# The technical on how a guitar pickup works....

fretman_2
July 26th, 2012, 10:08 AM
Excellent little article from an Associate Professor or Physics on how a guitar pickup works.

Since there are a few active threads on pickup winders and winding pickups, I thought you guys might find this interesting.

Barncaster
July 26th, 2012, 10:41 AM
Excellent little article from an Associate Professor or Physics on how a guitar pickup works.

Since there are a few active threads on pickup winders and winding pickups, I thought you guys might find this interesting.

Cool!

Thanks Fretman.

Rob

fretman_2
July 26th, 2012, 12:49 PM
Here's another very good technical resource...

The Secrets of Electric Guitar Pickups
http://buildyourguitar.com/resources/lemme/

jefrs
July 26th, 2012, 01:56 PM
The article is a bit dumbed-down aka "lies for children".

You do not need six magnets.

The vibrating string interferes with the magnetic field to cause the fluctuation in it that induces the signal current in the coil.

There are two magnetic factors: magnetic field strength; magnetic flux density.
The field strength is fairly obvious - how strong the magnet is, but a pickup does not need a very strong field, indeed it can be counter-productive.
The flux density is how close the lines of force are together, this provides the dynamic range, soft to loud.

fezz parka
July 26th, 2012, 01:58 PM
Electromagnetic induction. There, I said it in two words.:lol:

flatfive
July 26th, 2012, 02:02 PM
Excellent little article from an Associate Professor or Physics on how a guitar pickup works...

Thanks.

One thing I don't really get is this. Current is induced in the
pickup when the magnetic flux through the pickup coils changes.
The author of the article says the purpose of the magnets in
the pickups is solely to magnetize the strings -- I guess so that
string movement causes the needed change in magnetic flux
at the coils.

So far so good, but does the author really mean the strings
are getting permanently magnetized? Or are things more
complicated than that? I'm guessing it might be something
like the movement of the metal string in the presence of
the magnets causes current to be induced in the string,
which in turn causes a magnetic field to be induced around
the string.

Is that right?

(Answering my own question, I guess it is:

http://ocw.mit.edu/high-school/courses/guitar-building/lecture-notes/building-the-pickup/

So it seems misleading to say that the role of the magnets in
the pickup is to magnetize the strings.)

Also, the fact that the coils and the magnets seem to be
operating independently suggests that the coils don't need
to be near the magnets. Is that true?

fezz parka
July 26th, 2012, 02:04 PM
Old telephone handsets worked via electromagnetic induction. I don't think my voice got "magnetized".:lol:

guitarzan13
July 26th, 2012, 02:15 PM
Old telephone handsets worked via electromagnetic induction. I don't think my voice got "magnetized".:lol: But your old metal fillings might have :wink: :mrgreen:

fezz parka
July 26th, 2012, 02:17 PM
Hah! Another mystery solved!

BeeTL
July 26th, 2012, 02:35 PM
I look forward to reading up on this.

Jason Lollar also published a book that has been well received:

http://www.lollarguitars.com/mm5/merchant.mvc?Screen=PROD&Store_Code=LGP&Product_Code=WinderBook

fretman_2
July 26th, 2012, 03:42 PM
Good question. You can induce a magnetic field in the coil by putting a current through it. But that's not being done with a guitar pickup...it's passive.

My understanding of the article is that it's the moving of the magnetic field (magnetized strings) in proximity to the coil (pickup) that's inducing the current. Otherwise, you have to ask yourself why bother with a magnet at all? Would a string otherwise induce a current in a coil without a magnet??

My DVM has an inductance meter built in. I built a little cigar box pickup for three strings. The inductance didn't change very much, if at all, with the inclusion of a magnet to the coil.

So it seems misleading to say that the role of the magnets in
the pickup is to magnetize the strings.)

Also, the fact that the coils and the magnets seem to be
operating independently suggests that the coils don't need
to be near the magnets. Is that true?

JCollins
July 26th, 2012, 05:34 PM

The most amazing sounds are created by
combining the pickups out of phase, changing
again which harmonic modes are emphasised
or suppressed. It’s the out-of-phase combination
that creates the classic Stratocaster sound. Be
sure to listen for it at the festival.

