Elminating line level noise

Ok well I basically have my setup finally figured out and running the way I want it to, I finally figured out how to wire the true 4.1 surround (in 5.1 mode)

First off I have a Creative Audigy SE soundcard. The front and rear channels are connected to a 4-channel amp directly via mini to rca splitter cable. No noise on these channels.

Previously, I was simply splitting the front channel and sending it to my monoblock amp for the bass, but this was a half assed temporary solution. It worked, but I couldn't adjust the bass from the computer.

The reason I did it this way temporarily is because the voltage coming out the bass channel is insanely low and the bass was barely audiable.

Today I went out and bought a single channel line driver which I hooked up to the bass channel. It works perfectly, it amplifies the signal, problem is it also amplifies the noise.

It's really bad, it's a constant loud rumbling noise from my sub, basically what you'de expect noise from a sub to sound like....

Anyway now that all the background and bs is done, the issue at hand is how can I elminate this noise? The computer is at most 3 feet away from the amp, and I have a 6 foot mini to rca splitter running to the line driver, and a 3 foot RCA out of the driver to amp. I'm pretty sure this is part of my problem, but I can't find any shorter cables. Can I just take a big chunk out of the middle of the RCA cables to shorten them and crimp them together, or will that only make more noise?

Basically, what can I do to reduce the noise, this is line level noise, not alt whine.

Just thought I'd let you all know that I got it all fixed up.

Easiest fix ever, $15 ground loop isolator, done.

Now instead of a 6 foot rca splitter out of the soundcard to the line driver, then a 3 foot rca cable to the amp, I have about a 4 inch long rca splitter out of the soundcard, then that goes directly into the isolator, that goes directly into the line driver, and that goes to them amp with about a 6 inch long rca cable.

Absofreakinlutely no noise, I love it. Now that my amp is being fed the actual bass channel from a nice computer sound card that sound quality is just absolutely amazing. The bass hits so clean at just the perfect spots, and I can set the exact crossover frequency from the touchscreen without having to even touch the amp.

So for those of you with creative cards and weak bass, it can be fixed! Just make sure you cut your RCA cable's length down to absolutely as little as possible, use the sub channel not the mid channel, and most importantly if you have a group loop isolator hook it up BEFORE the line driver, that way it amplifies a clean signal instead of trying to sort through a loud *** noisy signal, which doesn't work at all.

Thanks for you post! I've been trying to find a solution to eliminate line in noise for too long. I have an Asus Xonar Essence XTS with two other computers going into its line in/microphone jack. The noise was always an annoyance requiring that I set the input jack’s volume level down to 5% to reduce the noise, but then the problem was that my main computer’s volume was much higher than the other two computers.

Once I replaced both standard computer stereo cables with ground loop isolator cables, my problem was solved. Now I have my line in volume set to 100% and all 3 computers have equal volume through my most powerful sound card. For anyone interested, I got the ground loop isolator cables at my local RadioShack for ~ $17.

He probably won't respond back, this is a 5 year old thread and he has not posted since 2008. But I'm glad you solved your problem! Posting your experience may help otehr swith similar problems.

BTW, welcome to MP3car :)