Understanding electronics in a guitar?

[Lillian]

What are you going to use for an amp?

[DarwinStrings]

What are you going to use for a guitar strap martin?

Jim

[Nick]

Toejam wrote:

What are you going to use for a guitar strap martin?

Jim

untitled.jpg (85.91 KiB) Viewed 17065 times

[kiwigeo]

Lillian wrote:

What are you going to use for an amp?

I'm going to do some mods to the rigs PA system. The rig has 5 gen sets and with them all on line I should be able to get the PA working loud enough so that Kim can hear it 1500km away down in Perth.

[Lillian]

That sounds promising.

DON'T forget you hearing protection. The only ringing you should hear is one of Shane's tops when you tap it.

[kiwigeo]

Getting a bit off topic here. Understanding magnetic pickups has become my mission for the month. Stay posted.

[Puff]

Martin -this may be of use. http://buildyourguitar.com/resources/lemme/
Many of the custom pickup builders also have insights on their websites but equally most leave bits of their equation out which, given it's their livelihood, is understandable. It is very much a matter of a snippet here and a snippet there to build a picture.

[Tim Mason]

Well Ive got 4 days of wireline logging ahead out here at work. One of the tools is a mag resonance tool with a huge (70kg) permanent magnet. Ive got a couple of packets of Martin medium guage strings with me so I'm going to rig up a little experiment......its going to be the biggest baddest most powerful guitar pickup ever built.

Skys the limit! sounds interesting. Maybe the military can use it for riot control

Oh, and im happy to stay on pickups for a while, have lots to do before i can move on to the pots(or my understanding of them) Great help so far Kiwi

[kiwigeo]

Puff wrote:

Martin -this may be of use. http://buildyourguitar.com/resources/lemme/
Many of the custom pickup builders also have insights on their websites but equally most leave bits of their equation out which, given it's their livelihood, is understandable. It is very much a matter of a snippet here and a snippet there to build a picture.

Thanks for the link Puff

Your link is actually one I looked at during the 4 hours I was trawling the net the other night.

Like 90% of the links Ive trawled up over a total period of 4 hours (were talking around 125 links) this site states that the vibrating string affects the flux around the permanent magnet and this in turn induces the current in the pickup coil. From your link:

"The magnetic field lines flow through the coil(s) and a short section of the strings. With the strings at rest, the magnetic flux through the coil(s) is constant. Pluck a string and the flux changes, which will induce an electric voltage in the coil. A vibrating string induces an alternating voltage at the frequency of vibration, where the voltage is proportional to the velocity of the strings motion (not its amplitude). Furthermore, the voltage depends on the string's thickness and magnetic permeability, the magnetic field, and the distance between the magnetic pole and the string.

The only sources maintaining that the magnetised string directly idcues the current in the coil are Seth Lovers article and some of the posters in this thread.

Until I read otherwise Im going for the theory that a vibrating ferrous string changes the flux around the permanent magnet in a pickup. The change in same flux in turn induces a current in the pick up coil.

Anybody feel free to convince me otherwise. I'll be discussing all this with my logging engineers when they get on board..theyre both electrical engineers and like I said some of their tools utilise magnetic fields and work on the principle of material interfering with fluxaround same.

[Puff]

Not playing one-upmanship here but probably well in excess of 100 hours trawling pickup and preamp info and taken aback somewhat by Mr Seth's bit. Given it was a transcript - and not a particularly good one - of an interview by "Seymour W Duncan" conducted 32 years ago there could be room for a conspiracy theorist there. I wondered if there was a degree of extracting the urine.

[kiwigeo]

100 hours on the net....good God man your eyes must be hanging out on strings!!

I could probably match that but the client monitors the net time like a hawk and surfing the net all day would take a bit of explaining to the client

[Puff]

That is cumulative over a few years Martin.

[Localele]

Puff wrote:

I wondered if there was a degree of extracting the urine.

I have been reading this with interest and find that I now have to respond in a positive manner.Yes, Puff, there is indeed a degree of which you speak.
I hope this sheds some light on this lively debate.

[Nick]

Nice one Micheal, bet you earnt it too!

[kiwigeo]

Don't laugh...that degree of Michael's is probably of more use than alot of degrees issued by bona fide tertiary institutions.

Four years studying for a Geology degree and here I am 25 years later sitting 200kms off the coast of Australia with a bunch of oil field loonies on a floating prison.

[Tim Mason]

Ok, so here is a PDF written by a PhD in Physics who is known for his work in the physics of audio electronics, backing Seths theory. Page 18 starts on pickups, and as Geochem, an MLP member tells me, winders can have a tendency to make Myth based sales, a researcher strives for truth.

