Guitar noise / interference problem

[fully funktional]

Hi,

I've just moved into a new flat and I'm having problems recording my Strat. I'm getting a loud buzz that gets quieter when holding the guitar at a different angle and when my fingers are touching the strings. It's very obvious and annoying and especially horrendous when overdriven. The guitar is connected directly to my audio interface (Emu-1616m) which is a PCIe interface with wall wort power-supply. The cable is 6m typical metal TS guitar cable.

Does anyone have any ideas whats going on? Any help appreciated.

Also here's a quick .wav of the guitar / noise. https://www.box.com/s/ti5cfa2tv8p4lbc5j6h3

-Tom

[Jim Lockhart]

Standard Strat pickups are not humbucking and will magnetically pick up hum from any transformer in the area (such as the one in a wall wart power supply). The amount of coupling will depend on the distance between the transformer and the guitar and the angle between the two. On some Strats with a 5-way pickup selector switch, positions 2 and 4 on the selector (the "in-between" positions) will give less hum. Otherwise, your best bet is to move all transformers as far from the guitar as possible.

Strats can also have capacitive coupling to mains wiring; typically you hear that more as "buzz". If putting your fingers on the guitar strings lessens the amount of buzz, it means that either the strings are not electrically connected to the cable shield (you can check with an ohmmeter) or that the cable shield needs a better earth ground. If the interface is powered by a wall wart, you may need to connect an earth ground to the interface chassis.

[zenguitar]

Jim is right on both counts. You problem could be related to one or both I'm afraid.

It's worth trawling through previous posts in the Guitar Tech forum where these issues have been covered at length many times before. But the first place I would look is at you ground connection through your audio interface.

Reading the SOS review of the Emu 1616M I see that it is powered by a 48V DC wall wart. I would expect that to be double insulated with a floating ground. If your computer is a laptop, which I would expect, it is likely that it also has a double insulated PSU. And in that case, when you plug in the guitar you don't have a true ground connection. The fact that touching the strings reduces the noise backs this up, as soon as you touch the strings your body provides the ground.

On the back of the Emu you have a ground connection screw, and these problems are exactly why it is provided. Hooking up a wire from that connection to a true ground should solve your problems. If your system includes other hardware with a ground connection all you need to do is connect the ground terminal on the Emu to that device's chassis with a wire. If you just have the Emu and laptop the safest way to do this is to connect a single wire from the ground terminal of the Emu to the ground connection of a standard electrical plug, and plug it in. Alternatively, you could ground through a radiator or water pipe as long as you are satisfied that the metal is grounded.

Hope that helps.

Andy

[fully funktional]

Thanks for the replies. I'm going to get some wire tomorrow and connect the ground from the interface to something and see if that does it. My computer is actually a desktop PC - should I try attaching the ground wire to the metal case of the PC? Also, would getting a shorter, better quality guitar cable help?

I didn't really have this problem in the house I lived in before (maybe a much quieter buzz but nothing serious). I thought it may be something to with the electrics of the building I'm in now or something.

P.S I tried moving the guitar and cable as far away from the wall-wort as possible but it made no difference.

[zenguitar]

Yep, definitely OK to try connecting the ground screw of the Emu to the PC case. Definitely worth trying different guitar cables too in case it has a poor/damaged screen.

Andy

[fully funktional]

So I got a wire and tried to connect one end to the ground screw of the Emu but the screw came out and the little piece of metal on the other end is now loose inside the case! Does the wire have to be connected to that ground screw? I've tried touching the wire with the outside case of the Emu (which is metal) and with the PC case, radiator, metal desk lamp but nothing seems to make the buzz even quieter except when I touch the strings.

What should I do now?

-Tom

[zenguitar]

OK Tom...

I have no idea exactly how the Emu is wired internally, but for the purposes of your problem I'll assume that the ground screw is also connected to the case (if it was me I'd open up the case, recover the loose part, and re-assemble - but that's the way I am).

In an ideal world what I would do next is borrow a decent quality guitar or two to use as a test. It's not essential, but doing that would give a useful reference and some valuable information.

If the problem disappears using another good guitar, then you can start looking at your guitar wiring as the most likely problem. If you really do have no option to try another guitar, I would work on the basis that there MAY be a problem with your guitar wiring, especially it's grounding.

A good, quick, test would be to take a grounded wire from your PC/Emu and link it to the strings behind the saddles. If that solves the noise problem, you need to look at your guitar wiring. Is it a trem strat, or a hardtail? Try the test and get back to us.

Andy

[fully funktional]

I've connected the ground wire to the strings (before and after the bridge saddle) and no difference. The bridge is a classic Strat tremolo. I noticed when I touch one end of the wire and the other with one of the screws of the Emu (instead of the case) it gets slightly quieter - presumably because the metal case is painted and the screw isn't. Interestingly, there seems to be minimal difference when touching the Emu with the computer case or radiator (because these are slightly insulated with paint also?)

Still the best noise reduction I can achieve is when touching the Emu directly with my finger or when I touch the guitar strings. Could the ring main not be properly grounded?

[zenguitar]

Still the best noise reduction I can achieve is when touching the Emu directly with my finger or when I touch the guitar strings. Could the ring main not be properly grounded?

OK... the symptoms all point to a grounding problem. Touching the strings and touching the Emu case both have the same result so that suggests that the ground link through the guitar cable is fine so we can eliminate the guitar.

So things are pointing to the ground link from the Emu. Definitely worth checking the ground link on the mains socket with a proper tester, especially as your problems started when you moved to the new flat.

Andy

[fully funktional]

How do I do the test?

