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Buzzzzz - plasma and amp.

goaliechris

goaliechris

Active Member
Hi all,

Is there anything that I can do about the following buzz problem? I have a 63" Samsung 8000 series plasma and it has a small buzz that you can hear in a silent room if the amp is not on. Not terrible but it's there. Well, turn the amp on (Rotel 1095) and now all the speakers are blaring that noise. Turn the amp off, no buzz through speakers. Turn TV off but amp on, no buzz. Amp and TV on? Buzz.

It's not the end of the world but I would like it go away without throwing out the TV or the amp (recent new home purchase has put the budget for this kind of stuff at near zero, according to my wife).

Thanks for the help. This is bugging so much it has affected my trivia scores. :D
Chris
 
Has there been any changes throughout your home as of late, i.e. new appliance added, electronics of any kind moved to different locations, new cable line, etc.?

Rope
 
Ground loop problem!

There are dozens of ways you might address it, but the best idea is to find the root cause. I recommend disconnecting all the wires and add them one at a time starting from the amp and working your way back.
 
Rope said:
Has there been any changes throughout your home as of late, i.e. new appliance added, electronics of any kind moved to different locations, new cable line, etc.?

Rope
Click to expand...


Actually it's all new. New house, new appliances, etc. But I had this happen at the old house also so probably in the system.


Thanks, Flint - will try that and report back. I am using XLR cables for interconnects and regular speaker wires coming out of the amp. So I will disconnect everything from every component and then start adding back, starting with the amp? Shouldn't be too hard - I don't have a lot hooked up: amp, preamp, direct TV box, Belkin power conditioner/surge protector, TV, ps3, and Xbox (I know it's not the last 2 as I just hooked these back up).
 
Ground loops cause noise even when the amp isn't on?

Sounds to me like the TV is the problem - documented many times for certain brands/models. One or more members here returned new TV's due to this problem IIRC...........
 
i had the same problem with sub,ended up being the comcast cable so check that also.
 
I was messing around with some stuff in a non-scientific sort of way and, for some reason, it's the right and left surround speakers that are causing the amplification of the hum(?). When I disconnect the wires from the amp or the wall terminal of the left surround, the buzz goes down a lot. When I do the same with the right surround, it also does this. Maybe due to the longer speaker wire runs to the back of the room they are more sensitive to the ground loop?

I am going to go through a process to isolate it if I can but I have to travel tonight which is why I started just removing things in no specific order. The XLR cables being disconnected didn't cause anything. Same with sub. I did try and hook up one of the front speakers to the surround amp terminal just to see if it was something there but that did not cause any noise.
 
goaliechris said:
I was messing around with some stuff in a non-scientific sort of way and, for some reason, it's the right and left surround speakers that are causing the amplification of the hum(?). When I disconnect the wires from the amp or the wall terminal of the left surround, the buzz goes down a lot. When I do the same with the right surround, it also does this. Maybe due to the longer speaker wire runs to the back of the room they are more sensitive to the ground loop?
Click to expand...

That's... bizarre. :think:
Where are you using the XLR's?
 
Yeah, it's odd. It's probably always there but for some reason the surrounds are really adding a lot to the noise. Remove one set of connections, either from the terminal at the amp or at the wall plate, the sound decreases. Touch the black wire to a post with one side connected and its back.

XLRs are from preamp to amp for all 5 speakers, all Dynaudio: Contour S3.4 L/R, Contour SC, Audience 52SE surrounds. Sub is SvS PC Ultra. Pre is Integra DTR 9.8, amp is Rotel RMB 1095.
 
That is a VERY odd occurrence. The speakers and speaker wires are not active and should not be grounded. Are the wall plates metal or plastic? If they are metal, perhaps one of the terminals is grounded somehow. Another potential is the ground loop is elsewhere in the system but the long wire and crossover are presenting just the right load to amplify the ground loop issue - but that is a long shot.

So... if nothing is plugged into the amp except the speakers, is there still a buzz?
 
I will see. Currently on the road and will be home tonight. So to start have all the speaker wires attached, disconnect XLRs, and unplug power to everything else (except amp)? Then start adding and removing components, each on their own.
 
yes... This is what I'd do.