Not true. All three Strat pickups are in phase with each other.

fezz parka
July 26th, 2012, 05:36 PM

The most amazing sounds are created by
combining the pickups out of phase, changing
again which harmonic modes are emphasised
or suppressed. It’s the out-of-phase combination
that creates the classic Stratocaster sound. Be
sure to listen for it at the festival.

Not true. All three Strat pickups are in phase with each other.

Bingo. It's comb filtering that makes the quack.

dsutton24
July 26th, 2012, 07:18 PM
Good question. You can induce a magnetic field in the coil by putting a current through it. But that's not being done with a guitar pickup...it's passive.

If you had a d.c. source you could use the coil itself as a magnet, then 'pick off' the a.c. (music) with a capacitor. Why isn't it done? I haven't done any math at all, but I think the resulting magnetic field would be very weak compared with the usual magnets. The wire in a pickup is very fine, and wouldn't tolerate much current without getting hot or failing.

Would a string otherwise induce a current in a coil without a magnet??

If the string itself was a permananet magnet, it would induce some current, but it would be very small. The flux lines would (probably) be along the axis of the string, and be very weak where they are influencing the coil. The same thing would happen if you were to pull the magnets out of your pickup and turn them on their sides. The pickup would still funtion, but it would be very weak.

My DVM has an inductance meter built in. I built a little cigar box pickup for three strings. The inductance didn't change very much, if at all, with the inclusion of a magnet to the coil

The inductance of a coil is influenced by the size of the coil, the number of turns, and the characteristics of the core (if any exists). A magnet within the coil would increase the inductance of the coil a little if the magnet is ferrous. If the magnet is 'behind' the coil, or ceramic, then it wouldn't change the inductance.

---

It's a fairly light weight article. It appears the author thinks there's a seperate coil wrappped around each magnet. Can you imagine how big that pickup would be? :cool:

Davecam48
July 26th, 2012, 07:36 PM
Too much "Mojo" has been attributed to the guitar pickup, it is essentially a speaker in reverse. In actual fact a speaker can be used as a crude microphone if you hook it up to a powerful amp and shout into the speaker cone a sound can be induced from the amp, albeit not loud and poor quality.
A magnetic field in proximity to a coil of conductor that has it's magnetic flux varied will produce an electrical current which we then amplify.

A speaker is a coil inside a magnet which then has an electrical current passed through it and produces which by the nature of the cone construction pumos in and out.
Let's say it pumps out on a +ive pulse and in on a -ive pulse, just the opposite of a pickup where the pumping action (string vibration) varies the flux thus producing the electrical charge which is AC by it's variable nature.

This is where I will upset the "Mojo" applecart! A pickup's sensitivity, tone and "gain" are purely dependant upon the NUMBER of turns in the coil, not the gauge of the wire or any other thing,"the number of turns!" and the relative strength of the magnetic flux as well as the ferocity of the string movement which varies the change of flux within the coil.

If you built a coil without a magnet and attached a magnet to a nylon string and plucked it in close proximity to the coil it will produce a "signal",weak but a signal nevertheless.

The kind of wax etc. is just all hype and sales fodder for the gullible sorry to say but it is amusing.

DC

dsutton24
July 26th, 2012, 07:51 PM
A pickup's sensitivity, tone and "gain" are purely dependant upon the NUMBER of turns in the coil, not the gauge of the wire or any other thing,"the number of turns!"

In a theorectical sense, yes, if the coil was wound on a plane. But, in the real world the guitar string's vibration amplitude is significant compared to the thickness of the coil, so as the string vibrates it's inducing current in varying parts of the coil.

The way the coil is wound has a big effect on the sound of a pickup, Flat wound pickups sound very different than scatter wound, or coils that have the bulk of the windings concentrated in the bottom, the top, or whatever the pattern might be.

Wire gauge does have an effect. Bigger wire means fewer turns in a given space, and also less resistance, so the coil will have a higher Q.

jefrs
July 26th, 2012, 07:55 PM
The magnets do not magnetize the strings.

However the movement of the string does interfere with the magnetic field around the coil.

