Equal turns will get you very close but it's really turns * area and the area of a 43 coil might average ever so slightly smaller than a 42 coil.
I'm trying to remember the answer to this question, but for the life of me I cant remember it...
If you were making a basic side-by-side coil humbucker with two different gauge wires (i.e. slug 43awg, and screw 42awg) what gives you the maximum hum cancelling? Is it equal number of turns on each coil or equal DC Res?
I remember dimarzio used to have a patent on multigauge pickups, but i think its expired now. Did anyone ever get a nasty letter from them about it?
bel
Equal turns will get you very close but it's really turns * area and the area of a 43 coil might average ever so slightly smaller than a 42 coil.
this may sound stupid, but can you define "area"? Do you mean the total volume taken up by the wire? Total surface area on the wire? How would I even begin to calculate something like that?
Mmm, I would define it as the area that fits inside the coil from what I understand. So presumably you would measure the area of the middle-most layer of wire in the coil. If your coil "A" starts being 1/4" x 2" and finishes at 1/2" x 2.25" your average coil size would be 3/8" x 2.125". The "A" coil area would be 0.797" multiply that by 5000 turns to get coil x turns of 3985.
If you know that your coil "B" is 43 awg and is say 5% smaller than coil "A" you might want to add 5% more turns to coil "B" or 5500 turns.
Hmm interesting. Seems totally unscientific. Ill try it. Hey so you remember the name of that crazy expensive solder we were talking about recently? I will cant find the discussion for the life of me
I was of the understanding that equal amount of turns of each would give best Hum Canceling.
I make one all the time, full screw coil with 42 SPN, and fairly full slug coil of 43 SPN.
It hums a little but not bad. I'm sure it would be quiter if both coils were equal.
Makes a good hot pickup.
T
Technicians Run the World, but Bankers, Lawyers, and Accountants, Take All The Credit!
Keep Rockin! B_T
Terry
Is it this thread ?
SAVBIT solder for attaching leads to fine copper wire
The law of induction works on the time varying magnetic flux for any closed path. That is, what matters in effect is the time varying flux through each turn, with all of them added up. So, if all the turns had the same amount of flux passing through them, it would just be the total number of turns that counts. And that's not such a bad approximation for a pickup with cores because the cores concentrate the flux more to the middle of the coil, and the varying size of the turns is less important than it might be.
(If the flux is constant throughout the loops, the area of each loop times the number of loops is very accurate. This is a very goo approximation in some cases)
(To be very accurate, you integrate the spatial varying time varying flux over each loop and add the results. We do not have accurate enough measurements or predictions to do it exactly.)
So, do we think that the quietest practical (although not particularly appealing) setup in a situation with two different wire gauges (same # of turns) would be to use the same core material in both coils and then add a small resistor to the heavier gauge coil to match resistance?
Well... after running out of the house immediately after posting this it occurred to me that this kindof kluge would only apply to the parallel configuration, so... in the immortal words of Gilda Radnor - "Never Mind!"
Bob Palmieri
Last edited by fieldwrangler; 10-29-2011 at 04:58 PM.
I do equal number of turns. You can also alter that for different tones.
It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein
http://coneyislandguitars.com
www.soundcloud.com/davidravenmoon
number of turns govern the inductance, not the gauge of the wire. You need to match the number of turns as long as the two bobbin is exactly the same. If the cross-sectional area in the middle of the coils are different, then all bets are off. Good example is the Suhr noise cancelling coil. It has much less turns but with a big loop, it can cancel noise with much fewer turns because the center area is much bigger and can sense much more magnetic flux.
Ok now that makes sense! Thanks. Your suhr reference was perfect.
It is not the number of turns, it's the area-turns count. That is the basic rule, absent any nearby iron. The "area" is that bounded by the turn in question. In practice, we use the average area of turns, and multiply by the turns count, and it's close enough.
