Seymour Duncan Little '59, Analysis and Review

[antigua]

www.seymourduncan.com/pickup/little-59-strat-set

Current version

First version (with one row of swapped out gold screws):




This set it one of Seymour Duncan't "little" single coil sized alternative to their full sized humbuckers. This set it supposed to be a little version of the full size '59 model.

Sometime in the '00's Seymour Duncan switched from a traditional fiber base (like DiMarzio or Barden) to the PCB style mounting and full plastic enclosure. Seymour Duncan had provided some sort of proof on their website, in the form of FFT analysis, that this new construction didn't impact the tone of their product. I also have a "first generation" Little 59  bridge pickup which I have measurements for below. It appears that the newer '59 bridge is wound a bit hotter than the older model.



Seymour Duncan Little '59 Bridge
- DC Resistance: 12.18K ohms
- Measured L: 8.305H
- Split DC Resistance: 6.09K ohms
- Split Measured L: 3.065
- Calculated C: 307pF (317 - 10)
- Gauss: 600G

unloaded: dV: 7.0dB f: 3.10kHz (black)
loaded (200k & 470pF): dV: 1.7dB f: 1.69kHz (red)
split unloaded: dV: 8.0dB f: 3.17kHz (green)
split loaded (200k & 470pF): dV: 4.6dB f: 2.50kHz (gray)




Seymour Duncan Little '59 Neck
- DC Resistance: 9.82K ohms
- Measured L: 5.567H
- Split DC Resistance: 4.9K ohms
- Split Measured L: 2.094H
- Calculated C: 333pF (343 - 10)
- Gauss: 600G

unloaded: dV: 6.7dB f: 3.64kHz (black)
loaded (200k & 470pF): dV: 2.6dB f: 2.13kHz (red)
split unloaded: dV: 7.4dB f: 3.76kHz (green)
split loaded (200k & 470pF): dV: 5.0dB f: 2.93kHz (gray)







Seymour Duncan Little '59 Bridge, First Generation, circa 2000
- DC Resistance: 11.80K ohms
- Measured L: 7.622H
- Split DC Resistance: 5.9K ohms
- Split Measured L: 2.854
- Calculated C: 248 (258 - 10)
- Gauss: 600G

unloaded: dV: 6.7dB f: 3.59kHz (black)
loaded (200k & 470pF): dV: 2.0dB f: 1.88kHz (red)


Bode plot comparing new and old style Little '59 bridge:



It can be seen that the first generation has a slightly higher resonant peak due to a lower inductance and capacitance. Unfortunately, I don't have a gen 1 neck, but it should be noted that the second gen has a higher DC resistance than the first, and that corresponds to the higher inductance, so, should the gen 1 neck have the same DC resistance as the gen 2 neck, I'd expect that they would perform identically. 










The obvious questions are 1) how does the Little '59 perform compared to a full sized '59, and 2) how much of a difference does the smaller size make? And then bonus question 3) is the split mode passable as a single coil?



Question 1, how does it compare electrically to a full sized humbucker? stratotarts had analyzed a '59 neck guitarnuts2.proboards.com/thread/7815/sd-sh-model-quick-test , and showed that it had a loaded peak of 2.99kHz and a peak dB of 2.4dB. In the Little '59 neck here we have 2.13kHz, that's a drop of nearly 1kHz relative to a full size '59. The dB rise of the Little '59 is very close though, at 2.6dB.

I don't have specs for a '59 bridge model, but similar pickups such as the Seth Lover bridge has a loaded peak of 2.6kHz, and the Pearly Gates bridge a peak of 2.5kHz. The Little '59 bridge has a loaded peak of 1.69kHz, again far below a typical PAF bridge.

The question becomes this: why must the resonant peak of a single coil sized humbucker be so much lower in order to get a pickup maker to feel that it approximates the sound of a full sized humbucker? I for one have no idea, but that brings us to:




Question 2, how does the smaller size effect the tone? The difference in width has two effects, but both ultimately result in different proportions of harmonic content being heard from the guitar. The first effect is that a wider pickup will see more harmonics, because it physically spans more nodes avoids placement directly below an anti-node. For this reason, a wider pickup tends to sound more harmonically rich. The second effect is comb filtering, which is where the physical width of a harmonic oscillation is roughly divisible by the width of the pickup, so that for each "up swing" of the harmonic, there is an equal corresponding "down swing" of that same harmonic, causing a net cancellation of the harmonic. J Donald Tillman created a "calculator" to quickly plot out the expected response of a pickup based on width an position www.till.com/articles/PickupResponseDemo/index.html. Going by the rough widths and position of the Little 59' and a full sized '59 neck we get..

Little '59 neck position



Full sized '59 neck position


Most of the audible action will happen below the resonant peak of the pickup, and in general you'd never hear much beyond 5kHz come out of a guitar speaker. There doesn't appear to be much of a difference with the estimated harmonic response of the Little and full sized '59 below 5kHz, and especially not below 3kHz.

