Amp catching and amplifying noise. How to "isolate" this?

Discussion in 'Archived Threads 2001-2004' started by Levesque, Oct 16, 2002.

  1. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    White noise" problem...RMB-1095...
    I have a "noise" in tweeters and mid-woofer looking like a white noise. I tought it was a ground-loop, but after regrounding everything with an electrician AND the Sat technician, it's not. Cheater plug don't works, and lifting all the common ground is not working to. So NO GROUND AT ALL is still doing this mix of hissing and humming.

    I have a Rotel RMB-1095 for amp and Yammie RX-V3200 for pre-amp. After 7 hours (yes 7 precious hours of my life) of unplugging everything, then starting 1 cable at a time, I discovered that with ANY source (DVD-player, CD-player) at a time, or all together, and only the Sat decoder not in there, I'm in silence heaven. But if I only plug the coax feed in the sat decoder, and then ANY cable from the Sat decoder to the pre-amp (S-Video, component, digital coax, RCA), and 1 at the time only, I always get this "white noise" that I ear at 10 feets from any speaker!!!

    The Sat decoder tech is telling me that the amp is amplfiyng video noise, and the amp tech tell me it's the Sat decoder's fault. The sat technician tell me that he cannot do anything for me. Rotel and Rotel dealer are telling me it's the Sat company problem. So I'm stuck, and really tired of trying to solve this problem.

    It's not a ground-loop. So what is it, and how can I solve this?? I'm really desperate here. Please. I've swap 3 different satellite decoder, and 2 different company with the same results. I've run a cable directly from the Sat antenna to the decoder across a window to avoid ctaching noise from the house. I've add a HTS-3500 with same result, add a 20 A dedicated circuit with same result. I've swap all the cables (all of them!!) with same result.

    I really think the Rotel is amplifying a noise or something, because with only the Yammie, I'm in silence heaven. I've try a 2nd Rotel with same result (I had to take this 83 pounds back for nothing arrrgghhh).

    Just reach my dealer. He says it's not the first time he hear a story like this. He tell me it's the Rotel and Sat decoder association that is bad, and that the Rotel is amplifying ground noise!?!? Here is the solution he is offering me:

    1) Putting aluminium foil (or any conductive "paper") around all interconnects between the pre-amp and amp and jumping and grounding this aluminium (or conductive) thing. Really?? Wow!

    2) Buying a new pre-amp with XLR balance input/output. I don't really like this idea, lot of money not put aside for this...

    Is he kidding or the aluminium foil idea can actually work. XLR could really make a difference here??

    I can't change my satellite dish because I live in an isolated region, and the only way to get TV and HD-TV is with a satellite dish (cable cannot reach my house).


    I'm a pharmacist for god sake!!! Not a sound engineer!! All this money for this. I'm so disappointed.
     
  2. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Btw, forgot to add that all the ground-loop isolators are not working (like Mondial Magic Box or Jenson one) with a Sat antenna because they interrupt the electrical current to the antenna. I've try both, so I know. I've try the one from RatShack to (RF-isolator). Nothing works. Sigh...[​IMG]
     
  3. Chu Gai

    Chu Gai Lead Actor

    Joined:
    Jun 29, 2001
    Messages:
    7,270
    Likes Received:
    1
  4. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Thanks Chu. But I live in Canada (Quebec) and Jensen are sending me to a part dealer in Vancouver... They talk about a ground breaking device with gas in it, but they don't sell those... What are they talking about??

    It would easily reach 1000$ CDn if I go with Jensen solutions (and I don't even know if it will work)... At this price, I better buy a new pre-amp!!

    What's my choice of pre-amp with XLR balance output?? Can someone make a listing for me please.

    BTW, the alumimnium foil thing didn't work...But my father-in-law was laughing his heart out at me!! "Preparing your christmas tree a little bit in earlier this year" ...

