Shielded cables

[thebigcheese]

I'm sure this has been asked before, but what is a good cable with good shielding? I've got a Monster cable and it picks up a ridiculous amount of interference. It's like an antenna for my guitar amp. If I move it around, I can cut down on some of the radio stations, but I usually still have at least some buzz. I know for a fact it is the cable because with nothing plugged into it except the amp it still picks up radio. My guitar is probably contributing a little bit, but not like this cable is. Any suggestions? Thanks.

[Massive Master]

Could be the amp also... Does it happen when using a different cable also?

[thebigcheese]

Well, when nothing is plugged in, I don't get any noise at all. Well, maybe a little bit, but I certainly don't pick up radio stations.

[SRR]

$10 says any cable will do that with your setup, another $10 says its your amp. Is it grounded?

[punkin]

Any pedals or effects in the circuit? Many effects with their PN junction devices act like rectifiers (AM RF into audio).

How many pups do you have in the guitar...does it change when you switch the pup selector?

Good call from the previous posters...amp have a 3 prong plug and are you sure the third connection is really grounded in both the amp and the outlet?

Have you tried moving the amp to another spot in the room?

[thebigcheese]

The amp is grounded, and I can only imagine the outlet is (this is at school, so I can't really check). I do have pedals, but as I've said before, even with nothing plugged into the cable, I can move it around and pick up signals like an antenna. The biggest differences in noise seem to come just from moving the cable around.

The guitar has two humbuckers, and generally there's a little less noise in the middle selection (it's a The Paul), but the difference isn't noticeable here at school because there's so much more noise from whatever else. I think it needs to be grounded better (I've noticed that the noise is virtually gone when I put my hand on the strings or bridge).

[boingoman]

Originally Posted by thebigcheese

(I've noticed that the noise is virtually gone when I put my hand on the strings or bridge).

Open the guitar up and look for loose wires, especially the one going from the bridge to ground. That will do it.

[punkin]

On some/many guitars, the cover/housing of the volume and tone controls is grounded. Check to see if any of them have come loose.

[thebigcheese]

ok, well that noise is not the larger issue here. It's hardly noticeable, even at home where I don't get radio signals. Nice to know how to fix it... but secondary at this point. What I really want to know is, am I going to pick up radio with all cables, or is it just that monster cables aren't shielded well?

[Farview]

its the same problem, just at school, there are radio stations near by. It really isn't the cable, it's some faulty wiring in the guitar.

[thebigcheese]

no, it really isn't the same problem, as far as I can tell. At home, it's a faint buzz that you can hardly even hear with distortion on. And like I said, at school I hear the radio stations without the guitar plugged in, but with just the cable plugged in. I'm not really sure how that can be faulty guitar wiring. Maybe it does have some grounding issues, but those are, from what I can tell, completely unrelated to the radio stations being picked up without the guitar plugged in. I'm not sure how it could be anything but the cable.

[SRR]

$10 says any cable will do that with your setup, another $10 says its your amp. Is it grounded?

Where did I see that before.....oh ya that was me a few posts back....

Ok I'll add that I got $1 riding on a bad cable. Go to the guitar store buy a $10 cable and you will have your answer.

[boingoman]

Why don't you just try another cable and get your guitar fixed and see what happens?

[Farview]

Originally Posted by thebigcheese

no, it really isn't the same problem, as far as I can tell. At home, it's a faint buzz that you can hardly even hear with distortion on. And like I said, at school I hear the radio stations without the guitar plugged in, but with just the cable plugged in. I'm not really sure how that can be faulty guitar wiring. Maybe it does have some grounding issues, but those are, from what I can tell, completely unrelated to the radio stations being picked up without the guitar plugged in. I'm not sure how it could be anything but the cable.

At home, you aren't as close to the radio tower. A shielded cable with the ground unhooked becomes an antenna. If you have ground issues in your guitar, the shield isn't hooked to anything and the cable becomes an antenna.

Most colleges have low output radio stations that only cover the campus or town. I'll bet you the radio antenna is on the top of your dorm, or on top of a building within 2 blocks of your rig. That is why you are having problem at school and not at home.

