Guitar Shielding and the Capacitor argument against it...

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GuitarlCarl
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Post by GuitarlCarl »

Sorry you took it like that.... it's more like the math would be wasted on me. I do go by what I've done and what I've heard. I believe experience should weigh in as more than just fingers in my ears. But you are entitled to your own opinion. I suppose when confronted by the onslaught of life some folks do prefer to put the fingers in their ears, foregoing the wisdom of experience... To bad I'm not allowed the option of an opinion without the controversy you're trying to stir up. When you decide to stop jumping to conclusions, please allow the conversation to continue.
I want it to sound like bees buzzing around in a 55 gallon drum...

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GuitarlCarl
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Post by GuitarlCarl »

FiveseveN wrote:
MoonWatcher wrote:So the tone could possibly change with shielding, but it doesn't seem to be an issue of capacitance as much as an alteration to the magnetic field around the pickup.
That sounds like a reasonable theory. But you'll have to explain how a static paramagnetic material creates a significant influence on a pickup's magnetic circuit.
Without anymore than a guess to go on I think the shape of the magnetic field is changed by being deflected. If so, then the area the strings are vibrating in is changed too. I know the height the pickup is at makes a difference in tone as much as volume. I believe this optimum height is a sweet spot we're looking for, and the tele pickups base plate material, and the bridge plate material effects the magnetic fields shape. Therefore effecting performance/sound/tone. I do know that either changing only the bridge plate or only the pickups base plate will effect the sound of your guitar. Logically if it didn't make a difference tone shouldn't have been altered.
I want it to sound like bees buzzing around in a 55 gallon drum...

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FiveseveN
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Post by FiveseveN »

It would be trivial to measure the change in magnetic field caused by the presence of a nearby pickup or baseplate or copper foil or conductive paint or Batman sticker.
It would also be possible to swap a pickup's permanent magnet(s) with an electromagnet and determine what amount of change in field strength becomes audible to a sample of people.
But why bother, when many of the very people that should be interested in such research proclaim their personal anecdotes as the ultimate proof?!
When investigating a phenomenon, you don't start with a conclusion and then try to rationalize it, because that excludes the possibility that the conclusion may be inferred from illusion.
Ignorance more frequently begets confidence than does knowledge. (Charles Darwin)

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GuitarlCarl
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Post by GuitarlCarl »

Why would you want to measure anything? Guitars aren't made to be analyzed, they're meant to be played. If your guitar is humming then it needs shielding, or a better ground or something is broken. I've rebuilt many guitars, none of mine are stock, and repaired many for my friends and for a local shop. I've never found a reason to measure anything beyond continuity. But I know what to do to quiet a noisy guitar, and I know what to do to to get an axe to sound a given way. I'm a guitarist who repairs guitars on the side. Ultimate? I never said that. I also didn't start with a conclusion. It's a unproven theory, based upon observations made by hands on repairs. Which I offered up as a possible explanation for the fields behavior. I'll leave it to the electron counters to prove or disprove it while I go play a gig.
I want it to sound like bees buzzing around in a 55 gallon drum...

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FiveseveN
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Post by FiveseveN »

GuitarlCarl wrote:Why would you want to measure anything?
Because that's how we prove or disprove hypotheses. Because we understand that our ears and brains are terrible instruments.
It's a unproven theory, based upon observations made by hands on repairs.
An "unproven theory" is a hypothesis, and yours is based on intuition. And the burden of proof lies with whoever makes the claim, you can't just say "the Invisible Pink Unicorn did it! Prove me wrong, eggheads!".
The conclusion I was referring to was "if it didn't make a difference tone shouldn't have been altered". Surely if you heard a difference, and your friends did, then there must be one, right? Wrong.
What gets to me is this dismissive attitude of the scientifically ignorant, usually based on some argument.
"Electron counters"... Ha! You wouldn't know an electron from a muon!
Ignorance more frequently begets confidence than does knowledge. (Charles Darwin)

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Post by MoonWatcher »

I think all of this has gotten off track. Allow me to try and get it back on track, w/o so much the need for absolutes of what has been experienced and what can be determined solely with scientific absolutes.

But I will start with theories, or will back up to them with wording as such.

Theory - the proximity of a paramagnetic material may have the capability to offer the tonal structure of guitar pickups.

