is interested, the front door woofers have a high pass filter at about 40-50hz.
Did you measure this high pass filter with an oscilloscope on the speaker outputs?
 

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Did you measure this high pass filter with an oscilloscope on the speaker outputs?
No, I have all the speaker inputs going into my DSP and I was playing around with the summing and listening to test tones. With the output for the front door woofers being fed to my sub I can't hear any real output until about 40 to 50hz. I thought this was worth noting as I wasn't sure if there was any high pass filter on the front door woofers as I wondered if just a 6 channel high level converter would be sufficient but I was too worried there would be a filter on it so I bought a dsp with at least 7 channel inputs (my existing one only had 6 channels but more importantly no summing).
The output for the subwoofer must be used to feed into your amplifiers if you want any decent low frequencies.
 

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So with my scope on pins 6 & 17 (labelled as either Left Front or Navi In) I had no signal when playing a 1kHz test tone at any volume level.
When I moved the scope to pins 4 & 15 (labelled as Left Rear or Left In) I saw a nice clean waveform with about 10v peak to peak. This was consistent from volume 1 through to 38. The only change was when I went down to volume 0 at which point I lost the signal altogether.
So it seems the Alfa multimedia document that I got the pin outs from is correct for the first set of labels and the ones in bracket are not correct i.e. THIS IS CORRECT:
Pin 4: Left in +
Pin 15: Left in -
Pin 5: Right In +
Pin 16: Right In -
Pin 6: Navi In +
Pin 17: Navi In -
Pin 7: HFP In +
Pin 18: HFP In -

So this confirms that the HK amp controls the volume and fade to rear etc. And it looks more than likely that the Sat Nav and handsfree Telephone inputs are sent separately to the HK amp too.
Did you test whether you could see Navigation or park assist tones on those additional channels?

If this is really how it works, then it is important to identify the right proxi alignment configuration to force the ETM back to standard Hifi mode. Summing all those signals after the amplifier makes no sense at all. I will test byte 112 and others in action as soon as I get the connector harnesses I now have on order.
 

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Did you test whether you could see Navigation or park assist tones on those additional channels?

If this is really how it works, then it is important to identify the right proxi alignment configuration to force the ETM back to standard Hifi mode. Summing all those signals after the amplifier makes no sense at all. I will test byte 112 and others in action as soon as I get the connector harnesses I now have on order.
No I didn't bother trying it because parking tones etc come out of the speaker under the steering wheel which is what happens when you unplug the amplifier and you get a speaker system failure warning on the dash.
 

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So with my scope on pins 6 & 17 (labelled as either Left Front or Navi In) I had no signal when playing a 1kHz test tone at any volume level.
When I moved the scope to pins 4 & 15 (labelled as Left Rear or Left In) I saw a nice clean waveform with about 10v peak to peak. This was consistent from volume 1 through to 38. The only change was when I went down to volume 0 at which point I lost the signal altogether.
So it seems the Alfa multimedia document that I got the pin outs from is correct for the first set of labels and the ones in bracket are not correct i.e. THIS IS CORRECT:
Pin 4: Left in +
Pin 15: Left in -
Pin 5: Right In +
Pin 16: Right In -
Pin 6: Navi In +
Pin 17: Navi In -
Pin 7: HFP In +
Pin 18: HFP In -

And the alternative versions in brackets are incorrect for me. i.e. THIS IS WRONG:
Pin 4: Left Rear +
Pin 15: Left Rear -
Pin 5: Right Rear +
Pin 16: Right Rear -
Pin 6: Left Front +
Pin 17: Left Front -
Pin 7: Right Front +
Pin 18: Right Front -


So this confirms that the HK amp controls the volume and fade to rear etc. And it looks more than likely that the Sat Nav and handsfree Telephone inputs are sent separately to the HK amp too.
Based on earlier findings and what you tested it is likely that there is proxi byte, which controls the mixing behaviour on ETM and actually that is the final piece of puzzle I need for a clean amplifier installation; I want ETM to provide line-level output of audio signals, but these park assist / navi signals mixed to the line outputs already on ETM. And I want ETM to have volume control on, even though I will also need additional volume control on the amplifier itself.

So:
Byte 31 is the AMP Node "Present / Not present" toggle, this is confirmed.
Byte 47 is likely the Engine sound enhancement module "Present / Not present" toggle, this is to be confirmed.
Byte 112 likely controls the amplifier / line-driver mode and I want it to stay on "line driver" mode in my installation. So, no need to tweak anything here.
Now, it is likely that byte 121 controls the mixing behavior and/or the volume control on/off.

When I get the necessary harnesses, I will test all this piece by piece.

Amplifier I chose in the end is JL Audio VX600/6i. I only need 6 channels + subwoofer output, since I have an Intermediate system and no need for more channels.
 

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Probably worth mentioning for those that are not aware; the 10v peak to peak voltage I saw on the line out equates to a 3.5v line out voltage (RMS). Not bad considering 4v is considered a decent head unit output (which is the most you will get out of a 12v headunit without some sort of line output amplification; 12v peak to peak is 4v RMS).
 
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