RampantAndroid
Head-Fier
- Joined
- Jul 30, 2008
- Posts
- 74
- Likes
- 0
Hi all,
Not sure if car audio is allowed here or not; I didn't see anywhere better for my thread.
I have an Audi A4 that I had a system put in last year. It's an odd setup, as a bunch of European cars use an optical system called MOST; it allowed me to insert a device called a MoBridge into the loop, which takes the optical input, decodes it (it allows me to keep bluetooth and all that) and then spits out 8 analog outputs: 4 front, 4 back. It also gives me a 12V ignition output to trigger the amp turn on. From there, wires are run to the amplifier which has the 4 door speakers as class-d amps, and the sub amp which is class AB and has a HPF and LPF filter on it..
Explanation of the setup out of the way: I have a hissing noise. It's always there regardless of whether the engine is running or not, so I think it shouldn't be alternator whine. I do not know if the system is grounded to the body or not. The power comes in directly from the battery and has an inline fuse. Does this mean it is correctly grounded?
Turning the amplifier's gain down does change the amount of hiss. I'm assuming this means that the hiss is somewhere on the input side, right?
The wires for input, 12V ignition wire and the powered output wires are all run next to eachother. Could this be causing noise to be picked up in the input wires creating the hiss?
My next steps are to put an oscilloscope on the output of the optical DAC and see if it is outputting the noise itself. When I unplug the input wires, the hiss goes away, but I'm unsure if this is because the noise is coming from the DAC, or if it is because the amplifies senses there is no cable plugged in and turns off that channel of the amp?
Here are links to the equipment:
MoBridge/DAC: http://www.mobridge.us/products/most-analog-pre-amp
Kenwood amp: http://www.crutchfield.com/p_113X7005/Kenwood-Excelon-X700-5.html?tp=35808
Front speakers are Morel Virtus 2 ways: http://www.morelhifi.com/car-audio/virtus-3
Back speakers are Morel Maximos, iirc: http://www.morelhifi.com/car-audio/maximo/maximo-2-way-2
Thanks in advance!
Not sure if car audio is allowed here or not; I didn't see anywhere better for my thread.
I have an Audi A4 that I had a system put in last year. It's an odd setup, as a bunch of European cars use an optical system called MOST; it allowed me to insert a device called a MoBridge into the loop, which takes the optical input, decodes it (it allows me to keep bluetooth and all that) and then spits out 8 analog outputs: 4 front, 4 back. It also gives me a 12V ignition output to trigger the amp turn on. From there, wires are run to the amplifier which has the 4 door speakers as class-d amps, and the sub amp which is class AB and has a HPF and LPF filter on it..
Explanation of the setup out of the way: I have a hissing noise. It's always there regardless of whether the engine is running or not, so I think it shouldn't be alternator whine. I do not know if the system is grounded to the body or not. The power comes in directly from the battery and has an inline fuse. Does this mean it is correctly grounded?
Turning the amplifier's gain down does change the amount of hiss. I'm assuming this means that the hiss is somewhere on the input side, right?
The wires for input, 12V ignition wire and the powered output wires are all run next to eachother. Could this be causing noise to be picked up in the input wires creating the hiss?
My next steps are to put an oscilloscope on the output of the optical DAC and see if it is outputting the noise itself. When I unplug the input wires, the hiss goes away, but I'm unsure if this is because the noise is coming from the DAC, or if it is because the amplifies senses there is no cable plugged in and turns off that channel of the amp?
Here are links to the equipment:
MoBridge/DAC: http://www.mobridge.us/products/most-analog-pre-amp
Kenwood amp: http://www.crutchfield.com/p_113X7005/Kenwood-Excelon-X700-5.html?tp=35808
Front speakers are Morel Virtus 2 ways: http://www.morelhifi.com/car-audio/virtus-3
Back speakers are Morel Maximos, iirc: http://www.morelhifi.com/car-audio/maximo/maximo-2-way-2
Thanks in advance!
