Strange Interference on Monitors
Posted on Jan 27, 2005 03:17 pm
Member Since: Sep 11, 2004
I bought a pair of Behringer 2030A's a little while back. They are being fed a stereo signal through unbalanced TRS cables. I have never had interference problems.
A few months ago my power supply fried my video card. I refunded the video card, and replaced the power supply. I am now using onboard video, and there is a buzzing that occurs whenever my computer is working. If I load a program, move/resize a window, i get a buzz sound through my monitors. Its extremely annoying.
I plugged headphones into my sound card in the back, using the EXACT same output my monitors use, and i can hear no noise. Also, i plugged my monitors into a minidisc player, and there is no noise! So it's not the monitors, but its not the computer?! What's going on here. Maybe my soundcard is putting out interference that only my monitors are able to pickup?
Im thinking of putting a video card back in my comp to see if that gets rid of the issue. Maybe the onboard video is causing it?
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Jan 27, 2005 03:21 pm Well, they say they are magnetically shielded, but as a shot in the dark, do you still get the noise if you PC is running and you shut your monitor off?
Jan 27, 2005 04:13 pm yes. heh. first thing i tried. =P
Jan 27, 2005 04:28 pm i have some behringer monitors and experienced a similar problem i was picking up radio freq. so i plugged my tuner and such into a receptacle that is on a seperate breaker from my monitors and the problem went away ,but i think generally speaking and bad ground is the reason for interference.although as for pc's i have no knowledge but i would try reaaranging some pluggs and checking that your sound card is snugged in and seated well to your pc's chassy.
Jan 28, 2005 12:19 am k, i'll try that. thanks!
any other suggestions are welcome
Jan 28, 2005 05:51 am I think its always good to use balanced leads for monitors man. What I understand is balanced leads carry the signal on two cables, which helps eliminate some kinds of externally generated noise. The two wires carry the same signal, but each wire is opposite in signal polarity to the other. A balanced input is built to only recognize the difference between the voltage two wires. Should any static interference or noise cut across a balanced cable, the noise voltage will appear equally, with the same polarity on both signal carrying wires.
The noise is therefore rejected by the balanced input.
This is probably why you hear no interference through your headphones (cause they are balanced).
Sorry to not really help with your problem though!
Jan 29, 2005 04:20 pm My headphones aren't balanced, so that makes this situation interesting, doesn't it?
Jan 29, 2005 04:53 pm they should be...check for two black rings on the connector
Jan 30, 2005 03:21 am that just means they're stereo.
when a cable has two black rings and its sending either the left OR the right (mono), then it's balanced because the "extra" channel is that opposite signal used to balance.
At least i think so
Jan 30, 2005 09:25 am i believe that if the TRS cnnectors has two black rings on it i think it's balanced
Jan 30, 2005 01:46 pm I agree with colonel sanders on using balanced cables with your monitors, especially powered moniters.
What I think is happening is that your cables are picking up a bit of interference and once it hits the amps in your monitors, the noise is magnified. Which would explain why your not hearing it in your headphones.
And yes, a TRS 1/4 inch cable is balanced.
Important part- make sure that you have separate, balanced outs, L and R, from sound card to monitors (check your manual if need be).
What sound card are you using? Reading back, it seems like your splitting up a single jack, stereo output into 2 cables. If this is the case, you won't be able to run balanced connections to your monitors without getting a new soundcard
Jan 31, 2005 01:43 am I only recently discovered this myself, TRS 1/4 inch = Stereo 1/4 inch. What a funny world we live in.
WaltChief Cook and Bottle WasherMember
Jan 31, 2005 11:08 am Do you have your monitors plugged into the same powerstrip / conditioner that the PC is plugged into. Sometimes you can develop a ground loop just by using different outlets in the home.
Since: May 10, 2002
And I definately agree with The Cornol. If it is a balanced input use TRS. Balanced ins and outs use phase reversal circuitry to cancel any noise picked up by the cord. Some folks make the mistake of using speaker cables like from an amp head to a cab for monitors. This is definately a no-no as with powered monitors it is a low level signal between the speakers and PC or mixer, not a speaker level signal.
Jan 31, 2005 11:36 am While a TRS can carry a balanced signal, just using one does not dictate that the signal will be balanced. The circuitry and jacks involved have to be balanced. If there's two contacts on your headphone jack, then it's stereo, not balanced.
Since: Apr 08, 2004
Balanced stereo would have to have 2 signal and one ground on both L & R channel. Inside the device (speaker) the two signals would be put back in-phase, thereby negating the newly out-of-phase noise.
As to the extra noise in your monitors, if it's a buzz, then I'd lean more towards a ground problem as Walt's mentioned.
Colonel, back in the day, a 2 contact jack was a TR jack, as the point was called tip, and the rest of it was called ring. This has a big history in telephone connection field. When they went to a 3 conductor jack, they added the sleeve designation, thereby creating the TRS jack, or Tip, Ring, Sleeve conductors. These can carry mono, stereo, or balanced mono, as we've been discussing.
Hope this helps
Jan 31, 2005 09:18 pm Ah, so a stereo signal is NOT a balanced stereo signal, and balanced cables can carry unblanced mono? Thanks for clarifying that pjk. I had no idea......
My bad Kamikaze, I still have a lot to learn :-)
WaltChief Cook and Bottle WasherMember
Feb 01, 2005 12:00 am Not to fret there Colonel!
Since: May 10, 2002
It takes a little getting used to. A TRS or (Tip, Ring, Sleve..old telephony gargon) plug is used for both stereo and balanced mono applications.
For stereo the Tip will be the hot side of the right channel, the Ring will be the hot side of the left channel and the sleeve will be the ground for both channels. I may have right and left reversed, I would have to refresh to make sure.
For balanced mono, the tip is an in phase signal hot, the ring is an out of phase (180deg out or reversed) hot and again the sleeve is a ground. For equipment where a patch is made from a balanced out to a balanced in the in phase and out of phase signals are recombined at the receiving end and any noise that has been acumulated in the patch will be rejected at the receiving end. A TRS cable can be used to patch two unbalanced pieces of equipment but will obviously not offer any greater noise reduction than a TR cable. In some rare occasions especially with smaller jacks 1/8 inch and smaller a TRS can cause problems as it will not match up well with the TR female connector in the equipment itself. For the most part 1/4 inch plugs are pretty much universal.
Hope this helps a little. Like I say, you'll get used to it. It's just a little wierd at first.
Feb 03, 2005 02:59 pm So, the problem isn't balanced connections. I'm using a Sound Blaster Audigy 2 ZS Platinum and this seems to be a common issue. It really started when my video card died. Apparently audigy drivers can generate noise like that if they conflict with the video card drivers, and since i'm using onboard video now, i'm thinking its the problem.
I'm sure its NOT the balanced issue because before i lost my video card i never had interference.
Thanks for the help guys!
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