Post by antigua on Oct 3, 2017 22:36:15 GMT -5
www.seymourduncan.com/pickup/custom-staggered-strat
The SSL-5 is one of the oldest models in the Seymour Duncan line. According to legend, it was originally created for David Gilmour, and called the "SSL-1C" before being renamed the SSL-5 and being sold as a production pickup.
By modern standards, the SSL-5, and the hotter SSL-3 are very, very hot Strat pickups. What passes for "hot" these days, such as Texas Specials, or Lollar Blackface Strat, don't come anywhere close. Where as those products have about 20% higher inductance than a typical Strat pickup, the SSL-3 and SSL-5 have closer to 250% higher inductance, or 2.5 times the inductance of, say, the "vintage" SSL-1. Modern tastes say that pickups with an in inductance result in a clean tone that is so dark, that the pickup ends up lacking versatility.
Truth be told, they're are very similar to a P-90, though with a higher resonant Q. The reason you never see this comparison made probably has a lot to do with context; you really never, ever see P-90's in Strats, and we've come to expect Strats to produce a chiming, clean tone that we never think to ask of P-90s.
Quality control...
I loaded three SSL-5T's into a Strat, and then installed a knob that "taps" them. The "T" stands for "tapped", probably, and since I have three SSL-5's in the guitar, it can also be seen how much variance there is between three allegedly identical products. Based on the printed digits, one SSL-5 was made in 2013, another in 2014, and sadly the sticker on the bottom of the 3rd went missing, but electrically, its nearly identical to the 2014 SSL-5.
The 2013 pickup is definitely a little hotter, it has a higher inductance and a higher DC resistance. This difference is trivial, though. There is a less trivial difference, though, that is very strange. The 2014 SSL-5, and the no-sticker model, have a very, very high Q factor, even for a low wind AlNiCo 5 Strat pickup, and that can be seen in the bode plots below. They have a 17dB rise in voltage output at resonance where has a typical AlNiCo 5 pickups with 6k ohms resistance only reached about 12dB. This suggests the AlNiCo 5 formulation in these pickups, the 2014 and likely-2014, has an unusually low conductivity, resisting eddy current loses and making these SSL-5's a little brighter at resonance that usual. The increase in Q is similar in effect to installing a 500k volume pot instead of 250k, as both of these things ultimately function as resonant dampers.
The 2013 SSL-5 has a lower, more typical Q factor by contrast, rising to 10dB, 2dB less than a typical AlNiCo 5 strat pickup. This matches with expectation, considering the 13.5k ohms copper wire resistance is about twice that of a typical Strat pickup.
The Guass readings at the pole tops shows about 1100G for all three pickups, so despite the apparent unusual AlNiCo 5 formulation of the 2013 SSL-5, it performs properly as a permanent magnet.
Tapping...
Tapping the coils reduces the inductance of the pickup to produce the tone associated with with a pickup that is not wound "hot". Transformers are often "tapped" in the same manner, and for the same reason, allowing for different impedances from a single transformer.
Based on the DC resistances, it appears that they tap the coils at precisely half of the total wind count. Since inductance and wind counts are not linear, the inductance doesn't halve, but in fact drops WAAAY below half, from six some odd henries down to less than two henries. Normally, this dramatic drop should cause the resonance of the tapped pickup to be extremely high, well above that of a typical Strat pickup, but for a reason that is not commonly known, this doesn't happen. What is not commonly known is that, when tapped, the unused portion of coil causes a large amount of parallel capacitance with the used portion of coil. As the current alternates back and forth, voltage is exchanged between the used and unused portion of coil electrostatically, the same way alternating current passes the plates of any capacitor. Where as the capacitance of the coil be itself is about 140pF, when tapped, the capacitance jumps to over 400pF, which is similar in ratio to the drop in inductance. The resonance of the pickup is decided by the total value of both inductance AND capacitance, and so it is this large capacitance that causes the "tapped" mode to no be very bright, despite the very low inductance.
Speaking of capacitance, the way the hookup wire is braided, out of the box, adds a bit of capacitance that you can do away with by untwisting the leads, but then you have more of a mess of wires to deal with.
So how close is the tapped coil to a true Strat pickup? From a voltage output standpoint, they are weaker. The inductance of 1.7H and 1.8H simply isn't as high as a typical Strat pickup with closer to 2.3H to 3.0H. This lack of impedance means less voltage for the same amount of magnemotive force. I found that a tapped SSL-3 has an inductance of 2.1 henries, which is closer to that of a true vintage output Strat pickup.
Output voltage aside, from an impedance curve standpoint, the loaded peak frequency of 3.8kHz is right on the money, which is probably why Seymour Duncan settles at this 50% tap point. The treble response is correct, but the voltage output is anemic. The Q factor of the 2014 SSL-5 is high enough to pretend to be a low output Strat pickup, but the 3dB rise of the 2013 model is a little soft for a Strat pickup. For this reason, I would suggest using 500k ohm volume and tone pots in tandem with SSL-5s, which is what I do, personally.