Theory - the alteration by said paramagnetic material alters the tone in a way that has nothing to do with capacitance.

What is unknown - how close said paramagnetics need to be, where within 3-D space they might have any/more/less of an effect, what the differences in paramagnetic material makeup, their thicknesses etc. might be.

The unknown effect of proximity extends to paramagnetics that cut thru the plane of a pickup, with examples being the bridgeplate on a Telecaster or foil on the underside of a pickguard. Since the two materials are probably not the same and are certainly not the same thickness, simply representing the effect of one is not sufficient to make a conclusion about the other.

What is known - a baseplate on a Telecaster bridge pickup will alter the tone. It has sufficient thickness, has sufficient proximity (actually touches the polepieces), is made of materials to alter the tone, and its location (under the pickup) is one where the effect can occur. Furthermore, some Telecaster bridge pickups must purposefully have the baseplate omitted to eliminate unwanted effects from the baseplate material. Furthermore, baseplates have been added to Strat and other types of pickups to alter their tones in a similar way.

What is known - a pickup cover will alter then tone. Some materials such as nickel seem to alter the tone more. Almost all materials seem to alter the tone to the point that a company (Harmonic Design) has produced a Telecaster neck pickup design that uses a plastic cover with a thin aluminized coating to eliminate the tonal alteration. Other companies have eliminated covers altogether, and yet other companies have replaced metal covers with plastic ones.

What is known - stacked humbucker-types will frequently have "vertical metal portions" just outside some of the windings, with the metal being a non-copper shielding type in most instances. Its location, orientation, and proximity all seem to have an effect. This metal is purposefully chosen for some reasons, maybe purposeful to changing the tone, or perhaps just used for functionality.

What is known - a guitar with 3 single coils will sound different in pickup selection positions 1 and 5 than the same guitar with 2 single coils with the selector set at positions 1 and 3. No theory can be obtained with respect to proximal paramagnetics, as it seems that the effect has more to do with the additional string pull of the third pickup, which in turn affects the string movement itself. In order to get to the point of determining if any effect is evident, non-traditional pickups with very low string pull should be used.

None of these things will advance towards a finite or precise conclusion, but they should at least get things closer to a point of knowing what the effect is, and what it is not. Or at least allow for the next phase of theories to be made.

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GuitarlCarl
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Post by GuitarlCarl »

FiveseveN wrote:
GuitarlCarl wrote:Why would you want to measure anything?
Because that's how we prove or disprove hypotheses. Because we understand that our ears and brains are terrible instruments.
It's a unproven theory, based upon observations made by hands on repairs.
An "unproven theory" is a hypothesis, and yours is based on intuition. And the burden of proof lies with whoever makes the claim, you can't just say "the Invisible Pink Unicorn did it! Prove me wrong, eggheads!".
The conclusion I was referring to was "if it didn't make a difference tone shouldn't have been altered". Surely if you heard a difference, and your friends did, then there must be one, right? Wrong.
What gets to me is this dismissive attitude of the scientifically ignorant, usually based on some argument.
"Electron counters"... Ha! You wouldn't know an electron from a muon!
Yes sir I only have a little two yr degree in electronics... so I have had theory, long ago, but find the practical hands on more to my liking than figuring out why things work the way they do... hence your problem with me. I was mistaken, I thought because we're on a forum that was based around musical equipment, that I would be interacting with musicians who used their ears and their brains to appreciate the application of said equipment. As far as dismissive, YOU sir are a jackass, you sir are the dismissive one, refusing to believe that any information not obtained by your anal probe is accurate. You also have repeatedly insulted me personally and tried to put words into print that I never wrote. I never said a lot of what you've insinuated, I'm not knocking your science and never said prove anything. I have tried to explain my opinions based on simple observations. I am not scientifically ignorant, I just find the need to know why a phenomenon happens less important, than to experience the sounds of my obsessions, rock n roll and electric guitars. You believe our ears are terrible instruments? Imagine where your jackass would be without them...
I want it to sound like bees buzzing around in a 55 gallon drum...

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matt239
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Post by matt239 »

Alright you two: KNOCK IT OFF.
You see how things escalate?

This, too me is a good argument for using science; if we stick to facts, there's less room for disagreement, and things getting personal.

