Use Multi-Section Windings to Reduce Self-Capacitance

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[Steve A.]

I recommend buying one of these so that you can see for yourself https://www.amazon.com/Gaussmeter-Fl...ds=tesla+meter

Just wondering if you do have one of these and whether it is accurate enough to determine how much older magnets have been degaussed by time, etc.
It is my understanding that many of the custom pickup makers will degauss humbucker magnets to specific values to capture the sound and response of vintage pickups. If that is the case would this be an appropriate gaussmeter to use?

Thanks!

Steve A.

P.S. So the cheap imported strat pickups with steel pole pieces and ceramic bar magnets do not have the problem with stratitus like those with Alnico 5 pole pieces?

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[Antigua]

Since this stage usually comes without gain control, Miller effect is quite an issue. In short: The higher the source impedance, the higher miller effect.

This seems to a be a plausible cause for high end attenuation as volume is rolled off, but it raises other questions: high end loss with volume roll off is a constant problem hence the popularity of treble bleed circuits and active pickups, and yet I don't see much discussion about Miller capacitance in relation to that issue. It also appears that this is specific to the amplifier, and the situation changes if there is an effects pedal in between the guitar and the amp. You've been reluctant to expand on the issue of Miller capacitance as it applies to the objective of lowering pickup capacitance, but for these reasons, it seems the issue needs to be expanded upon.

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[Antigua]

Just wondering if you do have one of these and whether it is accurate enough to determine how much older magnets have been degaussed by time, etc.
It is my understanding that many of the custom pickup makers will degauss humbucker magnets to specific values to capture the sound and response of vintage pickups. If that is the case would this be an appropriate gaussmeter to use?

Thanks!

Steve A.

It's very good for $110. The unit of measure is millitesla instead of Gauss, so it has one less precision point than the defunct Spin Doctor model, but for guitar pickup quality control and survey, that's adequate precision.

P.S. So the cheap imported strat pickups with steel pole pieces and ceramic bar magnets do not have the problem with stratitus like those with Alnico 5 pole pieces?

The Gauss at the top of steel pole pieces is about 400G on center. AlNiCo 3 usually reads about 550G, AlNiCo 2 around 700, and AlNiCo 5 around 1050. The Gauss gets stronger towards the edges, so I try to get the probe dead center for consistency. "Stratitus" is usually a non issue with anything other than AlNiCo 5.

[Antigua]

Sorry antigua, but may i ask you a question?

Why don't you simply type "Miller Effect" into your google and hit "GO!"? What is so difficult about it? Miller Effect is NOT complex. It is a simple relation - absolutely simple multiplication of capacitance. Sorry, but i am not used to such questions. Miller is standard.

Am I rude to you? I don't understand why I'm getting this attitude coming back in my direction.

I did "hit Go!" and but one example Miller capacitance being more a complicated issue than you make it out to be is presented here http://music-electronics-forum.com/t16129/

Consider a common emitter (or common cathode) amp. You amplify by placing a more or less high value resistor between rail and Anode(collector). So: Voltage wise, you have an amplified Version of the original present on the collector/anode. Now: Lets say amplification was 3 times. The Tube or Semiconductor has -say- 47pico BC (or GA) Capacitance. What happens with miller is, that the 47 pico is (theoretically) multiplied by 4. So you have about 200pico effective input capacitance.

That is miller.

Clear?

How about we consider the case were a tube amp is not even being used by the guitarist?

This is not an abstract issue: your claim is that when you turn down the volume controls on the guitar, the Miller capacitance goes up because the overall source impedance increases. Does this decrease the LC resonance of the guitar pickup, either in terms of frequency or amplitude?

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[Joe Gwinn]

I do not understand how you are so confident that the inductance does not change. Have you done this, and measured the result with an air core, or short cores as in a pickup?

Because the geometry of the turns of the coil or coils (in the two views) is essentially unchanged. Those turns have no ide what a single-section bobbin is, or how it differs from a two-section bobbin. Imagine the turns floating in space, ignoring all the stuff that holds those turns up off the floor.

[Joe Gwinn]

As for cable and amplifier input capacitance (including miller effect), the human ear is very sensitive to small changes in the spectrum of musical instruments like a guitar, so the only valid test of significance or irrelevance is a double-blind A/B listening test.

If miller effect is a problem, use a cascode input amplifier circuit.

Or go to low or at least lower impedance.

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