Unplug all the power and interconnects. Then:

1) Plug in speakers to amp, listen for any buzz (should be none)
2) Plug in the power to the amp, listen for any buzz (could be some hiss and very, very faint buzz - not a problem).
3) Plug in one interconnect to source A. Listen for buzz.
4) Plug in power for source A.
5) Plug in interconnects for sources followed by power one at a time.
6) Plug in TV interconnect, then power.
7) Plug in Satellite or Cable TV wire last.

At each new connection, take a few seconds to see if the familiar buzz sound starts. It could start moderately loud with one but get really loud with another.

Then, once you think you found the source of the problem, disconnect everything else except the source of the problem and the amp to see if there is interaction with other components. If the buzz isn't there when only the apparent source is connected, then it could be another device - try to isolate that other source. Ultimately, this is a trial an error approach to finding which device is the root of the problem. Usually it is a CableTV or Satellite wire.

Once you isolate the source, try simple things like reversing the AC plug (if it isn't one of those wide pin/narrow pin things or three pinned). Or, try a different interconnect wire (sometimes the shielding or connector will corrode and not provide a good grounding plane). Or, try touching a speaker cable wire to the chassis of the two offending devices and see if the ground potential is eliminated. Try moving the AC plug to a different source. Ultimately, a ground loop isolator may be required.
 
Flint said:
yes... This is what I'd do.

Unplug all the power and interconnects. Then:

1) Plug in speakers to amp, listen for any buzz (should be none)
2) Plug in the power to the amp, listen for any buzz (could be some hiss and very, very faint buzz - not a problem).
3) Plug in one interconnect to source A. Listen for buzz.
4) Plug in power for source A.
5) Plug in interconnects for sources followed by power one at a time.
6) Plug in TV interconnect, then power.
7) Plug in Satellite or Cable TV wire last.

At each new connection, take a few seconds to see if the familiar buzz sound starts. It could start moderately loud with one but get really loud with another.

Then, once you think you found the source of the problem, disconnect everything else except the source of the problem and the amp to see if there is interaction with other components. If the buzz isn't there when only the apparent source is connected, then it could be another device - try to isolate that other source. Ultimately, this is a trial an error approach to finding which device is the root of the problem. Usually it is a CableTV or Satellite wire.

Once you isolate the source, try simple things like reversing the AC plug (if it isn't one of those wide pin/narrow pin things or three pinned). Or, try a different interconnect wire (sometimes the shielding or connector will corrode and not provide a good grounding plane). Or, try touching a speaker cable wire to the chassis of the two offending devices and see if the ground potential is eliminated. Try moving the AC plug to a different source. Ultimately, a ground loop isolator may be required.
Click to expand...


Great list- thanks! I will follow this and see what I can find.
 
I cannot figure this out. Incredibly frustrating. If I leave the TV off, it's gone. Complete silence through the speakers. Turn the amp off, complete silence with TV on. It's definitely running through the speaker wires because if a wire is disconnected from any speaker, it of course stops making any noise.

If the TV picture changes, goes dark, or gets brighter, the intensity of the buzz changes. Dark, low buzz.

If I disconnect the hdmi cable from the TV to the preamp, it gets a little lower. Same with surround speakers as I mentioned earlier from the wall plate binding posts or the amp. But it doesn't go away.

Tried plugging the TV into a different outlet and a 3 to 2 plug but neither had an effect.
 
Samsung plasmas are well known for their buzzing. I've read many instances where the buzzing changes...and gets quite loud during bright scenes. Do you have an optical cable running from the plasma to the preamp? I wonder how the buzzing is going from the plasma back through your system.
 
It has to be getting through the amp in some way. With the amp off, there is no sound through the speakers.

I am going to go through the more rigorous process Flint laid out - just didn't have the time last night to do it right. I started it but didn't have to time to complete it. Having speakers wires plugged in, and all the XLR cables plugged in (added one at a time), with the amp off produced no buzz. Turning the amp on produced the normal amount of hiss. Then I turned the preamp on and got the same. I did the same with the cable box and got nothing. Then plugged in the TV, no sound, then turned it on, BUZZ. Turn the amp off at this point, no buzz or hiss.

Also odd - if I unplugged the coax cable (direct tv) from the wall, the sound changed (actually got louder). If I just touched the coax cable to the wall plate terminal, the buzz decreased to the normal level.
 
So it appears that the buzzing is definitely coming form the display?

So far all of the troubleshooting has been on the assumption that it is conducted noise, could it be radiated noise?
 
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