buzz humm coming from LP traditional and Swart AST Master in my house, but not...

[Jared Purdy]

I posted this in the guitar forum, but someone thought that it migh be better posted here:

It's been quite maddening trying to figure out the cause actually, but most people that I have been communicating with (a couple of techs, guys over on the music electronic forum, and the Gibson forum) think that it's an EMF issue. The drag is, that it happens in my house, but not elsewhere (at least the other place that I checked it at). And, it doesn't happen on both of my amps. I have a 75 SFPR that it does not do it with, and I have a Swart AST Master, and it does it with that amp. I also have a Strat Deluxe (silent PUs) and it is silent in the Swart. I took both the Swart and the LP down to a local music store, convincved that the sound would be replicated there. It was not, it was dead quiet. I also tried it at my neighbour's house, who has a load of dimmer switches, and it was much worse in his house. In my house, it is always there, though not always at the same intensity. I have had the amp checked, it's not the amp. It is also quieter when I hold the strings.

Is this normal? I am new to the LP. I figured that the LP with it's humbuckers wouldn't be victim to inadvertent electrical frequencies, but that does not seem to be the case. I was told that the 57 PAFs are assymetrical, and that will cause hum in the neck and bridge position (sometimes), but not in the middle position. And that is true to form where my guitar is concerned. One person suggested that I have the PCB removed from the guitar and get it hand wired, and have the cavity shielded, but I was under the impression that it was already shielded.

Any advice?

[big_teee]

Hello:
Are you handy with a soldering iron and willing to isolate components?

Terry

[Joe Gwinn]

Sounds like a grounding and/or electrostatic shielding problem in the guitar.

Is the cavity shield grounded to the shield (outer shell) connection of the output jack? The strings? Et al? Test this with an ohmmeter, not just your eyes.

[Jazz P Bass]

It sounds to me like the Swart is a high gain amp.
I have seen Marshalls that exhibit the buzzing on certain pickup arraingements.
You may want to try cutting off breakers one at a time on the Mains panel.
This may help to isolate exactly what is radiating EMI.

[David Schwab]

Hello:
Are you handy with a soldering iron and willing to isolate components?

Terry

If you are talking about star grounding in the guitar, don't waste your time. Everything gets reconnected at the output anyway.

To the OP, do you have anything unusual like an "invisible fence" as used for pet dogs? I was in a guy's rehearsal room/protools studio that was located in his basement. Everyone's gear was making this annoying whining buzzing noise. The guitarist had a Strat with single coils, but my bass had humbuckers and is normally very quiet. It turned out the guy had an invisible fence, and that was causing the interference. When he shut it off it stopped.

Someone at TalkBass had the same symptoms and when I asked about the invisible fence, he also had one.

Other sources of such noise are light dimmers and neon signs. You might also have dirty power in your home.

In these cases, extra shielding and stuff in the guitar wont help much. In the above example, my bass was fully shielded and normally dead quiet.