Question about recording guitar (direct input).

[Wax Moon]

I hope this is the right place to put this.
I've been using a lot of processed guitar lately, since that's the only hands-on instrument I'm semi-literate with. I've got my guitar going straight into the instrument pre-amp on my sound card, but I get this slight buzzing sound at around 5khz that becomes very frustrating when using distortion/etc. I've just been EQing the buzz out until now, but I'd rather get to the root of the problem..

Does anyone know what the cause of this buzzing is?

Would getting a DI box solve this problem? I've read up on them a bit, but they seem to be used for splitting guitar signals during live performances.

Thanks!

[aoVI]

A DI box converts an unbalanced signal into a balanced one, as well as lowers the impedance. It would probably help, but it also may be EMI from your computer hitting an unsheilded guitar cord or your pickups. I get noise when I get too close to my pc.

[seismic1]

...... I get noise when I get too close to my pc.

Have you had some questionable dental work in the past? :tu:

[aoVI]

Nothing too unusual, just a nice grill.

[Thought Experiment]

Aaargh!
Ahem, back to topic...if you have single-coil pickups on your guitar it's almost definitely interference from your monitor. A noise gate would be a better method of getting rid of the buzz than EQ. Even better though would be something like a Peavey Xport, a guitar-to-USB interface. It's inexpensive plus you get a cut-down version of Revalver, an excellent amp simulator.

[Wax Moon]

Thanks! I'm using my roommate's Les Paul, which has humbuckers with metal plating. I've noticed that the buzzing changes a bit depending on where I set up my gear and which outlets I use. Maybe there's some interference there? I've used a noise gate before, but I can still hear the buzzing when I'm playing the guitar, which quickly becomes irritating when I'm stacking effects to make the guitar sound like a dying whale. I imagine I can't use the Peavy Xport at the same time as my normal audio interface, plus I already have Guitar Rig.

I guess I'll have to hold off on that grill I was going to buy myself. :steam:

[GaryG]

Could it be some sort of ground loop? I get an awful buzz when I plug in at a friends, solved by unplugging my laptop from the PSU when playing.

[Wax Moon]

It's possible. My monitors used to pick up the local Christian radio station, so that's probably related. I'm on a desktop though, so I can't unplug. :/

[aoVI]

A DI box with a ground lift switch will help on a ground loop problem. You can find ok ones fairly cheap.

Guitar center

Sweetwater

Musician's Friend

Amazon

[Thought Experiment]

Just to be clear - what soundcard are you using? Is it the one that came with the PC? If so, the 'instrument' input is highly unlikely to be a preamp, and you're not getting a strong enough input level. Look into getting a decent external audio interface. Also be aware if you try out the DI box route, you'll need a balanced input on your soundcard interface (i.e. an XLR-type input).

[Wax Moon]

I'm using an M-Audio Fasttrack Ultra, which claims to have decent preamps (I'm not so sure).

[Thought Experiment]

M-Audio stuff is pretty good so that probably rules out the soundcard. This might sound obvious but have you tried another guitar? Sometimes the grounding wire can break loose from wherever it's soldered (usually the bridge or tailstop). If it isn't the guitar then I'm afraid it's most likely a ground loop, as GaryG suggested. The good thing is your audio interface is equipped with XLR inputs so you could try out the DI box with a ground lift switch as suggested by aoVI ;)

You could also try different power outlets just in case they're on a separate circuit and therefore not on the 'loop'.
Any other cures for fixing ground loops usually entail hiring an electrician and can become so expensive that it's cheaper to move house :eek:

[Wax Moon]

Thanks for the suggestions, I've had the same problem with other guitars. Changing outlets seems to change the problem, but not solve it. That might just be in my head though. I'll try out a DI box and report back.

Also, I'm renting, so definitely not going to hire an electrician.

[des]

You didn't mention the type of computer...laptop or desktop. If its a laptop the problem could be the power supply. A lot of laptop power supplies put noise onto the ground buss which gets into everything. Best way to find out is to disconnect it and try running on batteries. If it goes away you have your culprit. Fixing it would require replacing the offending power supply or plugging it into an isolator and plug that into the power strip/wall outlet.

If a desktop computer you can try using an isolator to see if thats the problem, but most desktop computer power supplies have tighter regulations preventing them from 'polluting' the local power.

The problem could also be something plugged into the wall...neon or fluorescent lighting, etc...

[magnesson]

i have noticed when you use power supplies for computer and effects on the same outlet or circuit you will gain a 60 HTZ hum. so it is best to use separate power outlet for recording preferably a outlet that has no one electronic devices connected.