Annoying guitar hum (recording direct)

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Eric U

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I have used a couple different recording setups in recent times ...... one a G3 desktop with a Korg 1212, and currently a G3 Wallstreet laptop ( with mods, of course .... VX Pocket sound card, 48 gig drive, extra ram, etc) ..... My question pertains to both setups I have used, and I'm sure many others. I mostly record direct - electronic percussion, synth, guitar, bass; the problem I'm having with "hum" is mostly with the guitars. I find that if I turn myself at an angle to my (recording) rig, I can minimize the guitar hum by turning myself at what is generally pretty close to a 45 degree angle from the computer. I am hoping, however, that there might be a more effective step or two I could take to avoid said hum. I experience the same result whether I use external analog to digital conversion, or just run direct into an analog in. I know you guys have experienced something similar ...... suggestions?
 
Give your guitar a slap and tell it to "SHUT UP!"

Seriously, there was another here experiencing much the same problem with his guitar rig. I don't know if he ever got the problem solved or not.

Sounds like a grounding problem or feedback loop. We suggested many fixes to the other person, but nothing seemed to cure the problem.

Hopefully someone knows the right answer.
 
Guitar pickups, except for contact mics and piezo's used on acoustic/electrics, are magnetic pickups. They have typically several hundred to a few THOUSAND feet of super fine magnet wire wound around the pole pieces (magnets) - when the guitar string moves back and forth across this device, it changes the magnetic field in the pole piece and causes a small current to be induced in the windings around the pole piece. This is the way the signal gets from the guitar into your amp or recording gear.

Unfortunately, this also makes your guitar a fairly efficient antenna for any stray electrical fields in its vicinity. When you get your guitar close to a CRT monitor, the guitar pickup recieves a signal induced by the Electromagnetic field from the CRT. You won't usually notice the pickup caused by the horizontal deflection, because virtually all computers now have horizontal frequencies 'way above human hearing range. However, the vertical refresh frequency is normally anywhere from 60 to 90 hZ, which is VERY audible.

The reason you can minimise the noise by rotating your guitar, is that you are changing the relationship of the coils in your guitar pickup to the field caused by your CRT. This is one of the reasons why people who can afford it are going to flat screen displays. Another advantage of that is not having to use shielded nearfield monitors. The disadvantage, obviously, is price.

Some other causes of hum/noise along this same vein - flourescent lights. The ballast in reasonably priced flourescent lights is a notorious hummer. Hum-bucker pickups usually suffer less from hum than single coils. Normally a Strat with 3 single coils is wired so positions 2 and 4 are using 2 of the pickups wired out of phase for a noticeable reduction in hum. I've found that the LCD displays in rack modules is not a good thing to have next to an open phone cord (plugged into a mixer but not into anything on the other end) - first time I accidentally did that I chased my tail for about 15 minutes looking for the noise.

If you can't afford a flat panel display, when you record electric guitar try sitting as far away from the monitor as possible. rotate the guitar for minimum noise, make sure no flourescent lights are on, keep as far away as possible from any "wall wart" transformers for equipment, make sure your guitar cord is NOT running close to or parallel to any power cords - If all that fails, take off the back cover under the controls of the guitar, and see if the cavity has been shielded with copper foil. If not, go to carvin.com and order one of their kits for this. About $9.95 for their "wiring" kit, has hookup wire, copper foil, etc - Make sure all cases of the pots have a ground wire soldered to them and connected to the common ground for the output jack -

If none of that works, there are pretty good noise reduction algorithms in some software - Sound Forge has an option, and Samplitude has it built in. You sample a portion of the waveform that should be silent, and tell the SW to remove anything like that from the sound.

Hopefully something in this post helped... Steve
 
If your computer monitor is causing the hum/buzz(sure sounds like it). Just turn it off before you hit the record button. Easy enough to set the levels with the monitor on, after that you really shouldn't need to look at the screen unless your doing film work or something.

Get good at keyboard shortcuts. Most software multitrackers can be 'mapped' so you can use your keyboard to do functions such as:

Spacebar=stop
record=*
delete=delete
RTZ= r
left marker = 1

etc.
 
Yeah, but then you don't get to see if the damn thing's actually tracking or not. :D

I seem to recall someone here a year or two ago who was having problems with monitor-induced noise, and the fix was to crank the brightness all the way up. Somebody else tried it with similar good results. I think. Well, that's what I remember, anyway. :D
 
anybody ever pick up strange radiostations while playing using distortion on their guitar. its the most F#%ked up thing ever and its happened 3 or 4 times now
 
Yeah, turn off your monitor every time you hit record. Especially if you're tired of it and want a new one. Every time you turn on a CRT, you cause a voltage/current surge in the filament of the CRT. If you have a project where you record 12 different takes on each of 8 tracks, you've just shortened the life of your CRT by about 100 TIMES !

Find a better way, unless you like buying monitors... Steve

Or, you could go ahead and toast the one you have, and replace it with a flat screen - that should cut down the noise considerably...
 
Eric U said:
I have used a couple different recording setups in recent times ...... one a G3 desktop with a Korg 1212, and currently a G3 Wallstreet laptop ( with mods, of course .... VX Pocket sound card, 48 gig drive, extra ram, etc) ..... My question pertains to both setups I have used, and I'm sure many others. I mostly record direct - electronic percussion, synth, guitar, bass; the problem I'm having with "hum" is mostly with the guitars. I find that if I turn myself at an angle to my (recording) rig, I can minimize the guitar hum by turning myself at what is generally pretty close to a 45 degree angle from the computer. I am hoping, however, that there might be a more effective step or two I could take to avoid said hum. I experience the same result whether I use external analog to digital conversion, or just run direct into an analog in. I know you guys have experienced something similar ...... suggestions?
Click to expand...


Try a direct box and some balanced cabling.

Scott
 
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