Note that the inductance is not the issue, it's the area-turns product, which controls the voltage generated by a coil immersed is a uniform changing magnetic field. The difference is that the inductance varies as the square of the turns count, while the area-turns count varies linearly with the turns count.
Joe - Do you have any good resources to learn more about area-turns product? Are you aware of any matematical way to calculate this measurement? I would be great to be able to have a formula to calculate "approximate" required measurements for hum cancellation when dealing with multigauge.
But don't you find anything in the general ball Park to be pretty much Hum canceling?
I Make what I call a Hybrid. I wind the screw bobbin Fairly full with 42SPN, and about all I can get of 43 SPN on the Slug Coil.
Not sure on the turn count, but pretty sure highly mismatched in favor of the 43GA.
It is nearly as quite as my 7.2k Symmetrical Wound Neck Pickup?
What is your Experience?
Terry
Last edited by big_teee; 11-05-2011 at 06:28 AM.
Technicians Run the World, but Bankers, Lawyers, and Accountants, Take All The Credit!
Keep Rockin! B_T
Terry
sure I could just start winding and try, but i'd like to try to get an understanding of why/how it is functioning. I'm having a difficult time understanding the "coil area".. Trying to remember back to my high school math class, I thought that area was a two dimensional measurement - So in a three dimensional coil, what area is it measuring?
The area around the core? i.e. a top down view?
one side of a side view?
Front view? (clearly unlikely)
I'm dumb as a cork, but I want to learn
Hopefully someone chimes in with a mathematical answer that satisfies you. In the mean time I find the rudimentary way to consider it is simply as an audio condition rather than a mathematical one. You have two signals summing. They don't phase cancel the audio, just the hum. So for hum cancellation perfection all you need is for each coil's noise to be as loud as the other's. Turn count is only one way to affect that. Creative shielding and purposeful ground or float decisions for each component can fine tune the noise level as well.
Bel,
I'll try to reply with a little more clarity. You are correct, you want to measure the top-down, 2 dimensional window through the coils, and yes, area is the width times the length of the bobbin core. As each layer of wire piles up on the bobbin, it takes in a slightly larger area. You can figure out the average area of each coil by measuring the area window through the layer that sits exactly half way through the wind. If you wax potted the 2 coils and sliced each off the bobbin and then peeled each apart right at the middle layer, you could lay those outer layers side by side (but reassembled and maintaining their former, oblong shape) and hopefully see that the 43 awg coil is the same percentage smaller in window area as the difference in wire diameter times π i.e. the wire cross section. (2πr is the area of a circle, the wire is round). To mathematically find the area you can break the coil shape into 3 parts, a half circle at one end, a rectangle in the middle and an identical 1/2 circle at the other end. Now we can presumably ignore the rectangles because they're going to be the same length on both coils and their widths are the same as the diameter of the two half circles from each coil. If I were really good at geometry I could pull the theorem out of my butt and prove to you that the difference in wire diameter is going to be the same as the difference in coil area between your 42 and 43 wire cross-sections. I absolutely stink at geometry and have no idea if that's actually true, right now it's a strong hunch.
I looked up on a table that AWG 43 = .0025 mm^2 and AWG 42=.0029 mm squared . I divide 29/25 = 1.16 or that for every 100 turns of 42AWG you might need 116 turns of the 43 to get to the same size coil. I don't think we need that many extra turns to equalize turns areas, I'm guessing we need about 1/2 as many or 108 turns but I can't tell you why.
Someone with better 8th grade math needs to come in and save me here.
Last edited by David King; 11-05-2011 at 08:27 AM.
So, I put one of my very-well-matched two-coils-on-the-same-axis pickups on my main axe and it seemed to hum a lot more than I would expect.
So, I figured maybe it wasn't as well matched as I thought and put in another one. Same deal, and the neck pickup was still dead quiet (it,in fact, is using two different gauges of wire on the coils.)