But let's try the bridge position:

Little '59 bridge position



Full sized '59 bridge position


Now it appears that the Little '59 has a sizable amount of harmonic amplitude beyond 2kHz, while it appears that the filtering of the full sized '59 causes a real dip in amplitude.

This could possibly be the reason a Little '59 bridge would need to have a lower resonant peak than a full sized '59' in order to sound similar. The smaller size of the Little '59 appears to boost the treble, so the loaded resonant peak of 1.7kHz, instead of ~2.6kHz like a full sized '59, might serve to cut down on that treble, and make the pickup more bass heavy.

The problem this presents in terms of having the Little and full sized '59 sound alike, assuming this is what's going on, is that the -12dB/oct drop off past that 1.7kHz resonant peak is a far more aggressive attenuation than harmonic comb filtering. You can see this with your own eyes by looking at the overall slope angle in the bode plots, and then in the Tillman simulations above.

The full sized '59 with a peak of 2.6kHz loaded peak and wide aperture filtering will still allow more treble through than a pickup with 1.7kHz loaded peak width and a narrow aperture. Eliminating the harmonics above 1.7kHz will have the effect of making the pickup have less treble response, and a character that is more thick and chunky, as the pick attack will sound softer, not delivering sharp, transient harmonics you get from pickups with higher resonant peaks. The Little '59's loaded resonant peak of 1.7kHz is more in line with a high output humbucker, like a JB or a Custom.

The neck pickup doesn't look to be as bad off as the bridge, in terms of preserving high end response, but the loaded peak of 2.13kHz is dark for a PAF, much more similar to a typical P-90 peak.

I assume during the R&D process Seymour Duncan would have tried Little '59's with resonant peaks that more closely aligned with full sized PAFs, and concluded that they must not have sounded "PAF" enough, whatever reason might have been




Finally question 3, is the single coil mode passable as a single coil? I personally don't mind using the split mode of the Little '59 , but I've heard some say it sounds a little weak. In the bode plots above, I show a loaded peak of 2.5kHz in the bridge and 2.9kHz for the split neck. These are low peaks, as a typical Strat pickup would usually have a peak closer to 3.8kHz, around 1kHz greater overall. The Q factors are very similar to a typical Strat pickup, though. I wouldn't say the split tone sounds especially dark, though it is darker than a typical Strat pickup. It definitely sounds bright in contrast to the "series" mode. 

The flux density at the pole piece tops is around 600 gauss, which is typical of an AlNiCo 3 Strat pickup, but then again the screws are a lot smaller than an AlNiCo pole piece, so less of that 600 gauss is seen by the guitar string.  

The combination of a lower resonant peak and weak magnetic interaction with the string probably combine to create what is perceived as a wimpy single coil tone. 






Pic:

Underside of a current production:


Inside a current production:   It can be seen that the coil is wrapped in copper shielding, surely increasing the capacitance by a healthy amount.


Underside of the first gen:


Under the cover piece of a first gen. Looking carefully, I see that the 1st gen also had copper foil around the coils.

[ms]

Mar 12, 2017 3:57:16 GMT -5 antigua said:

Question 2, how does the smaller size effect the tone? The difference in width has two effects, but both ultimately result in different proportions of harmonic content being heard from the guitar. The first effect is that a wider pickup will see more harmonics, because it physically spans more nodes. For this reason, a wider pickup tends to sound more harmonically rich. The second effect is comb filtering, which is where the physical width of a harmonic oscillation is roughly divisible by the width of the pickup, so that for each "up swing" of the harmonic, there is an equal corresponding "down swing" of that same harmonic, causing a net cancellation of the harmonic. J Donald Tillman created a "calculator" to quickly plot out the expected response of a pickup based on width an position www.till.com/articles/PickupResponseDemo/index.html. Going by the rough widths and position of the Little 59' and a full sized '59 neck we get..

A pickups does not sample a region of the string equal to its width.  The sampling is confined to an area over the pole piece.  This is the product of two factors. First, the the pole piece magnetizes the string with a signifiant component of B field pointing through the coil only over and close to over it.  Second, the pole piece directs the changing flux from the vibrating string through the coil, and it does it best with the flux originating right over the pole piece.  Since this is the product of two factors, the overall function falls off quickly as the distance from the pole piece increases along the string.

A pole piece is small enough so that its size is not a factor in decreasing audible harmonics for any string.  However, a hum bucker has two sampling areas for each string, one for each coil.  These add coherently, and so there is cancelation when an "up" and a "down" are over the two pole pieces.  In general, there is a function that relates the degree of reduction to the harmonic number, and so it is not just a matter of canceling or not.  The function is a comb filter much like the function for two pickups spaced very closely (which is what it is, after all), with complete attenuation beginning when the wavelength of the harmonic approaches the pole piece width.

