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Sound of magnet wire insulation(?)

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9/12/2002 9:01 PM

Sound of magnet wire insulation(?)

I have read in various places about different magnet wire insulations having effects on the tone of a pickup. Other than insulation diameter affecting turn capacitance, I can't figure how it would. The other effects like dielectric leakage would seem to be insignificant.

Any thoughts or experiences or opinions you would be willing to share, or is it smoke and mirrors like the paper bobbin transformer issue? Thanks!

9/12/2002 9:08 PM
SK	it's crap. maybe if we're talking about new poly(or anything else) vs an old pickup with old unpotted PE which has become brittle etc..

9/12/2002 9:18 PM

Oh, I can think of a few ways in which insulation could affect tone without resorting to voodoo handwaving.

Certainly insulation thickness sets the space requirement for the wire, and insulations of different types result in different outside diameters (which is distinct from the diameter of the conductive part itself). If it is the case that all insulations on magnet wire are equivalent thickness then my point is moot. Otherwise, when you think of the impact of a 5% difference in outside wire diameter over the course of 7000 turns, one ought to, in principle, end up with a coil having different inductive properties, DC resistance, etc.

The other aspect, which admittedly vanishes with perfect potting, is the degree to which different insulation materials "grip" the existing layers of the coil when winding. One would expect different microphonic properties, susceptibility to scatterwinding, and stuff like that.

Just a thought.

9/12/2002 9:34 PM
R.G.	In the output transformer world, potting was an acknowledged way to make the self capacitance of an OT go UP because any material you fill the gaps with inside the coil will have a dielectric constant greater than unity, and hence will make the self capacitance greater. R.G.

9/12/2002 10:25 PM

Dr. Strangelove

Mark Hammer wrote:

quote:
"[magnet wire insulation differences]"

Yah. I checked on dielectric constants for insulation. Most are all close enough to be insignificant, and although volume resistivities differed over an order of magnitude, those were very high to begin with.

Good wire resistance and insulation dielectric chart at:
<http://www.elexp.com/t_wire.htm>

The pertinent part is dielectric constant & loss factor table at the bottom:

Material ------ Dielectric Const. / DF x 10^-3

TZT .......... 3.7/5.6
APTZ ......... 3.86/6.9
ML ........... 3.34/0.9
Formvar* ..... 3.6/11.2
Soldereze .... 3.85/11.3
Nyleze ....... 4.07/19.7

[Note: Teflon ...... ~1.92/0.1 (source: Dupont.com)]

Alas, there's no such thing as teflon-insulated magnet wire. Now THAT would cut your distributed capacitance in half right away.

If my choices are enamel, Formvar, and something modern, then I'll go modern (e.g., solderable polyester-nylon) because those insulations are tougher and/or slippery so are less likely to be cut into by an overlying wind and cause a short.

Most magnet wire is available in different thicknesses call single, double, or triple build.

Polyimide "ML" is the toughest but also most expensive (by 3X) so it's not the best choice. FYI, Kevlar & Kapton are types of polyimides.

More magnet wire insulation info is at:
<http://www.mwswire.com/inschar.htm>
<http://www.superioressex.com/oem/oem_magnet.htm>

-drh
--

9/12/2002 11:24 PM
SK	The original question included "other than insulation thickness" so I left that out. The rest is crap...

9/13/2002 11:42 AM
MKB	Thanks for all the responses, that certainly clears it up some more. Hmmm, teflon insulated magnet wire, sounds really slippery and really expensive. Maybe that's a way to pull in high bucks for a pickup, i.e. marketing crap? "Wound with military grade Teflon insulated magnet wire, guaranteed not to melt when you torch your Strat".

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