That said, we can reach a point of diminishing returns in terms of getting practical results, but where that point is, varies with individual taste and aptitude.
If someone ENJOYS, and is good at doing the science, then it is worth it to them.
We are talking not only about what is true or not, but also if it is significant.

I personally would be interested in seeing more scientific testing/evaluation of how non-ferrous materials interact with a guitar pickups magnetic field; I believe this is not well understood, and there is a lot of mojo-mystery-hype surrounding the subject.

How a STEEL plate beneath a pickup alters the shape of the magnetic field is much better understood, and easier to get our heads around.

The original question in this thread however, was: does the foil shielding in a guitars' control cavity create capacitance that affects the tone.
The answer was a clear and resounding NO; there could not be enough capacitance to alter the frequency response in a meaningful way, detectable by human hearing.

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phatt
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Post by phatt »

Hey Matt,

Yes I agree with Your theory of diminishing returns. :lol:

I once worked with a rather painful apprentice who spent every last cent on hotting up his beloved obsession (Car).
Every Monday lunchroom He would babble on about how some new gizmo saved fuel and improved performance. (This went on for months and we where all getting sick of him) :roll:

Well my foreman who was a rather quite man of few words finally had a gutful of this mindless fool. [smilie=rlp_smilie_207.gif]

He said;

Mate I'm sorry but I've added up all the percentages you claimed in the last 6 months and if it was true then Your noisy pile of crap you call a car should be able to travel at the speed of light and never need petrol.

The whole lunch room stood up and applauded the intelligent observation. :applause: :applause: :applause:
Freddy Cranckcase (as We all called him) was ever so quite after that.
___
Back on topic,
For those interested in the science this might be of interest. (3D Magnetic flux lines)
http://www.moore.org.au/pick/06/06_gobd.htm

Re the effect of Non ferrous metals.
Look at the history surrounding Chet Atkins for clues and note that he was never really happy with the tone of early Gretsch pu's (especially single coils) Gretsch made open frame HB's which improved it a bit but once Gibson handed him the fully covered HB the tone was then mellow. (I believe he stuck with Gibson ever since)

The Covers do inhibit higher frequencies and help to sweeten the sonic result.
just slide some copper over your coils or whatever Non ferrous metal you can find and hear for yourself [smilie=a_whyme.gif]

Of course Chet was playing clean country finger picking licks (And Wow He was talented) :thumbsup
But along comes R&Roll and Big loud Amps. Distorted HB's where rather dull.

So off came the covers again.

I'm not sure of the actual mixture of metals that was used but *German Silver* was one name it went by.
Cheers, Phil.

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Post by induction »

FiveseveN wrote:
MoonWatcher wrote:So the tone could possibly change with shielding, but it doesn't seem to be an issue of capacitance as much as an alteration to the magnetic field around the pickup.
That sounds like a reasonable theory. But you'll have to explain how a static paramagnetic material creates a significant influence on a pickup's magnetic circuit.
Just spitballing here, so no numbers, and I might be totally off-base.

It might be important to consider the plate's electrical conductivity in addition to magnetic susceptibility. In a conductive, but not magnetic bridgeplate, the vibration of the magnetized string will generate eddy currents which induce a time-varying magnetic field. With a perfect conductor, the induced field will directly oppose the changes in the field from the vibrating string at the surface of the conductor, though the extended shape of the induced field will not mimic that of the pickup's field, or the one from the vibrating string. In a less perfect conductor there will be some phase lag, which might be important in terms of frequency response (but might not). The effect of this induced field could easily change the magnetization of the string itself, which could have implications on the frequency response of the magnetic circuit, compared to one with no plate.

If the plate is paramagnetic as well as conductive, the initial magnetic field will be shaped differently (compare the field from a magnetized plate to the elongated dipole of a pickup) and the attempt to change the paramagnetic field will generate its own set of eddy currents that oppose the first set, and it will not create the same amount or type of alteration in the magnetism of the string, and the circuit will behave differently. There may be some kind of field-focusing effect going on.

I haven't worked out enough of the details to convince myself that any of this is relevant, if the predicted effects would be large enough to measure, or if they would go in the right direction. It's about a half of a hypothesis at this point, so take it with a grain of salt.

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