Whether this makes a difference is a function of which string.  That is, harmonics of the same number for the high E string are four times higher in frequency than for the low E string.  For a standard hum bucker, it works out that this is audible for the three wound string (barely for D), but very little for the three plain strings.  For these strings, the effects are pretty much outside of the 5KHz window. With the close spacing of the single coil sized hum bucker,  perhaps effects could be heard on the low E string, but is very small for other strings.

Also this: "The first effect is that a wider pickup will see more harmonics, because it physically spans more nodes." makes no sense to me even if a pickup did sample uniformly across its width.  A wider uniform sampling window starts losing response at lower harmonic numbers than a narrow one, meaning that the wider response function results in fewer harmonics..

[antigua]

Mar 12, 2017 8:06:46 GMT -5 ms said:

]A pickups does not sample a region of the string equal to its width.  The sampling is confined to an area over the pole piece.  This is the product of two factors. First, the the pole piece magnetizes the string with a signifiant component of B field pointing through the coil only over and close to over it.  Second, the pole piece directs the changing flux from the vibrating string through the coil, and it does it best with the flux originating right over the pole piece.  Since this is the product of two factors, the overall function falls off quickly as the distance from the pole piece increases along the string.

A pole piece is small enough so that its size is not a factor in decreasing audible harmonics for any string.  However, a hum bucker has two sampling areas for each string, one for each coil.  These add coherently, and so there is cancelation when an "up" and a "down" are over the two pole pieces.  In general, there is a function that relates the degree of reduction to the harmonic number, and so it is not just a matter of canceling or not.  The function is a comb filter much like the function for two pickups spaced very closely (which is what it is, after all), with complete attenuation beginning when the wavelength of the harmonic approaches the pole piece width.

Whether this makes a difference is a function of which string.  That is, harmonics of the same number for the high E string are four times higher in frequency than for the low E string.  For a standard hum bucker, it works out that this is audible for the three wound string (barely for D), but very little for the three plain strings.  For these strings, the effects are pretty much outside of the 5KHz window. With the close spacing of the single coil sized hum bucker,  perhaps effects could be heard on the low E string, but is very small for other strings.

Even Tillman acknowledged that the approximation is difficult to define www.till.com/articles/PickupResponse/index.html "This isn't completely accurate, the pickup sensitivity will be greater in the middle than at the ends, but this makes a fine first approximation.", and by going with the width of the pickup, I've even chose narrower windows than he had: "Figure 10 shows the response of a neck pickup 1.0 inches wide on the low E of a Stratocaster. Figure 11 is the same thing, but the pickup is 2.5 inches wide."

Flux that is off-center of the pole piece does generate voltage, because even flux change that is at an angle to the coil constitutes flux change; it's simply not as much flux, since flux at an angle sees a narrower coil than flux that is directly over the coil. Imagine your visual perspective represents a vector of magnetic flux, and you look straight head at a hula hoop that represents the coil; the hula hoop looks like a big circle, but if you turn it sideways, it becomes a smaller oval from your perspective, but there is still a loop there, just a smaller one. The pole piece will amplify flux that is perfectly head on, or from an imperfect angle, alike.

Just for my own satisfaction, I held a connected single coil over a Stratocaster, and approached the string as it vibrated, and I could hear quite a lot of volume before the pickup was even above the string at all, so I think I might have actually underestimated when I went with the width of the pickups themselves, but I still think 2.5 inches is probably too generous for a humbucker.

Accurately presenting harmonic response isn't really the goal though; just looking for some kind of difference, given consistent methodology, is, and it appears that, for a given methodology, there is not much change in the neck pickup, but there does appear to be a bigger difference with respect to the bridge single coil versus humbucker width.

Mar 12, 2017 8:06:46 GMT -5 ms said:

Also this: "The first effect is that a wider pickup will see more harmonics, because it physically spans more nodes." makes no sense to me even if a pickup did sample uniformly across its width.  A wider uniform sampling window starts losing response at lower harmonic numbers than a narrow one, meaning that the wider response function results in fewer harmonics..

For example, if you place a thin pickup in the neck position:



the plucked open note lands over an anti-node of the 4th harmonic. If that pickup is made to be wider, it won't be completely blind to the fourth harmonic.

A neck humbucker extends towards the bridge, relative to a single coil, so looking at the diagram, you can see that it would pickup a little more of everything shown, aside from the fundamental, as that movement decreases closer to the bridge.

[ms]

Mar 12, 2017 13:11:05 GMT -5 antigua said:

Mar 12, 2017 8:06:46 GMT -5 ms said:

Just for my own satisfaction, I held a connected single coil over a Stratocaster, and approached the string as it vibrated, and I could hear quite a lot of volume before the pickup was even above the string at all, so I think I might have actually underestimated when I went with the width of the pickups themselves, but I still think 2.5 inches is probably too generous for a humbucker.

