Hum and Hiss HELL!

Discussion in 'AV Receivers' started by Joe Mollura, Mar 23, 2002.

  1. Joe Mollura

    Joe Mollura Stunt Coordinator

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    I just purchased a Rotel 1095 amp and am using a Yammy 795 for my preamp. I have the Rotel plugged directly into the wall and the 795 into a Monster HTS 1000. When I have the 1095 on I have a slight hiss and barely audible hum. I can only hear this when my ear is up to the tweeter. When I turn on the 795 it increases the hiss and hum (especially the hum). I can't hear it from my listening position but can hear it from about a foot away. The rears have a louder hum then the front's. I've tried a dedicated 20 amp circuit, a different preamp, a 2 prong power adaptor, unhooking everything (including the cable), cleaning all the groundrod clamps and 2 different sets of interconnects between the amp and preamp, different surge protector (Monster HTS 2000), plugging the amp into the wall and into the surge protector. Should I just except this noise since I can't hear it from my listening position? Do you think the hum could damage my speakers? PLEASE HELP[​IMG]
     
  2. John Morris

    John Morris Guest

    Hi Joe!

    Sorry that no one else would try to tackle this problem... let me try. First, try NO, absolutely, NO connections to the Yamaha from any unit which connects to the TV or cable or DirectTV. Try listening to only a system which consists of your CD player(if it is a DVD player, disconnnect the video hookup), your Rotel 1065, the Yamaha receiver, and the speakers. If it still buzzes, you have a component problem or a cable problem. If not get back to us.
     
  3. Joe e h

    Joe e h Stunt Coordinator

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    Joe

    I just hooked up mynew Rotel RMB-1095 to my Yamaha 2090 this past Thursday. I have a low hum or zzzzzz coming from all the speakers.

    As soon as I unhooked the Yamaha from the amp the zz stopped. I then started backtracking and unplugging everything. I started with the antennea feed to the reciever. Anyways when it was all done I found my DVL-700 was introducing the buzz.

    I had everything unplugged from the reciever and as soon as I plugged in one cord from the DVL-700 the buzz started. So I thought I would just leave the Analog outputs from the DVL-700 unplugged.

    I then started to plug in the DDP-1 Decoder, same thing. As soom as I plugged in one cord back to the buzz. I unplugged the cord and tried my 3 cd players, no problem. I tried my Sat no problem.

    It is from the DVL-700 or the DDP-1 decoder. I am using Monster MK400 connections. The equipment is ran tough a Triplitte Isobar. The amp is on a 20 amp circuit.

    The only other thing I have not tried is seeing if the S video going from the DVL-700 to the RPTV is getting a feed back from the Sat/Ant connections at the RPTV.

    I planned on using the 2090 as a pre/pro for a few months. I am looking long and hard at the Anthem AVM-20. However I am waiting to see if Parasound and B&K come out witha new Pre/Pro this year.

    Let me know what you find.

    BTW any breaker problems with the 1095?

    Joe
     
  4. Joe Mollura

    Joe Mollura Stunt Coordinator

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    Thanks guys for trying to take a stab at this. The only thing I have hooked up now is my 1095 directly into the wall and my 795 pluged directly into the wall. Here's what I'm hearing: Fronts and center a hiss from the tweeter which I can only here from about a foot away. Rears Hum from Bass/Midrange driver, hum from the bass driver, hum/hiss combo from the tweeter and it seems like the hum from one rear is louder then the other. When I shut off the preamp the noise drops considerably. Joe e h- no breaker problems so far. Any other suggestions.[​IMG]
     
  5. Joe Mollura

    Joe Mollura Stunt Coordinator

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    Bump
     
  6. John Kotches

    John Kotches Cinematographer

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    The hiss you hear is your systems noise floor. There's only one way to get rid of the low level hiss. Upgrade your components to quieter pieces.

    The reason the level of the hiss increases is that the receiver has a higher noise floor than the amplifier, so the noisier components noise floor rules.

    For hum, I would try putting on back to back 75-300 Ohm transformers on the satellite feed and see how that does for alleviating the problem.

    If that doesn't fix it, your next test involves using known good cables between the DVL-700 and the receiver and the DD Decoder and the receiver.

    Once you've done that, you'll see if the audio cables are introducing some hum. If that's the case, you will need to replace each interconnect that causes hum.

    Regards,
     
  7. Joe Mollura

    Joe Mollura Stunt Coordinator

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    John,
    Thanks for the advice but still no luck, I have tried hooking up both the amp and preamp to one of these cheater plugs, no luck. I still have a hum (more so in my rear speakers) even when the ONLY thing I have hooked up is my amp to my pre-amp. As soon as I shut off the preamp the noise drops to an acceptable level (I tried different interconnects). Is there any chance that there is something wrong with my amp.[​IMG]
     
  8. Chriss M

    Chriss M Second Unit

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    try plugging the amp and preamp into an outlet in another room on a seperate ciruit. Their could be something on the same circuit as your equipment that is generating interference and causing the hum.
     
  9. John Morris

    John Morris Guest

    John M: Man, this is a tough one. You probably have already done these things, but I still have to ask anyway.

    You do not have any connections other than the Yami to the Rotel to your speakers correct?

    You do not have ANY connection to your TV, correct?

    Another thing to check is each and every interconnect. Make sure that they are secure both internally and with their connection to the units.

    Also, try what Chriss suggested as well.
     
