Hey guys...I want to pick your brains before I just go out and buy an amp to replace my factory amp.
Car is a 2006 Volvo S60R. I just did a CarPC conversion and I am getting some noise in 4 of the 5 channels. The 5th channel (center speaker) is now driven off a separate Alpine amp because the original Head Unit used to drive that speaker directly. I do not get noise in that speaker, and I use a simple stereo --> RCA cable to the amp for the Line-In.
My soundcard is a USB Sound Blaster 5.1. I was advised that avoiding on-board soundcards is better for noise reduction. I used to have an obnoxious amount of noise, until I isolated the power supply case from the PC casing. I no longer have the "whine" associated with engine noise, etc., but I still have a high-pitch noise that is quiet, but still noticeable when the music is OFF. Since my battery is in the trunk, that is my grounding point. The Alpine Amp, Factory Amp, and DC-DC PC Power Supply grounds are all tied to the negative terminal.
The tricky thing about my factory amp is that it uses a 5-wire input. One wire for each channel, and then one common Audio Ground....so for the outputs from the PC, I just tied all the grounds together and coupled it with the Audio Ground into the amp, but did not tie the Audio Ground wires to an actual ground.
I tried ground loop isolators for all 4 channels but that didn't really do much for me. Somewhere there is still a loop, but I am unable to figure
I already took a look at this thread...
http://www.diyaudio.com/forums/showthread.php?threadid=118769
Car is a 2006 Volvo S60R. I just did a CarPC conversion and I am getting some noise in 4 of the 5 channels. The 5th channel (center speaker) is now driven off a separate Alpine amp because the original Head Unit used to drive that speaker directly. I do not get noise in that speaker, and I use a simple stereo --> RCA cable to the amp for the Line-In.
My soundcard is a USB Sound Blaster 5.1. I was advised that avoiding on-board soundcards is better for noise reduction. I used to have an obnoxious amount of noise, until I isolated the power supply case from the PC casing. I no longer have the "whine" associated with engine noise, etc., but I still have a high-pitch noise that is quiet, but still noticeable when the music is OFF. Since my battery is in the trunk, that is my grounding point. The Alpine Amp, Factory Amp, and DC-DC PC Power Supply grounds are all tied to the negative terminal.
The tricky thing about my factory amp is that it uses a 5-wire input. One wire for each channel, and then one common Audio Ground....so for the outputs from the PC, I just tied all the grounds together and coupled it with the Audio Ground into the amp, but did not tie the Audio Ground wires to an actual ground.
I tried ground loop isolators for all 4 channels but that didn't really do much for me. Somewhere there is still a loop, but I am unable to figure
I already took a look at this thread...
http://www.diyaudio.com/forums/showthread.php?threadid=118769
What kind of output voltage is the PC card?
Early Volvo factory amps (80's-90's) by Clarion and Alpine expected a fairly low voltage. Higher voltages would cause noticeable hiss at low volumes, and a significant impedance mismatch can cause all sorts of noises. I may still have some info on those somewhere.
I have no idea what the newer Volvo products are like, but it sounds like they are still using a 5-pin DIN input.
Where is the factory amp mounted? Have you tried unbolting it from the chassis?
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