[zenguitar]

Unless you are one of those qualified and experienced guys like Hugh, it's probably best to treat yourself to one of these Mains Socket Testers as featured at Maplins.

Seven quid well spent. Especially if you gig, you can test the sockets in every venue.

Andy

[fully funktional]

Ok cool. If I test the mains and it turns out there's no ground what can I do then?

-Tom

[zenguitar]

If you own the flat, get a qualified electrician to fix it. If you rent, call the landlord and politely explain that the electrics are faulty and require prompt attention.

Andy

[fully funktional]

The mains tester is coming in the post. Without a ground connection is there anyway round this problem? What about a DI box before the interface?

[zenguitar]

I wouldn't expect a DI box to make much, if any, difference. The problem appears to be that the guitar is picking up electro-magnetic radiation which doesn't have a safe path to ground. A DI box won't provide that ground path.

While you are waiting for your tester it might be worth running a long mains extension lead to another room in the flat, or even another flat, and running your equipment from a single distribution strip. I would also look at opening the Emu and making sure that ground screw is properly attached again, and also plugging and unplugging it in your computer a few times to make sure it is properly seated and making good connections.

Andy

[fully funktional]

Update:

The tester arrived and apparently my mains are properly grounded (I checked both sockets and the socket expansion my PC and Emu are plugged into). I opened up the Emu and reinstated the ground screw which turned out to be just touching the metal case anyway. I've screwed the ground wire from the Emu into the earth pin of a plug and plugged it in to the mains.

Unfortunately... no difference

This is now becoming really bizarre I know and thanks for all the help so far. What can I do next? One thing I've noticed is there's less noise when the guitar is upright (i.e when in the stand) and also when it is at one side of the room..

Should I consider buying a new guitar cable? I don't know anyone with another guitar to try.

There is a cafe downstairs and a boiler in my room - could these be creating any kind of electrical interference?

[zenguitar]

Good news first... the money spent on the socket tester isn't wasted. It's a handy thing to have in the tool box that might save your life one day.

I think at this point you really do need to try with another guitar. OK, I know you say you don't know anyone else with a guitar, but I am SURE you are wrong. The odds are that you know loads of people with guitars, you just don't know that they have them

I live in the the village where I was born 50 years ago, I drink almost every night in the same pub that I first used when I was 18 (I would have started earlier but my dad was a regular at the time), I am well known as having working in the music business and being a trained guitar maker with over 20 years experience, yet people I have known for years still are surprised to discover I am a guitarist and I am equally surprised when they tell me they have a guitar too.

Trust me, you know loads of guitarists. You just don't realise it yet.

Andy

[Jim Lockhart]

I'm with zenguitar in thinking you really need to try another guitar and also another guitar cable. You can also use an electric bass if that's easier to find.

Does the cafe below you have any neon-lighted signs? They can be a major source of electrical interference, as can some fluorescent lighting and some lighting dimmer controls. One way to check this out is to find an AM transistor radio, tune it between stations, and walk around your flat with it to see how the RF noise changes near the floor, etc.

If you have a microphone and mic cable available, you might also check whether you get the same kind of hum and buzz with the microphone connected to your interface and the mic channel gain up fairly high.

[Dr Huge Longjohns]

If you still haven't tried a new lead, get a good one. Again, not wasted dosh because you always need a spare. A decent lead like a Whirlwind will last for ever. A friend of mine got their son a cheap Squier Strat set 'complete with lead and amp' and it was unusable in their living room because of the interference from the lights. I swapped his lead for one of mine and the problem was 90% solved. You haven't said what make/model your Strat is? Shielding on anything less than a Fender US Standard etc is pretty non-existent. Half an hour with some copper self-adhesive tape and a soldering iron can work miracles.

[fully funktional]

I have just tried my cheap condenser microphone and no noise! There are indeed neon lights in the windows downstairs so would this be the culprit if only my guitar is effected?

My Strat is a 10 year old Squier classic design. I know where I can get an electro acoustic so I could test that if that would help.

[Dr Huge Longjohns]

Could be. I'd be looking at new lead and shielding the guitar. Again, shielding will cost you about a fiver assuming you've got a soldering iron or can borrow one and it's a very worthwhile upgrade to most guitars. Basically you just line the inside of the guitar, and the back of the scratchplate with copper foil. Make sure it all joins up when the scratchplate goes back on. Solder a wire from the foil inside the guitar to the back of the volume pot and bingo. Like I said about half an hour. If you're on facebook you can look at my page which has lots of pics of this: My Guitar Page

[fully funktional]

Ok thanks for very much. I'll get some copper foil - I have a soldering Iron somewhere...

Do I just unscrew the scratchplate to get inside? Can I do this without taking the strings off?

[Jim Lockhart]

Lack of noise with the microphone suggests that the problem is with the guitar or guitar lead. You might want to look at the "Confused & Happy with RF Problem" thread in the Recording Techniques forum for a discussion of how some guitar cables work much better than others in a bad interference environment like yours. Shielding the guitar with copper foil is a very good idea -- I did that with my Strat.

[Dr Huge Longjohns]

Can I do this without taking the strings off?

Well, you can, but it's really fiddly and there's a danger you pull a wire off when you'r wiggling the scratchplate off under the strings and twisting it to put the foil on it. I'd do it properly. Take the strings off, take the scratchplate off, remove all the pots then cover the back of the scratchplate and then relocate the pots.You probably don't need to take the pickups off.

[zenguitar]

The only thing better than reducing a guitar to a pile of bits is reducing someone else's guitar to a pile of bits

Andy