Bad hum from Audigy card when connected to Home A/V.

I read as many posts as I could first and now my eyes are getting blurry. I have had the card for 5 years and it always has worked well. When connected to my 3way computer speakers (with subwoofer) sound is perfect. I recently ran a circuit through my attic to my home stereo to play mp3's and as soon as I connect the sound card there is a low frequency hum that would drive you crazy! I plug my Nomad to the circuit and it is perfect. Is there something I need to know about grounding the sound card and the stereo together to avoid a ground loop?

Using a shared ground like a UPS or power strip would help.

"ran a circuit"

What do you mean by this? you ran the output jack with a wire three rooms long?

This is normally caused by the PC (Power Supply) voltage that is being picked up by the A/V receiver. With the Nomad, because it is DC (Battery Operated) you shouldn't have the issue. I would recommend using a Ground Loop Isolater for RCA plugs as it comes into the A/V receiver. This should fix the problem. You can pick them up at Radio Shack or a Car Audio Shop.

Yeah, this will happen if the PC and audio componentry are on different wall circuits. It is as you have noted a ground loop. The easiest and cheapest solution will likely be getting the powered devices onto the same power circuit. I might try running an extension cord to the PC from the outlet that the A/V eqipment is plugged into.

Hang in there, just keep trying stuff till you figure out what makes it go away. It isn't impossible to fix but this kind of thing always freaks people out.

do both your Audio card and your Reciver support a fiber optic audio cable, becuase that eliminate any electrical differencials as they are non conductive. Thats whay i use and i am loving it. Just a thought.

that sucks, i mean about the reciever. I hope the ground loop isolator thingy works out for you.

I would disagree in that if the ground loop is truly eliminated there will be no hum at any volume.

Case in point, my own system. PC is connectd to home theatre system, front channels have 600W each. While PC is source but with no music playing I can turn the volume all the way up and only hear white noise. There is absolutely no audible hum.

I think you may have said this in your story but it really all boils down to maintaining a solid single point ground. It is a common theme in electronics. You will even see ham radio guys talking about the single point ground in their ham shacks. Why? It seems to work.

whatever bud. maybe you need to get your dad to set your stuff up if you are getting ANY hum. Maybe that is the person who should be posting solutions here too since it seems you are trying to give advice about a problem you haven't even been able to solve yourself.

PS what makes you think I am lying about my sound system? I am looking at a set of 2500W (bridged) amps to replace the 600Wer's as they don't seem to be enough to drive my main speakers to my satisfaction. Believe what you want, but soon with the new amps you will be able to hear my system whether you like it or not.

Here is an update, I have wired my stereo and computer to the same outlet to avoid ground loop No Luck. I have plugged my wifes computer to the stereo to see if the noise is unique to my system, and it still persists. With heavy extention cords I plugged my stereo into an outlet across the house that I know has a good ground (new circuit) and the noise is louder through the added power extention cords. I will continue to keep you all up to date. Next try will be grounding cases together like in a professional sound system... it will be difficult through the wall though!

Quite simply I use large custom power strips from my office with digital correction (verister technology?) I have one on my computer that everything is plugged to and one at my stereo that everything is plugged to. I basically used a heavy guage extension cord to carry the computer power strip to the outlet the stereo was plugged in and then reversed the extension cord to carry the stereo power strip to where the computer was plugged in. Same noise no difference?

I know that when securing rack mountable signal processors in a PA rack there are isolation tabs to use that will elliminate noise but I dont understand the science of it. I had 5 units installed I would turn one off at a time untill the noise went away then I would isolate the chassis of the noisy unit from the rack rail with the isolation grommets.. no more noise!

In my situation now the frame grounds are not touching. In theory with the above example I will introduce more noise by grounding frames together? I have not yet been able to try anymore experiments.

I seem to be having a similar problem to the original poster but my setup and 'debugging' has given different results... can someone shed some light on this?

(I live in an apartment)
I have my PC setup on one power strip and am running a 2.5mm stereo cable from the line out on my Asus A8N-E onboard sound to a single power strip setup consisting of a Logitech Z-5500 with an HDTV. Using the option of multiple stereo inputs, I have the line from my PC and a RCA<->2.5mm stereo audio line from the TV hooked into the Z-5500. When the sound input is set to the TV, there is no hum. However, when the sound is set to the PC, there is a notable hum.

