When Grounded shielding makes no difference

[petemoore]

  I thought shielding a noisy 3SC guitar's pickup positions 1,3 and 5.
  Reasoning being that the guitar is a directional antenna, there is a few degrees of yaw relative to amp in which noise is markedly reduced. Playing without having to keep the guitar in this position is something I was to be able to do with this, and eliminate the excessive noise which was and is still in 1/3/5 sw positions.
  The weight of the shiedling may improve sustain, but that wasn't a problem.
  This is on a 386 test amp, I think it's the same noise, typical 1/3/5 Positions strat noise because the tone and amplitude [of the noise] differences to positions 2/4 sound the same as before.
  I tested ground is being made through the soldered wire on all copper pieces, pots, switch, existion ground tape around the pickguard potholes, And..the plug sleeve. I can't figure out how noise can penetrate that, perhaps somehow pickups get noisey?
  The weight of the shiedling may improve sustain, but that wasn't a problem, the installation went quickly, 2hrs. neatly...covering: Behind/sides of the 3 all pickups[1 sheet following up the sides of the 3 pickup large rectangle cavity, but nothing on the ends [neck bridge there are 3/4'' x 3.5'' ground openings], the entire control cavity, letting the original grounded shieldtape do around the pots...so there is a small gap all the way around the pots/switch where the tape ends and shielding sheet begins [3/8'' or so].

[Khas Evets]

I did the same thing to my strat. There may have been a very slight reduction in noise, but I'm disappointed. I'd like to know how much noise reduction should be expected.

[BrianJ]

Pickups are inductors.   They are the most efficient antenna in your rig.  They are way more sensitive to nose than wire or pots.  That's why the noise changes as you move around, the polar responce of the pickups is moved, in a sense, "off axis."

[Paul Perry (Frostwave)]

IF the picked up noise is dependant on angle, then it is probably magnetic field pickup. (from the power transformer in the amp).
The only thing that will fix that is some ferromagnetic material to shield the magnetic field..
normal RF shielding (foil or braid) isn't going to help. That's why God invented humbuckers.

[Processaurus]

IF the picked up noise is dependant on angle, then it is probably magnetic field pickup. (from the power transformer in the amp).
The only thing that will fix that is some ferromagnetic material to shield the magnetic field..
normal RF shielding (foil or braid) isn't going to help. That's why God invented humbuckers.

Wow, thanks Paul, I've been wondering about that for a while.  I get alot of that noise with my Jaguar (that has copper plates for blocking RF) when its near my monitor, turn off the monitor and peaceful silence descends.  The mysteries of magnetism...

its a jungle out there if you're a single coil.

[petemoore]

  Naturally noisey...but why only 1,3 and 5...probably because in those switch posistions it's trunly 1 single coil, good for very 'accurate core samples' being thin like they are but, not so good for noise.
  Yes the shielding I did, seems to help mainly the direction/proximational control of noise, IOW a sharper, more pronounced onset of noise with the same amount of yaw change...yupp, just got back from trying it out ont the 15w...decidely reduced/increases noise in the guitar, much more focused tuning w/antennaguitar thing recieving transformer noise info.
   
  Paul wrote "IF the picked up noise is dependant on angle, {<Which it IS>} then it is probably magnetic field pickup {<HAS to be>}. (from the power transformer in the amp)...this is where the idea comes in. Shield the Xformer...I didn't exactly follow layout on the amp...just checked...the iron's stacked plates are inline with the long dimension of the chassis directing< magnoise directly at the guitar!!!
  Any advice about [not?] shielding transformers now is welcomed...I have a 45 degree, 6'' angle aluminum strip, or flat one [I'm thinking the 45 degree thing might 'shoot' the electrons 'around the sides to behind' the iron as opposed to a flat one, 'mirroring' electrons mosly right back into the iron....but...
  The 'EZ" Pieces I have are aluminum, but I'm wondering is that 'shieldy' enough for iron emission electron reflection plate.
  I believe the 5e3 has the PT on the 'other side' of the chassis, shooting most of the 'noise electrons' up/down, 'behind the amp...I gotta go look at some pics...mine is laid out sort of like my 50w MkII, except the OT is hanging off the back of the chassis. Other than some hiss, a 'good dose, the newly built amp is low noise.

{BTW I need to look up 'ferromagnetic''

[petemoore]

  I put in a grounded metal plate, where it came from looked like a shield housing from over a PCB, like plain med/thin metal, and put that inbetween the transformer and pickup/no difference.
  After trying out w/shielding in guitar w/amp I use, 5e3, pickups 1,3,5 seemed much more usable...probably because I'm the pickups are then 6-8 feet from the amp, there are spaces in this shielding effort...if I knew noisound was getting through one of them in a particular spot, I'd try to put some shielding right there..lol.
  Also I seemed to have noticed a slight difference in...overall sound, nothing detrimental, or I can't tell for sure, but the high end seems smoother or less?
  So...no luck with Xformer shield plate sfars I can tell, maybe a teeny bit...and the guitar shielding did something, seems more usable in practice.
  last nights tests were with an LM386 amp, switching the pickups from 2 or 4 positions caused lots if not more noise than w/out shielding, waving the antenna worked good for some noise amplitude modulation...I figured a 386 amp w/no xformers would be less noise...ahhh...see, I probably had the adjusto-quartz lamp on, it just now dawns on me, and now I'm certain that was the case, that lamp, about 10 feet away from where I was working is what was inducing the increased noise on all pickup settings, 2 &4 still being about 1/3 noise source compared to 1/3/5.
  Can't figure the hiss of the amp, maybe I messed the caps up with a 'hard' first fire up'? another topic.
  With noise tuned out or down, the guitar sounds great on all pickup positions.
   Woudn't mind to have a 3SC setup like 'dude's'...'dude' that has the great sounding 5way GuitSwitchRig W/low Noise.