That fluctuation in the field is what induces a current in the coil. It takes a changing magnetic field to induce electrical current in a coil.

Unlike the loudspeaker which can be used as a moving coil microphone, the pickup is a form of moving magnet microphone, except the magnet does not move but its field is caused to wobble.

Arbiter
July 26th, 2012, 08:01 PM
Electromagnetic induction. There, I said it in two words.:lol:

You could say it in one, and it would even be somewhat more accurate: electromagnetism.

flatfive
July 26th, 2012, 08:50 PM
...However the movement of the string does interfere with the magnetic field around the coil...

If I understand this right, you mean (in more detail) that the
(changing) magnetic field around the string is responsible
for a change in flux at the pickup coil -- right?

And the changing magnetic field around the string is
caused by the movement of the string in proximity to
the pickup magnet -- right?

R. Stratenstein
July 26th, 2012, 10:15 PM
Something to ponder: how would a pickup made with steel wire sound? Would it sound at all? Copper coils, of course, are not magnetic sensitive, they just have current induced through them by magnetism, which is commonly abbreviated m.o.j.o. But obviously steel magnet wire (let's ignore the relative conductance for a moment) would be affected by the magnets. Would it totally dampen the induced current and thus the signal? Maybe cause some phase shift of varying degrees? Dunno. It just occurred to me while reading this.

Even if not totally, technically accurate, I enjoyed the article and probably would have done much better in physics class if somebody had related it to electric guitars way back then!

Nick JD
July 26th, 2012, 10:45 PM
http://2.bp.blogspot.com/_wdzTCiWk9xY/SI3AHPWeTMI/AAAAAAAAAEE/q-mYDNQ75y0/s320/magnet%2Bcrane.jpg

piece of ash
July 27th, 2012, 12:04 AM
Something to ponder: how would a pickup made with steel wire sound? Would it sound at all? Copper coils, of course, are not magnetic sensitive, they just have current induced through them by magnetism, which is commonly abbreviated m.o.j.o. But obviously steel magnet wire (let's ignore the relative conductance for a moment) would be affected by the magnets. Would it totally dampen the induced current and thus the signal? Maybe cause some phase shift of varying degrees? Dunno. It just occurred to me while reading this.

Even if not totally, technically accurate, I enjoyed the article and probably would have done much better in physics class if somebody had related it to electric guitars way back then!

A coil wound from steel would concentrate the flux more tightly around the magnets... and probably kill the ouput.

fezz parka
July 27th, 2012, 12:21 AM
You could say it in one, and it would even be somewhat more accurate: electromagnetism.

Too broad a brush. Strings vibrate, modulating the magneitc flux in the coil, inducing AC current.For pickups, it's Electromagnetic Induction.:razz:

joshwertheimer
July 27th, 2012, 02:08 PM
The author makes the common mistake of interchanging "phase" and "polarity." As Fezz says, that Strat sound is due to comb filtering, which is a product of phase cancelations, even though strat pickups are all wired the same polarity.

The most amazing sounds are created by
combining the pickups out of phase, changing
again which harmonic modes are emphasised
or suppressed. It’s the out-of-phase combination
that creates the classic Stratocaster sound. Be
sure to listen for it at the festival.

Not true. All three Strat pickups are in phase with each other.

jefrs
July 29th, 2012, 10:08 AM
If I understand this right, you mean (in more detail) that the
(changing) magnetic field around the string is responsible
for a change in flux at the pickup coil -- right?

And the changing magnetic field around the string is
caused by the movement of the string in proximity to
the pickup magnet -- right?

I think you got it.

There is a standing magnetic field from the erm, magnets.

If you waggle a string around in it, or any other ferro magnetic metal object, then you disrupt the field. A changing magnetic field is what induces a current in the coil.

It doesn't have to be a coil, a straight wire is a coil of zero turns, wrapping the wire around into a coil just places more wire into the field.