The reason your amp is silent when you unplug the cable is because the input jack is a switching jack that ties the hot to ground so it doesn't make any noise when unplugged. The only way to test if it is the cable that is the problem is to borrow another cable and check it out.

[thebigcheese]

So what you're saying is that the cable could be shielded just fine, but it only ceases to be an antenna when it's plugged into my guitar? or the amp? or both?

And yeah, we do have a radio tower within two blocks, I knew that was why it happened here, I just figured that there ought to be a way to get it to not do that.

I opened my guitar, and all the connections seem to be secure (I pulled on them a little bit and they didn't move or anything). I don't know a whole lot about the wiring, so I can only assume that they are the correct connections (I don't know why the previous owner would have changed them, and they look like original wires). This doesn't explain why I get less buzzing with my hand on the strings (no less radio intereference, tho), so I can only assume that there must still be a ground issue somewhere. I just tried another cable straight into the amp, and there's noise without the guitar plugged in and the same noise with the guitar plugged in.

[Farview]

Originally Posted by thebigcheese

So what you're saying is that the cable could be shielded just fine, but it only ceases to be an antenna when it's plugged into my guitar? or the amp? or both?

It only becomes an antenna when something isn't grounded properly.

[thebigcheese]

So if just the cable is plugged into the amp, and nothing into the other end, and I get radio interference, is it safe to say that the problem is probably that the outlet is not properly grounded? Or that the problem is at least somewhere in that connection?

[Farview]

Originally Posted by thebigcheese

So if just the cable is plugged into the amp, and nothing into the other end, and I get radio interference, is it safe to say that the problem is probably that the outlet is not properly grounded? Or that the problem is at least somewhere in that connection?

No, it means that your guitar isn't grounded. Go beg, borrow, or steal another guitar cable and try it. Try a different guitar, see if that helps. You surely can't be the only guitar player at the school, you normally can't swing a dead cat without hitting 3 guitar players.

[127Riot]

You normally can't swing a dead cat without hitting three guitar players.
I LOVE THAT!!!!

[Massive Master]

I swung a dead cat at UIC once and only hit two guitarists, but I also hit a timpanist in there - which I thought was odd...

[thebigcheese]

Both of my cables gave me the same results... one isn't a Monster (Horizon, I think, I stole it .... I mean I was given it by a friend). Is this grounding issue something I can easily fix myself, or should I take it somewhere? I checked all the soldering, and it seems to be good, and the wire doesn't seem to be broken anywhere, but I noticed the cable runs through the wood somewhere, but where does that go? That's the one I haven't checked. I guess if anyone has a picture of what the back of the Paul should look like, that'd be nice, but probably any Les Paul is the same (right?).

[Farview]

It's the guitar. Take it someplace because it everything looks OK, there is a component failure.

[punkin]

The grounding issue could be within your amp. If the jack inside the amp or the power supply or some part of the chassis (a million little place), or something like a decoupling capacitor has given up the ghost, the guitar cable is going to act exactly as you say, an antenna.

Seems like you've tried all the normal/prudent things short of getting into an electronics troubleshooting mode. There's one more thing you might consider, open up the amp, and look for the obvious but I warn you to do this with extreme caution. But to be honest, it seems like it's time to take it in.

If you decide to take it in, insist on showing the tech exactly what you're experiencing. The most costly and time consuming thing you could do is take it in, drop it off and get a call back a couple hours later from the tech saying, I did xyz and it's ready. If you can't show him exactly what the problem is, eg. he can't duplicate it, you might be able to save yourself the bench charge for a "no trouble found" ticket.

[thebigcheese]

Well, this happened with a different small amp I had last year, too, a Danelectro (now I'm using a little Marshall 15 watt, I think), but it doesn't seem to happen at all for my friends, even if they don't have a guitar plugged in. So I guess it could be the guitar, which would explain why I'm the only one with this problem. So basically, from what I gather, if I get the guitar fixed, even if there's a radio signal without the guitar plugged in, it should go away when I do plug the guitar in? Or am I misreading that? Thanks guys.

Actually, I just noticed that my brand new Takamine still gets the radio, so maybe it is the amp? Or do acoustics just sort of do that?