Differences between AlNiCo and ceramic/steel Strat pickups
Sept 25, 2016 2:11:34 GMT -5
atherisinnovations likes this
Post by antigua on Sept 25, 2016 2:11:34 GMT -5
A common question in these forums is "is it worth spending money on new pickups for my Squier / MIM Fender???" It wouldn't surprise me if this is the question that fuels much of the aftermarket pickup industry. The Short Answer - Yes
The Medium Lengthed Answer - Ceramic single coil pickups lack in high end response, with a bandwidth that is well over 1kHz narrower that of AlNiCo single coil pickups. A lot of players buy Strats for the "quack", and you need high end response in order to get that "quack" (or "twang" in the case of a Tele).
To illustrate this point in exact detail, I've selected four pickups: two AlNiCo and two ceramic. The are, as pictured:
An AlNiCo Lollar Blackface Neck | A Ceramic Fender Mexico
An AlNiCo Fender Mexico Strat pickup | A Ceramic Fender Japan
Note that I have included a highly regarded boutique Lollar Blackface AlNiCo neck pickup, and a lowly Fender Mexico AlNiCo pickup, complete with plastic bobbin, to show that you won't need to spend a lot of money when you buy an AlNiCo single coil to replace you stock ceramic pickups. The Lollar is also a "hand wound" pickup, where as the three Fenders are fully machine wound.
The bandwidths of these pickups can be easily seen in bode plots. The first bode plot shows the pickups measured "as is":
Looking at the graph above, the two defined mountains (high Q) are the two AlNiCo pickups, and the two stubby hills (low Q) that nearly overlap are the ceramic pickups.
When you hook the pickups up to your guitar, and then plug in a guitar cable, a large amount of parallel resistance and capacitance is added to the pickups, and this is infact the context in which we're used to hearing pickups. With an added 200k resistance and 470pF capacitance, this plot comes out like this:
In this plot, the AlNiCo pickups are, again, the two taller peaks, and this time they overlap, which just goes to show what a great equalizer a guitar cable can be, and the two lumps are the ceramic pickups.
The key detail in both plots is that the AlNiCo pickups both a) extend farther into the treble range, peaking near 4,000 Hz, and b) produce more voltage at that peak (due to the high Q factor), relative to the baseline voltage, where as the ceramic pickups peak out at about 2,900 Hz, and produce a lot less voltage at that peak (due to the low Q factor), relative to their base line voltage. That is over 1,000 Hz, or roughly 33% of, additional harmonic content you get with those AlNiCo pickups that you won't hear with stock ceramic pickups.
This overall pattern will hold for 95% of the AlNiCo and ceramic pickup on the market.
Again, you do not need an expensive boutique AlNiCo pickup to get these benefits, as even the Fender Mexico AlNiCo exhibits the same positive benefits of expanded bandwidth and a higher Q factor.
- - ----===----=--=---=------- - - - -
The Long Answer - The reason why ceramic pickups ditch over 1kHz of high end response is not actually because of the ceramic magnet, it's entirely due to the the steel slugs. The steel slugs have a very high permeability and conductivity compared to the AlNiCo. Those two factor cause the inductance to almost double, and it is that doubling of inductance that causes the resonant peak to drop so far.
The higher inductance caused by the slugs is also the reason why, in the plots above, the ceramic pickup's voltage plot lines are 5 decibels higher than the AlNiCo pickups. It's a fact that ceramic pickups are higher output than a comparable AlNiCo with an equal number of winds on the bobbin. That being said, I'd rather get higher output by turning my amp up, rather than lose out on that high end clarity.
Then there's the issue of the ceramic pickups have shorter "hills" to the AlNiCo's taller "mountains". The higher permeability and conductivity of the steel pole pieces has the additional consequence of causing substantial eddy current resistance. This is a reactive resistance that increases with frequency, again causing losses specifically in the high end response. The changing magnetic field of the moving string and inductive pickup coil causes an electric current to move around in the steel, that current in turn creates yet another magnetic field that pushes back against the original magnetic field (Lenz's Law), hence eddy current resistance.