If you run a current through a straight wire and place a magnetic compass by it, the needle will spin round because the electricity is generating a rotating magnetic field in the copper wire (copper is non-magnetic by itself). An electric current generates a moving magnetic field and it is reversible - a moving magnetic field induces a current. A coil of wire "straightens up" the rotation (the effect sums to assume a direction) and so you see N and S magnetic poles, but that magnetic field is still spinning around each individual strand of wire. James Maxwell and Michael Faraday.
And John Fleming
http://en.wikipedia.org/wiki/Right-hand_rule
http://en.wikipedia.org/wiki/Fleming%27s_left-hand_rule_for_motors

You can magnetize some ferro magnetic materials: iron, nickel, cobalt, gadolinium, and their alloys. All of them are attracted to a magnet but some alloys do not retain a magnetic field well (most guitar strings), those that do become magnetized are termed permanent magnets, incl our favourite, alnico.

Mojotron
July 29th, 2012, 03:13 PM
The electromagnetic induction. is the - _primary_ - part of how the signal get's generated: We can prove that Maxwell was right in how he laid out how that works. Magnetic lines of flux - something with Iron in it influencing the field - flux induces electron movement through the wire... I totally agree - the magnets don't magnetize the strings - that is a gross oversimplification that totally misses the way it works - as I understand it.

So - something like a base plate with iron in it - steel - would reflect some of the magnetic field back into the coil... making the field more efficient.

There is a whole other area of influences having to do with the parasitic loss (maybe generalizing it to "efficiency") of the pickup though:

1) The internal capacitance of the pickup - that has everything to do with the diameter of the wire, the insulation, the potting material, the tightness of the wind the proximity of one layer of wire on top of the others, the depth of the coil.... That does have a significant secondary effect on the tone of the pickup. IMO - capacitive loss is a very significant factor - but sort of gets into the cork sniffing side of things.

2) The location of the EM field - that is does the field have significant delusion of the field away from the coils - making the pickup less efficient: A good example of this is a Tele neck pickup - the magnets on some are designed to extend below the lower flatwork. That puts some of the EM field below the strings, away from where the strings - but that gives it it's tone characteristics.

3) The number of turns and the spread of the bobbin - IMO - equals the density of the field, and maybe the shape of the field... A few weeks ago I wound a Tele neck pickup with approximately just as much 42 awg wire as one would wind a strat neck pickup: That pickup still has a lot of that Tele neck pickup character, as well as a good deal of a Strat sound - very interesting tone.

This is a great discussion, one that helps me for sure, but I think a mental or physical model of a pickup's tone would need to be much more complex than just representing primary effects of the wire and the strength of the field.

piece of ash
July 29th, 2012, 04:05 PM
The strings DO become magnetized... though not very much... and this effect does not substantially contribute to induction. The do however carry magnetic flux.

The induction is the ONLY way signal gets generated.

Steel does not strictly reflect magnetism... steel invites magnetic flux to flow through it. This "invitation" remains until the steel becomes magnetically saturated... any additional flux will travel around the steel.

A single wire is indeed one turn... somewhere, the two ends of that wire meet an impedance... that is if a: current is flowing, or a voltage being measured.

Now to really muck things up: the current flowing in a LOADED (plugged in) coil generates a field that opposes the field creating it.

flatfive
July 30th, 2012, 12:40 AM
I've been googling around on this subject, and there seems
to be basic disagreement about how electric guitar pickups
work.

The usual explanation is that the vibrating strings disrupt
the magnetic field produced by the pickup's magnet, thereby
inducing current in the pickup's coil.

This idea is widely repeated, but it's not much of an explanation
because there's no law of physics that says that a vibrating wire
will disrupt a magnetic field.

What there is, is Faraday's law, which says that that if you
have a changing magnetic field close to a wire, an electric
current will be induced in the wire. (Equally the wire can be
moving in a fixed magnetic field.) It's also known that
a wire with current flowing through it will have a magnetic
field around it.

I've seen two basic explanations of how a pickup works, and
I've seen both of them coming from university physics
departments:

1. The guitar string is magnetized by the pickup magnet, and
then the moving guitar string causes a change in the magnetic
field in the pickup's coil. (The theory given in the article by the
OP.)

2. When the guitar string vibrates in the presence of the pickup's
magnet, a current is induced, and so then a (changing) magnetic
field is produced, which induces a current in the pickup's coil.

