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

[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]

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 thatīs 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 shouldnīt make such a big fuss, heīll be back in a few minutes.

[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.

[Helmholtz]

Have you been appointed the Forum Press Representative or something?

By whom?

By the way: how do we know thatīs 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 shouldnīt make such a big fuss, heīll 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?

[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

[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 didnīt 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, itīs a complex mystery.
Just as starters:
https://edition.cnn.com/2013/06/18/u...ery/index.html

[ken]

Actually, the OP's idea was a good one - to discuss *basic* differences in parts and finished pickups measurably, clearly, and distinctly. That could be useful to people like us, who need to make decisions on what parts to use in a certain product. IMO it's sorta like a cook trying to decide whether to use mild chile peppers or ghost peppers in his salsa and how much of either - the wrong amount could be a major disaster. If everybody would discuss their products in ads the OP's way, it would be a lot easier to give a customer exactly what kind of sound he or she wants to make.

The only problem is when the marketeers and engineers take over, and this entire idea flies out the window. You know... 'this pickup is potted in wax from South American killer bees for a real killer tone' or 'this pickup was wound on a machine that was buried in a time machine in Kalamazoo in 1955 right after it was used to wind the original pickups in Scotty Moore's goldtop he played with Elvis'. Or 'this pickup has a .0001db bump at 1Khz played in a 1951 Tele using 10-52 strings at 70F with 62% humidity, the player was drinking Budweiser beer and eating beans while recording this... and dont even go there about the amp'.

If your pickup sounds good, it is good. You can set quality and performance differences easily enough, and you should, but obsessing about the fifth or sixth significant digit of a measurement can be counterproductive.

Rant over

Ken

[ken]

Some believe Hoffa was buried in a highway onramp somewhere, some believe he's part of a major league ball diamond, others believe he was made into canned dogfood or hot dogs.

Hard to say what happened to him.

[Enzo]

They pretty much gave up on the end zone at Giants Stadium. Here in Michigan, every couple years someone decides they have evidence and they dig up some poor sap's barn. The last place he was known to be was the Machus Red Fox on Telegraph, but even that is now gone.

[David King]

Won't the impedance of the circuit that the pickup is attached to affect the string's sustain. A dead short in the coil would quickly stop the string due to eddy currents in the coil, I'm not sure if a 50k ohm load would have any effect but what if you turn the volume way down to where most of the signal is shunted to ground?.

[Mike Sulzer]

I think that a magnet can cause additional damping, although I have no proof. The mechanism would be through increased string bending. Does bending cause energy loss? Of course: this is part of why higher harmonics decay faster than lower harmonics; there is more bending for given amplitude of vibration. I think that the additional bending results mostly from the two different vibrational rates you mentioned. This is speculative, but I do not think that it is right to dismiss the possibility of magnet induced damping with a simple physical explanation.

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.

[Mike Sulzer]

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.

I do not understand this. I think that the Alumitone is just a single turn pickup with a very high step up ratio.

[Mike Sulzer]

The string is under tension so that it resonates a a set of frequencies; that is, it moves easily at those frequencies. The pickup moves very little because art is heavy and fastened to the guitar.

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]

I think that a magnet can cause additional damping, although I have no proof. The mechanism would be through increased string bending. Does bending cause energy loss? Of course: this is part of why higher harmonics decay faster than lower harmonics; there is more bending for given amplitude of vibration. I think that the additional bending results mostly from the two different vibrational rates you mentioned.

Yes, string bending involved in the vibration means material deformation. Though mostly elastic (non-dissipative), there is also has a lossy component in non-ideal materials. As higher harmonics bend the strings at a higher rate, they lose energy faster.
I just don't see neither a higher bending rate nor a higher bending amplitude in the presence of a magnetic force. The field just minimally shifts the equilibrium or rest position of the string in the plane perpendicular to the fingerboard.

The slightly different frequencies of up-and-down vs. sideways vibration caused by a strong magnetic field produce a beating effect as seen in the waviness of the signal decay. A local minimum in the decay means that the energy content in the up-and down vibration has momentarily decreased while the energy in the horizontal motion has correspondingly increased. This energy exchange repeats at the beat frequency. I can't think of a reason for increased losses produced in the energy exchange between the two vibrational modes. If the amplitude (and thus the bending) of one mode increases, the amplitude of the other one decreases.

Did I adress what you meant?

[Chuck H]

The string is under tension so that it resonates a a set of frequencies; that is, it moves easily at those frequencies. The pickup moves very little because art is heavy and fastened to the guitar.

Yesser. I actually DO get that. But pickup mounting systems aren't all THAT secure really. Surely there is SOME movement. I admit I never thought about it before Helmholtz mentioned it. I just don't think it makes sense to ignore it. After all, we do strive for that extra five percent on this forum. If all we wanted to do was play our guitars we could ignore a lot of what's discussed here.