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Thread: Coil settling.....

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    Old Timer Possum's Avatar
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    Coil settling.....

    Anyone ever experience the "settling in" of a newly wound pickup? I have a very discerning pickup client who swears a strat set I did after two weeks is getting brighter from playing and settling in. I've never noticed this but then again, wasn't looking for it either. I did a new proto wind last week and I swear I can hear the set cleaning up a bit over the week. Wonder what is happening that causes this, that is if its real and not imagined. Pickups are wax potted, plain enamel. Magnets degaussed about 25%.
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    You're bringing up a very interesting point!
    Over the years when I put new PUs in I always thought they sounded better a few days/weeks later and attibuted that to my ears getting used to them...now you're bringing in a different perspective.
    I still believe it is my ears that are changing...but now you got me thinking!

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    Quote Originally Posted by Possum View Post
    Anyone ever experience the "settling in" of a newly wound pickup? I have a very discerning pickup client who swears a strat set I did after two weeks is getting brighter from playing and settling in. I've never noticed this but then again, wasn't looking for it either. I did a new proto wind last week and I swear I can hear the set cleaning up a bit over the week. Wonder what is happening that causes this, that is if its real and not imagined. Pickups are wax potted, plain enamel. Magnets degaussed about 25%.
    Well for one thing, the winding tension (~34 grams for #42 is recommended by the wire maker) really adds up, when multiplied by 10,000 turns: (34)(2)(10000)=680 Kg= 1,496 pounds. Now, I imagine that people wind pickup coils at a fraction of this recommended 34 grams tension, but still the force squeezing the coil form and connected parts can be quite large. Over time, things will rearrange themselves to accommodate the forces. This is just like settling in a new house.

    Has anyone measured their winding tension? The 34 grams is expected to cause 10% or 20% stretching of the wire, and we do see wire stretch in pickups, so the tension must be at least 10% of the recommended value.

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    ken
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    I have noticed this effect too with my pickups, I had pickups sound smoother and brighter if they sat around for awhile.

    I can see why coil wire would 'settle'. I imagine that there is quite a bit of difference in winding tension in different parts of a coil, since the coil wire going around the ends of the bobbin seems much tighter than in the middle area.

    Do you pot your pickups as soon as you wind them? Maybe letting the coil windings 'settle' overnight before potting would relieve stresses in the coil, and then the pickup would brighten up quicker then if you potted as soon as you wound them.

    Ken

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    Quote Originally Posted by ken View Post
    I have noticed this effect too with my pickups, I had pickups sound smoother and brighter if they sat around for awhile.

    I can see why coil wire would 'settle'. I imagine that there is quite a bit of difference in winding tension in different parts of a coil, since the coil wire going around the ends of the bobbin seems much tighter than in the middle area.

    Do you pot your pickups as soon as you wind them? Maybe letting the coil windings 'settle' overnight before potting would relieve stresses in the coil, and then the pickup would brighten up quicker then if you potted as soon as you wound them.
    Potting in wax isn't likely to make much difference, as wax is so soft.. Epoxy would be another matter.

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    I believe wax potting will make a difference. The heat of the wax will cause the wire to expand relieving stresses at the ends of the coil primarily(and elsewhere) allowing the wire to relax and settle. When the coil cools the wire settles in it's new position. The longer the stay in the wax (up to the point of the entire coil reaching temperature saturation) will increase the effect. It is not that uncommon to find a loose wind or two after wax potting which wasn't there before.

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    ken
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    I have seen this 'loosening' effect myself a couple of times. It drives me crazy whenever I wind a nice neat coil and after potting I find a loose coil wind. Now that I think about it, it makes sense to me that the wire will 'stress relieve' when you pot the coil.

    Wouldn't the magnets be possibly affected as well while potting? After all, if you use an electric stove or wax melter you are not only heating the magnets somewhat but also putting the coil very close to a very large magnetic field at the same time too.

    Ken

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    Old Timer Possum's Avatar
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    potting.....

    I'm not so sure potting has anything to do with it. My customer noticed a brightening and clearing of the tone over a two week period, took a week for him to get them so thats 3 weeks. I can see maybe potting might let the winds slip around eachohter if they are too tight or maybe some kind of tempering that does something to the copper if its stretched. Maybe. But thats 3 weeks for something that is changing. Must have something to do with tensions in stretched wire settling down I guess.

    Sure you need to be careful in potting about your magnets and a magnetic field from the heater, but I don't think this is a problem really. You would notice the magnets vibrating as you got them near the element if it was demagnetizing them, you can clearly feel this effect if you use a soldering gun near magnets, the coils in it will heavily vibrate the magnets and you are demangetizing them when this is going on.
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    Quote Originally Posted by ken View Post
    I have seen this 'loosening' effect myself a couple of times. It drives me crazy whenever I wind a nice neat coil and after potting I find a loose coil wind. Now that I think about it, it makes sense to me that the wire will 'stress relieve' when you pot the coil.
    More likely is that there was a flyaway turn all along, but it was too hard to see until the coil was waxed. In my setup, flyaway turns are caused when the wire momentarily hangs up on the edge of the bobbin flange. Things are happening too fast at 1000 rpm for such mechanical hang-ups to be seen, let alone controlled, so the solution needs to be mecanical. My solution is a pair of plates into which the bobbin flanges fit, so there is no edge for the wire to hang up upon.

