Hello everyone,
I'm trying to complete a simple car audio setup, but I ran into some ground loop noise problems
First, I got rid of the HU, connected 12V ACC+/GROUND- and speaker wiring to the amp (Lepai 2020a+) and RCA --> 3,5mm to my phone - so far so good:
then I added a bluetooth receiver to the whole thing, it's a 5V (USB) device, so I connected a converter:
But now I can hear a noise which increases with RMP, (caused by a ground loop I guess). So I added a ground loop isolator:
That worked (the humming was gone) but unfortunately it also got rid of ALL the bass.
I don't know much about neither car electric system nor audio, but this all seemed like a simple task, until I ran into the noise problems with the bluetooth stick. By the way, when I connect the bluetooth stick to another power source (portable phone charger for example) the noise is gone.
Does anyone have any suggestions? Thanks!
I'm trying to complete a simple car audio setup, but I ran into some ground loop noise problems
First, I got rid of the HU, connected 12V ACC+/GROUND- and speaker wiring to the amp (Lepai 2020a+) and RCA --> 3,5mm to my phone - so far so good:
then I added a bluetooth receiver to the whole thing, it's a 5V (USB) device, so I connected a converter:
But now I can hear a noise which increases with RMP, (caused by a ground loop I guess). So I added a ground loop isolator:
That worked (the humming was gone) but unfortunately it also got rid of ALL the bass.
I don't know much about neither car electric system nor audio, but this all seemed like a simple task, until I ran into the noise problems with the bluetooth stick. By the way, when I connect the bluetooth stick to another power source (portable phone charger for example) the noise is gone.
Does anyone have any suggestions? Thanks!
Well, the GLI is this one
so I suppose the female RCA's get the signal from the bluetooth receiver, and the male ones plug into the amp?
Should I try reversing the wires on the GLI by cuting/soldering?
so I suppose the female RCA's get the signal from the bluetooth receiver, and the male ones plug into the amp?
Should I try reversing the wires on the GLI by cuting/soldering?
I was referring to positive and negative. Assuming that you only connected shields to shields, I don't think you could have the polarity wrong.
There are isolators that will decrease the bass output if they're connected backwards but not completely remove the bass.
Try connecting only one channel at a time to see if that makes a difference.
There are isolators that will decrease the bass output if they're connected backwards but not completely remove the bass.
Try connecting only one channel at a time to see if that makes a difference.
well, I checked, and everything's connected correctly. The bass is reduced, but maybe it's not as bad as it seemed at first, I'll look for a better isolator, I read somewhere that the cheap ones kill more bass than the more expensive ones.
But I also read that the GLIs are just a band-aid for the problem, not a proper solution.. I wonder how to ground everything properly, so that the noise is gone
But I also read that the GLIs are just a band-aid for the problem, not a proper solution.. I wonder how to ground everything properly, so that the noise is gone
The problem here is that the amp you're using isn't well suited for car audio. Similar amps that I've seen don't have the proper input circuit to compensate for ground loops. Grounding all components (including the power supply for the signal source) to the same point with short wires may help.
I see.
I already tried grounding everything like you said, but that didn't help even a little bit. I think that maybe the problem is in the usb stick bluetooth receiver, because I tried sticking it in my mac pro, connected it to the speakers and I still heard that humming and beeping, which is strange, because the speakers have separate power source from the computer (it worked fine when connected to my logitech pc speakers though).
In the future, I should probably invest in better quality components (for example, a 12V bluetooth receiver for car costs ~50$ at Crutchfield, I got this one for ~5$ from dx.com)
Anyway, thanks for your replies, this is a great forum!
I already tried grounding everything like you said, but that didn't help even a little bit. I think that maybe the problem is in the usb stick bluetooth receiver, because I tried sticking it in my mac pro, connected it to the speakers and I still heard that humming and beeping, which is strange, because the speakers have separate power source from the computer (it worked fine when connected to my logitech pc speakers though).
In the future, I should probably invest in better quality components (for example, a 12V bluetooth receiver for car costs ~50$ at Crutchfield, I got this one for ~5$ from dx.com)
Anyway, thanks for your replies, this is a great forum!
I read somewhere that ferrite beads could help, what do you think? because, to be honest I don't think it's the amps fault - when I plug it in my phone directly the noise is gone. Also, when the BT is not connected there is no noise.
I would try this Amazon.com: Milennia Bluetooth Dongle: Computers & Accessories but I'm not sure it would make any difference?
I would try this Amazon.com: Milennia Bluetooth Dongle: Computers & Accessories but I'm not sure it would make any difference?
The noise is gone because you don't have a ground for the devices that cause no noise.
The amp is almost certainly the problem. With no RCAs plugged into the amp, what is the resistance from the RCA shields on the amp to the amplifier's ground wire?
The amp is almost certainly the problem. With no RCAs plugged into the amp, what is the resistance from the RCA shields on the amp to the amplifier's ground wire?
I'll check that as soon as I can.
What do you think about this thread:
power supply - Ground Loop? Noise from 12v to 5v converter manifest in bluetooth audio source - Electrical Engineering Stack Exchange ?
The guy has exactly my setup and the same problem. Do you think the first advice could help (cut the RCA's ground from BT to amp) ?
I read here:
Fixing the Prius ground loop hum without sacrificing audio quality. | Streaming Freebies
that also the same noise issues with BT were fixed with ferrite beads, what do you think about that?
What do you think about this thread:
power supply - Ground Loop? Noise from 12v to 5v converter manifest in bluetooth audio source - Electrical Engineering Stack Exchange ?
The guy has exactly my setup and the same problem. Do you think the first advice could help (cut the RCA's ground from BT to amp) ?
I read here:
Fixing the Prius ground loop hum without sacrificing audio quality. | Streaming Freebies
that also the same noise issues with BT were fixed with ferrite beads, what do you think about that?
Also, take a look at this video at about 3min - the guy runs into basically the same problem with ground loop when using a bluetooth adapter with an amp, both powered from the same battery
http://youtu.be/-frBfOsSOR0
http://youtu.be/-frBfOsSOR0
- Status
- Not open for further replies.