Rick's 38ga 1000wind bucker challenge

[Rick Turner]

Once again, you're missing the point entirely. I want to know what the pickup is doing first, and then we might be able to predict it's effect on a preamp or amp. The idea of only using "real world" distorted data is like trying to scan the heavens with the Hubble telescope before they figured out the correction algorithms.

First comes the pickup...then comes the effect of the pickup on the amp. You're never going to know what causes the effect if you don't back up and eliminate some of the distorted data. You're all about coil response totally mixed up with magnet effect. You've got to isolate one or the other to get a real handle on what's going on.

If you take the time to analyze what the pickup is actually doing...with different magnets instead of "X" number of turns of "Y" wire, you might gain a lot more control over your results. But if all you want to do is sell the mojo of attempting to reproduce some magic Parsons St. bygone day, then you'd doing fine the way you are.

I happen to think you're staying deliberately blind to what could be some very interesting information...stuff they just didn't know about in 1958. I hope to have the time to delve into more of this post-NAMM.

Here's a question you might ask yourself, and it's kind of been suggested here. What if you deliberately charged an Alnico 5 magnet to the same strength as an Anico 2? Would they sound the same? What if you put in a weak ceramic with the same total gauss? Same? Different? Remove the coil filter from the test and make it a low Z. Same sound among all equally charged magnets? Different? These are the kinds of questions that will come up in a scientific inquiry, and that's exactly what I propose here. This is below the level of cranked and distorted, though it all will have an incredible effect on how amps overload.

[ScottA]

Here's a question you might ask yourself, and it's kind of been suggested here. What if you deliberately charged an Alnico 5 magnet to the same strength as an Anico 2? Would they sound the same?

This one can already be answered based on measurements of the pickup itself (at least in the case of AlNiCo as the pole piece, and the same response could probably be extrapolated to the PAF case but the effect would be far less dramatic):

No, they won't sound the same since the inductance and frequency response will be significantly different. The AlNiCo 2 will sound "fatter", for lack of a better term.

Not to minimize the value of what Rick is proposing, but to highlight the complementary ability of AC electrical and frequency dependent measurements to capture these kinds of material dependent effects.

[JGundry]

Okay Rick I don't think you are getting my point either but so be it.

I can tell you that unoriented A5 and and A2 sounds different in a PAF style pickup and they both have similar gauss and coercive force levels. Yes it is a PAF but I have done these magnet swap tests so many times that there is no questions that just different makes of any given Alnico grade sound different at the same gauss level. This is because all magnet makers have their own variation of an A5, A2.... metal mix.

But if anyone is doing this low Z test and wants me to send them an unoriented A5 magnet let me know. The unoriented A5 I have is USA made and was very hard to get. I didn't think it would be hard to do but apparently there was some catch. One Chinese maker sent me some unoriented A5 samples that could not be charged. They could never get it to work for some unknown reason. I don't want to sell these but if one or two people are doing this test and want a pair let me know. That includes you Rick.

[salvarsan]

Electronic_Transducers_for_Musical_Instruments glosses the aspects of pickup design which affect their sound. In short, everything affects the sound in this guy's opinion, but he takes the time to explain it in more detail.

Page 27 is where it gets interesting.

A few quotes:

3.) The lumped inductance, L of an electric guitar pickup is due to both the self-inductance of the pickup coil itself, multiplicatively enhanced by the magnetic permeability (μ) of all of the magnetic materials used in the pickup – i.e. the permanent magnets and e.g. any magnetically permeable soft iron pole pieces and/or “booster” plates, etc. used in the construction of the pickup.

The sonic properties of pickup also depends on how “fully charged” the permanent magnets are, because all permanent magnets, as well as magnetically permeable materials such as soft iron pole pieces, copper or zinc-coated mild-steel booster plates, etc. also have non-negligible/non-trivial, frequency and signal amplitude-dependent power dissipation (i.e. power losses) associated with them.

Non-magnetic metal pickup shielding covers (if used) as well as e.g. copper or zinc-plated mild steel booster plates and use of metal pickup frames also have sonic impact on the pickup output – due to a.) frequency-dependent induced eddy currents (also buck change in magnetic flux) and b.) increased pickup capacitance.

[Mike Sulzer]

Electronic_Transducers_for_Musical_Instruments glosses the aspects of pickup design which affect their sound. In short, everything affects the sound in this guy's opinion, but he takes the time to explain it in more detail.

Page 27 is where it gets interesting.

