[OTO335i]

Title correction: Ground loop noise isolator (Aux cable enhancement "pre-amp") recommendations

Hey guys,

Ever since I've owned my car I've been streaming my music straight from my phone to the aux port under the armrest (white wire pictured below) the sound from this wire is actually really good, I have zero complaints about audio quality with this wire.

I've tried a few Bluetooth receivers and they weren't working well until I got recommended this Anker Bluetooth Audio streaming device by forum member Bennye90 https://www.anker.com/products/varia...Drive/A3351011 which only cost me $30. I hooked it up and fished it through the center console and mounted it near my handbrake, I like this product because it has actual buttons that I can skip tracks forward and backwards without picking up my phone. The only downside is that I have to power it on every time I start the car (it's not that bad, takes 2 seconds and connects directly to my phone) and I'm hearing a buzzing sound in the speakers.

Can anyone inform me as to why the audio quality from my white wire would be amazing and the audio quality from the Bluetooth device isn't as good? Would it be because the white wire has four poles compared to three?

Does anyone have any recommendations for a booster that would be good to use?

Thanks

[Emilime75]

Is it a steady buzz that does not change, or more like a whine that changes with engine RPM?

Only 3 poles are required for 2 channel, unbalanced audio like your phone. The 4th pole is likely for a microphone, like if you were using it for a wired headset. It shouldn't make a difference in sound, except that it just might be a better cable than what the Anker comes with as far as interference suppression.

Ground loop isolators tend to distort the audio, often making it sound muffled. I wouldn't bother with one.

Couple of things you can try is moving the cable around to see if a different position makes any difference in the buzz, and slightly pulling up on the Aux cable to see if it's a jack/plug alignment problem and you're losing the ground.

[OTO335i]

Originally Posted by Emilime75

Is it a steady buzz that does not change, or more like a whine that changes with engine RPM?

Only 3 poles are required for 2 channel, unbalanced audio like your phone. The 4th pole is likely for a microphone, like if you were using it for a wired headset. It shouldn't make a difference in sound, except that it just might be a better cable than what the Anker comes with as far as interference suppression.

Ground loop isolators tend to distort the audio, often making it sound muffled. I wouldn't bother with one.

Couple of things you can try is moving the cable around to see if a different position makes any difference in the buzz, and slightly pulling up on the Aux cable to see if it's a jack/plug alignment problem and you're losing the ground.

It's a steady buzz. I do believe the 4 pole wire is better quality as the sound and bass is better when I use it (louder). Really it would muffle the sound? I have tried to move it around and pull it up a touch but the buzz remains.. I'm sure there's a product that would be good to help this.

Thanks for your input

[ctuna]

http://www.e90post.com/forums/showthread.php?t=1002984

[OTO335i]

Originally Posted by ctuna

http://www.e90post.com/forums/showthread.php?t=1002984

I forgot to mention that I have an android lol

[ctuna]

No matter what you have the aux works the same .
Left and Right stereo signal and a ground.
The Source signal can vary in quality and output though
which is a function of your source device.

[OTO335i]

Originally Posted by ctuna

No matter what you have the aux works the same .
Left and Right stereo signal and a ground.
The Source signal can vary in quality and output though
which is a function of your source device.

So I'd have to find a good portable amp/DAC to wire in before the aux is what you're saying? Sorry I though you were pointing me to the airplay unit.

[ctuna]

That thread I put up is one of the ones that discusses the limitations
of the aux the most . Basic conclusion is Aux is not a good input. It sounds
a little better with a good DAC. There are many threads discussing this.
Discussion on this starts at entry 78 in that thread .
If you have the Hi Fi or Base system the quality is even worse its bad plus bad. (If you have a base or hi fi system you need to upgrade it to something decent)

[OTO335i]

Originally Posted by ctuna

That thread I put up is one of the ones that discusses the limitations
of the aux the most . Basic conclusion is Aux is not a good input. It sounds
a little better with a good DAC. There are many threads discussing this.
Discussion on this starts at entry 78 in that thread .
If you have the Hi Fi or Base system the quality is even worse its bad plus bad. (If you have a base or hi fi system you need to upgrade it to something decent)

Yeah I have the logic 7. When I use the white cable from my phone to the aux port the sound is actually really good, as soon as I use the Bluetooth device the base and volume are a little lower with a small buzzing sound. That's why I was looking into these pre amps for aux input as some people have had success. Also, with these DAC units I see that they use a coaxial cable for the input, would I still be able to plug my aux from the Bluetooth unit into that?

[OTO335i]

I think something like this may work:
http://phpaudio.jigsy.com/passive-preamp

[Emilime75]

I wouldn't bother with that. A passive device can not amplify a signal. The only way it can have any effect is by placing a larger load(impedance) on the input(in this case your car's aux in). This is not the right way to do it. Yes, it may make it louder, but no, it will also add distortion and could quite possibly blow up the input stage on your head unit(although not likely). Also, the input on our cars can already be over driven easily, so adding a device like that would only "amplify" the problem.