Accurately presenting harmonic response isn't really the goal though; just looking for some kind of difference, given consistent methodology, is, and it appears that, for a given methodology, there is not much change in the neck pickup, but there does appear to be a bigger difference with respect to the bridge single coil versus humbucker width.


the plucked open note lands over an anti-node of the 4th harmonic. If that pickup is made to be wider, it won't be completely blind to the fourth harmonic.

A neck humbucker extends towards the bridge, relative to a single coil, so looking at the diagram, you can see that it would pickup a little more of everything shown, aside from the fundamental, as that movement decreases closer to the bridge.

When I try your test I get very different results.  The level half a pole piece width from the edge of the pole piece compared to the level at the center is 6 db down. You normally defines the width of a filter as where it is three db down, but I do not have enough precision to make that measurement.  A whole pole piece width away is more than 10 db down, and so it is a rapidly falling function .  This is not an easy measurement; careful plucking is required, and there are significant errors I am sure, but the width of the pickup is not a good indicator of the width of the string it samples.

I do not buy your other argument at all.  Making the sampling region wider in such a way that the center of of the sampling region changes will reduce the amplitude of harmonics other than  the one you are concentrating on, especially higher ones.  The harmonics we are concerned here are the really high ones, on the order of the separation between the two coils of a hum bucker, or even higher, the width of a pole piece.

[ms]

Mar 12, 2017 13:11:05 GMT -5 antigua said:

Even Tillman acknowledged that the approximation is difficult to define www.till.com/articles/PickupResponse/index.html "This isn't completely accurate, the pickup sensitivity will be greater in the middle than at the ends, but this makes a fine first approximation.", and by going with the width of the pickup, I've even chose narrower windows than he had: "Figure 10 shows the response of a neck pickup 1.0 inches wide on the low E of a Stratocaster. Figure 11 is the same thing, but the pickup is 2.5 inches wide."

In the Tilrman article you referred to he makes this statement:

"Pickups do not sense the string at a single point source, but rather over an area due to the width of the magnetic field. This sensing area is called the "aperture" of the pickup and is about an inch wide on a thin single coil pickup and about 2.5 inches wide on a wider pickup such as the Gibson hum bucker."

This is wrong. Tillman has never taken the trouble to understand how this works in theory or even to make decent simple measurements.  I think it is appalling that this statement has remained on the web for so long when it is so clearly wrong.

The one inch sampling width implies the filtering out of picking transients that are present in spectral measurement made right after the string is picked.  Harmonics are present that imply that it is the width of a pole piece that is the limiting factor.

[antigua]

Mar 12, 2017 15:41:17 GMT -5 ms said:

Mar 12, 2017 13:11:05 GMT -5 antigua said:

Just for my own satisfaction, I held a connected single coil over a Stratocaster, and approached the string as it vibrated, and I could hear quite a lot of volume before the pickup was even above the string at all, so I think I might have actually underestimated when I went with the width of the pickups themselves, but I still think 2.5 inches is probably too generous for a humbucker.

Accurately presenting harmonic response isn't really the goal though; just looking for some kind of difference, given consistent methodology, is, and it appears that, for a given methodology, there is not much change in the neck pickup, but there does appear to be a bigger difference with respect to the bridge single coil versus humbucker width.


the plucked open note lands over an anti-node of the 4th harmonic. If that pickup is made to be wider, it won't be completely blind to the fourth harmonic.

A neck humbucker extends towards the bridge, relative to a single coil, so looking at the diagram, you can see that it would pickup a little more of everything shown, aside from the fundamental, as that movement decreases closer to the bridge.

When I try your test I get very different results.  The level half a pole piece width from the edge of the pole piece compared to the level at the center is 6 db down. You normally defines the width of a filter as where it is three db down, but I do not have enough precision to make that measurement.  A whole pole piece width away is more than 10 db down, and so it is a rapidly falling function .  This is not an easy measurement; careful plucking is required, and there are significant errors I am sure, but the width of the pickup is not a good indicator of the width of the string it samples.

If you load this tool Tillman made www.till.com/articles/PickupResponseDemo/index.html and set the pickup width to something very narrow, like 0.2", and 0.6", or even if you enter two separate pickups with a width of 0.2" and place them side by side and call that a humbucker, you still see more variance between sizes near the bridge, where as near the neck position, the variance is smaller and occurring mostly above 5kHz. So any way you look at it, the effect of width is more profound at the bridge position. It makes sense that things become more extreme approaching the terminal ends.

Regarding the test, when I did it, I was plugged into a Fender Deluxe, which seems to have a compressed quality to it. I think it's possible that compression virtually "widens" a pickup, because that -6dB drop would be less than -6dB if subject to signal compression.

