Is it possible to accurately describe the tone of magnets and/or pickups?

[J M Fahey]

Sorry, if I made a mistake. I am no longer in contact with the OP.
Who is Jimmy Hoffa?

Sorry, maybe I understood you the wrong way.

FWIW after my detailed Technical reply, the OP also wrote me a personal message, apparently to discuss it item by item.
Since that is useful to nobody and against the Forum spirit (*any* Forum, since by definition all are *open* idea exchange places) I didn´t even *open*, let alone read it, waiting instead for any answer or comment to appear on the main, Public view thread.

As of Jimmy Hoffa, it´s a complex mystery.
Just as starters:
https://edition.cnn.com/2013/06/18/u...ery/index.html

[Chuck H]

The pickup will barely moved at all, no matter how you frame it.

Of course. Not arguing that. Just pointing out that the comparison of mass doesn't complete the picture.

I'm pretty sure the damping ratio is independent of the amplitude,..

Well it actually can't be if pickup movement is even partly responsible. But this has nothing to do with whether you're right about the primary antagonist being eddy currents.

...at least within the range of what a damping system can handle.

But just because something can "handle" a force doesn't make it immune to movement.

A shot gun delivers a force that exceeds the operational range of most systems, such as pumpkins.

I might sig this

[Helmholtz]

Have you been appointed the Forum Press Representative or something?

By whom?

By the way: how do we know that´s what he said?

How do we know he actually wants you to publish his decisions in his name?

The OP is a Forum Member in full standing, and he can post whatever he needs to in these pages.





Oh, by the way, Jimmy Hoffa told me we shouldn´t make such a big fuss, he´ll be back in a few minutes.

Sorry, if I made a mistake. I am no longer in contact with the OP.
Who is Jimmy Hoffa?

[Helmholtz]

Maybe there is an "eddy current break" thing happening, the more I think about it, the more curious I'm becoming about it. It's a weak effect, because spread out over a period of several second, maybe significant. You're knowledgeable in physics and I'm curious what you think about the potential of eddy current breaking working to resist movement of the guitar string.

Thanks for your question.

As I wrote above, from the point of physics I see two possibilities to induce increased string damping by transferring/extracting vibrational energy. One is eddy currents and the other is parasitic PU vibration induced by the varying magnetic field (this could be visualized by a weak stretched rubber band between string and PU). Both effects increase with stronger fields and closer string-PU distance. (The magnetic field by itself cannot produce energy loss/absorb energy. It is purely reactive.)

The eddy currents in alnico are very small as its conductivity is relatively low, at least compared to low carbon steel. This also shows in the high unloaded resonant peaks in strat PUs. There might be some contribution, though. To completely exclude eddy currents would require to use ferrite pole pieces.
I have never read about an "eddy current break", interpreting this as an abrupt increase in eddy currents under certain conditions?(see edit below)

From the above, I still think that parasitic PU vibration might be the dominant loss effect. But without quantitative data this is admittedly speculative. It should be easy for you to verify/falsify in your test jig by mounting the PU very loosely and compare string damping.
Anyway, both damping effects seem to be rather small.

I appreciate your measuring efforts but miss some explanation of scales and data. Which software do you use?


Edit: Sorry, did you mean the eddy current "brake" effect? (had to look up this term in my dictionary, the german word is "Wirbelstrombremse") That's exactly what I meant by eddy current string damping: The eddy currents close to the strings produce a string motion-braking counter-field. The strongest contender for this would be the Alumitone as it's principle is based on eddy currents.
Theoretically there is a very weak third effect, that might induce string damping. This is the tiny counter-field produced by the signal current in the PU. It will increase with lower load resistance.

[J M Fahey]

Of course!

Would you have preferred me not sharing this information?

Have you been appointed the Forum Press Representative or something?

By whom?

By the way: how do we know that´s what he said?

How do we know he actually wants you to publish his decisions in his name?

The OP is a Forum Member in full standing, and he can post whatever he needs to in these pages.





Oh, by the way, Jimmy Hoffa told me we shouldn´t make such a big fuss, he´ll be back in a few minutes.

[Helmholtz]

Do I see a contradiction here?

or:

if the OP feels he has something to say, he is warmly invited to do so ... all by himself

Of course!

Would you have preferred me not sharing this information?

[J M Fahey]

The OP has informed me that he " decided to discontinue posts and other discussions about this topic".

- Own Opinions Only -

Do I see a contradiction here?

or:

if the OP feels he has something to say, he is warmly invited to do so ... all by himself

[Antigua]

Yes, but the additional energy loss required for a little more string damping is also very, very small.
The vibrational energy of a body is proportional to its mass times the oscillation amplitude squared for a given frequency. This means the higher the mass, the lower the amplitude for the same energy content. Consequently the vibration of the PU will be hardly noticeable without special equipment (e.g. a laser-vibrometer). Also the PU will transfer/lose energy to connected parts (springs, pickguard etc.) further reducing its vibration amplitude.

Apart from that, where else could the energy loss go, if there is actually a damping effect caused by strong magnets?