    Quote Originally Posted by ken View Post
    Wouldn't the magnets be possibly affected as well while potting? After all, if you use an electric stove or wax melter you are not only heating the magnets somewhat but also putting the coil very close to a very large magnetic field at the same time too.
    The temperature of hot wax is far too low to affect any alnico magnet, which have Curie temperatures in the red-heat range. Ferrites and rare-earth magnets have lower Curie temperatures, but still the wax isn't that hot. The consensus is that one should wax-pot at about 150 degrees F (66 degrees C).

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    Quote Originally Posted by Joe Gwinn View Post
    My solution is a pair of plates into which the bobbin flanges fit, so there is no edge for the wire to hang up upon.
    That's a great idea!

    Quote Originally Posted by Joe Gwinn View Post
    The temperature of hot wax is far too low to affect any alnico magnet, which have Curie temperatures in the red-heat range. Ferrites and rare-earth magnets have lower Curie temperatures, but still the wax isn't that hot. The consensus is that one should wax-pot at about 150 degrees F (66 degrees C).
    From what I've read that's 1580F for Alnico and 860F for ceramic... don't think we have to worry about that too much!

    This is an interesting thread... I can't say I've ever noticed this happening... I'll have to pay more attention to my next pickups.
    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


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    Quote Originally Posted by Possum View Post
    I'm not so sure potting has anything to do with it. My customer noticed a brightening and clearing of the tone over a two week period, took a week for him to get them so thats 3 weeks.
    What I meant to say is I think wax potting will help minimize the "settling" over time. Any time something is stressed it will seek to find a balance over time. Put tension on the coil wire and the wire will eventually stretch to a "relaxed" state...it's malleable enough to do that.
    I think that if you wind with excessive tension, excessive scatter, large variances in tension, poor technique, or combinations then you may see "settling" and it may be more pronounced if the pickup is not potted.
    I personally haven't had these issues reported nor noted them for myself so this is speculation on basic principles.

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    ken
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    I have a large halogen light over my winder so I can see better and avoid snagging wire on bobbins, and the area under my faceplate is white so I have better color contrast and can see my wire better. As for hanging up wire on my bobbin edges, I swiped my wife's diamond fingernail board and use it to debur all my bobbins whether they need it or not.

    I was wondering about the electric stove's magnetic field around the burner if you do pot on the stove, since we do know that TV's, microwaves, motors, and many other electrical items will demag pickups. If this is true, then why wouldn't the EMF going thru a resistive stove burner do it too? After all, the stove is one of the biggest electrical energy consumers in a house, much larger than any monitor.

    When I was talking about potting, I wasn't talking about the wax's actual temperature. When I pot, wax temp is at about 150F.

    Ken

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    Could it be the acoustical energy from actually playing the PUs with a loud amp that is causing them to settle somewhat?
    Just a thought...

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    Quote Originally Posted by ken View Post
    I have a large halogen light over my winder so I can see better and avoid snagging wire on bobbins, and the area under my faceplate is white so I have better color contrast and can see my wire better. As for hanging up wire on my bobbin edges, I swiped my wife's diamond fingernail board and use it to debur all my bobbins whether they need it or not.
    I do all this too, but still would get snags. With a mechanical solution, such care isn't required, so I went mechanical.

    Quote Originally Posted by ken View Post
    I was wondering about the electric stove's magnetic field around the burner if you do pot on the stove, since we do know that TV's, microwaves, motors, and many other electrical items will demag pickups. If this is true, then why wouldn't the EMF going thru a resistive stove burner do it too? After all, the stove is one of the biggest electrical energy consumers in a house, much larger than any monitor.
    The magnetic field around an ordinary electric stove hob isn't very large, of iron pans would be attracted (or rattled), which would annoy many cooks. The reason the field is so low is that the coil has perhaps ten turns, and is made of nichrome (not copper).

    The exception is that induction electric stoves http://en.wikipedia.org/wiki/Induction_cooker use a high-frequency induction field to heat pots and pans by inducing heavy eddy currents in their bottoms. It's probably a bad idea to use such a stove near a pickup, if only because the pickup coil will generate a very large voltage while near such a hob.

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    The french fry wagon outside of work (and many others around town) generally provide customers the choice of "salt and vinegar halfway", noting that some things are difficult to apply uniformly on the "full serving", but much easier to apply uniformly if one applies precompletion, and then applies again post-completion.

    Is potting generally done to ONLY complete pickups, or do people ever "pot halfway" and then continue winding, with a second potting at the end? I'm wondering if winding the second half of the coil on type of a waxy base might result in less potential for settling over time because the coil is more stable during winding.

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    I've "baked" some newly wound PUs in an oven. Something like a few hours at 80 C. I feel it may release possible strain and may make a PU sound better. Or at least it doesn't damage the PUs. If I remember it right, some specs change a little (under 5 %).

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