OK, electrical smart guys....am I just getting lucky?

[Zippy]

I posted a while back that all my single coils were silent since I learned a lesson years ago and employed a certain shielding formula. Nobody called BS on me straight up but I figured somebody wanted to as it's just down right fun. So naturally, I figured something had to be wrong. Anyway, I just employed my old formula and it worked again. I'll explain from the beginning and y'all tell me if I'm just getting lucky or if something else is going on here.

Years ago at a club in Wichita Falls I found single coils buzzed at a friend's club more than others. A girlfriend gave me a Fender vintage cloth covered cable as a gift and I used it to my demise one night. Until then I always used cables built from a guy recommended on this site whom I can't remember, but the obvious difference made me investigate. The cable from him were always great cables, cheaper than most, and way quieter than the gifted Fender cable. Anyway, I consulted and asked about cable differences and found "double shielding" didn't mean twice as much, but rather two different metals in the shielding of the cable. It was explained to me that only aluminum shielded certain things, mainly neon dimmers. I thought this might work for guitars as well since I always shielded with copper.

I incorporated aluminum and copper in my guitar shielding and low and behold, it worked. I first intalled a sheet of aluminum, then followed using conductive adhesive copper. I made sure each metal was exposed and made contact with the pickguard and also star grounded. I went back to my original "double shielded" cable and it was dead silent.

I just did this again on a MIM Strat. It now makes zero noise at a local club with lots of EMI/RFI issues.

Am I just getting lucky here? Is something else going on? The club to which I refer has neons very close if one is stage right, so it's avoided like the plague.

Thanks for the input from the intelligent. Once again, humor is always welcomed in place of knowledge.

Zippy

[NickHorne]

Hi Zippy,

Something good is most definitely going on.
Aluminum, in a moving / alternating magnetic field, experiences eddy currents much more than other everyday metals.
Swing a slice of copper sheet, which is a great conductor of electricity, through the poles of a big magnet, and it will slow it down a bit.
Now do the same with aluminum, and its movement will stop really quickly. The eddy currents oppose the external field strongly.

Aluminum is great shielding for e/m interference, including higher-frequency, buzzy stuff.

But aluminum is a bit weird as a conductor for electricity. It conducts fine, but Its surface oxidises really quickly, and its oxide is an insulator.
My guess is that combining it with copper mesh braid in a cable keeps electrical contact with the aluminum by a mixture of sheer contact area and also rubbing / scraping between the two metals, combining to keep good electrical ground connection between the interference-absorbing aluminum and the less-fussy copper conductor by friction and scraping as the cable is used, cleaning the oxide from the aluminum sufficiently to keep it well grounded.

Anodising also creates an insulating surface, which needs to be abraded away locally to get a decent grounding connection to, say, the back of a pickguard.

Using aluminum in pickguard shielding will definitely work significantly well. Again, contact with a large area of copper, to help ensure electrical continuity, will be good. Aluminum will shield against e / m interference much more than copper alone.

It may also mellow-out your tone a little. Leo Fender used thin aluminum sheet, around .014" in early Strats and Precisions, to help screen from noise, and also, I strongly suspect, to fine-tune the instruments' upper-mid character, reducing brittleness.

[Zippy]

Nick, thanks for the response. I forgot all about eddy currents. I only know about them from pickups so I don't think much about them in other aspects.

I can A/B test this but wonder if this has already been done? I can borrow a stock Strat for testing since all my stuff is shielded. Funny, normally you can't swing a dead cat around here without hitting a Strat.

If I'm already shielding and star grounding a guitar, this is an easy and cheap addition but really is only needed by working players. I've not noticed any tone change at all. Neither have the guitar owners to my knowledge. The only tone feedback I've received is I was told the guitar has more sustain and dynamics. I didn't say anything to him but I don't know how that can be possible unless my process eliminates some type of phase cancellation that may be happening to unshielded guitars. Maybe it's that the signal to noise ratio has changed so highs can be heard easier and notes seem to last longer. Maybe the 60hz hum "steals" part of the finite energy available so when it's eliminated, the signal is stronger. I guess those last two are the same, aren't they?

Anybody who's done this chime in please.

Thanks,

Zippy

[bassman]

Larry,
The increased sustain is just the note decay that can now be heard unmasked by the previous noise and RF.

One question about your shielding. You are putting two layers - one of copper and then one of aluminum in each guitar and getting great results.

Have you tried to use two layers of either metal to see if you get the same result?