Im leaning heavily towards this theory, making more sense to me anyhaw

http://online.physics.uiuc.edu/courses/ ... uments.pdf

[kiwigeo]

Um Er...doesnt Seth Lover maintain that the magnetised string directly drives the pickup coil????

This is not what is being proposed in your latest link...this guy quite clearly states that the vibrating string affects the magnetic flux around the pickup magnet and it is THIS which drives the coil.

[Tim Mason]

Hang on, let me skip back, im reading page 24 and might just be ahead of myself there

[Tim Mason]

Hmm, seems its a little of both, the triangle shaped flux produced by the magnetic strings vibration dictates the inductance by manipulating the flux of the magnet thus inducing voltage into the coil.

SNIP

"When the now-magnetized string(s) of an
electric guitar are plucked, ~ triangle-shaped
standing waves on the string are set up, consisting
of a harmonic superposition of the fundamental,
and higher harmonics{The detailed geometrical
shape of the standing wave dictates which
harmonics are present (by Fourier’s theorem)!}

The now-magnetized string(s) of an electric
guitar vibrating in proximity to the guitar pickup
cause changes in the magnetic flux linking the
pickup coil and induce an EMF (i.e. a timevarying
voltage signal) in the pickup coil
(Faraday’s Law of Magnetic Induction)"

[kiwigeo]

This is the way I'm seeing it all:

Seth Lover:

"That’s right, the magnetic field comes up to the stings there and magnetizes the strings. That’s one of the things that most people don’t understand. They figure that string is waving there and cutting the magnetic lines of force. Nuts. That isn’t it. The magnet, all it does is magnetize the string. Now you’ve got a waving magnetic field. And we have a fixed coil with a waving magnetic field to induce voltage.

My understanding: magnetic flux around string directly induces current in pickup coil.


Errede:

The now-magnetized string(s) of an electric
guitar vibrating in proximity to the guitar pickup
cause changes in the magnetic flux linking the
pickup coil and induce an EMF (i.e. a timevarying
voltage signal) in the pickup coil

My understanding: magnetized string affectes magnetic field around pickups permanent magnet and this in turn induces current in coil.

This statement from Erred is also significant:

"The guitar strings, in proximity to the pickup become magnetized – amazingly, two magnetic poles are induced in the string directly over the
pickup (here south poles) – the majority of magnetic flux is confined to the interior the magnetically permeable string –"

My understanding: the magnetic field around a string is not strong enough to directly drive the pickup coil. There may be a small amount of direct coupling between the magnetized string and the coil but most of the signal in the coil is being generated by the changes in the magnetic flux around the permanent magnet.

Maybe Ive got it totally wrong but unless someone can convince me otherwise Im going with Erreds explanation of how a magnetic pickup works.

[kiwigeo]

Tim Mason wrote:

Hmm, seems its a little of both, the triangle shaped flux produced by the magnetic strings vibration dictates the inductance by manipulating the flux of the magnet thus inducing voltage into the coil.

My bolding above. Probably not made clear in my posts but my understanding is that the weak flux around the magnetised string affects the flux around the larger permanent magnet. The changed flux around the permanent magnet induces current in the coil.

[Tim Mason]

I have to agree, the pickup is put to rest for now, thank god!

I have a new custom handwound 12.6k Zangbucker comming in a few weeks after all this, Alternate wind 42/43 wire(hot with clarity:), with 4 wire for coil split slug or screw side and series/phasing(its a secret ) to pair up with a SD jazz in the neck. Should be good, ill post a clip when its in.

[kiwigeo]

Tim Mason wrote:

I have to agree, the pickup is put to rest for now, thank god!

I wouldnt be too sure...Ive been known to be wrong (all the time if you believe my wife).

[Tim Mason]

Ah, a wise man knows he knows nothing at all, but it feels good to think you do for a little while

[matthew]

Yep, but everything affects everything. If you move a magnetic metal (string) in a magnetic field you WILL "bend" the flux, causing a current to be induced into the coil AND any metal in the vicinity. So this movement will also induce a small current in the string , AND both the (tiny) current in the string and its proximity to the magnet will magnetise the string itself (think picking up pins with other pins on an electro- magnet) - which will have its OWN magnetic flux, albeit much weaker, and if the strings are hard steel (which they are) they will not be permanently magnetised. More like small electromagnets. ANY change in a magnetic field will induce a current in any metal inside the magnetic field, and the faster the change the greater the voltage. An electric fence or sparking coil works merely by an electromagnet with a sudden collapse in the magnetic field causing a nice spark and a nasty jolt, high voltage and low current. A tiny string waving over an alnico will only have a small effect. By far the biggest current effect, however will be induced in the coil, the many turns acting like an amplifier.

I think, you're right, Seth's right, but HE's wrong to discount the other effects too.

We're really chasing our tails here.