Here are the technical details of the four test pickups:
AlNiCo's:
Lollar Black Face Neck
DC R: 6.70K
L: 2.531H
Peak: 9.59 kHz
Calculated C: 99pF (109-10)
Coil width: 0.60" (with cloth tape)
Fender Mexico ALNiCo Single Coil
DC R: 5.81K
L: 2.153H
Peak: 7.99kHz
Calculated C: 174pF (184-10)
Coil width: 0.52"
Ceramics:
Fender Mexico Ceramic Single Coil
DC R: 7.13K
L: 4.376H
Peak: 6.07kHz
Calculated C: 147pF (157-10)
Coil width: 0.42"
Fender Japan Ceramic Single Coil
DC R: 5.44K
L: 4.016H
Peak: 5.87kHz
Calculated C: 173pF (183-10)
Coil width: 0.50
Notice just how much higher the inductance is with the ceramic pickups, 2.xH versus 4.xH, all due to the steel pole pieces. Fun fact: the ceramic magnet is not metal, so from an permeable/conductive standpoint, it's as if nothing were there at all.
Also worth noting is that the Lollar has a much lower capacitance than these other three machines wound pickups. That is because Lollar likely winds the coils with a lower tension, and uses a lower 'turns per traverse' than these machine wound pickups, which causes the wire to be spaced farther apart, throughout the coil. This is also evidenced in the fact that the Lollar also has a somewhat wider coil width than the three Fender machine wound pickups.
Another Important Difference
Another common misconception is that you will get a higher magnetic pull with ceramic magnets, since ceramic tends to be stronger than AlNiCo, but the magnetism that really matters is that which able to reach the guitar strings, and the ceramic magnet is not located near the guitar strings; the steel slugs are. Those steel slugs are not capable of communicating the strong flux of the ceramic to the strings. A simple proof of this fact is that you only ever experience "Stratitus" string pull problems with AlNiCo pickups, not ceramic, and it usually only happens with AlNiCo 5, specifically.
Here is the measured flux of the Lollar, with its AlNiCo 5 poles, reading ~900G at the pole top. Note that Strat pickups usually read closer to 1100, but these Lollar "flat stagger" magnets are shorter than typical pole pieces:
And here you can see the flux at the tops of the steel pole pieces in the Fender Mexico ceramic pickup, ~350G, well below half of the flux density of the AlNiCo 5 pickup.
The decrease in flux density means less current and less output, but it also may have an effect on tone, because so much about magnetism is non linear, such as the BH curves of the metals involved, and the fact that flux density decreases cubically with distance. So I can't say how it effects tone, all I can say is that a physical difference exists between the way the string interacts with AlNiCo poles versus steel poles.
The Medium Lengthed Answer - Ceramic single coil pickups lack in high end response, with a bandwidth that is well over 1kHz narrower that of AlNiCo single coil pickups. A lot of players buy Strats for the "quack", and you need high end response in order to get that "quack" (or "twang" in the case of a Tele).
To illustrate this point in exact detail, I've selected four pickups: two AlNiCo and two ceramic. The are, as pictured:
An AlNiCo Lollar Blackface Neck | A Ceramic Fender Mexico
An AlNiCo Fender Mexico Strat pickup | A Ceramic Fender Japan
Note that I have included a highly regarded boutique Lollar Blackface AlNiCo neck pickup, and a lowly Fender Mexico AlNiCo pickup, complete with plastic bobbin, to show that you won't need to spend a lot of money when you buy an AlNiCo single coil to replace you stock ceramic pickups. The Lollar is also a "hand wound" pickup, where as the three Fenders are fully machine wound.
The bandwidths of these pickups can be easily seen in bode plots. The first bode plot shows the pickups measured "as is":
Looking at the graph above, the two defined mountains (high Q) are the two AlNiCo pickups, and the two stubby hills (low Q) that nearly overlap are the ceramic pickups.
When you hook the pickups up to your guitar, and then plug in a guitar cable, a large amount of parallel resistance and capacitance is added to the pickups, and this is infact the context in which we're used to hearing pickups. With an added 200k resistance and 470pF capacitance, this plot comes out like this:
In this plot, the AlNiCo pickups are, again, the two taller peaks, and this time they overlap, which just goes to show what a great equalizer a guitar cable can be, and the two lumps are the ceramic pickups.
The key detail in both plots is that the AlNiCo pickups both a) extend farther into the treble range, peaking near 4,000 Hz, and b) produce more voltage at that peak (due to the high Q factor), relative to the baseline voltage, where as the ceramic pickups peak out at about 2,900 Hz, and produce a lot less voltage at that peak (due to the low Q factor), relative to their base line voltage. That is over 1,000 Hz, or roughly 33% of, additional harmonic content you get with those AlNiCo pickups that you won't hear with stock ceramic pickups.