I believed theory 2, but now I have my doubts, because I think
a guitar pickup would work even if current can't flow through the
guitar strings because there is no "circuit".

But theory 1 also seems a little dubious to me -- for example,
wouldn't it take a little time for the string, in the area of the
pickup, to get magnetized? I've never noticed any change in
the sound of a pickup in the seconds after putting a string on.

What's the right theory?

dsutton24
July 30th, 2012, 12:49 AM
This idea is widely repeated, but it's not much of an explanation
because there's no law of physics that says that a vibrating wire
will disrupt a magnetic field.

A vibrating string will disrupt a magnetic field if the string is ferromagnetic. You can demonstrate this by doing the old grade school trick of putting a piece of paper over a magnet and shaking iron filings over it. You'll see the lines of magnetic force. Now hold a nail close to the experiment, and move it around as you tap the paper, you will disrupt the lines.

Ever drive through a latticework bridge, and have it interfere with the radio? Same effect on a big scale.

piece of ash
July 30th, 2012, 01:02 AM
Flatfive,

Both descriptions are correct enough... they have been watered-down and the jargon mis-used for clarity. Suffice it to say that any magnetic material vibrating in the presence of a magnetic field will alter that field. That varying magnetic field can, and will, induce a VOLTAGE (not a current) in a loop (coil) intersecting a portion of that field.

Westerly Sunn
July 30th, 2012, 04:57 AM
I've been googling around on this subject, and there seems
to be basic disagreement about how electric guitar pickups
work.

The usual explanation is that the vibrating strings disrupt
the magnetic field produced by the pickup's magnet, thereby
inducing current in the pickup's coil.

This idea is widely repeated, but it's not much of an explanation
because there's no law of physics that says that a vibrating wire
will disrupt a magnetic field.

What there is, is Faraday's law, which says that that if you
have a changing magnetic field close to a wire, an electric
current will be induced in the wire. (Equally the wire can be
moving in a fixed magnetic field.) It's also known that
a wire with current flowing through it will have a magnetic
field around it.

I've seen two basic explanations of how a pickup works, and
I've seen both of them coming from university physics
departments:

1. The guitar string is magnetized by the pickup magnet, and
then the moving guitar string causes a change in the magnetic
field in the pickup's coil. (The theory given in the article by the
OP.)

2. When the guitar string vibrates in the presence of the pickup's
magnet, a current is induced, and so then a (changing) magnetic
field is produced, which induces a current in the pickup's coil.

I believed theory 2, but now I have my doubts, because I think
a guitar pickup would work even if current can't flow through the
guitar strings because there is no "circuit".

But theory 1 also seems a little dubious to me -- for example,
wouldn't it take a little time for the string, in the area of the
pickup, to get magnetized? I've never noticed any change in
the sound of a pickup in the seconds after putting a string on.

What's the right theory?

Here's my take on it. The "magnetized String" description; although misleading, is getting towards what is going on.

IMHO, it's like this: The string material has a higher permeability to the magnetic flux than the surrounding air. Therefore; being placed above the magnetic source, the flux becomes concentrated in the string as it passes through the vicinity of the string. The string is the "path of least resistance" in that area for the magnetic flux, so the flux "wants" to pass through the string. It is this same idea that is used in tape machine tape heads; for instance, to "concentrate" the magnetic flux in the gap of the tape head where the tape contacts the head.

Therefore, when the stings moves, the field follows and moves along with it.
This is what causes the movement of the field in the area of the coil winding and induces the voltage in the coil.

Ricky D.
July 30th, 2012, 06:40 AM
Excellent little article from an Associate Professor or Physics on how a guitar pickup works.

Since there are a few active threads on pickup winders and winding pickups, I thought you guys might find this interesting.

Almost 100% wrong. Just goes to show how little those university credentials are worth.

Thanks.

One thing I don't really get is this. Current is induced in the
pickup when the magnetic flux through the pickup coils changes.
The author of the article says the purpose of the magnets in
the pickups is solely to magnetize the strings -- I guess so that
string movement causes the needed change in magnetic flux
at the coils.