In the plots below, I used a constant driving voltage, so you can actually see how much the voltage output drop when you tap the coil by comparing the top lines dBV' to the lower lines. Based on all three plots, it looks like a 6dB to 7dB drop when the pickup is tapped. This is a rather big drop in volume, and it tends to make tapping mid-song hard to do. Although, you could leave the coil tapped by default, and switch into "full" mode for a lead boost when it comes time for the guitar solo after the second chorus.
The tapped coil design mostly suffers due to that capacitance, because it necessitates a low inductance to compensate. The only way to fix this would be to disconnect the unused portion of coil at both ends in order to prevent it from passing any current into the circuit. Since most all tapped pickups have only three lead wires, this is impossible to arrange, and there's really no way to modify an completely pickup to accept a fourth lead, since only two to three millimeters of wire are exposed at the tap point. Even if the pickup makers out there offered a four lead tapped pickup, it would require a dedicated DP/DT to tap the pickup, where as a convention tap can be done with a simple SP/ST.
Seymour Duncan SSL-5T, likely 2014
DC Resistance:
full: 13.58K
tapped: 6.56K
Inductance:
full: 6.155H
tapped: 1.794H
Resonant Peak:
full: dV: 16.7dB f: 5.30kHz (black)
tapped: dV: 17.4dB f: 5.61kHz (green)
Loaded Resonant Peak (200K ohms & 470pF):
full: dV: 4.3dB f: 2.36kHz (red)
tapped: dV: 8.9dB f: 3.89kHz (gray)
Calculated C:
full: 137pF (147-10)
tapped: 439pF (449-10)
Gauss strength: 1100G at pole tops, AlNiCo 5
Seymour Duncan SSL-5T I0MO3 20130702
DC Resistance:
full: 13.88K
tapped: 7.05K
Inductance:
full: 6.382H
tapped: 1.700H
Resonant Peak:
full: dV: 9.8dB f: 5.30kHz (black)
tapped: dV: 9.4dB f: 5.61kHz (green)
Loaded Resonant Peak (200K ohms & 470pF):
full: dV: 2.8dB f: 2.20kHz (red)
tapped: dV: 6.1dB f: 3.76kHz (gray)
Calculated C:
full: 131pF (141-10)
tapped: 463pF (473-10)
Gauss strength: 1100G at pole tops, AlNiCo 5
Seymour Duncan SSL-5T iI0ZNT 20141120
DC Resistance:
full: 13.59K
tapped: 6.56K
Inductance:
full: 6.015H
tapped: 1.817H
Resonant Peak:
full: dV: 16.3dB f: 5.24kHz (black)
tapped: dV: 17.4dB f: 5.54kHz (green)
Loaded Resonant Peak (200K ohms & 470pF):
full: dV: 4.4dB f: 2.38kHz (red)
tapped: dV: 9.3dB f: 3.89kHz (gray)
Calculated C:
full: 143pF (153-10)
tapped: 444pF (454-10)
Gauss strength: 1100G at pole tops, AlNiCo 5
Pics:
The SSL-5 is one of the oldest models in the Seymour Duncan line. According to legend, it was originally created for David Gilmour, and called the "SSL-1C" before being renamed the SSL-5 and being sold as a production pickup.
By modern standards, the SSL-5, and the hotter SSL-3 are very, very hot Strat pickups. What passes for "hot" these days, such as Texas Specials, or Lollar Blackface Strat, don't come anywhere close. Where as those products have about 20% higher inductance than a typical Strat pickup, the SSL-3 and SSL-5 have closer to 250% higher inductance, or 2.5 times the inductance of, say, the "vintage" SSL-1. Modern tastes say that pickups with an in inductance result in a clean tone that is so dark, that the pickup ends up lacking versatility.
Truth be told, they're are very similar to a P-90, though with a higher resonant Q. The reason you never see this comparison made probably has a lot to do with context; you really never, ever see P-90's in Strats, and we've come to expect Strats to produce a chiming, clean tone that we never think to ask of P-90s.
Quality control...
I loaded three SSL-5T's into a Strat, and then installed a knob that "taps" them. The "T" stands for "tapped", probably, and since I have three SSL-5's in the guitar, it can also be seen how much variance there is between three allegedly identical products. Based on the printed digits, one SSL-5 was made in 2013, another in 2014, and sadly the sticker on the bottom of the 3rd went missing, but electrically, its nearly identical to the 2014 SSL-5.
The 2013 pickup is definitely a little hotter, it has a higher inductance and a higher DC resistance. This difference is trivial, though. There is a less trivial difference, though, that is very strange. The 2014 SSL-5, and the no-sticker model, have a very, very high Q factor, even for a low wind AlNiCo 5 Strat pickup, and that can be seen in the bode plots below. They have a 17dB rise in voltage output at resonance where has a typical AlNiCo 5 pickups with 6k ohms resistance only reached about 12dB. This suggests the AlNiCo 5 formulation in these pickups, the 2014 and likely-2014, has an unusually low conductivity, resisting eddy current loses and making these SSL-5's a little brighter at resonance that usual. The increase in Q is similar in effect to installing a 500k volume pot instead of 250k, as both of these things ultimately function as resonant dampers.
