Connecting Preamp to Amp .. Does the cable matter?

Discussion in 'Archived Threads 2001-2004' started by corey_allen, Dec 3, 2002.

  1. corey_allen

    corey_allen Extra

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    Hello,

    I'm trying to connect a marantz av550 preamp to a parasound hca855a amp. Whenever I connect the rca cables the speakers began to make a hum noise. I'm trying to figure out if it is the cables or something else. I have tried 3 different brands cables.

    1) assortment of cables i had lying around that come with dvd players and things.

    2) Radio Shack Gold Series Audio Cables

    3) Acoustics Research Audio Cable.

    The most expensive cable was the AR at $15. Should I try some more expensive cable Or Could it be something else. Anyone have a parasound amp? What Kind of cables are you using.

    Thanks for your help
     
  2. Jason Bell

    Jason Bell Stunt Coordinator

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    Hi Corey,

    I'm not familiar with Parasound amps but I've read about a million posts describing your problem. Its called a Ground Loop Hum. The easiest way it seems to diagnose this for sure is to use one of those cheater plugs its just a converter to switch your 3 prong plug of your amp power cord to a two prong. This lifts the ground of the amp. If the hum goes away then you can fix the problem from there. WARNING:Most people say this should only be used as a diagnostic and not as a permanent fix. Becaus with no ground if your amp shorts and you touch the housing you could get shocked. Someone else I'm sure will come along with suggestions for eliminating the problem safely. Hope this helps.
     
  3. corey_allen

    corey_allen Extra

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    I dont know if it is a ground loop hum or it. I dont know how the ground loop hum goes. But If i Just have the amp on with no RCA cables hooked up there is no hum. However as soon as I hook up my RCA Cables there is a hum. This hum occurs even with the preamp turned off.
     
  4. Guy Usher

    Guy Usher Supporting Actor

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    Corey,
    It iis probally a 60hz hum (ground loop) try a cheater plug on yourr amp, if the amp only has a 2 prong plug try turning it over if it will let you. Ground your amp to the pre-amp, you can loosen a screw on the back of the amp and pre -amp and use a small wire tto connect them.
    You have tried enough diffferent cables, it may not like tthe amp, put it on another to heck it,
    I too have a AV550 and they are noted for their silence.
    Try 1 cable at a time tto see if it does this with all or just one noisy output, Do you have a powered sub connected? Unnhook it. Make suure you have the power off when unplugginng and plugging in.
    Grond loop hum can get tedious. . good luck!!
     
  5. corey_allen

    corey_allen Extra

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    I should have made a search before I made my post. I read about other users and their humm. I found out when I unhook my Digital Satellite Reciever from the preamp the sound goes away. So I guess It is something with my cable. Going to see if radio shack has something to fix it.

    Thanks
     
  6. Guy Usher

    Guy Usher Supporting Actor

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    Does your AV5500 hum when only connected to your DSS by optical cable only, with mine I runn no analog cables to the 550 from DSS only opticall, my sound is either PCM or DD, never had it connected with analog audio only S-Vid, for taping I rran the analog cables to my tape deck, did havve analog audio from the VCR with no hum, mine has never had any hum or hiss very quiet.
     
  7. corey_allen

    corey_allen Extra

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    I typed Digital Satellite Reciever but I was thinking Digital Cable Reciever. I have digital cable and not satellite. I have to use analog for the analog channels and I use digital out for the digital channels. However I get the hum when I have just the Digital Hooked up or Just the analog hooked up.
     
  8. Guy Usher

    Guy Usher Supporting Actor

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    DCBs are extremly noisy, very poor sound, I jjust went thru 3 GI boxes before they put an old scruffy Motorola on iit, it is fine, looks like crap but works (AT&T broadband) very disappointed
    I amm in Columbus Ohio now, hope it is better. . .Thhinking abbout going back to BUD also disappointed with DSS had a little dish since 92 got so bad recently that I turned itt off, going OTA for HD we will see.
     

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