Mar 12, 2017 15:41:17 GMT -5 ms said:

I do not buy your other argument at all.  Making the sampling region wider in such a way that the center of of the sampling region changes will reduce the amplitude of harmonics other than  the one you are concentrating on, especially higher ones.  The harmonics we are concerned here are the really high ones, on the order of the separation between the two coils of a hum bucker, or even higher, the width of a pole piece.

I'm not following; the blue colored diagram I posted above shows the neck pickup intersecting the anti node of the 4th harmonic. A thin Strat pickup will land dead center on that 4th anti node, but a wider humbucker will sample some portion of the 4th harmonic, since one of its coils will be off center of the anti-node. 

In a similar respect, a bridge humbucker extends away from the bridge, picking up content that is otherwise out of reach of a single coil bridge pickup. Leo Fender slanted his single coil bridge pickup so that the bass half of the pickup would see more fundamental movement, and generate more bass amplitude.

To my ear, it's apparent hear that a neck humbucker sounds different than a single coil sized pickup, even if the frequency response is otherwise the same, so if doesn't explain it, I feel that something else must.

Mar 12, 2017 17:33:39 GMT -5 ms said:

"Pickups do not sense the string at a single point source, but rather over an area due to the width of the magnetic field. This sensing area is called the "aperture" of the pickup and is about an inch wide on a thin single coil pickup and about 2.5 inches wide on a wider pickup such as the Gibson hum bucker."

This is wrong. Tillman has never taken the trouble to understand how this works in theory or even to make decent simple measurements.  I think it is appalling that this statement has remained on the web for so long when it is so clearly wrong.

The one inch sampling width implies the filtering out of picking transients that are present in spectral measurement made right after the string is picked.  Harmonics are present that imply that it is the width of a pole piece that is the limiting factor.

I agree that it's sort of crude, but Tillman seems to admit it's crude, also. I'll try to devise a test to get a straight answer to this question. Perhaps with an ebow, a pickup, a guitar and a ruler, we can get some good data.

[ms]

Mar 12, 2017 19:51:27 GMT -5 antigua said:

Mar 12, 2017 15:41:17 GMT -5 ms said:

I'm not following; the blue colored diagram I posted above shows the neck pickup intersecting the anti node of the 4th harmonic. A thin Strat pickup will land dead center on that 4th anti node, but a wider humbucker will sample some portion of the 4th harmonic, since one of its coils will be off center of the anti-node. 

In a similar respect, a bridge humbucker extends away from the bridge, picking up content that is otherwise out of reach of a single coil bridge pickup. Leo Fender slanted his single coil bridge pickup so that the bass half of the pickup would see more fundamental movement, and generate more bass amplitude.

To my ear, it's apparent hear that a neck humbucker sounds different than a single coil sized pickup, even if the frequency response is otherwise the same, so if doesn't explain it, I feel that something else must.

This is what you are trying to show: "The first effect is that a wider pickup will see more harmonics, because it physically spans more nodes."
Showing that the fourth harmonic is no longer nulled when you sample it off center does not show that.

[antigua]

Mar 12, 2017 20:44:19 GMT -5 ms said:

Mar 12, 2017 19:51:27 GMT -5 antigua said:

I'm not following; the blue colored diagram I posted above shows the neck pickup intersecting the anti node of the 4th harmonic. A thin Strat pickup will land dead center on that 4th anti node, but a wider humbucker will sample some portion of the 4th harmonic, since one of its coils will be off center of the anti-node. 

In a similar respect, a bridge humbucker extends away from the bridge, picking up content that is otherwise out of reach of a single coil bridge pickup. Leo Fender slanted his single coil bridge pickup so that the bass half of the pickup would see more fundamental movement, and generate more bass amplitude.

To my ear, it's apparent hear that a neck humbucker sounds different than a single coil sized pickup, even if the frequency response is otherwise the same, so if doesn't explain it, I feel that something else must.

This is what you are trying to show: "The first effect is that a wider pickup will see more harmonics, because it physically spans more nodes."
Showing that the fourth harmonic is no longer nulled when you sample it off center does not show that.

Maybe it was a poor choice of word to say "more nodes", but do you disagree that a wider neck humbucker would be seeing more of that 4th harmonic displacement?

[ms]

Mar 13, 2017 0:54:29 GMT -5 antigua said:

Mar 12, 2017 20:44:19 GMT -5 ms said:

This is what you are trying to show: "The first effect is that a wider pickup will see more harmonics, because it physically spans more nodes."
Showing that the fourth harmonic is no longer nulled when you sample it off center does not show that.

Maybe it was a poor choice of word to say "more nodes", but do you disagree that a wider neck humbucker would be seeing more of that 4th harmonic displacement?

No, I do not disagree, as implied by my previous message.

