Question about HUM --

[zgrav]

:shock: Are fuse panels for house wiring a major source of hum?  I was playing my strat (fully shielded body and 3 shielded single coils pickups) last night into a battery powered amp and getting oodles of hum through the system.  I realized I was close to the fuse panel for my house, and could vary the hum from very quiet to noisy as hell based upon how the guitar was turned.

Given that the fuse panel is already behind a metal enclosure, is there anything else that can be done to shield the noise at its source?  Or should I just keep playing in a different room :?:

[petemoore]

Hum's ALWays a bummmer but
I used to try a different guitar...but I think now I can tell alot by just unplugging it.
 could be anything...a different guitar will tell only how a different guitar reacts to that setup under those conditions

[Rob Strand]

The humm you are experiencing is electromagnetic, a shielded box and guitar shielding doesn't do much for this type of humm.   You would need a closed steel box around the fuse to stop it which is a little impractical. The single coil pickups will pickup this humm directly and there not much you can do about it.  Depending on your pickup phasing you should be cancel some humm by switching the pickup selector to two pickup combinations.  Humbuckers on the other hand are designed to stop this type of field induced humm.

To be honest the best and simplest solution is not to stand near the fuse box and not to aim the pickups in it's direction.

[Ansil]

you can take 60 hz and all its multiples in the guitar range, and make notch filters for all the overtones,  i have only built two of these, and the first one worked better than the seoncd.(which i don't understand since the second was built better and i actually etched a board for it. hmmm)
anyway,  i only did eight filters and it sounded pretty good, i only really needed four i think i could have even got away with two, but with eight filters i definately was a little anal retentive and got some strange sounds.  so anyway sorry for the rant.

[JJRockford]

Ansil, how did you built this filter? I'm always intrested in anything that can eliminate eventual problems, without affect the sound!

[Ansil]

look at the  boss seven band eq  i believe there is a schematic for it.  there is a formula on one of the schemes that tells you what caps you need for certain frequencys.  my original one used simple notch filters, i believe you can find out more on notch filters at RG's site. all i did was used the same frequency formual 1/(6.28RC) then doubled the freq to get the over tones.   and made a sharp, deep filter.  my very first attempt was with and old eq, that i canabilized for parts.

unfortuneately i don't have a scheme anymore. it crashed with my laptop.  if  i can get a mouse i will try to draw one up in my spare time but i can't draw real well on a touch pad.

one could do this though using and inverting amplifier. you could make your standard gain amplification and for your highpass filter you could cutit off just before the freq you want to remove, say you want to make your low cut off 63hz, so you don't get your hum, then you just have to worry the overtone frequencys.  

of course you could try one other fairly simple things ..  make a freq. generator with a 555 timer,  make it use a gated input, and set the freq at exactly the hum that is botthering you,  say 60hz.  for 60 cycle hum, and make sure this freq is exactly out of phase with your hum,  and run your guitar with this, set the gate to trigger the freq when you play.  set the mix to the desired level with your hum.

of course if the hum changes phases where ever you are standing at, then you would get a hum tremelo.  

i tried this timer oscilater thing with the 555 and it worked well with my flurescent lights that i had in this garage apt. that i lived in.

if i have a chance i will see if i can draw something up.

[Andy]

are you sure that hum wasn't caused by the batteries in the amp being low?  were u near a flourescent light?  was the washer/dryer on?  lol