Use Multi-Section Windings to Reduce Self-Capacitance

[Antigua]

It's a bit like the difference between a Wikipedia article versus and educational website. Wikipedia articles often presume you already understand everything, and use lots of arcane terminology, where as a decent educational website, such as allaboutcircuits.com, will take you step by step from no understanding to a working understanding.

[Helmholtz]

What was missing was the visual picture and qualitative physics.

Sounds as if you are going to provide the missing info?

[Joe Gwinn]

Sounds as if you are going to provide the missing info?

Already did - it's a mental picture that's provided, using as little math as possible. The square root in posting 129 scared me off.

More generally, most pickup makers never took electronics or physics, and yet they manage to make good pickups. They do it by listening and tweaking, and what they most need is an idea which things to fiddle with to go in this or that desired acoustic direction.

[Helmholtz]

Already did - it's a mental picture that's provided, using as little math as possible. The square root in posting 129 scared me off.

More generally, most pickup makers never took electronics or physics, and yet they manage to make good pickups. They do it by listening and tweaking, and what they most need is an idea which things to fiddle with to go in this or that desired acoustic direction.

O.K. then, thanks for the "translation". I don't seem to have the right feel for this forum yet and I appreciate any help.

Nevertheless I hope I could contribute something interesting/useful at least for some.

[Antigua]

Most pickup makers these days are just copying existing designs, and tweaking trivial aspects of the overall design, such as the coil's turn count. A deeper understanding can lead to something wildly different like the Lace Alumitone, but it's not economical to acquire a six year degree in physics and EE, just to design a totally new pickup that may never turn a profit. Helmuth Lemme's book does a good job of making the science accessible to people without a formal degree, and more books written by more authors would be even better. Threads like this help, too.

[bbsailor]

Most pickup makers these days are just copying existing designs, and tweaking trivial aspects of the overall design, such as the coil's turn count. A deeper understanding can lead to something wildly different like the Lace Alumitone, but it's not economical to acquire a six year degree in physics and EE, just to design a totally new pickup that may never turn a profit. Helmuth Lemme's book does a good job of making the science accessible to people without a formal degree, and more books written by more authors would be even better. Threads like this help, too.

When you are designing passive pickups you will need many turns of fine wire to produce enough voltage to drive the amp and overcome any noise pickup. Passive pickups need a guitar cable that typically has about 35 pF per foot of cable. A 10 foot cable then adds 350 pF to the total coil capacitance and puts the typical electric guitar pickup resonant in about the same range, typically near 3 to 4 KHz which creates the typical “electric guitar” sound. Those choosing to go low impedance passive, typically around 300 to 500 Ohms need to feed either a passive mic matching transformer mounted at the amp or a mic mixer input operating at a lower impedance for an output level between 5 to 10 millivolts.

If you decide to go active, you isolate the pickup from the guitar cable capacitance and can run the pickup at a higher resonant frequency, but as you say, your ears need to be the judge. The science just tells you what you might expect by altering some variables. The best learning comes from tinkering with changing variables, taking fundamental measurements with common test equipment, deducing pickup characteristics and finally trying to relate what you hear to what you have measured with your knowledge of relevant electronic theory.

Here is a common point to consider. All passive pickups have their highest impedance at their resonant point which could be a few hundred K Ohms. Most passive volume controls will load the resonant peak to a lower peak value and the cable capacitance will also lower the resonant frequency. Once you see and hear how this is all a balancing act, you can begin to appreciate what variables you can control and begin to become the master of your new creations.

Joseph J. Rogowski

[Antigua]

That's a good summary. I'd add to the part about experimenting that the Q factor and and resonant peak can be experimented with by using alligator clips, a box of various capacitor values to move the resonant peak of an existing pickup around on the fly, and a potentiometer, to deliberately load the pickup and hear how different Q factors effect the treble response. Both of these things saves a lot of time over winding many different pickups which would ultimately only vary in these respects.

[Helmholtz]

When you are designing passive pickups you will need many turns of fine wire to produce enough voltage to drive the amp and overcome any noise pickup. Passive pickups need a guitar cable that typically has about 35 pF per foot of cable. A 10 foot cable then adds 350 pF to the total coil capacitance and puts the typical electric guitar pickup resonant in about the same range, typically near 3 to 4 KHz which creates the typical “electric guitar” sound. Those choosing to go low impedance passive, typically around 300 to 500 Ohms need to feed either a passive mic matching transformer mounted at the amp or a mic mixer input operating at a lower impedance for an output level between 5 to 10 millivolts.

If you decide to go active, you isolate the pickup from the guitar cable capacitance and can run the pickup at a higher resonant frequency, but as you say, your ears need to be the judge. The science just tells you what you might expect by altering some variables. The best learning comes from tinkering with changing variables, taking fundamental measurements with common test equipment, deducing pickup characteristics and finally trying to relate what you hear to what you have measured with your knowledge of relevant electronic theory.