By the way, another indication that small displacements matter is found in this material: Kirk T. McDonald www.physics.princeton.edu/~mcdonald/examples/guitar.pdf. He showed that there is a frequency doubled component in the pickup output from vibration across the pole piece.  This shows that the field varies even for small displacement; it does not apply completely to change in sensitivity along the direction of the string, but it is a pretty good indication since the magnetization from a pole is pretty symmetrical around the axis pole piece.  This work shows that there is some change in sensitivity even for the small distance of the string vibration, and so the fall off should get large quickly as the distance is increased.

[antigua]

Mar 13, 2017 5:07:43 GMT -5 ms said:

Mar 13, 2017 0:54:29 GMT -5 antigua said:

Maybe it was a poor choice of word to say "more nodes", but do you disagree that a wider neck humbucker would be seeing more of that 4th harmonic displacement?

No, I do not disagree, as implied by my previous message.

By the way, another indication that small displacements matter is found in this material: Kirk T. McDonald www.physics.princeton.edu/~mcdonald/examples/guitar.pdf. He showed that there is a frequency doubled component in the pickup output from vibration across the pole piece.  This shows that the field varies even for small displacement; it does not apply completely to change in sensitivity along the direction of the string, but it is a pretty good indication since the magnetization from a pole is pretty symmetrical around the axis pole piece.  This work shows that there is some change in sensitivity even for the small distance of the string vibration, and so the fall off should get large quickly as the distance is increased.

I fixed the wording up, thanks for calling attention to that. 

I don't deny that there's a change in sensitivity over the pole piece, at not point is there a perfect or ideal homogeneous flux field, at least not with a round pole piece, a blade is a different story. I'm not sure that speaks to a particular distance / amplitude ratio though. I'd like to do a practical test, but they're a pain to set up.

[ms]

Mar 13, 2017 11:47:48 GMT -5 antigua said:

Mar 13, 2017 5:07:43 GMT -5 ms said:

No, I do not disagree, as implied by my previous message.

By the way, another indication that small displacements matter is found in this material: Kirk T. McDonald www.physics.princeton.edu/~mcdonald/examples/guitar.pdf. He showed that there is a frequency doubled component in the pickup output from vibration across the pole piece.  This shows that the field varies even for small displacement; it does not apply completely to change in sensitivity along the direction of the string, but it is a pretty good indication since the magnetization from a pole is pretty symmetrical around the axis pole piece.  This work shows that there is some change in sensitivity even for the small distance of the string vibration, and so the fall off should get large quickly as the distance is increased.

I fixed the wording up, thanks for calling attention to that. 

I don't deny that there's a change in sensitivity over the pole piece, at not point is there a perfect or ideal homogeneous flux field, at least not with a round pole piece, a blade is a different story. I'm not sure that speaks to a particular distance / amplitude ratio though. I'd like to do a practical test, but they're a pain to set up.

This is hard to measure with great accuracy.  I am going to start by using an unmagnetized pickup over a pickup in the guitar.  This can be slid along the strings and the output measured.  I am sure you can see some problems with this, so you have to start by  making some measurements that tell you how big the problems are, such as measuring the change in signal from the pickup in the guitar when the unmagnetized pick up is placed over it.  I will just have one pole piece in the unmagnetized pickup; the other holes can be used as sights to help determine the displacement along the string.

[yanyan]

Great stuff as always, antigua! I'm slowly going through all threads in this forum and each new one i read is an exciting discovery for me.

In general, how do individual screw/slug polepieces compare to rails/blades, both in the context of full-sized humbuckers and single coil-sized humbuckers?

Further, how do they compare when the pickups are coil split?

[antigua]

Dec 29, 2019 10:02:24 GMT -5 yanyan said:

Great stuff as always, antigua ! I'm slowly going through all threads in this forum and each new one i read is an exciting discovery for me.

In general, how do individual screw/slug polepieces compare to rails/blades, both in the context of full-sized humbuckers and single coil-sized humbuckers?

Further, how do they compare when the pickups are coil split?

The screws make the magnetic field weaker by replacing permeable steel with air. In technical terms, they increase the magnetic reluctance path, for the sake of aesthetics. 

The blade also reduces second order harmonics, but those harmonics are barely audible to begin with. This happens because pole pieces represent discrete magnetic fields under the guitar string, voltage is produced when the string moves over it side to side, but a blade is a homogeneous magnetic field, side to side, and in order to get a voltage, and if the string is moving across a homogeneous field, per Faraday's Law, you wont get a voltage from string movement along that vector.  Most of the voltage, though, comes from the strings movement towards and away from the pickup, not side to side, so that loss of side to side voltage (which manifests as 2nd order harmonics) is always trivial. That's why blade style pickups don't sound noticeably different from regular pickups. 

