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Computer CPU noise bleeding into recordings?

N

Nyarlathotep

Inactive
Feb 5, 2006
8,987
10
43
West Coast of Canada
www.soundclick.com
#1
If you need an example just go to the soundclip link in my sig and listen to most any of the Swollen Pickle tracks.

The higher the gain on the pickle, the more bubbly noise there is. I really sounds like the noise I get thru my amp when I have the laptop AC powered and my computer hooked up for recording. As soon as I switch to DC battery power on the laptop the noise disappears from the amp.

I didn't get this before I got an active/buffered 4 channel mixer (AFAICT/IIRC). I basically am gonna use it to mix my 2 channel FX rig, but I had it made with 2 outputs so 1 could go to my amp and the other to my M-Audio JamLab USB interface.

So, my setup is Bass->FX->Mixer->Amp and JamLab.

I do have 1 thought on it: Since the noise is present at the amp when the laptop is AC powered, but not when its on batts, could it be some kind of ground loop? The JamLab is USB powered, so im wondering if thats where the noise is "entering" the signal, even tho its not coming out of the amp.

Hopefully this is enough info for someone to make a suggestion :D

QUICK EDIT: Oh, and the sound seems to only "appear" when Im playing a note on the bass.
 
#2
Have you or can you trade out some of the cables? Start with the bass' cable and work your way up the chain. Other than that, you have me stumped, and I'm a engineer (electronics, that is). But I haven't tried any direct to/thru the PC recording yet. I'm still stuck in the stoneage.
 
#3
My laptop has a two-wire power cord on its charger, and I have gotten some interference when I don't have a physical grounding wire hooked up somewhere along the signal chain. I was not doing recording when I found this out, but using my PC for audio measurements.
 
#4
fdeck said:
My laptop has a two-wire power cord on its charger, and I have gotten some interference when I don't have a physical grounding wire hooked up somewhere along the signal chain. I was not doing recording when I found this out, but using my PC for audio measurements.
Click to expand...

So, do you think it could be a ground loop/connection thru the USB connection to the JamLab.

The 1st thing I might try when I get home is recording thru the line in, instead of the USB interface. See if that makes a diff.

Since I don't get any noise like on the recording AT ALL thru my amp, except when the LT is AC powered Im gonna go out on a limb and say that my cables are fine.
 
#9
Ok, so I did some recordings using my Swollen Pickle.

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That is recorded thru my Line In. There is a little bit of comp noise if I hear correctly.

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And that is thru the USB. Definitely some noise. Listening to the recordings via the raw data in Audacity, none seem to have that noise (EDIT: on listening yet again knowing what to listen for, the USB has a little bit, and the line in has none), but as soon as I export to MP3 its there :hmm:

Bad LAME encoder + USB = :(?
 

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