ampage Tube Amps / Music Electronics	For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

foil wrapped single coils.Complex question?

2/28/2004 9:47 PM
neil ( scotland)	foil wrapped single coils.Complex question? My son is a small mided humbucker die hard. I also like using humbuckers because of their instant trouble free power but on the other hand I love the "bluesy" clean but ragged sound single coils can deliver with a delicate touch in a live situation and the way that they can also really power up at volume.(Hendrix playing Power of soul intro " His complaint is the HUM. I normally wind My single coils round Alnico 5 5mm mags to 6-8k but when near our computer or stereo they make an unholy noise . I then lose the fight. If I wrapped them in foil and grounded them would they retain tone ... but quieted down a bit ...the last time I tried something like this I got no hum but also very little output ..Any ideas. I understand stacked pickups etc. but any simple fixes? I cant lose this one help!

2/28/2004 9:47 PM

neil ( scotland)

foil wrapped single coils.Complex question?

My son is a small mided humbucker die hard. I also like using humbuckers because of their instant trouble free power but on the other hand I love the "bluesy" clean but ragged sound single coils can deliver with a delicate touch in a live situation and the way that they can also really power up at volume.(Hendrix playing Power of soul intro " His complaint is the HUM. I normally wind My single coils round Alnico 5 5mm mags to 6-8k but when near our computer or stereo they make an unholy noise . I then lose the fight. If I wrapped them in foil and grounded them would they retain tone ... but quieted down a bit ...the last time I tried something like this I got no hum but also very little output ..Any ideas. I understand stacked pickups etc. but any simple fixes? I cant lose this one help!

3/3/2004 8:23 PM
Mark Hammer	One solution that has been tried over the years is a dummy coil. This is an essentially identical coil that lacks any magnet. It picks up the same huma and interference as the actual pickup but doesn't sense the strings. When the "antenna collections" of the dummy coil and the actual pickup are added out of phase, the non-string signals cancel out and what remains is string signal. Ideally, the dummy coil should be positioned and oriented such that it picks up the identical non-string noise that the actual pickup does. Of course this is more likely to happen if the two coils are as close to occupying the same physical space as possible. Some of the "noiseless" single coil designs are essentially stacked humbuckers with the lower coil being a dummy coil. The Kinman pickups, for instance, magnetically isolate the upper coil from the lower one. Since the lower dummy coil is facing the same way, in almost the same place, has the same dimensions, etc., the non-string signal it detects will be very, very close to what the upper coil detects, which will result in almost perfect cancellation of non-string signal. You can situate a dummy coil elsewhere, and I have done so successfully, but this will result in less than 100% hum/noise rejection. On the other hand, 70% noise reduction and retention of 100% of the tone is still a big improvement. Dummy coils should be as well-matched to the active coil as possible, but less than perfect matching is acceptable too, again with the expected decrements to noise reduction. They should probably be as snugly wound as active coils. Now obviously, tacking a second coil in parallel or series with the first one does not have the same DC resistance, nor the same inductance. On the other hand, one does not hear major complaints from people about the tonal changes resulting. The simplest way to get yourself a dummy coil is to get hold of a cheap ceramic magnet type of Strat replacement and remove the bar magnet. If you can find a cheap pickup that uses a plastic coilform and a slug in the middle, so much the better. Obviously the shallower the profile, the easier it is to find places to unobtrusively stick it. I stuck one in the control cavity of a guy's Tele years ago, and it worked just fine.

3/3/2004 8:23 PM

Mark Hammer

One solution that has been tried over the years is a dummy coil. This is an essentially identical coil that lacks any magnet. It picks up the same huma and interference as the actual pickup but doesn't sense the strings. When the "antenna collections" of the dummy coil and the actual pickup are added out of phase, the non-string signals cancel out and what remains is string signal.

Ideally, the dummy coil should be positioned and oriented such that it picks up the identical non-string noise that the actual pickup does. Of course this is more likely to happen if the two coils are as close to occupying the same physical space as possible.

Some of the "noiseless" single coil designs are essentially stacked humbuckers with the lower coil being a dummy coil. The Kinman pickups, for instance, magnetically isolate the upper coil from the lower one. Since the lower dummy coil is facing the same way, in almost the same place, has the same dimensions, etc., the non-string signal it detects will be very, very close to what the upper coil detects, which will result in almost perfect cancellation of non-string signal.

You *can* situate a dummy coil elsewhere, and I have done so successfully, but this will result in less than 100% hum/noise rejection. On the other hand, 70% noise reduction and retention of 100% of the tone is still a big improvement.

Dummy coils should be as well-matched to the active coil as possible, but less than perfect matching is acceptable too, again with the expected decrements to noise reduction. They should probably be as snugly wound as active coils.