[LyleCaldwell]

Proper shielding won't eliminate the 60Hz endemic to passive single coils (and still present at a greatly reduced volume with humbuckers) but it can eliminate all other noise sources between the pickup and the amp input.  A properly shielded and star-grounded guitar will have no noise level difference regardless of whether you are or are not touching the strings or other grounded metal components.  A CRT or noisy transformer will still make the pickups hum.

[loki]

i just shielded my bass today... been wanting to do it for a while but i needed the copper tape which i couldn't find until a couple of days ago...
i had a very noisy hum coming out of it, pretty much 'cause i rewired it and there were a lot of ground loops i suppose...
anyway it's a fender jazz, with non hum cancelling single coils. i wired it with a master volume pot, a master tone pot, a gibson-style 3 way pickup selector, and a killswitch
i shielded the back of pickguard, the pickup cavities and the control cavities with self-adhesive conductive copper tape, made all the connection ensuring no ground loops, and used coaxial shielded cable for the hot signal.
now it's FAR more quiet... sure the hum is still there, but much much less noticeable. i wish i had done it long ago

[petemoore]

  I looked up 'ferromagnetic' the best one I found that I might have around here is Iron, I don't happend of have nickel plates here, the only cobalt I have is in heater element wire.
  I should note in this thread that the amps chassis is aluminum, and I don't know yet if that matters.
  HB's are an easy fix, but the amp sure likes the SC's, which aren't 'good' noisewise, but usable at this point.
  I later figured to remember that there Was a quartz dimmer lamp I was using at the time of initial testing, those definitely induce noise into  signal problems.

[petemoore]

  Ok...Looking directly at the word "ferromagnetic", Dropping the 'ferro' we have > "MAGnetic"...which 'says'... indicates "Not Copper".
  First I looked up 'ferrous' an adjective, which brings this definition:
>  Of or containing iron, especially with valence 2 or a valence lower than in a corresponding ferric compound.
  Then: "Ferromagnetic" >Of or characteristic of substances such as iron, nickel, or cobalt and various alloys that exhibit extremely high magnetic permeability, a characteristic saturation point, and magnetic hysteresis.
  saturation point >The point at which no more can be absorbed or assimilated.
  magnetic hysteresis >The lagging of an effect behind its cause, as when the change in magnetism of a body lags behind changes in the magnetic field.
  Potential candidates I've recognized are Iron, Nickel, Cobalt...
  IRon...heavy, hard to work', Rusts.
  Cobalt >A hard, brittle metallic element, found associated with nickel, silver, lead, copper, and iron ores and resembling nickel and iron in appearance. It is used chiefly for magnetic alloys, high-temperature alloys, and in the form of its salts for blue glass and ceramic pigments. *Atomic number 27; *atomic weight 58.9332; melting point 1,495°C; boiling point 2,900°C; specific gravity 8.9; valence 2, 3.
  *I don't think I want the words marked with *'s associated with my guitar, besides it's brittle.
  That leaves Nickel, like in ...' nickel plated amp chassis {Mine is aluminum"...
  Now searching for nickel plated copper...
  And then I looked more closely at... That's why God invented humbuckers.
  Soft refrigerator magnets, and speaker magnet were used to try to interfere with interference, waved in different orientations between Iron and Pickup, near both...this seemed to have maybe a slight 'tuning' of the hum effect [could be my imagination] but no 'cancellation' of it.
  Positioning the guitar within about a 12 degree yaw 'limit', 8ft. from the amp it's actually not much if any louder hum/noise than HB's...which tends to be where/how I stand with the guitar anyway, or at least that position isn't encumbering.
  I've seen 'Strat-antenna's' waved around without the accompanying 'noise tune in/out' effect, I wonder how that's done.
  I'm super liking the 3SC's Tone dept. and 5way switch, living with, but not giving up on possibility for noise reduction. 
  ...I looked up 'nickel Plating' looking for if that can be done with copper sheet [maybe get the shaped shielding pieces I have nickel plated, but haven't found anything...and seem to recall something about 'ferrous and non-ferrous' metals having some 'interactive restrictions or something like that.
 

[KMS]

I have a similar problem...posted as....."150amp hum...help".

I can get the hum to stop if I put the guitar on just the right angle and it is much less without distortion FX.

I realized that because the angle change also changes the hum that it is indeed a magnetic problem....so I connected a very long ground wire from my power supply and started touching it to anything metallic in the room.  Almost everything I touched had no affect except the water pipes and the duct work where I noticed an increase in hum when I touched those metallic objects.

So I checked the duct work first and found that the furnace was grounded to the water pipe so they were in common connection.  I then found the 150amp service for my house was connected to the water pipe so I disconnected neutral wire from the water l pipe (last night I did this) and the hum was 100% gone=zero hum, but my blower motor on my furnace would not work and my lights flickered (another problem I am working on today).

I'll keep everybody updated on my work with this hum problem.

Question;

Do you get your hum if you hook up on a long extension cord outside (away from the building)?

I am wondering how many people have this same problem and do not realize the source.