Here are the scenarios of what I tried but kept the hum going:
- Unplugged power to TV
- Turned TV off
- Switched between back/front panel ports on PC

The only way I was able to cut the hum was to break the connection between the TV and Z-550

I think I'm missing the key element here that causes this hum. I also noticed that when I drew the audio from my laptop instead, the hum was not there. I am guessing that the aforementioned ground resolution is worth a try but why does it work fine when the TV connection is not there then?

Any explanations will be like 'wow'.

Thanks.

I have completed the dedicated AC circuit to the computers and stereo and the noise was still there! I then knew it was coming from the sytem itself, I believe it is noise on the 75 ohm coaxial cable line plugged to my vcr/tv. If I isolate the Tv system from the audio system no noise but then I cant use my surround sound while the computer is plugged in! I now have to figure out the best way to ground the cable signal? I have seen the grounded cable blocks but I dont understand where to use it except for where it comes into the house for safety from lightning? I am making progress though.

Shoreway,

This is exactly the information I was looking for when I said:

Note that in this instance a TV with cable hooked to it would have been one of the peripherals I was referring to.

It may have seemed very subtle to you at the time but this step is critical in troubleshooting the hum problem.

In fact it is very very common to get ground loops through the cable for cable TV. This is because the shielding is typically earth grounded back at the utility pole, sometimes where it enters the home if you are extra special. Your A/V equipment will tyically be earthed at the service entrance of your home with a big copper rod driven into the ground. This situation creates a large ground "loop". If I am right then with all other gear hooked up in a star config as I described, by unplugging the cable TV cable the loop will be broken and the hum will disappear, and thus the reason I had suggested unplugging everything but what is needed.

If this turns out to be your problem there are commercially available video isolation solutions which go inline with the coax.

Let an old fool make a suggestion here . I was certified as a power generation and transmission systen relay engineer in 1975. You obviously have a ground loop in the system. In tube stereo systems the drill is to isolate each source using an isolation transformer the way hospitals do for their most sensitive equipment. A 250va tripplite will cost you about $75 a 1kva about $150. You don't need to shell out the extra money for the hospital plugs since what you have is digital and not sensitive enough to warrant the extra expencse. check the continuity of your cable ground/shield since you pulled it through the attic. It is not uncommon for nicks or separations to occurr. Make sure you don't parallel any AC circuits in the attic. Cross AC condutors at a90 degree angle. Since it seems to be ok when you have the TV disconnected, isolate that power supply first. If that doesn't work then the ground loop is internal to the TV usually in the picture tube section and there is little you can do except try a wireless connection. Also it is not clear. Did you run a video connection from the computer to the TV. If so lifitng that will cure the problem. It is very common for the loop to come in through the cable system If that is the case then hthere is very little you can do . It also occurrs with satellite dishes as well. If it is comming from adelphia then it is resonating in ythe video circuit. Do you have HDMI compatiblity since that would isolate the video stream from the audio circuits assuming the source is not internal to the cable box.

I'm sure you're using good quality cable, but 3 rooms distance gives your high end ample chance to escape, meaning you have to put on more treble on the amp, which usually sounds artificial.

It's a figure of speach, Jim.

If you're in an area of high interference there may be no solution (I am in a high interference area and I haven't found any solution.)

When I play my guitar, it acts as almost an aerial for interference, with more in some areas and less in others. The massive transformers in my Mark IV Boogie also seem to do this.

Back to PCs, my Hi-Fi is about 3-3.5m from my main PC. I use good quality cable to connect, but there is still quite a lot of hum that just seems to find it's way into the cable (another figure of speech, not the escape hatches this time lol). When I use shorter cables, there is next to no noise.

Just my experiences. It'd be great if someone could sort that one out for me, too actually

I'm no technical expert, but my friend phoned me tonight and said that he was experiencing a low hum on his z5500's using Digital out (Din to Coaxial) through Live! 24bit in a media center setup. What he neglected to tell me was that he used dual view briefly with CRT and normal TV, after which he left the montior intact.

A few years ago I experienced the same problem, but with analogue speakers. My problem was specific in that my X800XT was generating something that bothered my Audigy2 seeing that I used the slot adjacent to my gcard. I moved two spaces down and voila - humming gone.

In my friends case, the monitor was next to the computer case, and hence the disturbance that caused the sound card to "hum".

It would seem that from these two options, that the sound card is highly susceptive to interference. Especially if you are running long distance, and I'm willing to put my neck on the block that the extension passes geyser and main AC supply distribution network for lights - a sure way to pick up interference.