snuew
New Member
Posts: 3
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Post by snuew on Nov 26, 2022 6:02:32 GMT
Hi from New Zealand, my 2014 Golf MK7 Highline is Japanese spec (imported into NZ)
I upgraded to a Helix sub, and connected it to my own amp to power it, the issue I am having is the volume will only output up to 50%, and when I go beyond 50% I don't get any increase in volume out of the speakers, instead it just distorts. Now I know its not the Amp, as when I reset the head unit (i.e. hold the power for 10 seconds) it outputs up to 100% clean audio; so it seems like these is some sort of protection that when the car starts, it limits the volume output to 50%, but when I reset the head unit after the car has started, it outputs 100% and also sounds prefect with no distortion; so I'm hoping this is something I can code out of it.
Is there anything I can change to fix this? I am new to OBD11 long coding, but I use it often to scan and clear faults.
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Post by vwjap on Nov 26, 2022 8:04:59 GMT
Did you swap the mib by any chance?
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snuew
New Member
Posts: 3
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Post by snuew on Nov 26, 2022 8:13:34 GMT
no - everything else is stock other then installing the Helix and Amp. I'm guessing this is some sort of protection from the head unit only allowing the volume to reach 50% to prevent the speakers breaking, but when I reset the head unit by holding the power button for 10 sec, it outputs 100% as it should; its only when the car first turns on it does it, every time.
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snuew
New Member
Posts: 3
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Post by snuew on Nov 26, 2022 8:18:35 GMT
This is what happens.
I unlock the car, get in, put the key in and start the car, head unit lights up and plays music, but it's only outputting 50%, but then I'm able to reset it by holding the power button for 10sec, I get the VW logo screen as it reboots, then I play music and I get 100% volume. And this is every time I go to drive my car.
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Post by vwjap on Nov 26, 2022 10:54:26 GMT
Well there’s a couple of reasons why it would do that
Component protection (but you’ve not swapped mib)
Firmware (some had a low audio bug)
And I heard something about a tweeter loop (but that may have been on earlier RCD units)
If you disconnect the amp does it all work ok?
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Post by dv52 (Australia) on Nov 26, 2022 22:48:11 GMT
vwjap : Doesn't OP's problem suggest that there is an impedance mismatch between the various pieces of audio equipment (signal clipping)? The fact that OP can make the sound 100% during the reset process for the MIB might indicate that there is a software block imposed subsequent to the module boot-up. As you are aware, there is a bunch of channels in the hex5F module that determine the input gain for each audio function. I recall that you provided an excellent set of instructions on the Ross-Tech forum for modifying the gain values in these channels via the green-engineering screen (see HERE)
Do you think that this same process might be worth investigating in this instance?
Don
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Post by vwjap on Nov 27, 2022 8:23:54 GMT
Did I post that on Ross-tech? I don’t think I have a account there,
Anyhows
That’s the input levels so the levels going into the unit, it wouldn’t do much to the outputs to the speakers/amp
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Post by dv52 (Australia) on Nov 27, 2022 23:14:08 GMT
vwjap : OOOoops - my bad about Ross-Tech forum!!! My suggestion was prompted by OP's words "I don't get any increase in volume out of the speakers, instead it just distorts".
As you are aware, there are many reasons for amplifier distortion - but the problem might be signal clipping which can happen when an amplifier is either over, or under driven and it attempts to deliver an output voltage or current beyond its linear design limits. As I have said, this can sometime happen when audio components are connected together - but their internal impedance doesn't match.
Now, I'm not certain that this is the cause of OP's problems - but if the reason is that the amplifier input circuits are being over-driven (because impedance matching is not correct), maybe altering the amplifier input gain might help?
Again, total guess - but since your method is such an easy try, it might be worth a shot, perhaps?
Don
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