  10. Ken Shiring

    Ken Shiring Agent

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    Joe, try doing this also:



    In addition to John Morris' good advice, check for the existence of two things:
    1. A grounding bolt on your pre (the Yamaha). They are usually marked with a 'GND' symbol. These bolts are almost always located on the back of the unit, with a little washer around the bolt also. They are a very popular feature for connecting record players.
    2. A grounding bolt on your amp (the Rotel). Looks exactly the same as described above.[/list=1]



      If both your units have these bolts, I have a solution for you that may cure your hum problem. Take a piece of copper wire and connect the two grounding bolts (with the equipment unplugged please!). For starters, you can use just one conductor of a speaker wire. If this solution works, post again and I can give you a more permanent reccomendation.



      After you have connected them in this way, power them on in isolation and see if the hum is still there. Ideally, this should allow the two ground references of the electronics to both be at the same level.
     
  11. Joe Mollura

    Joe Mollura Stunt Coordinator

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    Thanks everyone for the advice I'm going to keep working on it tonight, hopefuuly I'll get somewhere. Ken, there is a grounding bolt on the Yam. but not on the Rotel. Do you guys think it's wierd that there is much more hum coming from the rear speakers? Is there a chance that something is wrong with my amp? I thought a could rule that out since the hum starts when I turn on the Yam. When I only have the Rotel on the noise level is acceptable. What an introduction into the world of seperates!!!!!!!!
     
  12. Joe Mollura

    Joe Mollura Stunt Coordinator

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    O.K, I give up. I guess I'm going to have to live with it. I can't really heae it from my lisening postion. (But I know it's there[​IMG] ) I'm going to try some marantz mono blocks and see if there is any difference. Do you think something could be wrong wth my amp? Any ideas why the hum is MUCH louder in my rear speakers.
     
  13. Leo

    Leo Second Unit

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    Joe,

    Welcome to my world. I too have a Yamaha Receiver (RX-V995) and get the increased noise floor when I turn on this receiver. I am using 5 Marantz MA-500 monoblock amps in my system and hear the increased noise floor when I turn on the Yamaha. I can't get rid of it (even after testing everything - cables, power, connections, etc.) so for now I'm biding my time till I get a better separate pre/pro. I can not hear it from the listening position, but again, I know it's there, but once I start up a film I don't notice it. So for now I'm waiting to hear from Outlaw as to when I can order their new pre/pro.
     
  14. Chris Barker

    Chris Barker Auditioning

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    I haven't studied your problem in detail but I conjecture the problem could be different ground potentials between your sat dish feed and the rest of the system.

    I had a problem with this and it was suggested I connect a wire from the chasis of the sat receiver to the ground screw (middle screw on wall outlet) on the nearest electrical outlet. This solved my problem. I assume it brought the sat's ground into line with the rest of my system.

    An easy thing to try.

    -CB
     
  15. Joe Mollura

    Joe Mollura Stunt Coordinator

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    Chris,
    Thanks for the advice but I don't have a sat dish, I think you may be getting me confused with Joe e h (who posted on this thread. Do you think I could try this idea with the ground bolt on the back of my receiver (preamp).
     
  16. Chris Barker

    Chris Barker Auditioning

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    Sorry, I guess I did get confused with all the posts going back and forth. Anyway, I think my solution of running a chasis ground to your electrical outlet ground is worth a try. That is after all the root of your ground in your entire house ground system. It could result in a ground loop but that will be immediately obvious. I do not believe there is any electrical danger. I will say the usual caveat that I am not an electrician - I just play one on forums!

    Good luck.

    -CB
     
  17. David Barteaux

    David Barteaux Stunt Coordinator

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    Joe,

    I have the 1095 amp and a Denon 3801 reciever as pre/pro. I have the exact same problem you have! Even the buzz in my rear speakers is louder. I even swapped amps from my dealer..same problem. I suspect that the longer speaker cable run for rear speakers may make the hum louder than front speakers. I have tried eveything. I contacted Rotel and they tell me that noise generated from other appliances plugged into my house and even on the street is getting into the amp. They said they have seen power problems in different areas. It could be a noisy transformer on the street? I have tried to isolate everything as you have and I do believe it is noisy power comming from the utility pole.

    Also my older 12 year old TV generates mechanical hum in the transformer of the amp and increases the hum in the speakers where I can hear it from my listening position. When I turn the TV off and unplug it the hum and buzz goes away except for the low level noise as described earlier.

    I would like to try a PS Audio power regenerator to see if it is a power related problem.

    Good luck and let me know if you find a solution.
     
  18. Luke_Khuc

    Luke_Khuc Stunt Coordinator

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    that darn video cable!

    i just got my rotel amp (1095) tonight and got some hum already. here's the situation: i have a creaky old sony receiver which does not have any preout. to test the rotel amp to make sure all the channels work, i let my cd player signals go to the receiver. the signals then go through an eq (to reduce the loudness) then to the rotel. i got some loud hum from the speakers. i changed the cables (generic ones) to acoustic research pair and the hum was much less (but it was still there!!!). i started to unhook everything and finally realized that it was that darn video cable from my dvd player to my tv. after unhooking that video cable, no more hum!!! one more note. my tv does not have video in jack so i have to use the radio hack RF modulator. if i let the video cable go through the RF modulator, the speakers will hum. i think that it's the modulator but if you have any suggestions, please let me know. thank you.
     
  19. David Barteaux

    David Barteaux Stunt Coordinator

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    Where can you purchace a cheater plug in Canada. I've looked everywhere! Well at least in the greater metro area.:b
     
  20. dpippel

    dpippel HTF Premium Member
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