Now obviously, tacking a second coil in parallel or series with the first one does not have the same DC resistance, nor the same inductance. On the other hand, one does not hear major complaints from people about the tonal changes resulting.

The simplest way to get yourself a dummy coil is to get hold of a cheap ceramic magnet type of Strat replacement and remove the bar magnet. If you can find a cheap pickup that uses a plastic coilform and a slug in the middle, so much the better. Obviously the shallower the profile, the easier it is to find places to unobtrusively stick it. I stuck one in the control cavity of a guy's Tele years ago, and it worked just fine.

3/10/2004 9:53 PM
Toby M.	Magnetic Shielding? What do you mean when you say the dummy coil is "magnetically shielded"? Does this simply mean the coil has no magnets inside it- that it's an empty coil? Or is something more elaborate required to prevent the dummy coil from picking up any actual signal? I'm interested in the design of stacked humbuckers- I have a couple of Bill Lawrence L-280s in my Strat that sound like they have about the same output as standard Strat pickups, but read 12 kilo-ohms. This is the first good explanation for that I've heard!

3/10/2004 9:53 PM

Toby M.

Magnetic Shielding?

What do you mean when you say the dummy coil is "magnetically shielded"? Does this simply mean the coil has no magnets inside it- that it's an empty coil? Or is something more elaborate required to prevent the dummy coil from picking up any actual signal?

I'm interested in the design of stacked humbuckers- I have a couple of Bill Lawrence L-280s in my Strat that sound like they have about the same output as standard Strat pickups, but read 12 kilo-ohms. This is the first good explanation for that I've heard!

3/12/2004 3:43 PM
Mark Hammer	Mu-Metal from what I understand, though I might be wrong. The same sort of thing that makes home theatre and computer speakers "magnetically shielded" so they don't bugger up your TV. The old Fender humbucker pickups, like you'd see on the Tele Custom did not use a bar magnet like the Gibson HB/PAF pickups. Rather it used a dozen threaded magnetic polepieces that could be height adjusted. Although only 6 of the 12 peeked through the pickup cover (3 per coil so that you could mimic an angled single-coil via height adjustment), you could go underneath the pickup and remove all 6 from a given coil. Since the polepieces were reverse polarity and the coils were reverse wound, if you yanked one set of polepieces, you ended up with a single-coil pickup with an adjacent hum-rejecting dummy coil in a HB package. The Kinman has what is essentially an empty coil underneath. As long as there is no way to induce any magnetic influence in the middle of the coil (i.e., no bar or polepieces running through it), it won't pick up string signal, although it WILL pick up EMI/RFI. Since the two coils are stacked in the Kinman, and there are rod-type polepieces in the upper coil, the mag shielding is needed to essentially truncate the sensing area, otherwise it would extend down through the lower coil. Remember that the human user may see the two bobbins as two distinct coils but from the vantage point of the polepiece it is simply one long coil with part of it hanging off the lower (body) side of the coil. The mag shielding allows it to behave as if the sensing area physically ends at the lower part of the first coil. Realistically, that is a necessary adaptation to mimic in a single-coil package what would happen naturally in something like the Fender HB pickup described. Why is preventing the sensing area from extending below such a big deal? I don't know. I do know that some 15 years ago I had a lengthy conversation with the guys at now-defunct Evans pickups about stacked humbuckers and they were very negative about them (The Evans Eliminator was a Strat-sized dual coil pickup that had one coil for E/A/D and another RWRP coil for G/B/E), noting that "You just can't get 'the tone'" with a stacked humbucker even though they tried.

3/12/2004 3:43 PM

Mark Hammer

Mu-Metal from what I understand, though I might be wrong. The same sort of thing that makes home theatre and computer speakers "magnetically shielded" so they don't bugger up your TV.

The old Fender humbucker pickups, like you'd see on the Tele Custom did not use a bar magnet like the Gibson HB/PAF pickups. Rather it used a dozen threaded magnetic polepieces that could be height adjusted. Although only 6 of the 12 peeked through the pickup cover (3 per coil so that you could mimic an angled single-coil via height adjustment), you could go underneath the pickup and remove all 6 from a given coil. Since the polepieces were reverse polarity and the coils were reverse wound, if you yanked one set of polepieces, you ended up with a single-coil pickup with an adjacent hum-rejecting dummy coil in a HB package.

The Kinman has what is essentially an empty coil underneath. As long as there is no way to induce any magnetic influence in the middle of the coil (i.e., no bar or polepieces running through it), it won't pick up string signal, although it WILL pick up EMI/RFI. Since the two coils are stacked in the Kinman, and there are rod-type polepieces in the upper coil, the mag shielding is needed to essentially truncate the sensing area, otherwise it would extend down through the lower coil. Remember that the human user may see the two bobbins as two distinct coils but from the vantage point of the polepiece it is simply one long coil with part of it hanging off the lower (body) side of the coil. The mag shielding allows it to behave as if the sensing area physically ends at the lower part of the first coil. Realistically, that is a necessary adaptation to mimic in a single-coil package what would happen naturally in something like the Fender HB pickup described.