So far so good, but does the author really mean the strings
are getting permanently magnetized? Or are things more
complicated than that? I'm guessing it might be something
like the movement of the metal string in the presence of
the magnets causes current to be induced in the string,
which in turn causes a magnetic field to be induced around
the string.

Is that right?

(Answering my own question, I guess it is:

http://ocw.mit.edu/high-school/courses/guitar-building/lecture-notes/building-the-pickup/

So it seems misleading to say that the role of the magnets in
the pickup is to magnetize the strings.)

Also, the fact that the coils and the magnets seem to be
operating independently suggests that the coils don't need
to be near the magnets. Is that true?

The MIT article is much better.

Keyser Soze
July 30th, 2012, 04:25 PM
The author of the article says the purpose of the magnets in
the pickups is solely to magnetize the strings -- I guess so that
string movement causes the needed change in magnetic flux
at the coils.

The magnet(s) exist to create a magnetic field. The coil needs to be within this field.

Any disturbance in the magnetic field (such as caused by a vibrating string) will induce a current in the coil.

But you don't even need a string. If you moved the coil within the magnetic field it would still generate a current (see what I did there?)

The coil really doesn't care who is moving - so long as the magnetic field is moving relative to it's position the electricity will flow.

flatfive
July 30th, 2012, 06:07 PM
A vibrating string will disrupt a magnetic field if the string is ferromagnetic. You can demonstrate this by doing the old grade school trick of putting a piece of paper over a magnet and shaking iron filings over it. You'll see the lines of magnetic force. Now hold a nail close to the experiment, and move it around as you tap the paper, you will disrupt the lines...

Thanks -- I think this gets to the right idea, which is that
the string acquires a (temporary) magnetic field because of
the permeability of the guitar string. And it's the movement
of this temporary field that induces current in the pickup's
coil.

I'm guessing that the explanation that "the string gets magnetized"
is an easy way to try to get the main idea across.

flatfive
July 30th, 2012, 06:12 PM
Flatfive,

Both descriptions are correct enough... they have been watered-down and the jargon mis-used for clarity. Suffice it to say that any magnetic material vibrating in the presence of a magnetic field will alter that field. That varying magnetic field can, and will, induce a VOLTAGE (not a current) in a loop (coil) intersecting a portion of that field.

Hi piece of ash. I can see how saying that the string gets
magnetized is a bit misleading, but I don't see how the other
theory (that the movement of the string in the presence of
the pickup's magnet induces a current in the string and hence
a magnetic field) is right. I don't think pickup operation
depends on the ability for current to flow through the string.

flatfive
July 30th, 2012, 06:17 PM
Here's my take on it. The "magnetized String" description; although misleading, is getting towards what is going on.

IMHO, it's like this: The string material has a higher permeability to the magnetic flux than the surrounding air. Therefore; being placed above the magnetic source, the flux becomes concentrated in the string as it passes through the vicinity of the string. The string is the "path of least resistance" in that area for the magnetic flux, so the flux "wants" to pass through the string. It is this same idea that is used in tape machine tape heads; for instance, to "concentrate" the magnetic flux in the gap of the tape head where the tape contacts the head.

Therefore, when the stings moves, the field follows and moves along with it.
This is what causes the movement of the field in the area of the coil winding and induces the voltage in the coil.

Excellent! Very clear, and seems correct from my understanding
of the physics.

(A tiny nitpick: as I understand it, shouldn't you say
"magnetic field" instead of "flux" in the above?)

Keyser Soze
July 30th, 2012, 06:20 PM
Flatfive,

Both descriptions are correct enough... they have been watered-down and the jargon mis-used for clarity. Suffice it to say that any magnetic material vibrating in the presence of a magnetic field will alter that field. That varying magnetic field can, and will, induce a VOLTAGE (not a current) in a loop (coil) intersecting a portion of that field.

Ohms law I = V/R

The only way a voltage could appear without a corresponding current is if the resistance was effectively infinite (given I = 0, and V is some positive number, R must approach infinity.)

But this certainly does explain why the current generated by a guitar pickup is miniscule (or alternately, why pickups are high impedance devices.)

flatfive
July 30th, 2012, 06:27 PM
Almost 100% wrong. Just goes to show how little those university credentials are worth.

