Electromagnetic interference?

[ejp626]

Just today I noticed that when I turn on my turntable, I am getting a low hum that seems to be transmitting through to the output jacks. I am transferring most of my LPs to computer, so the computer is too close to the turntable, but I can't really change that. I've had this set up for months now, and I think it just started today. Any suggestions, other than unplug wires and straighten them out and start over? Is there a piece of hardware that cuts down on this kind of interference? Thanks.

Eric

[frank m]

the cheapest and easiest thing to try first is to move the computer away from the turntable. Cables are cheap--for God's sake don't get sucked into the hundred dollar cable scam. As long as they're a reasonable brand, one coax is as good as another.

[clandy44]

One of my audiophile (high-end) friends swears by this remedy: buy a gray "3 prongs into 2 prongs" type and plug your TT plug into the gray plug.

[sonic1]

Hey is this about a new kind of improv??

[wolff]

Does the hum go away when the computer is away from the TT?

The computer may be too close to the Pre-amp(phono stage), not the TT.

Is the hum low in volume or frequency? Or both?

What clandy44 mentions may work for ground loop hum, which is usually loud and low in frequency(60 cylcles?). Does the hum get louder as you turn up the volume?

More details if you can....

Edited May 15, 2005 by wolff

[Kevin Bresnahan]

One of the easiest ways to stop this is to swap the RCA phono cables. These cables do fail occassionally.

If it doesn't go away, it could be a grounding problem. Most phonos don't have a three-prong plug so that trick won't work. If they still sell it, Radio Shack had a special RCA phono cable that had ground loop isolators in each signal path. I had one set up where this cable was the only way I could get rid of the hum... and I believe it may have been when I had my TT hooked up to my PC through a phono pre-amp.

Kevin

[lectronicsgeek]

One of the easiest ways to stop this is to swap the RCA phono cables. These cables do fail occassionally.

If it doesn't go away, it could be a grounding problem. Most phonos don't have a three-prong plug so that trick won't work. If they still sell it, Radio Shack had a special RCA phono cable that had ground loop isolators in each signal path. I had one set up where this cable was the only way I could get rid of the hum... and I believe it may have been when I had my TT hooked up to my PC through a phono pre-amp.

Kevin

if they dont have the cables any more, you can get an isolation xformer <aka a 1:1 xformer, line isolator..etc.> and put that in line. if radio hack doesnt have it, try a local electronics supply store. any questions on how to do it, pm me.

Edited May 17, 2005 by lectronicsgeek

[ejp626]

It seems the interference was worst when I changed from a set of computer speakers to a set of headphones coming out of the computer sound card. It appears there really is no significant problem with the stereo system, but rather the turntable and computer interface. Of course, that doesn't help me too much, since the whole point of the set up is to convert LPs over. What I am trying right now is to record without the headphones plugged in, then do the editing later with the headphones. If that is ok, I'll stick with it for now.