As for coil splitting, there's no remarkable difference as compared to splitting a regular humbucker, but IMO the increased magnetic strength of a blade over individual pole pieces is important if you want the split coil to sound more like a Fender AlNiCo pickup, as they have very strong magnetic fields themselves. 

[aquin43]

Referring back to the discussion of humbucker nulls higher up the thread, consider a 24.75 inch scale length and a humbucker having  0.7 inch coil spacing (PAF) and good mirror symmetry about the line between the coils. The wavelength of the fundamental on the string is twice the scale length. Assuming that the first deep null due to dual sampling occurs when the coil spacing spans a whole wavelength, it will be at a harmonic number of 24.75 * 2 / 0.7 = 70.71. Is there evidence that the 70th or 71st harmonic of a real wound guitar string is excited to any significant degree in normal playing?

When I push the bottom string sideways with a sharp edge, I dont see a sharp angle at the contact point. It is more like a smooth curve, implying that very short wavelengths will not be produced to any degree with normal picking.

Arthur

[ms]

Jan 6, 2020 7:40:43 GMT -5 aquin43 said:

Referring back to the discussion of humbucker nulls higher up the thread, consider a 24.75 inch scale length and a humbucker having  0.7 inch coil spacing (PAF) and good mirror symmetry about the line between the coils. The wavelength of the fundamental on the string is twice the scale length. Assuming that the first deep null due to dual sampling occurs when the coil spacing spans a whole wavelength, it will be at a harmonic number of 24.75 * 2 / 0.7 = 70.71. Is there evidence that the 70th or 71st harmonic of a real wound guitar string is excited to any significant degree in normal playing?

When I push the bottom string sideways with a sharp edge, I dont see a sharp angle at the contact point. It is more like a smooth curve, implying that very short wavelengths will not be produced to any degree with normal picking.

Arthur

They are there.  In that other place where they do not like measurements, I posted some results concerning what the spacing of the two humbucker coils does to the spectrum and the sound.  I think that the attachments disappeared long ago.

The interesting question is how these harmonics are generated and why they stick around long enough to be measured and heard.  My guess (total speculation just asking to be shot down!) is that with a wound string these harmonics are generated continuously by the bending of the string as it vibrates.  If true, this would also explain why wound strings sound so different from plain strings

[antigua]

Jan 6, 2020 7:40:43 GMT -5 aquin43 said:

Referring back to the discussion of humbucker nulls higher up the thread, consider a 24.75 inch scale length and a humbucker having  0.7 inch coil spacing (PAF) and good mirror symmetry about the line between the coils. The wavelength of the fundamental on the string is twice the scale length. Assuming that the first deep null due to dual sampling occurs when the coil spacing spans a whole wavelength, it will be at a harmonic number of 24.75 * 2 / 0.7 = 70.71. Is there evidence that the 70th or 71st harmonic of a real wound guitar string is excited to any significant degree in normal playing?

When I push the bottom string sideways with a sharp edge, I dont see a sharp angle at the contact point. It is more like a smooth curve, implying that very short wavelengths will not be produced to any degree with normal picking.

Arthur

This spectrogram is of a plucked D, excited by a needle rather than a guitar pick, so the break angle is about as acute as it can be i.imgur.com/9NZRmh2.jpg , the fundamental is 146Hz, the graph cuts off at 5kHz, the 34th harmonic. Beyond that frequency the output would be heavily attenuated by most guitar pickups anyway, especially a PAF type. I found a harmonic series calculator that permits an arbitrary number of partials www.michaelnorris.info/theory/harmonicseriescalculator , so that harmonics can be correlated to frequencies. 

As for how the string is able to bend sharp enough to even support a high frequency partial, I think the answer is just in the fact that the string doesn't have to bend very much in order to constitute a tiny increment of displacement. The curves in the string can be very shallow, but still produce a significant voltage, because Faraday's Law says you get greater voltages for a higher frequencies. That's probably why the harmonic voltages look so even in the spectrogram as frequency increases, even though the actual physical energy of each partial becomes less as it increases in number.  

It's the stiffness of the string that causes those transient harmonics to be so short lived, though. They decay so rapidly, that they're perceived as being a feature of the pick attack, and not the overall "voice" of the pickup. The "round wound" strings are known to sustain higher harmonics than "flat wound" strings, the rounded winding allows the string to be a lot more flexible, where as a flat wound string is structurally more similar to a plain string. Round wound strings are also physically easier to bend. When you bend the string with a sharp edge, it might be that the break angle of the inner core is also sharp, but that it's visually obscured by the round windings. 

[aquin43]

Yes, the pickup responds to the velocity so an ideal string plucked at a point would produce a triangular displacement wave with the harmonics falling in proportion to frequency but a square velocity wave, with harmonics all at the same level.

I can't see any amplitude calibration for the spectrogram. Is it  dB horizontally and frequency vertically? What is the amplitude scaling?  The harmonic amplitudes above the first few seem far from equal.