A few quotes:

Professor Errede's work has been discussed in this forum before. Some comments on the passages you quoted:

Effects of magnets on inductance: The permeability of steel is higher than that of alnico. A magnetic material inside the coil has more effect on the inductance than a material outside of it. In a humbucker, the steel is inside the coil, the alnico magnet is outside, and not well-coupled to the steel. One expects the direct effect of the magnet on the inductance to be small. There is a possible indirect effect where the magnetic field alters the permeability of the steel by moving it along its B-H curve, but this effect is also expected to be small since the field is not that strong. Measurements show very little change in inductance from removing the magnet. Single coils with the magnet inside and no steel are another matter.

About "The sonic properties....": For the dissipation in the things he mentions to change possibly significantly due to changes in the strength of the magnet one would have to move their magnetic states well along their B-H curves. This does not happen in the steel cores of a humbucker, and it seems unlikely that other parts are affected more strongly. But there might be some exceptions, and I suppose one has to measure it all to find out what is really going on.

[Joe Gwinn]

Electronic_Transducers_for_Musical_Instruments glosses the aspects of pickup design which affect their sound. In short, everything affects the sound in this guy's opinion, but he takes the time to explain it in more detail.

Page 27 is where it gets interesting.

The sonic properties of pickup also depends on how “fully charged” the permanent magnets are, because all permanent magnets, as well as magnetically permeable materials such as soft iron pole pieces, copper or zinc-coated mild-steel booster plates, etc. also have non-negligible/non-trivial, frequency and signal amplitude-dependent power dissipation (i.e. power losses) associated with them.

This sounds like a description of hysteresis loss in the bulk alnico material, which will very much depend on the level of magnetic saturation of the alnico sample being tested, as well as the frequency and amplitude of the test signal.

Hysteresis loss energy is incurred per cycle of the magnetic field, and so loss power is proportional to frequency.

Amplitude of the magnetic field cycle also matters - the larger the cycle the larger the energy loss per cycle.

Hysteresis - Wikipedia, the free encyclopedia

Hysteresis loss is the basis of the magnetic brake in the Tanac "Meteor" magnetic tensioners discussed recently and described in US patent 4,526,329.

[cbs]

This is a little off topic, but I've always wondered about the heavy treble emphasis in tube guitar pre-amps (through use of cathode by pass caps). Seems that the treble emphasis is used to counter balance the falling (hi) freq response of the high impedance pickups. Would a low impedance pickup (600 ohm) into a flat frequency response tube amp yield a more acoustic like dynamic response and phase coherent timbre?

[David Schwab]

I'm not testing amps, I'm testing pickups just like other musicians do, with an amp.

So, if you plugged into a really crappy sounding amp, like one of those old Fender solid state amps CBS introduced, does that mean your pickups sound crappy too? because they will. Likewise if you plug into a very nice sounding amp, everything tends to sound good.

So it's not a good test to see what the pickup sounds like, however, you do want to hear the pickup in various environments that it might be used in, like through an over driven amp.

Now as far as what other musicians do; I'm a musician. I've been playing guitar since 1969. Some people here have been playing longer. The first thing I listen to on a guitar is the clean tone. And these days that is DI with no effects. If I don't care for the tone of the pickups direct and flat, I wont like them through an amp either. And that's from my experience in listening to guitars for the last 41 years. For me I want something that's versatile, not a one trick pony. A lot of these new PAFs and such seem to be going to a preset tone. They are often too warm sounding, based on people's misconceptions of what a PAF sounds like.

I'd rather hear a clear sounding pickup with a nice balance of lows and highs and mids. Then I can make it sound the way I want through an amp. I think that's why Strats had become more popular than Les Pauls for a long time. They were brighter and had less mids than humbuckers, so you could shape them into the tone you wanted.

[JGundry]

I'm a musician too. I guess if you count Suzuki lessons I have been playing a stringed instrument since I was 4, that would be since 1971. Guitar since 1980. I have a blues band and play mostly clean. I got to have great cleans. It is just that some pickups sound great clean but don't sound as good on the edge of distortion. Some sound great both ways. I like those.

In fact here I am playing with a dirtier tone than usual. Hard to keep a Princeton Reverb clean with a Les Paul. I know we suck and I look like a bobble head but we are having fun. I'm playing the guitar here. I wrote the song also so no covering it without paying the royalties please. This is so exciting. This thread might bump the views for this above 300!!

[Steve Conner]

This is a little off topic, but I've always wondered about the heavy treble emphasis in tube guitar pre-amps (through use of cathode by pass caps). Seems that the treble emphasis is used to counter balance the falling (hi) freq response of the high impedance pickups. Would a low impedance pickup (600 ohm) into a flat frequency response tube amp yield a more acoustic like dynamic response and phase coherent timbre?