So, while I was scratching my head about this my eyes went over to this big honkin' piece of metal a half-inch away from the pickup (namely the integrated bridge/tailpiece on my Melody Maker) and I began to wonder if its proximity to one coil could explain this phenomenon. I haven't yet done any of the obvious tests yet, and I need to leave for a trip early this morning.
So, before I do test for this, whaddya think?
Bob Palmieri
I just wound some stewmac humbuckers both around 9k... screw bobbin with 42 awg 5000 winds and slug bobbin slightly overwound 5400 or so winds with 43 awg and covered with gold cover and AllStar Magnetic Alnico II. Made the mistake of not wax potting again after I put the covers on, so bridge was pretty feedbacky, and I had to take he cover off. I think the bridge was a little too thin and strident... need to come up with a warmer recipe, but a fine experiment!
Last edited by big_teee; 11-10-2011 at 12:31 AM.
Technicians Run the World, but Bankers, Lawyers, and Accountants, Take All The Credit!
Keep Rockin! B_T
Terry
It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein
http://coneyislandguitars.com
www.soundcloud.com/davidravenmoon
It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein
http://coneyislandguitars.com
www.soundcloud.com/davidravenmoon
Definitely.
I'm planning to check out the hairbrained idea that maybe proximity to the bridge is unbalancing the thing this weekend.
Definitely in-phase? Humbuckers are wired out-of-phase. That might be why its humming. Either that, or it doesn't know the words.
Wire them start to start, or finish to finish, wound the same direction.
Many of my bridge pickups use multi gage wire. That's not the issue.I'm planning to check out the hairbrained idea that maybe proximity to the bridge is unbalancing the thing this weekend.
It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein
http://coneyislandguitars.com
www.soundcloud.com/davidravenmoon
OverWound Bridge P/Us do seem to pickup more noise and are more sensitive, and have more gain, than a low wound neck P/Us.
Some Amps are way more noisey than others.
IME Head Amps are usually quieter than Combos.
B_T
Technicians Run the World, but Bankers, Lawyers, and Accountants, Take All The Credit!
Keep Rockin! B_T
Terry
It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein
http://coneyislandguitars.com
www.soundcloud.com/davidravenmoon
Well... in this case they're sidewinders. I've been winding these for 20 years (perhaps almost as long as you!) and I actually connect them in electrically in-phase series (head to tail) but point them in opposite directions. Not that there's not a big chance of me screwing up, but if I had done so I'd notice a quite unexpected timbral quality before the hum thing became apparent.
And in fact, my neck pickup (also a sidewinder) is also a multi-guage unit and is nearly dead quiet.
By the way, this "sidewinder" term is something I learned from you, and is much more convenient than my previous "horizontally opposed coaxial" monicker.
Bob Palmieri
So no one is willing to come out with a workable mathematical formula for hitting the hum-canceling nail on the head with two different gauge wires?
It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein
http://coneyislandguitars.com
www.soundcloud.com/davidravenmoon
Oh I didn't realize you were talking about sidewinders. I notice if the sidewinders are wired up wrong they hum but don't sound all that much different. I also find i have to make sure the poles are grounded and I shield the entire pickup, otherwise they seem susceptible to buzzing.
I set my coils up with both tops facing the poles. Because of that the windings are in opposite directions, then I wire them in phase. The same magnetic polarity is facing the poles.
I didn't make it up!And in fact, my neck pickup (also a sidewinder) is also a multi-guage unit and is nearly dead quiet.
By the way, this "sidewinder" term is something I learned from you, and is much more convenient than my previous "horizontally opposed coaxial" monicker.
It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein
http://coneyislandguitars.com
www.soundcloud.com/davidravenmoon
Yes; and this sort of thing sometimes scares me. Makes me feel that there's something fundamentally funny about this design, sorta like early stacked Strat pickups with limited magnetic isolation between the coils. I do however, continue to bark up this tree with a vengeance.
I'm pretty obsessive about those grounding/shielding issues.
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