Arthur

[antigua]

Jan 6, 2020 16:34:07 GMT -5 aquin43 said:

Yes, the pickup responds to the velocity so an ideal string plucked at a point would produce a triangular displacement wave with the harmonics falling in proportion to frequency but a square velocity wave, with harmonics all at the same level.

I can't see any amplitude calibration for the spectrogram. Is it  dB horizontally and frequency vertically? What is the amplitude scaling?  The harmonic amplitudes above the first few seem far from equal.

Arthur

The amplitude is represented by color, the brighter yellow is higher, darker blue is lower amplitude. The amplitudes are not perfectly equal, but they don't rapidly fall off with each increasing harmonic, as you might expect them to in a physical sense. Why, if not for the Faraday effect, would the 25th up through the 35th harmonic have such similar amplitudes, if they become increasingly smaller in physical size and displacement?

[stratotarts]

The theoretical amplitude of a harmonic of a square wave is 1/n times the amplitude of the fundamental where n is the order of the harmonic. Hope this helps...

[antigua]

Jan 7, 2020 18:25:00 GMT -5 stratotarts said:

The theoretical amplitude of a harmonic of a square wave is 1/n times the amplitude of the fundamental where n is the order of the harmonic. Hope this helps...

Yes, I wasn't sure what the math was, but as you can see from the colors of the harmonics, the color doesn't change at a rate 1/n. The Faraday influence must be causing the magnetic guitar pickup to not appear to honor the 1/n formula, instead giving it a strangely linear appearance. An acoustic guitar probably does, since there is not conversion of velocity to amplitude. 

[dayanddream]

antigua  First off thank you, this was extremely helpful!



I’m interested in putting a Little ’59 in the Bridge of my custom MIM strat.



It already has these DiMarzio pickups:

• Neck: BC-1 (290 output)
  
• Middle: Chopper (260 output)
  
• Bridge: BC-2 (315 output)
  

However, the Bridge PUP is doesn’t have enough treble for my taste. So replacing the BC-2 with a ’59 I think should work in my favor.



Here’s my question: Would you know what the output in mV on the ’59 Bridge PUP is?



DiMarzio provides this info on their site and Customer Support told me this is how they measure it:


“The DCR specs are shown below. Our published output specifications show RMS mV into a 20 Kohm resistive impedance measuring the envelope of all frequencies at 333 milliseconds after initial pick attack on the A string of a particular test guitar with all other strings muted, the string picked medium hard with a mechanical picker that gives repeatable results. Please note there is no direct relationship between output voltage and DC resistance.”


I reached out to Seymour Duncan support, their site shows a vague color scale for output (means nothing to me). Unfortunately, they told me they couldn’t get me that information.

[antigua]

Apr 12, 2020 14:34:19 GMT -5 dayanddream said:

antigua   First off thank you, this was extremely helpful!



I’m interested in putting a Little ’59 in the Bridge of my custom MIM strat.



It already has these DiMarzio pickups:

• Neck: BC-1 (290 output)
  
• Middle: Chopper (260 output)
  
• Bridge: BC-2 (315 output)
  

However, the Bridge PUP is doesn’t have enough treble for my taste. So replacing the BC-2 with a ’59 I think should work in my favor.



Here’s my question: Would you know what the output in mV on the ’59 Bridge PUP is?



DiMarzio provides this info on their site and Customer Support told me this is how they measure it:


“The DCR specs are shown below. Our published output specifications show RMS mV into a 20 Kohm resistive impedance measuring the envelope of all frequencies at 333 milliseconds after initial pick attack on the A string of a particular test guitar with all other strings muted, the string picked medium hard with a mechanical picker that gives repeatable results. Please note there is no direct relationship between output voltage and DC resistance.”


I reached out to Seymour Duncan support, their site shows a vague color scale for output (means nothing to me). Unfortunately, they told me they couldn’t get me that information.

I own the BC pickups also, but I've never measured them because they're in a guitar and I've been dragging my feet about taking it apart. I've analysed the Chopper though www.strat-talk.com/threads/dimarzio-chopper-analysis-review.501107/  

If you want brightness, the inductance ought to be compared, the Little 59 is 8.3H bridge and 5.5H neck. The Chopper is 5.9H, which puts it very close to the '59 neck pickup. I dont have values for the BC 1 or 2, but they're more than likely closer to 8 henries. I don't think the 59 bridge model will get you what you want, but another Chopper or 59 neck model might. 

DiMarzio's output voltage ratings are of little value. Raising and lowering the pickups will increase or decrease the output voltage also, and I notice that in the description they provided you they didnt even mention pickup height. Having done mechanical pluck testing myself, I can tell you that it's very difficult to get consistent results, and so Im very disinclined to believe these claims unless there is an extraordinary amount of disclosure, of which there is not in this case.