Yes, it would! You're absolutely right. But would it sell?

[Mike Sulzer]

Amplitude of the magnetic field cycle also matters - the larger the cycle the larger the energy loss per cycle.

Hysteresis loss is the basis of the magnetic brake in the Tanac "Meteor" magnetic tensioners discussed recently and described in US patent 4,526,329.

Exactly. To get a substantial loss you need to move far enough so that there is movement around a loop, not just nearly along a line. In practice, this means moving the material in and out of states at least approaching saturation in one or both directions. The guitar signal does not do that because the signal is too small. The good professor surely knows that, and so I think he was talking about the different states that a material is in when biased by different strengths of field. But I am not sure where the different loss comes from in that case. What he means is not clear.

A more everyday application of hysteresis loss, if I am not mistaken, is induction heating cook tops such as the one I got for Xmas. It only works with ferromagnetic pots and pans, kettles, etc., and can boil a tea kettle full of water in a short time without putting much heat into anything but the kettle. Thus it is very efficient and safe.

[Mike Sulzer]

A more everyday application of hysteresis loss, if I am not mistaken, is induction heating cook tops such as the one I got for Xmas. It only works with ferromagnetic pots and pans...

Induction cooker - Wikipedia, the free encyclopedia explains that only about 10% of the heating is due to hysteresis loss, most being due to eddy current loss. Why only ferromagnetic pans and pots? It is a matter of impedance matching. Copper and aluminum are way too low in resistance; even steel is too low unless the pan is very, very thin, except for the effect of the permeability on the skin depth. This forces the current to flow in a much thinner layer of steel than it would otherwise, increasing the resistance and making a good impedance match to the coil in the cooker. (Also it means that the thickness of the pan has little effect on how well it heats.)

Permeability-controlled skin depth has an application to pickups. In steel core humbuckers, if the skin depth of the steel cores were due to the resistance alone, the output would be shorted out over much of the frequency range. The decrease in skin depth due to the permeability of the steel increases the effective resistance, allowing the pickup to function, but leaving some influence on the tone.

[Joe Gwinn]

Exactly. To get a substantial loss you need to move far enough so that there is movement around a loop, not just nearly along a line. In practice, this means moving the material in and out of states at least approaching saturation in one or both directions. The guitar signal does not do that because the signal is too small. The good professor surely knows that, and so I think he was talking about the different states that a material is in when biased by different strengths of field. But I am not sure where the different loss comes from in that case. What he means is not clear.

I think that the good professor probably did understand that this is a sub-saturation hysteresis effect, but didn't want to overload the audience. While the maximum loss occurs when one is switching between opposite saturation flux levels, there is significant loss at less than saturation. The Meteor winder modulates the flux level (by moving magnets closer or farther from the hysteresis disk) to modulate the drag on the wire.

The Wikipedia article also shows the effect in figure 2 - the hysteresis loop has finite area, even though it is at the center of the B-H curve.

On rereading the recent part of the thread, I see that I used the word "saturation" in both of its common meanings: the current flux level, which may vary; or the maximum possible flux level in the material.

[Mike Sulzer]

The Wikipedia article also shows the effect in figure 2 - the hysteresis loop has finite area, even though it is at the center of the B-H curve.

True, but even the weakest case is still a pretty strong field, and the applied field varies sinusoidally, not what we are doing in a pickup. We apply a field, moving to a point in the B-H plane. Then we apply a small ac perturbation. I think that the loop is pretty flat in this case.

[cbs]

Is hysterisis slew rate?

For what it's worth, here's my theory.
Magnetic fields 'move' when effected by a ferrous material, right? A pickups magnetic field is vibrated by the string, the magentic field then moves/vibrates across the winding to induce current/signal.

Perhaps the softer magnetic fields require more time to re-establish the shape of the un-disturbed field, in essence the mag field strength has a slew rate and a finite memory. Properties that are time dependent are by definition properties of frequency and slew rate is proportional to frequency responce.

A pickup with a low slew rate magnetic field would act like this; the event (string movement) would move the field but it would be slow to spring back, i.e. reduced high frequency responce and the first event (string) would distort the mag field so that following events would have reduce affect on the field. i.e. less string seperation.

P.S. Maybe an alternative approach is testing pickups with an electromagnet, same core (inductance) at varing field strengths, and different cores (inductances) with same fiels strength.