This overall pattern will hold for 95% of the AlNiCo and ceramic pickup on the market.
Again, you do not need an expensive boutique AlNiCo pickup to get these benefits, as even the Fender Mexico AlNiCo exhibits the same positive benefits of expanded bandwidth and a higher Q factor.
- - ----===----=--=---=------- - - - -
The Long Answer - The reason why ceramic pickups ditch over 1kHz of high end response is not actually because of the ceramic magnet, it's entirely due to the the steel slugs. The steel slugs have a very high permeability and conductivity compared to the AlNiCo. Those two factor cause the inductance to almost double, and it is that doubling of inductance that causes the resonant peak to drop so far.
The higher inductance caused by the slugs is also the reason why, in the plots above, the ceramic pickup's voltage plot lines are 5 decibels higher than the AlNiCo pickups. It's a fact that ceramic pickups are higher output than a comparable AlNiCo with an equal number of winds on the bobbin. That being said, I'd rather get higher output by turning my amp up, rather than lose out on that high end clarity.
Then there's the issue of the ceramic pickups have shorter "hills" to the AlNiCo's taller "mountains". The higher permeability and conductivity of the steel pole pieces has the additional consequence of causing substantial eddy current resistance. This is a reactive resistance that increases with frequency, again causing losses specifically in the high end response. The changing magnetic field of the moving string and inductive pickup coil causes an electric current to move around in the steel, that current in turn creates yet another magnetic field that pushes back against the original magnetic field (Lenz's Law), hence eddy current resistance.
Here are the technical details of the four test pickups:
AlNiCo's:
Lollar Black Face Neck
DC R: 6.70K
L: 2.531H
Peak: 9.59 kHz
Calculated C: 99pF (109-10)
Coil width: 0.60" (with cloth tape)
Fender Mexico ALNiCo Single Coil
DC R: 5.81K
L: 2.153H
Peak: 7.99kHz
Calculated C: 174pF (184-10)
Coil width: 0.52"
Ceramics:
Fender Mexico Ceramic Single Coil
DC R: 7.13K
L: 4.376H
Peak: 6.07kHz
Calculated C: 147pF (157-10)
Coil width: 0.42"
Fender Japan Ceramic Single Coil
DC R: 5.44K
L: 4.016H
Peak: 5.87kHz
Calculated C: 173pF (183-10)
Coil width: 0.50
Notice just how much higher the inductance is with the ceramic pickups, 2.xH versus 4.xH, all due to the steel pole pieces. Fun fact: the ceramic magnet is not metal, so from an permeable/conductive standpoint, it's as if nothing were there at all.
Also worth noting is that the Lollar has a much lower capacitance than these other three machines wound pickups. That is because Lollar likely winds the coils with a lower tension, and uses a lower 'turns per traverse' than these machine wound pickups, which causes the wire to be spaced farther apart, throughout the coil. This is also evidenced in the fact that the Lollar also has a somewhat wider coil width than the three Fender machine wound pickups.
Another Important Difference
Another common misconception is that you will get a higher magnetic pull with ceramic magnets, since ceramic tends to be stronger than AlNiCo, but the magnetism that really matters is that which able to reach the guitar strings, and the ceramic magnet is not located near the guitar strings; the steel slugs are. Those steel slugs are not capable of communicating the strong flux of the ceramic to the strings. A simple proof of this fact is that you only ever experience "Stratitus" string pull problems with AlNiCo pickups, not ceramic, and it usually only happens with AlNiCo 5, specifically.
Here is the measured flux of the Lollar, with its AlNiCo 5 poles, reading ~900G at the pole top. Note that Strat pickups usually read closer to 1100, but these Lollar "flat stagger" magnets are shorter than typical pole pieces:
And here you can see the flux at the tops of the steel pole pieces in the Fender Mexico ceramic pickup, ~350G, well below half of the flux density of the AlNiCo 5 pickup.
The decrease in flux density means less current and less output, but it also may have an effect on tone, because so much about magnetism is non linear, such as the BH curves of the metals involved, and the fact that flux density decreases cubically with distance. So I can't say how it effects tone, all I can say is that a physical difference exists between the way the string interacts with AlNiCo poles versus steel poles.