Here is a common point to consider. All passive pickups have their highest impedance at their resonant point which could be a few hundred K Ohms. Most passive volume controls will load the resonant peak to a lower peak value and the cable capacitance will also lower the resonant frequency. Once you see and hear how this is all a balancing act, you can begin to appreciate what variables you can control and begin to become the master of your new creations.

Joseph J. Rogowski

The knowledge about the essential PU parameters and their influence on PU frequency response has been around for at least 40 years. Helmuth Lemme's first book on PUs was published in 1977 and covered everything you mentioned. Of course measuring wasn't as easy in those days as today. And yes, Lemme did a great job explaining things as simple as possible. But these things were still relatively simple to someone knowing a little electronics.

If you want to dig deeper, things get increasingly more complicated to discover, to understand and to explain.

[bbsailor]

The knowledge about the essential PU parameters and their influence on PU frequency response has been around for at least 40 years. Helmuth Lemme's first book on PUs was published in 1977 and covered everything you mentioned. Of course measuring wasn't as easy in those days as today. And yes, Lemme did a great job explaining things as simple as possible. But these things were still relatively simple to someone knowing a little electronics.

If you want to dig deeper, things get increasingly more complicated to discover, to understand and to explain.

Do you have an example of something at that deeper level?

[Antigua]

The knowledge about the essential PU parameters and their influence on PU frequency response has been around for at least 40 years. Helmuth Lemme's first book on PUs was published in 1977 and covered everything you mentioned. Of course measuring wasn't as easy in those days as today. And yes, Lemme did a great job explaining things as simple as possible. But these things were still relatively simple to someone knowing a little electronics.

If you want to dig deeper, things get increasingly more complicated to discover, to understand and to explain.

A lot of disinformation has come along since the 70's. Someone with basic electronic experience might still might take stock in concepts that were not a big issue back in the 70's, such as "scatter winding", or the dielectric value of the magnet wire insulation, and a lot has been made of the difference between various grades of AlNiCos, or there is talk about how a filister screw results in a different tone than a hex screw, because sometimes these claims are not disprovable with just a basic understanding of electronics or physics. Most all of these supposed distinctions are baseless, and a lot of the disinformation comes from business trying to differentiate their product, and it takes more than a superficial understanding of EE and physics to tell what is fact and fiction. The problem isn't even so much what people don't know, it's even worse that that, people "don't know what they don't know". At some point real chemists came along and called out the snake oil for what it was, something like that has yet to happen in this domain.

[Helmholtz]

A lot of disinformation has come along since the 70's. Someone with basic electronic experience might still might take stock in concepts that were not a big issue back in the 70's, such as "scatter winding", or the dielectric value of the magnet wire insulation, and a lot has been made of the difference between various grades of AlNiCos, or there is talk about how a filister screw results in a different tone than a hex screw, because sometimes these claims are not disprovable with just a basic understanding of electronics or physics. Most all of these supposed distinctions are baseless, and a lot of the disinformation comes from business trying to differentiate their product, and it takes more than a superficial understanding of EE and physics to tell what is fact and fiction. The problem isn't even so much what people don't know, it's even worse that that, people "don't know what they don't know". At some point real chemists came along and called out the snake oil for what it was, something like that has yet to happen in this domain.

What makes you insinuate that I am not aware of "disinformation" or more precisely, marketing lies?. Why are you repeatedly trying to discredit me?


(Noticed and appreciate your last edit of post #145)

[Antigua]

What makes you insinuate that I am not aware of "desinformation" or more precisely, marketing lies?. Why are you repeatedly trying to discredit me?

I'm not trying to discredit you, and I don't know why you believe that I am. You're among the most technically informed posters to come along in a long time.

I am responding to your remark "But these things were still relatively simple to someone knowing a little electronics." The disinformation that is prevalent today is hard to disprove on a factual basis without a deeper understanding of physics.

Take for example, a claim "scatter winding reduces capacitance and makes a pickup sound more clear", to someone knowing a little electronics, this statement is plausible on the surface, and so this claim is effectively validated, and it takes a deeper understanding of the particulars to realize that the difference in capacitance that might result is inconsequential.

[Helmholtz]

Do you have an example of something at that deeper level?

We already discussed some examples here. Things like reflected capacitance between windings sections, the real aperture width, influence of the coil shape on output, self-capacitance and inductance, mutual inductance in humbuckers.. Other interesting examples can be found in Manfred Zollner's book " Physik der Elektrogitarre".
Futher topics could be e. g. inherent PU distortion and frequency maybe even ac flux amplitude dependance of inductance caused by magnetic skin effect in ferromagnetic, conductive cores. I am not ready to start corresponding discussion yet.

[Helmholtz]

I am responding to your remark "But these things were still relatively simple to someone knowing a little electronics." The disinformation that is prevalent today is hard to disprove on a factual basis without a deeper understanding of physics.

What I was trying to get across is, that Lemme was/is great at explaining the more "simple" stuff, while I may fail to explain the more complicated stuff simply enough.

[GunbarrelCustom]

Thanks for the info! Trying to study electricity at my advanced age has been full of surprises like this.

I expect when scientists realize the Big Bang theory is incorrect it will be an Electric (guitar) Universe.