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I'm doing some upgrades on my new Mazda Axela 2.0 Metero Grey Mica.

This is the thread I show what I've done so far and maybe it should have been inside this section instead of interior and appearance since I did a shitload of sound deadening and audio.
https://mazda3revolution.com/forums/2014-2018-mazda-3-skyactiv-appearance-interior/234821-mazda-axela-3-2-0-sedan-2017-upgrade-thread-2.html


I've installed new Alpine speakers in the doors and with the stock unit they are sounding much better than the original paper cone throw-away things.. Then I went a step further and installed an Alpine PWD-X5 subwoofer/amp/dsp and got it running. But, there is a whine in the rear speakers. Mostly left rear but sometimes right rear too. Sometimes it disappears for a bit but always comes back. I've got the ground combined with an official Mazda ground point where more ground wires gather. (maybe this isn't smart and I need to use a separate spot for the Alpine system.) I've looked for other points but the Cable is not that long. One other options would be under the chair bolts but I don't know if this would be a good idea. The weird thing is just that it's only rears... and I thought if something is wrong with the grounding then it should be all speakers....

I tried to relocate my power line that is coming from the battery but no luck also.

It's clearly the Alpine unit that is making the noise and not the head-unit. Since the head-unit doesn't do it when connected alone. could it be the combination of the both being grounded in different spots?


Does anyone have any idea what I can try next ?
 

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2018 Mazda 3 GT called Coffee.
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My Alpine PDR-V75 works perfectly..Audiocontrol LC8..ran power from the fuse box with a Stinger interconnect. No sub though..that 350 watt line is ready for an enclosure in the hatch spare tire well though.
CK
 

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Meaning..it's not the component parts..it's your wiring work and how you are powering it. Stinger interconnects...look 'em up.
CK
 

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Discussion Starter #5
I clearly describe that I'm having wiring issues. Probably the grounding. Just stating it's the Alpine unit that's doing it. So it's something I'll have to fix there.

I'm not using RCAs since I'm using the high output of the Mazda Head unit to the Alpine. It's how this system works. First through the DSP then into the amp inside the Alpine.

I'm just not well informed how I should deal with the grounding. And why it's just the rear speakers.
 

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Stinger amp power kit 6000 4 GA w/ in line midi SK6241. This is what I have installed.

What DSP are you using? The AudioControl LC8 connects to the head unit and compresses/processes the signal into 8 channels. Maintains all factory installed controls and features and then feeds the amp a full signal for splitting off with the Stinger interconnects to the speakers/tweeters.
CK
 

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It's a 3 in one combination like the title states.

https://www.alpine-usa.com/product/pwd-x5

DSP, subwoofer and 4 channel amp.


Mazda Head unit high out -> DSP high in -> internal 4 channel amp -> speakers


Tomorrow I'll ground the head unit better seperately and find another grounding spot for the Alpine unit. See if that helps.
 

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Discussion Starter #8
I moved the ground wire of the Alpine unit and grounded the head unit once more. The problem comes and goes.

I have a feeling it still might be the power line. Since it's only left rear and the powerline to the Alpine unit is going close past it. Might be interference. The other speakers have no issues at all.
 

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Glad you got it sorted out and sorry I wasn't of more help.
CK
 

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Discussion Starter #10
Not sorted. It's only left rear. And only with the Alpine activated. Just using the head unit doesn't do this. So it's either the powerline having an influence on the speaker wire about 10cm away from it or I need to check the wiring part of the ground wire of that speaker between head unit and amp. Faulty ground connection maybe. Either way I'll probably get it sorted soon. Troubleshooting. If I find the solution I'll post it here.
 

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Discussion Starter #11
Sorry it's still both rear speakers. And mostly when the unit warmed up. When. It's cold it doesn't do it. Until I drive a bit and played a bit of music.
 

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I'm shielding the powerline with copperfoil now. It seems to help. Let's hope it was just that. And I'll finish shielding the whole cable.
 

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I'm shielding the powerline with copperfoil now. It seems to help. Let's hope it was just that. And I'll finish shielding the whole cable.
Does the wine change frequency with engine speed (alternator wine) or is it there when the engine is off (amp generated and coupled over to speaker wire close to power wires)? That will determine best rectification. In any case if you have to have power wires close to speaker wires cross them at 90 degree angle or as you found shield both the power wire and the speaker wires, only ground the shield on one end (at the amp), don't let the shield short to the car frame (I.E. don't make additional grounds), insulate shield wires at the end to ensure no grounds later due to vibration etc. Also are the speaker wires from amp already shielded or just straight runs of wire? If runs of wire then at least twist them together all the way or use shielded wiring for them.
 

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Discussion Starter #14
Useful info.

It's the whine does change with revving the engine and but not linear and not consistently.

Another weird thing is that sometimes it dissappears and then comes back. Mostly turning the engine off and on again does help. It sometimes magically dissappears. And randomly comes back.

Today it became louder when braking.. like the tone lowered. From very high pitch to lower pitch when releasing the gas (thus lowering RPM) and braking.

The wires are stock mazda speaker wires. Only the rear speakers are affected and only when using the Alpine amp/DSP for them. When using the stock mazda head unit there is no issue.

This tells me it must be the power line or grounding of the amp/DSP. I can't do much with the speaker wires for now. I tried to remove the power line away from the speaker lines as far as possible. But at some place it must still come pretty close. I might reroute it all together. Guide it through the midtunnel of the car instead of the sides. That must help.

One other thing is that I had to pull it through the rubber in the firewall where all other lines go through from the engine bay. I figured these could not be signal carrying lines though. I shielded the powerline as soon as it comes through there.

One last thought is that if it's not the power line then how can it be the grounding if the front speakers are ok on the same unit ? Also might it be the Alpine unit itself ?
 

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Also when turning off the engine it does often dissappear. But one time I thought I also heard it with the engine off. But I'm not sure if it anymore.
 

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First car and amplifier manufacturers go to great lengths to reduce the noise and effects of noise including from the alternator and other devices in the car. If it is from the alternator the frequency will follow the engine speed - it would double in frequency if you double the engine speed. It could be a defect in the car (partially failed alternator or battery - battery is the primary filter in the car electrical system, or bad electrical ground around the battery) or in the amplifier (bad amplifier in just the effected channels or just poor design etc).

I'd contact Alpine and see what they say - they should be able to point you in the right direction based on how you have hooked it up and the car. Just because the Mazda unit does not have this problem does not mean it is an issue in the car or wiring - maybe it is just better designed etc. You cannot do much about the Mazda wiring you are connecting to so just try and follow good practices in grounding and shielding of the wiring you have installed. In older days when alternators and amplifiers were not so good the first thing tried would be a filter that went into the power supply line - see what Alpine says.
Some tips here:
https://www.crutchfield.com/S-dhsJe6r2weM/learn/learningcenter/car/noise_suppressors_installation_guide.html
Alternator Whine in Car Audio
 
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