Why is preventing the sensing area from extending below such a big deal? I don't know. I do know that some 15 years ago I had a lengthy conversation with the guys at now-defunct Evans pickups about stacked humbuckers and they were very negative about them (The Evans Eliminator was a Strat-sized dual coil pickup that had one coil for E/A/D and another RWRP coil for G/B/E), noting that "You just can't get 'the tone'" with a stacked humbucker even though they tried.

3/12/2004 6:22 PM
Sheldon Dingwall	"I had a lengthy conversation with the guys at now-defunct Evans pickups about stacked humbuckers and they were very negative about them (The Evans Eliminator was a Strat-sized dual coil pickup that had one coil for E/A/D and another RWRP coil for G/B/E), noting that "You just can't get 'the tone'" with a stacked humbucker even though they tried. " Mark, were the Evans coils two typically shaped (oval) coils butted end to end, or did they (as I heard from an unreliable source) have angled ends so that they overlapped a bit in the center?

3/12/2004 6:22 PM

Sheldon Dingwall

"I had a lengthy conversation with the guys at now-defunct Evans pickups about stacked humbuckers and they were very negative about them (The Evans Eliminator was a Strat-sized dual coil pickup that had one coil for E/A/D and another RWRP coil for G/B/E), noting that "You just can't get 'the tone'" with a stacked humbucker even though they tried.
"

Mark, were the Evans coils two typically shaped (oval) coils butted end to end, or did they (as I heard from an unreliable source) have angled ends so that they overlapped a bit in the center?

3/15/2004 9:23 PM
Mark Hammer	I did get to see the setup close up, so I will label myself a "reliable" source as far as their shape goes. The Evans coilforms were angled at one end and round at the other. This allowed them to use the identical coilforms in yin-yang manner and produce what I gather was a more structurally sound pickup since there was no empty space between the coilforms. I gather it made it more easy for them to align the two coilforms since they were self-aligning along the diagonal in the middle. Given that Evans used a closed top cover (like a Lace or EMG), as opposed to having exposed polepieces like a regular Strat cover, it probably helped that the slanted end provided the alignment that the cover could not. I'm speculating here, though. Personally, I always found them a little too shriek-ey, although I'd be the first to admit that the tendency of regular users (SRV, Colin James, Jeff Healey) to always use them with a Tube Screamer, or something similar, probably distracts from the true sound of the pickups. I bought some polepieces from the guys and have been pleased with pickups I wound myself (including some stacked humbuckers), but I would not confuse my pickups with theirs and never had a chance to play with theirs.

3/15/2004 9:23 PM

Mark Hammer

I did get to see the setup close up, so I will label myself a "reliable" source as far as their shape goes. The Evans coilforms were angled at one end and round at the other. This allowed them to use the identical coilforms in yin-yang manner and produce what I gather was a more structurally sound pickup since there was no empty space between the coilforms. I gather it made it more easy for them to align the two coilforms since they were self-aligning along the diagonal in the middle. Given that Evans used a closed top cover (like a Lace or EMG), as opposed to having exposed polepieces like a regular Strat cover, it probably helped that the slanted end provided the alignment that the cover could not. I'm speculating here, though.

Personally, I always found them a little too shriek-ey, although I'd be the first to admit that the tendency of regular users (SRV, Colin James, Jeff Healey) to always use them with a Tube Screamer, or something similar, probably distracts from the true sound of the pickups. I bought some polepieces from the guys and have been pleased with pickups I wound myself (including some stacked humbuckers), but I would not confuse my pickups with theirs and never had a chance to play with theirs.

3/3/2004 9:14 PM
neil	Re: foil wrapped single coils.Complex question? Thnks for that info.I've been meaning to get into stacked single coils but I had to buy 100 6mm alnico 5 magnets from my UK supplier and as I make about 4 guitars /year I've been mainly trying out strat types. I have made humbuckers by making two strat type pup's reversing polarity and building them up to look visually like a humbucker with no cover. These work very well and can be split to sound like a normal single. Would wrapping alu. foil around the finished coil and grounding it help with noise. Thanks neil.

3/3/2004 9:14 PM

neil

Re: foil wrapped single coils.Complex question?

Thnks for that info.I've been meaning to get into stacked single coils but I had to buy 100 6mm alnico 5 magnets from my UK supplier and as I make about 4 guitars /year I've been mainly trying out strat types. I have made humbuckers by making two strat type pup's reversing polarity and building them up to look visually like a humbucker with no cover. These work very well and can be split to sound like a normal single. Would wrapping alu. foil around the finished coil and grounding it help with noise. Thanks neil.

Page 1 of 3

Next>

Last Page>>