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Guitar noise / interference problem

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Guitar noise / interference problem

Postby fully funktional » Thu Mar 07, 2013 5:53 pm

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
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Re: Guitar noise / interference problem

Postby Jim Lockhart » Thu Mar 07, 2013 11:57 pm

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.
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Re: Guitar noise / interference problem

Postby zenguitar » Fri Mar 08, 2013 1:07 am

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.

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Re: Guitar noise / interference problem

Postby fully funktional » Fri Mar 08, 2013 5:23 pm

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.
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Re: Guitar noise / interference problem

Postby zenguitar » Fri Mar 08, 2013 8:18 pm

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.

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Re: Guitar noise / interference problem

Postby fully funktional » Sat Mar 09, 2013 8:59 pm

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
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Re: Guitar noise / interference problem

Postby zenguitar » Sun Mar 10, 2013 12:47 am

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.

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Re: Guitar noise / interference problem

Postby fully funktional » Sun Mar 10, 2013 3:27 pm

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?
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Re: Guitar noise / interference problem

Postby zenguitar » Sun Mar 10, 2013 4:03 pm

fully funktional wrote:
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.

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Re: Guitar noise / interference problem

Postby fully funktional » Sun Mar 10, 2013 4:23 pm

How do I do the test?
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Re: Guitar noise / interference problem

Postby zenguitar » Sun Mar 10, 2013 8:25 pm

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.

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Re: Guitar noise / interference problem

Postby fully funktional » Sun Mar 10, 2013 9:42 pm

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

-Tom
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Re: Guitar noise / interference problem

Postby zenguitar » Sun Mar 10, 2013 11:43 pm

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.

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Re: Guitar noise / interference problem

Postby fully funktional » Mon Mar 11, 2013 5:44 pm

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?
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Re: Guitar noise / interference problem

Postby zenguitar » Mon Mar 11, 2013 8:34 pm

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.

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Re: Guitar noise / interference problem

Postby fully funktional » Wed Mar 13, 2013 8:43 pm

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 :headbang:

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?
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Re: Guitar noise / interference problem

Postby zenguitar » Thu Mar 14, 2013 1:41 am

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. :lol:

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Re: Guitar noise / interference problem

Postby Jim Lockhart » Thu Mar 14, 2013 3:14 am

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.
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Re: Guitar noise / interference problem

Postby Dr Huge Longjohns » Thu Mar 14, 2013 10:57 am

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.
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Re: Guitar noise / interference problem

Postby fully funktional » Thu Mar 14, 2013 1:43 pm

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.
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Re: Guitar noise / interference problem

Postby Dr Huge Longjohns » Thu Mar 14, 2013 3:17 pm

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
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Re: Guitar noise / interference problem

Postby fully funktional » Thu Mar 14, 2013 5:22 pm

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?
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Re: Guitar noise / interference problem

Postby Jim Lockhart » Thu Mar 14, 2013 6:17 pm

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.
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Re: Guitar noise / interference problem

Postby Dr Huge Longjohns » Fri Mar 15, 2013 2:33 pm

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.
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Re: Guitar noise / interference problem

Postby zenguitar » Fri Mar 15, 2013 5:59 pm

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

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Re: Guitar noise / interference problem

Postby Dr Huge Longjohns » Sat Mar 16, 2013 1:27 pm

Isn't that what you do for a living, Zen! :D
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Re: Guitar noise / interference problem

Postby DAGGILARR » Sat Mar 16, 2013 5:19 pm

zenguitar wrote: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 :beamup:


Hmmmn
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Re: Guitar noise / interference problem

Postby zenguitar » Sat Mar 16, 2013 5:40 pm

Huge Longjohns wrote:Isn't that what you do for a living, Zen! :D

Kinda...

the hard part is putting those bits back together again ;)

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Re: Guitar noise / interference problem

Postby fully funktional » Tue Mar 19, 2013 4:16 pm

Hey guys, update:

I've just applied copper foil to the back of the scratch plate and half of the inside where the pickups go. I need to get some more copper to finish the job though.

Do I also need to cover the area around the jack socket? And what about the bit at the back where the springs for the tremolo bridge are?
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Re: Guitar noise / interference problem

Postby Gary_W » Tue Mar 19, 2013 7:15 pm

Have you got a multimeter? They start at about a fiver and will allow you to test for continuity. You need to ensure you've got a good connection from your guitar lead sleeve (earth) to the bridge.....there will be a wire connecting this but the quality of soldering I've seen in some of my guitars makes bird crap look pretty. And a decent earth to the back of all of the pots. If you haven't, out with the soldering iron....

Anyway, if you've got a decent connection between bridge and your jack sleeve then you can make sure you get this connection followed along to your scratch plate copper and body cavity copper..... This can be achieved by the fact that the earthed pots clamp onto the earthed scratch plate. Then the scratch plate clamps down onto the little bit of cavity screening that I leave out to squash between plate body cavity.

As to the jack, I just make sure I use screened wire :)

Even with all of the above, you will still get noise on a Strat from dimmers, fluorescent lights, computers, your mobile phone, werewolf activity and possibly other things that I've forgotten. However, the screening is well worth it IMO as it makes it MUCH more forgiving of all such external things (*) so, whilst it'll still buzz, it won't be anywhere near as bad.



* werewolves still upset it. Unless you remember to use silver solder and even then it's dicey.
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