Maybe there is an "eddy current break" thing happening, the more I think about it, the more curious I'm becoming about it. It's a weak effect, because spread out over a period of several second, maybe significant. You're knowledgeable in physics and I'm curious what you think about the potential of eddy current breaking working to resist movement of the guitar string.

[Antigua]

The OP has informed me that he " decided to discontinue posts and other discussions about this topic".

That doesn't mean the topic isn't still of interest to others.

[Helmholtz]

The OP has informed me that he " decided to discontinue posts and other discussions about this topic".

[Antigua]

I keep seeing this mentioned, BUT...

The pickups mass being greater than the string is only significant if they are left to their own inertia. The string is at considerable tension and YOU pluck the string to disturb that tension. How far would a pickup move if you plucked it?

The pickup will barely moved at all, no matter how you frame it.

My finding, which can be seen in the screen shot I posted a few posts back, and this is something that anyone with a Strat can try for themselves, is if you put the neck pickup so close to the strings that "Stratitus" sets in, the relative amplitude drops off more quickly than when the pickup is set lower. So it appears to me it's not a question of if it happens, it's a question of why, and the idea that the pickup itself servers as a damping agent seems very far fetched, due to the pickup's relative immobility. Not only is the pickup many times heavier than the strings, but it's attached to a guitar, which is many times heavier than the pickup.

Eddy currents are a more plausible cause of damping, and that's the same principle on which eddy current breaks work with trains and power tools (here's a demo https://www.youtube.com/watch?v=mopfuVfeIhc ) There again, the degree of coupling between the string and pickup is very low compared to an actual eddy current break, but maybe it's just strong enough to dampen the string movement over a long duration of time.

My point is that the vibrating strings lower mass is considerably countered by energy. Consider that a 12 ga. bird shot load weighs a lot less than a pumpkin and perhaps reconsider the equation

I'm pretty sure the damping ratio is independent of the amplitude, at least within the range of what a damping system can handle. A shot gun delivers a force that exceeds the operational range of most systems, such as pumpkins.

[nosaj]

I keep seeing this mentioned, BUT...

The pickups mass being greater than the string is only significant if they are left to their own inertia. The string is at considerable tension and YOU pluck the string to disturb that tension. How far would a pickup move if you plucked it? My point is that the vibrating strings lower mass is considerably countered by energy. Consider that a 12 ga. bird shot load weighs a lot less than a pumpkin and perhaps reconsider the equation

I like your backwoods analogy. there chuck like a comet pinging the earth or maybe a meteorite. Which some should be in view this evening.

nosaj

[Chuck H]

But the mechanical coupling between the pickup and string is very, very low, and the pickup's mass is many times greater than that of the strings, so the degree to with the pickup could reduce the sustain through that mechanism is very, very, very small.

I keep seeing this mentioned, BUT...

The pickups mass being greater than the string is only significant if they are left to their own inertia. The string is at considerable tension and YOU pluck the string to disturb that tension. How far would a pickup move if you plucked it? My point is that the vibrating strings lower mass is considerably countered by energy. Consider that a 12 ga. bird shot load weighs a lot less than a pumpkin and perhaps reconsider the equation

EDIT: I guess for the "physics" guys I should have said "the vibrating strings lower mass is considerably countered by velocity." Resulting in the significant energy needed to impact the circumstances. Past experience has taught me that I'd better correct this here before I get flamed as a matter of semantics

[Helmholtz]

..so the degree to with the pickup could reduce the sustain through that mechanism is very, very, very small.

Yes, but the additional energy loss required for a little more string damping is also very, very small.
The vibrational energy of a body is proportional to its mass times the oscillation amplitude squared for a given frequency. This means the higher the mass, the lower the amplitude for the same energy content. Consequently the vibration of the PU will be hardly noticeable without special equipment (e.g. a laser-vibrometer). Also the PU will transfer/lose energy to connected parts (springs, pickguard etc.) further reducing its vibration amplitude.

Apart from that, where else could the energy loss go, if there is actually a damping effect caused by strong magnets?

[Antigua]

Of course the pickup moves due to string vibration pushing on the pickup magnets. And of course it's a very small amount of movement. But small isn't none. At guitar amp gain levels I'll bet the affect isn't insignificant.

You're suggesting that the pickup movement might create an overtone addition to what is there otherwise. First, I don't see a credible claim that it leads to an overtone, I only see a credible claim that it could cause a reduction in sustain, because the moving pickup would serve as a damper; the rubber or string mounts that allow the pickup to move up and down slightly would be the agent of damping. But the mechanical coupling between the pickup and string is very, very low, and the pickup's mass is many times greater than that of the strings, so the degree to with the pickup could reduce the sustain through that mechanism is very, very, very small.

Even if there was an overtone that the amplifier could bring to prominence through gain, it would be drowned out by everything that is of much higher amplitude. Imagine you have an audio recording of a crowd talking, with some faint voices in the background and some loud voices up front. What you're suggesting is that if you just cranked up the gain on this audio, you'd be able to clearly hear what the faint voices in the background were saying, but we all know that's not what ends up happening.