    I am really tired of this problem, and by the fact that Rotel, Rotel dealer, Sat dealer and tech and Yammie dealer don't try to help me at all. They take my money, and then, I'm on my own. I'm not an electrician nor a sound engineer!! Guess I will have to forget this separate world, and go back to a receiver only. Talk about a terrible trip in the separate world. Sigh.
     
  5. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Some people are pointing me to isolation transformers for RCA cables, where can I find those?? Others are telling me to disconnect one end of the shield on the cables...how do I do this? and this cable will become an antenna if no sheilding, no?
     
  6. JackS

    JackS Supporting Actor

    Joined:
    Jan 17, 2002
    Messages:
    634
    Likes Received:
    0
    Levesque- You have already tried more solutions to fix the problem than most people would even attempt. You've already tried different Rotel amps so I wouldn't think that the problem is with the amp. That leaves the receiver that may need to be replaced. Like you, I have no electronics experience but, this seems to be the one thing that you haven't tried. If you really like your Yamaha, try another Yamaha and maybe even a different model. If the problem still exist after the swap, try a different brand receiver. Using receivers as pre-amps could be a hit or miss propisition. If this solution fails, well we're back to square one. The best of luck, Jack
     
  7. Yogi

    Yogi Screenwriter

    Joined:
    Jul 25, 2002
    Messages:
    1,741
    Likes Received:
    0
    First, I applaud you for having tried all these different things in order to nail this problem. Man do you have patience or what. Second, I understand how frustrating this can be after having this much money invested in your gear if it doesn't give you the enjoyment you seek then what will?

    OK, there are three variables in the equation:

    1) Pre-amp/receiver.
    2) Rotel Amp.
    3) Sat receiver.

    any combination of 2 and 3 with 1 yields silence. All three together have hiss. That leaves the problem with 2 and 3. Since he has tried changing 3 with other sat receivers and had the same problem I believe it is now time to change 2. Having changed to other Rotel amps doesn't constitute a change as they would have the same design/topology. Its time to change to a different amp. If that gives you silence then you have your answer.

    My 2 cents.

    Best of luck and let us know of your findings.
     
  8. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Thank you for your help. I will have my wife read your comment about my patience, because always complain about my lack of patience (LOL)... I'm a scientist, so I'm always methodical in every problem solving... But here I think I have reach my "zero tolerance" point.

    Finally, I was able to reach someone at Rotel, and they say they will send someone over to look at my problem, and solve it. So I keep faith in them, because I really love this amp.

    I will keep you posted on this. If anyone know how to disconnect the shielding on a cable, or knows where to find those isolation transformers for RCA cables, don't hesitate to point me to it!!
     
  9. Saurav

    Saurav Cinematographer

    Joined:
    Feb 15, 2001
    Messages:
    2,174
    Likes Received:
    0
     
  10. Saurav

    Saurav Cinematographer

    Joined:
    Feb 15, 2001
    Messages:
    2,174
    Likes Received:
    0
    Oh, one more thing - I would suspect the satellite box - preamp interconnect, not the preamp - amp interconnect. RFI doesn't work in very intuitive ways. At least, not for me, which means (a) I don't understand it fully, and (b) there are many different factors which affect it, so it's hard to predict how something will behave. Anyway, if it were the preamp - amp interconnect that was picking up RFI, you should hear the noise with no sources connected. If you're hearing it only when you connect the satellite box, then that's where the noise is coming in from, most likely.

    Some more questions - do you get the noise with the satellite box connected but a different source selected on the preamp? And do you have a multimeter?
     
  11. Chu Gai

    Chu Gai Lead Actor

    Joined:
    Jun 29, 2001
    Messages:
    7,270
    Likes Received:
    1
    if you're looking for isolation transformers for the RCA cables, you might want to just look up a local car stereo installation place as they likely will have them. Don't recall if Radio Shack has them. I hope you share with us what Rotel's suggestion will be after the visit [​IMG]
     
  12. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Wow Saurav, thanx a lot!

    I get the noise when the satellite box is connected and with any source selected. I don't have a multimeter... Will probably buy one if it's useful tough! (I'm a sucker with new gadget!!). Please explain how it could help me.

