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Thread: Hard disk interference noise. (long)

  1. #11
    Low Bitrate Ritalin Kid's Avatar
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    Just remember the best way to get rid of ground loops is to make the ground for each component as short as possible and each component is on a seperate ground..

    As make sure every ground is a nice clean ground to the frame or chasis.. and the ground loop isolators are an expensive solution that barely works.. bought two for my car and they filter only about 50% of the noise.

    I also found that when I plugged my 95 watt AC-DC PSU into my inverter and ran my carputer I got much much better results as most inverters also do a good job of filtering that noise out as well.

  2. #12
    Maximum Bitrate MikeHunt79's Avatar
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    I eventually managed to get some time to try and sort this lot out, and I spent most of yesterday trying the things suggested in this thread, and then some. No progess tho.

    I tried gounding everything to the cars chassis. Front amp, rear amp, and carputa. There was still hard disk whine on the front amp's speakers, and rear amps speakers sounded great, as usual.

    I tried mounting the PC in the boot, and using the rear amps power cables for the PC's power. Still whining from the front amp's speakers.

    I then starting trying random things like using the wires that powered the headunit to try and power the front amp, then the computer... Still no luck.

    Finally, I tried my laptop (which i use to generate test signals, and test speaker phase and such), using the cigarette lighter socket power adaptor. First I had it connected to the rear amp, and there was some noise, but then I tried the front amp and it sounded awful! I could barely make out a test tone. Still, I was only using the laptop for testing, so i`m not really that bothered.

    Tried two other sets of rca cables - again, nothing changed.

    A few Other things I tried: Higher rated fuses and thick power wires. - Didn`t help.

    I`m starting to think that this isn`t a grounding issue... But what else could it be?

    I might take my front amp in the house, and try running just the computer and amp from a battery, and go from there.

    I've also got hold of an osilliscope, so i might be able to "see" what the noise looks like. It's definately hard disk releated tho.

    I`m stuck with using my portable minidisc player in the meantime.

  3. #13
    Low Bitrate Ritalin Kid's Avatar
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    Have you tried turning the gain down on both your amps?

  4. #14
    Maximum Bitrate MikeHunt79's Avatar
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    Good idea! I`ll give it a try tomorrow when it's light, then post here with the results.

  5. #15
    Maximum Bitrate MikeHunt79's Avatar
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    Ok, I eventually got round to turning the gain down on the buzzing amp (took almost a month but anyway...), and noise went down when I turned the gain down. I`ve now got the amp gain at the lowest level, and the computers volume higher, and it does sound better, but the noise is still really annoying, expecially when changing songs...

    I also now have a car battery in my room, so i`m gonna try it all out in the house when I get time, and see if I can sort it then.

    Any other ideas I couls try out?

  6. #16
    Low Bitrate Ritalin Kid's Avatar
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    Don't take this the wrong way but is your amp a kinda cheap car amp? On some of the cheap amps it doesn't seem to matter how low the gain is the noise is always there though the rule of thumb is to never turn the gain past 50% for clean sound.

  7. #17
    Maximum Bitrate MikeHunt79's Avatar
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    Originally posted by Ritalin Kid
    Don't take this the wrong way but is your amp a kinda cheap car amp? On some of the cheap amps it doesn't seem to matter how low the gain is the noise is always there though the rule of thumb is to never turn the gain past 50% for clean sound.
    I think you've hit the nail on the head. I tried my setup on a car battery in my room, and the buzzing was still there. Later on my mate came round, and said "Oh, I've got a car amp like that and I get the same thing. I've had it in 3 (!) cars, and the noise was there each time." which further proves your point. He also said his noise gets worse when he changes CD's, since he's using a CD changer and not an MP3player.

    It seems stange how this noise disappears when I use my portable-AA-battery-powered-minidisc-player tho. Maybe it's because it's not using the car battery for power?

    Now I know why you guys must hate Pyramid and other cheapy amp brands so much. Just for the record, this amp was made by "Ratho Hamburg", but I only payed about 15 for it, so I`m not too bothered really.

    Anyway, I'm off to buy a ground loop isolator, which should sort it. I`d rather loose a bit of top and bottom frequencies than have this damn noise all the time.

  8. #18
    Low Bitrate Ritalin Kid's Avatar
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    Before you spend the money on the ground loop isolator I would save your money. I bought 2 and they really didn;t help much at all.. definately not enough to justify the price.

    I would try getting a better quality amp with. Also I would see about sheilding you PSU better as well.

  9. #19
    Maximum Bitrate MikeHunt79's Avatar
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    I went in town yesterday, and they wanted 15 for a ground loop isolator, which is the same as what I payed for the amp; So I never bothered buying it in the in the end. Even the person in the shop thought they were a bad idea.

    In the meantime, I`m gonna try and mount the gain pots from the amp in the dash somehow, and leave the computer on full volume, in order to get the best signal to noise ratio I can. It should last me until I get a decent amp. Thanx for the advice, Ritalin kid.

  10. #20
    Low Bitrate Ritalin Kid's Avatar
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    NP. I'm still battling some small amount of noise with my carputer. The only problem with noise in a DC environment is that it could be caused by so many different elements.

    LMK how everything goes and if I get any more good advice from my neighbor I'll post it.

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