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Problem with 60Hz Hum in Guitar pickups.

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LAN_403

GODSFUSION

Sat Apr 22 2006, 05:46AM

Registered Member #157 Joined: Sun Feb 12 2006, 08:00PM
Location:
Posts: 76

I havent really used my guitar anywhere except the garage; since it wasent anywhere near any household lines i never had hte problem on the pickups exhibiting hum from said lines. i was under the impression that the humbucker pickups on my guitar were designed to eliminate the 60hz hum?

Im also under the impression that low E string Vibrates on its own, because whenever i silence the string with anything the hum goes away...

Can any one help with these problems?

- wayne -

Carbon_Rod

Sat Apr 22 2006, 07:01AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

I have repaired a few guitar amps for friends over the years, but I am not much of a strings man myself. Did it just start or was it always there?

Some possible issues:
1.) It could be your outlet may have grounding or power factor issues.
2.) It could be your cable ground shield is shot or input line jack(s) have corroded open (they get dirty too.)
3.) It could be your amp â€œmotor-boatingâ€ as it died.
4.) If you set the instruments output level wrong and the amps gain to high you may even hear some radio with cheap set-ups.
5.) A friend of mine used to have a noise problem with his amp when his â€œeffectsâ€ adjustments started to wear out (or set to low.)

To get different sounds Musicians often modify these types of instruments wiring. If you have a modified unit then getting an accurate picture of whatâ€™s going on may difficult.

Good luck, =D

Hazmatt_(The Underdog)

Sat Apr 22 2006, 07:32AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

Okay....heheh....to start get your rig going and touch the individual pole pieces of the pickup without touching the strings. If you hear a buzz, BINGO! Cheap Pickups.

This happens A LOT! Fender especially! and with steel slugs its a major problem. They NEED to be grounded. Once they are grounded it eliminates the noise coupling. How do I know, I've rewired my strat and personally grounded each pickup slug!
This meant de-waxing the bar magnet, cleaning, pushing the inserts in, connecting them all to a thin shim of steel and checking continuity, then rewaxing, and grounding the foil.
THEN I got the copper tape out and foiled around the windings with a ground shield!

Most pickups now have a ground lead to eliminate hum, except for cheap pickups.

This will reduce almost all of your noise. The secondary issue is flourscent tubes, then of course your effects supply (Mine is pretty clean 25000 S:N ratio). And if you're using a Fender amp, the bias voltage is halfwave rectified with 120% ripple which is just plain stupid.
If you measure the bias voltage and make a note, then change to a fullwave between the tap and ground it will give you 42% ripple. This is a tremendous improvement! And on top of that you can then put 1000pF capacitors across every diode in your supply system to eliminate backlash.

You can see some details about this on my Carvin Mods page after going to my Tube amp page. I should probably put an effects supply there too. I hate seeing anyone pay $250 for a crummy little supply when it costs $50 to build.

I would show you pics of my rewire job inside my guitar...but its strung right now. What I can say is that its all grounded and terminated with RG-174U Coax with heatshrunk ends, clean and pretty. I have a Van Zant, Duncan little '59 and a Lace Sensor. Wierd combo, but it works for me.

GODSFUSION

Sat Apr 22 2006, 09:05AM

Registered Member #157 Joined: Sun Feb 12 2006, 08:00PM
Location:
Posts: 76

Its a Ibanez custom from the factory, and a standard 'cube' amp. I boguht it with my income tax money back in January. Ill check out the pickups when i get back home. I just started noticing it about a week ago when i brought In from the garage. Ill also turn off the flouresant lights and se what happens.

- Wayne -

Carbon_Rod

Sat Apr 22 2006, 10:46AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

â€œ$50 to build.â€ ???

Or less. $3.50 total as the box was free -- as the epoxy casting would not pull free.
This was s a quick improvised battery powered Headset unit I built for a friends kid learning to play. It was designed around a LM380 with some anti-clipping and gain follower filters. It was nice as it fit in his case and the battery lasted quite well â€“ admittedly it sounded pretty awkward though.

It was either this or a Hendrix style solution to the problem. Mu ha ha ha =P

Dr. Shark

Sat Apr 22 2006, 12:44PM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

You are going to hate me for saying this, but I found that the only reliable, permanent solution to noise it to switch to active pickups. The usual humbuckers are just such an outdated concept, it takes PERFECT conditions for them to be quiet when the gain is reasonalby turned up. Save yourself the trouble and get EMGs.

Hazmatt_(The Underdog)

Sat Apr 22 2006, 07:54PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

Joe, I crank up my gain and play guitar within a few feet of my computer, because I use it as a Jukebox, and I must say that I don't have such a bad noise problem as you would think!

The EMG's are no better then putting your guitar into a Seymore Duncan line booster/preamp with grounded pickups. Why? because its the same dammed thing.

I also don't like active pickups beause there's a battery in the guitar! Gah, now I have to have spares in case my guitar dies while I'm playing, that sucks!!!!!!!

Active pickups, then I'd just preamp my guitar. Not only that, but when I redesign my tube amp I will have that feature. Small gain preamp to lower the impedance and bring the signal up by 10 dB.

Steve Conner

Mon Apr 24 2006, 02:13PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Hi fellow axe slingers!

I've always found that even humbuckers don't reject hum perfectly, although they are much better than Fender type single coils.

I've also noticed that many guitars pick up a loud buzzing noise any time you, the player, are NOT touching anything grounded. That's why it goes away when you touch the strings, which are grounded.

I believe it's caused by your body (which is basically several cubic feet of goop that conducts electricity pretty well) picking up 60Hz hum capacitively and coupling it (again capacitively) into the wires inside the control cavity in the guitar's body. (the little compartment where the pots, jacks and switches live.) Better quality guitars have this cavity screened with nickel paint and tin foil, and it seems to work.

GimpyJoe

Mon Apr 24 2006, 03:07PM

Registered Member #316 Joined: Mon Mar 13 2006, 01:30PM
Location: Marietta, GA
Posts: 212

Wait, is this the battery-powered Cube amp? Well, that would explain it!
I use EMG-81 and 85 active pickups and don't notice any difference between the hum from the actives and the hum from my passive Gretsch humbuckers. I think the main factor in how much hum you experience is what amp you use.

Bjørn

Mon Apr 24 2006, 03:52PM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

The logical solution would be to use a 100 Mips CPU to filter out the hum by sampling the signal and calculating the perfect negative hum and adding it to the original signal using numerous valves and transformers. That way you don't destroy the imaginary properties of the sound.

Or you could try the logical step from Steve Conners idea and ground yourself.

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