There are surely idiots with degrees, but I completely
disagree if you're saying the author is not an accomplished physicist.

The problems in the article are probably mostly a matter
of trying to simplify the subject.

flatfive
July 30th, 2012, 06:33 PM
But you don't even need a string. If you moved the coil within the magnetic field it would still generate a current (see what I did there?)

The coil really doesn't care who is moving - so long as the magnetic field is moving relative to it's position the electricity will flow.

Thanks. I did see the Faraday's law part of the picture, but didn't
see a explanation from first-principles of how moving a string in
the presence of a magnet "disrupts the magnetic field".
Now I think that explanation has to do with permeability of the
guitar strings.

piece of ash
July 30th, 2012, 08:51 PM
Ohms law I = V/R

The only way a voltage could appear without a corresponding current is if the resistance was effectively infinite (given I = 0, and V is some positive number, R must approach infinity.)

But this certainly does explain why the current generated by a guitar pickup is miniscule (or alternately, why pickups are high impedance devices.)

Exactly... I was merely trying to clarify that EMF (voltage, not current) is what is induced in the coil. The current only flows as a result of this EMF... and only then if there is some non-infinite resistance completing the circuit.

Ricky D.
July 31st, 2012, 01:48 AM
There are surely idiots with degrees, but I completely
disagree if you're saying the author is not an accomplished physicist.

The problems in the article are probably mostly a matter
of trying to simplify the subject.

I'm not calling him an idiot. That would be unfair to a lot of people who had a hard time in school. I'm calling him incompetent and unprofessional. This is basic physics. His profession consists of understanding and explaining things like this. You should be able to rely on an Associate Professor of Physics to be technically correct on the physics regardless of his audience and not make stupid mistakes about strat pickups being out of phase.

I can read ill-informed pseudo-technical baloney like this guy's article all over the internet. :roll:

chezdeluxe
July 31st, 2012, 08:31 AM
He would not make Full Professor under my watch.

Rob DiStefano
July 31st, 2012, 10:50 AM
guitar pickups work because someone made them. i dunno how they made them, but they work and some do sound purty nice. don't need to know much more than that. kinda like how a top indy drive don't know squat about the mechanics; he's just the guy putting the car to good use. :D

fretman_2
July 31st, 2012, 11:05 AM
LMAO...so true.

guitar pickups work because someone made them. i dunno how they made them, but they work and some do sound purty nice. don't need to know much more than that. kinda like how a top indy drive don't know squat about the mechanics; he's just the guy putting the car to good use. :D

jefrs
July 31st, 2012, 03:55 PM
He would not make Full Professor under my watch.

Nah! - some journalist bought him a drink down the pub, asked him to explain pickups, and tried to write down what he said.
Result - one really dumbed-down article.

flatfive
July 31st, 2012, 04:42 PM
guitar pickups work because someone made them. i dunno how they made them, but they work and some do sound purty nice. don't need to know much more than that. kinda like how a top indy drive don't know squat about the mechanics; he's just the guy putting the car to good use. :D

I will defend to the death your right to not be curious! :razz:

Nah! - some journalist bought him a drink down the pub, asked him to explain pickups, and tried to write down what he said.
Result - one really dumbed-down article.

I believe this.

I've been scrounging the web for good information. Here are a
few good references:

www.physics.princeton.edu/~mcdonald/examples/guitar.pdf

http://videolectures.net/mit802s02_lewin_lec16/

http://online.physics.uiuc.edu/courses/phys406/Lecture_Notes/Guitar_Pickup_Talk/Electronic_Transducers_for_Musical_Instruments.pdf

The last document has lots of info, both historical and technical.
The author (Steve Errede of UIUC) seems to have looked into the
physics of electric guitar pickups more deeply than anyone else.

I asked him about the two theories of how pickups work; he said
both play a role but the theory based on the permeability of the
strings plays a much bigger role than the other theory. He said
that if you put conducting but non-magnetically permeable strings
on a guitar you will get a signal, but a very weak one.

fezz parka
July 31st, 2012, 05:24 PM
guitar pickups work because someone made them. i dunno how they made them, but they work and some do sound purty nice. don't need to know much more than that. kinda like how a top indy drive don't know squat about the mechanics; he's just the guy putting the car to good use. :D

:lol: A big "yep" from me.

