Bzzzzt! What was THAT?

D

Doctor Varney

Cave dwelling Luddite
I wonder if anyone could explain what is happening here?

Just lately, I've been running a line from the output of the on-board Realtec sound chip of my internet/ office computer to a line-level stereo input on my Behringer 1204FX mixer. The connection comprises a 6 meter audio cable which goes from a small jack to phono x2 and converted to 1/4 in. x2 jack using phono->jack mono adapters.

On a couple of occasions I have received slight (but noticeable) shocks when handling the 'live' phono connectors and accidentally touching the ends.

Last night, I was listening to a Youtube video on line 7/8 with the preset level selector button of that strip set to +4. Part way through the song, the sound scragged out to a blurred crackling mess, so I stopped the video and pulled back the fader. I tried several different videos (which I've listened to before) and the same happened again. So I toggled the level preset button to -10 and the problem went away.

I have discovered that if I use this particular connection with +4 selected the sound starts off fine, then suddenly degrades but if I keep the button set to -10, the problem doesn't occur. Obviously, it's a quieter setting but easily compensated for by giving it a little bit more on the fader.

Is this normal and anything to do with 'balanced/ none balanced lines' or would you suspect there could be something wrong? Is it normal to receive an electric shock from (what I assumed was) a passive audio cable coming from the computer?

Thing is, I can't say I've ever noticed this phenomenon when I have connected other machines to my mixer in the past using the same cable and adapters. So, naturally, I felt I just had to ask.

Thanks

Dr. V
 
You've most like an electrical wiring problem, or you're using ground-lifters. All your electronic gear should be plugged into the same line, properly wired, though if you can't do that you should have an electrician check your outlets -- reversing hot and neutral is a common problem that can cause this. This is a dangerous condition, by the way. I recall a guitar player who was electrocuted during a performance when the strings of his guitar touch the a mike stand.
 
The most voltage coming out of Line Level outputs should be around 2 volts. This is not enough to feel a shock, unless you're saturated with water and salt; like sweat. Then you ~might~ feel a tiny little something.

You should set your mixer to -10 and leave it. That is the 'consumer' level standard and your realtec soundcard is set up for that. The +4 is for Pro gear. I don't know why you are experiencing noise while viewing videos. Maybe it's your Behringer mixer. They are not known for quality or reliability.

With your poor history of computers, I'm surprised you didn't blow up your computer.
 
It's not a massive shock. It's just like a tingle - but makes me jump. Many years ago, I survived a 'Full English' off a direct power line, so I know what a 'real shock' feels like.

There aren't any issues with my house wiring as far as I'm aware. I have everything safely and properly set up at the 'consumer end'. I've never actually experienced anything like this from any of my other audio gear, although I'm not one for habitually hot-plugging hi-fi components. I normally turn everything off, first... but with this, sound engineering, I can be prone to a spot of hot-plugging when trying something out. I always make sure faders and gain levels are off if a unit is live but I never thought to mute the PC sound output.
 
moresound said:
It's a conspiracy Dr. V I tell you. A conspiracy!
Click to expand...

That cave is still beckoning you, Dr! You should not be getting any kind of a shock from the line outs of your computer. As Chili says, Behr mixers are not the most reliable pieces of Shi...err... equipment around.
 
I would check the ground connection on the computer and the power socket asap. The mixer should have a floating earth so there sound not be a problem there (famous last works).

Of course if you used a mac you would get a better quality and a more arty / designer shock.

alan.
 
Partly... yes. It was a combined effort and I took some advice from elsewhere. Do you have some problem with that? No? Alright then...
 
You must log in or register to reply here.
Back
Top