I had a customer come in the shop with his Harley Benton ST and a set of boutique pickups AND a printout from Premiere Guitar about wrapping single coils in copper tape. I’m going to do it for him, but I figured that y’all have batted this topic around and I want to know if it really does anything. Seems silly to me. I’ve known about it but I never paid any attention to the topic. 😼 Thoughts?
Post by blademaster2 on Mar 4, 2021 16:40:41 GMT -5
I would have expected to hear the difference, but I purchased a set of Strat-type replacement pickups from StewMac a few years back (Golden Age pickups) for my brother in law and installed them. They had copper tape around them, connected to ground. Comparing their sound to the Seymour Duncan SSL-1 pickups I have used in my own guitars, and a set of Tonerider Surfari's in another guitar I own, I cannot say that this was in any reducing the high frequencies that I could discern. All of them had the expected glassy-highs I have come to know in Strats.
In theory any metal nearby in the changing magnetic field will introduce more eddy current losses and reduce the high frequencies. I understand that it varies depending on the metal used, so perhaps copper is not as sensitive.
I can’t understand why someone would pay another to add tape to guitar hardware. Is it actually just wrapping each single coil with copper tape?
Sry this adds nothing to the advice/conversation asked for.
(Sigh, sorry, I understand now. Get that someone has a guitar they love, and they find an “improvement” article somewhere, and they don’t want to “ruin” their guitar during the application of the article’s “improvement”, so they put their trust in a professional.)
I can't really see as it's any different from having covers on a hummer, Tele neck pup, filtertron or "Lipstick" etc etc. I suppose there is the capacity to "ground" to consider, but surely that can only affect the very outside layer of the turns because the vast majority of inner turns are Faraday screened by the few surface turns?
frets; you could enquire whether the customer has any other guitars with the pickup covers removed.
Yes, we have discussed this fairly extensively, way back in the dim mists of time. I trust that if tragichero couldn't find the thread in question, neither could I.
But we had a member who did some pretty extensive testing of various wrapping schemes, looking at loss of highs vs. noise reduction. IIRC, he found it did somewhat reduce the high frequencies as well as reducing noise, but his final take-away was that, if one left a small gap in the copper wrapping, going only like 9/10s of the way around and leaving about a 10% gap, the noise reduction was roughly equivalent to wrapping the coil completely but without the loss of the highs.
But it's been a long time, so I could be way off base. Maybe JohnH will recall the thread; it's hard to search for because there are so many possible search terms.
As suspected, I was unable to find the thread in question, although I found many other places where the thread is referenced.
What I did find was these two links. The first one is from old time member D2o, scroll down to reply #25. There, D2o decribes his process for shielding the inside of Strat pickup covers w/ aluminum HVAC tape:
And this link from old member woody, where he discusses using copper mesh to wrap coils, and recommends leaving about a 5% gap. Woody may have been the one with the original thread on this, now that I've read through this subsequent one. Unfortunately, his pix have gone bye-bye over the years:
Per the wisdom of Woody, who was a presence here back "in the day", I'd leave a 5% gap. The issue is that, if you go completely around, you have effectively added another layer to the coils. Leave the gap, the copper doesn't connect to itself and you nonetheless get the noise reduction.
I had forgotten the bit from D2o about how he shields the insides of his Strat covers. Have to give that a try one of these years . . .
Post by thetragichero on Mar 5, 2021 14:45:18 GMT -5
I'd imagine the effect is much like "cloth wire sounds best": more perceptible "between the ears" than something that can be measured using science. guitarists tend to be an easy mark for this kinda spin
The copper tape does cause eddy currents, because there is continuity around the coil, and if the coil were cut down the side, that wouldn't be the case. It's still not as bad as brass cover because most of the eddy current losses come from the top down. It's a lot like an open top cover, but the copper tape is hugging the coil a lot more closely. It also adds some degree of capacitance, more so if the start of the coil is on the outside, right beside the shielding.
Even though neither the eddy currents not the capacitance makes a huge audible difference, I would remove the copper tape out of principle. Just knowing that it's there getting in the way of vintage correctness and not providing much benefit, bothers me. They're a cheap pickup that can be made vintage correct with relatively little effort, but lately I'm seeing vintage correct AlNiCo pickups on Amazon that are even cheaper and don't require any modifications, such as the "OriPure" for $31.
I have an Duncan Designed SC 101, I measured it in 2018, but I'll test it again later, sometimes this week, because at the time I wasn't as concerned about the copper shield so much as the inductance and the overall sound, so I didn't test that as thoroughly as I wish I had.
Post by thetragichero on Mar 7, 2021 20:02:10 GMT -5
that's something i've wanted to try but already have so much on my plate... currently learning more than i've ever wanted about drums/cymbals putting a kit together to donate to the church (while also upgrading the kit in the studio)... at this point i might as well learn how to play since i've always had so much trouble finding a drummer
With regard to your customer, check if the coils' finish is to ground or hot. If they're wired to coil finish to ground, then adding the copper tape will make no difference of any kind, it won't even block noise. If they pickup wired coil start to ground, then it will block noise, but it will virtually add one foot of guitar cable capacitance, which is not audible IMO.
If the tape is wrapped all the way around, and it has continuity with itself, such that electrical current can flow around the shield, there will be about 2dBV drop at resonance, barely audible, sort of like turning the tone knob down by 1/20th. For the sake of preserving the vintage single coil sound as much as possible, I'd avoid the unnecessary eddy currents, even though it's not much. In fact the pot tolerances alone can make more than 1/20th a turn of difference, but I'm not above doing things for the sake of doing it.