A better question would be: "Why do doughnuts have holes in the middle?":cool:

Rob DiStefano
July 31st, 2012, 05:31 PM
guitar pickups work because someone made them. i dunno how they made them, but they work and some do sound purty nice. don't need to know much more than that. kinda like how a top indy drive don't know squat about the mechanics; he's just the guy putting the car to good use. :D

I will defend to the death your right to not be curious! :razz:

actually, i understand transducer processes and theories quite well. :cool:

flatfive
July 31st, 2012, 06:54 PM
actually, i understand transducer processes and theories quite well. :cool:

Then I guess I defend to the death your right to parody? :eek:

fezz parka
July 31st, 2012, 07:03 PM
As I will defend your right to be curious. Some things don't need a proctoscope to see/hear what they're doing.:lol:

Rob DiStefano
July 31st, 2012, 07:10 PM
As I will defend your right to be curious. Some things don't need a proctoscope to see/hear what they're doing.:lol:

dude, love yer new avatar and sig line. :mrgreen:

Rob DiStefano
July 31st, 2012, 07:12 PM
:lol: A big "yep" from me.

A better question would be: "Why do doughnuts have holes in the middle?":cool:

i could never figure out how them dang things get there ... hmmm, kinda like figuring out how a dang coil of wire and magnet can make music ,,, ?

fezz parka
July 31st, 2012, 07:12 PM
:lol:

Rob DiStefano
July 31st, 2012, 07:21 PM
dang, i must be stupid. the donut dough wraps AROUND the holes. now i is smarter.

dsutton24
July 31st, 2012, 07:37 PM
now i is smarter.

I are envious of your donut smartness. I don't know how donuts work, but I know how to work 'em.

flatfive
July 31st, 2012, 08:19 PM
For those of you who like to dislike threads on
"the theory of", here are some quotes you'll like:

“Theory helps us to bear our ignorance of facts” - George Santayana

"An ounce of action is worth a ton of theory" - Friedrich Engels

and finally

"My theory of evolution is that Darwin was adopted" - Steven Wright

stevieboy
July 31st, 2012, 09:04 PM
I push the first string down
The music goes down and around
Whoa-ho-ho-ho-ho-ho
And it comes out here

(with apologies to Ella)

flatfive
August 1st, 2012, 12:29 AM
Looking again at that article that started this thread, I see
that the author was not referring to the pickups being electrically
out of phase, but rather phase cancellation in the audio signal
in strat positions 2 and 4.

This issue's just been discussed over in Just Pickups:

http://www.tdpri.com/forum/just-pickups/337085-strat-sounds-position-2-4-a.html

and there's more at:

http://www.till.com/articles/PickupMixing/index.html

Ricky D.
August 1st, 2012, 01:01 AM
From the caption on the photo:

"The distinctive Stratocaster
the voltage from pairs of
pickups out of phase."

Nick JD
August 1st, 2012, 01:04 AM
The hole is in the doughnut so it cooks evenly quicker.

A guitar pickup works by picking up the sounds of the strings.

Gimme another one.

Davecam48
August 1st, 2012, 05:05 AM
A good doughnut shop will sell you the holes separately !

Westerly Sunn
August 1st, 2012, 08:49 AM
The hole is in the doughnut so it cooks evenly quicker.

This...

...and my mama used to get them there by punching them out with a drink bottle...

Nick JD
August 1st, 2012, 09:17 AM
Last time I was in Canadia I got a box of "doughnut holes".

jkingma
August 1st, 2012, 10:21 AM
Last time I was in Canadia I got a box of "doughnut holes".

We call those "timbits"... after our national hockey and doughnut hero Tim Horton. :mrgreen:

http://www.dougtheslug.ca/images/03.02.12/timbits2.jpg

nosmo
August 1st, 2012, 10:34 AM
Wow - that little one in the front looks like a hole with a hole in it. What a great place TDPRI is. I opened up this thread expecting to learn something about pickups and here we are discussing donuts! Awesome.