[OTO335i]

Originally Posted by Emilime75

I wouldn't bother with that. A passive device can not amplify a signal. The only way it can have any effect is by placing a larger load(impedance) on the input(in this case your car's aux in). This is not the right way to do it. Yes, it may make it louder, but no, it will also add distortion and could quite possibly blow up the input stage on your head unit(although not likely). Also, the input on our cars can already be over driven easily, so adding a device like that would only "amplify" the problem.

I played with my EQ settings in my HU and it actually helped quite a lot with the sound and bass, the only thing I have left now is a small buzzing noise in the background. What would be the best way to get rid of that?

[Emilime75]

I'd suggest trying a different cable, but in your case that means a new BT receiver since the cable is fixed to the device.

[Emilime75]

Can also try powering the BT receiver from a different source. It just might be susceptible to the noise present on the car's USB power supply.

[OTO335i]

Originally Posted by Emilime75

Can also try powering the BT receiver from a different source. It just might be susceptible to the noise present on the car's USB power supply.

That's a posibility as well. I don't think I own 12V USB charger though lol so do I buy one 9f those to try it out or do I pay a little more and try a ground isolator.. Seems like it's a hit or miss with people as it does remove the buzz for some with more loss in sound or it works great with no "side effects".

[OTO335i]

I was reading this article and this would seem to make sense since my unit uses both the Aux and USB ports to function.
https://www.lifewire.com/whining-noi...x-input-534592

I theory, this explains that because the AUX and USB ports use different grounding locations that there's different ground potentials "an unwanted current flow, which can create noise, is introduced into the system".

So maybe I just need to trace the grounds for these ports and put them into one?

[Emilime75]

Originally Posted by OTO335i

That's a posibility as well. I don't think I own 12V USB charger though lol so do I buy one 9f those to try it out or do I pay a little more and try a ground isolator.. Seems like it's a hit or miss with people as it does remove the buzz for some with more loss in sound or it works great with no "side effects".

Regular wall charger and extension cord? Just for testing purposes, obviously.

[Emilime75]

Originally Posted by OTO335i

I was reading this article and this would seem to make sense since my unit uses both the Aux and USB ports to function.
https://www.lifewire.com/whining-noi...x-input-534592

I theory, this explains that because the AUX and USB ports use different grounding locations that there's different ground potentials "an unwanted current flow, which can create noise, is introduced into the system".

So maybe I just need to trace the grounds for these ports and put them into one?

Your problem very likely IS a ground issue. That's where I was heading when I asked about the type of buzz/whine you're hearing. It's also very likely that the aux ground, and the USB ground are in 2 different locations with the potential for a ground loop. I assumed you wouldn't be willing to take your car apart and rewire it...correct? So, looking at the possible left over fixes from best to worst, the isolator is worst, even though it may be the easiest. As far as the best, the list starts with a ComBox retrofit, which is the hardest and costliest. After that is a different BT receiver since others are using various products with no reported noise issues.

Have you tried having your phone and old audio cable, along with a USB cable plugged into the phone at the same time?

[OTO335i]

Originally Posted by Emilime75

Your problem very likely IS a ground issue. That's where I was heading when I asked about the type of buzz/whine you're hearing. It's also very likely that the aux ground, and the USB ground are in 2 different locations with the potential for a ground loop. I assumed you wouldn't be willing to take your car apart and rewire it...correct? So, looking at the possible left over fixes from best to worst, the isolator is worst, even though it may be the easiest. As far as the best, the list starts with a ComBox retrofit, which is the hardest and costliest. After that is a different BT receiver since others are using various products with no reported noise issues.

Have you tried having your phone and old audio cable, along with a USB cable plugged into the phone at the same time?

Originally Posted by Emilime75

Regular wall charger and extension cord? Just for testing purposes, obviously.

I could try it out that way, I thought about doing exactly that actually lol

Originally Posted by Emilime75

Your problem very likely IS a ground issue. That's where I was heading when I asked about the type of buzz/whine you're hearing. It's also very likely that the aux ground, and the USB ground are in 2 different locations with the potential for a ground loop. I assumed you wouldn't be willing to take your car apart and rewire it...correct? So, looking at the possible left over fixes from best to worst, the isolator is worst, even though it may be the easiest. As far as the best, the list starts with a ComBox retrofit, which is the hardest and costliest. After that is a different BT receiver since others are using various products with no reported noise issues.

Have you tried having your phone and old audio cable, along with a USB cable plugged into the phone at the same time?

I wouldn't mind taking my car apart to fix the issue as I do all of my own work anyways, the thing is I looked at the wiring for the AUX and USB inputs online and it doesn't seem like I can just open the wire up and pull the ground out to re-route it. Seems like these are fully covered the whole way through all the way to both ends of the connectors. I ordered an isolator just for the hell of it because it was inexpensive but we'll see what results it gives.. I would do a combo retrofit but I cannot do it since I do not have Idrive, I would have to add the whole dash with CIC and that doesn't really interest me since it'll cost a fortune.