    For the aluminium foil, you need to explain in detail, because I didn't really knew what I was doing. Even my cat was in aluminium foil suit after my initial wrapping...Seriously, are you able to post a picture of your copper "system", or a detail explanation of what I have to do. I've tried to wrap every RCA cables, then joining this wrapping to a chassis screw or the main ground. I didn't knew if I had to touch the chassis or not with aluminium.

    My interconnects are AR Master Series, so I can remove the cap and expose a green cable that is the ground I think. There is already a big "ferrite" ball at this end of the cables in the Master series.

    My Sat tech just told me that they have a new STB with an optical digital connection on the market, and that I will be the first to receive one when he will got one (back-ordered...the usual)...

    BTW, what cables should I cover with aluminium? Between the pre-amp and amp, or between the Sat-decoder and pre-amp? Should I try to cover the coax feed from the antenna before it goes in the decoder (I mean the cable between the Monster HTS-3500 antenna out to the decoder)?

    Last question, what do I do after all this wrapping-up? (above taking photos to laugh at this in a couple of months)... My dealer told me to "wrap the cables in aluminium, then jump them and ground them"... What does he mean by "jump them and ground them"? Should I ground the aluminium? And if yes where do I ground it?

    Thanx.
     
  13. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Thanx Chu. I will definitely post back what Rotel will do to help me. I hope it will be fast, and not in a couple of weeks.

    It's incredible how a noise like this can grow exponantially after you notice it. It's like I don't hear anything else! In every quiet scene, I go "arrrghhh". My wife don't believe how much work I put on this!
     
  14. Saurav

    Saurav Cinematographer

    Joined:
    Feb 15, 2001
    Messages:
    2,174
    Likes Received:
    0
    Let's see if I can answer all of your questions [​IMG]
     
  15. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    Saurav. Thanx a lot. You are a wealth of information!! I really appreciate it![​IMG]
    I think I will take my christmas tree out and use the spare aluminium foil on it.[​IMG]
    Will keep you inform. Hope this thread will be able to help other people with the same noise problem. I think it is more common they we think, with all those good quality amps out there.[​IMG]
     
  16. David Barteaux

    David Barteaux Stunt Coordinator

    Joined:
    Jan 6, 2001
    Messages:
    179
    Likes Received:
    0
    I own the Rotel-1095. This thing is like an AM radio reciever, where it will pick up and amplify noise based on where you locate it and what direction its facing; I'm not kidding! I still have some noise with it but finding the right location has minimized it. Also my 1095 will be noiser depending on the time of the day. I suspect its picking up noise off the AC lines to my house.
    I know this sounds strange, but this is what is happening to me.
    I have had my Rotel 1095 replaced to confirm it was not the amp.
    Good luck
     
  17. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    David, did you contact Rotel to see if they can provide a fix, like an isolation transformator or something to isolate any interference? Did you find a "solution to minimize this?
     
  18. Saurav

    Saurav Cinematographer

    Joined:
    Feb 15, 2001
    Messages:
    2,174
    Likes Received:
    0
     
  19. Levesque

    Levesque Supporting Actor

    Joined:
    Mar 21, 2002
    Messages:
    586
    Likes Received:
    0
    I just bought a Rotel RSP-1066 to replace my RX-V3200. Will install it tonight after work. So will be using a real pre/pro now.

    I'm just wandering if using the db25 connection behind my RMB-1095 wouldn't solve my "noise" problem. I know we can find cables with 5 RCA at one end and db25 at the other?? I don't have a clue what db25 is BTW...

    I was able to find (after a lot of phone calls) an isolation transformers for RCA cables that they use in car audio. Will try it tomorrow only tough. Will see if it's making a difference.
     
  20. Chu Gai

    Chu Gai Lead Actor

    Joined:
    Jun 29, 2001
    Messages:
    7,270
    Likes Received:
    1
    I believe there's a toll free number for jensentransformers and if so you might want to discuss your situation with them for some insight.
     

Share This Page