The 2013 SSL-5 has a lower, more typical Q factor by contrast, rising to 10dB, 2dB less than a typical AlNiCo 5 strat pickup. This matches with expectation, considering the 13.5k ohms copper wire resistance is about twice that of a typical Strat pickup.
The Guass readings at the pole tops shows about 1100G for all three pickups, so despite the apparent unusual AlNiCo 5 formulation of the 2013 SSL-5, it performs properly as a permanent magnet.
Tapping...
Tapping the coils reduces the inductance of the pickup to produce the tone associated with with a pickup that is not wound "hot". Transformers are often "tapped" in the same manner, and for the same reason, allowing for different impedances from a single transformer.
Based on the DC resistances, it appears that they tap the coils at precisely half of the total wind count. Since inductance and wind counts are not linear, the inductance doesn't halve, but in fact drops WAAAY below half, from six some odd henries down to less than two henries. Normally, this dramatic drop should cause the resonance of the tapped pickup to be extremely high, well above that of a typical Strat pickup, but for a reason that is not commonly known, this doesn't happen. What is not commonly known is that, when tapped, the unused portion of coil causes a large amount of parallel capacitance with the used portion of coil. As the current alternates back and forth, voltage is exchanged between the used and unused portion of coil electrostatically, the same way alternating current passes the plates of any capacitor. Where as the capacitance of the coil be itself is about 140pF, when tapped, the capacitance jumps to over 400pF, which is similar in ratio to the drop in inductance. The resonance of the pickup is decided by the total value of both inductance AND capacitance, and so it is this large capacitance that causes the "tapped" mode to no be very bright, despite the very low inductance.
Speaking of capacitance, the way the hookup wire is braided, out of the box, adds a bit of capacitance that you can do away with by untwisting the leads, but then you have more of a mess of wires to deal with.
So how close is the tapped coil to a true Strat pickup? From a voltage output standpoint, they are weaker. The inductance of 1.7H and 1.8H simply isn't as high as a typical Strat pickup with closer to 2.3H to 3.0H. This lack of impedance means less voltage for the same amount of magnemotive force. I found that a tapped SSL-3 has an inductance of 2.1 henries, which is closer to that of a true vintage output Strat pickup.
Output voltage aside, from an impedance curve standpoint, the loaded peak frequency of 3.8kHz is right on the money, which is probably why Seymour Duncan settles at this 50% tap point. The treble response is correct, but the voltage output is anemic. The Q factor of the 2014 SSL-5 is high enough to pretend to be a low output Strat pickup, but the 3dB rise of the 2013 model is a little soft for a Strat pickup. For this reason, I would suggest using 500k ohm volume and tone pots in tandem with SSL-5s, which is what I do, personally.
In the plots below, I used a constant driving voltage, so you can actually see how much the voltage output drop when you tap the coil by comparing the top lines dBV' to the lower lines. Based on all three plots, it looks like a 6dB to 7dB drop when the pickup is tapped. This is a rather big drop in volume, and it tends to make tapping mid-song hard to do. Although, you could leave the coil tapped by default, and switch into "full" mode for a lead boost when it comes time for the guitar solo after the second chorus.
The tapped coil design mostly suffers due to that capacitance, because it necessitates a low inductance to compensate. The only way to fix this would be to disconnect the unused portion of coil at both ends in order to prevent it from passing any current into the circuit. Since most all tapped pickups have only three lead wires, this is impossible to arrange, and there's really no way to modify an completely pickup to accept a fourth lead, since only two to three millimeters of wire are exposed at the tap point. Even if the pickup makers out there offered a four lead tapped pickup, it would require a dedicated DP/DT to tap the pickup, where as a convention tap can be done with a simple SP/ST.
Seymour Duncan SSL-5T, likely 2014
DC Resistance:
full: 13.58K
tapped: 6.56K
Inductance:
full: 6.155H
tapped: 1.794H
Resonant Peak:
full: dV: 16.7dB f: 5.30kHz (black)
tapped: dV: 17.4dB f: 5.61kHz (green)
Loaded Resonant Peak (200K ohms & 470pF):
full: dV: 4.3dB f: 2.36kHz (red)
tapped: dV: 8.9dB f: 3.89kHz (gray)
Calculated C:
full: 137pF (147-10)
tapped: 439pF (449-10)
Gauss strength: 1100G at pole tops, AlNiCo 5
Seymour Duncan SSL-5T I0MO3 20130702
DC Resistance:
full: 13.88K
tapped: 7.05K
Inductance:
full: 6.382H
tapped: 1.700H
Resonant Peak:
full: dV: 9.8dB f: 5.30kHz (black)
tapped: dV: 9.4dB f: 5.61kHz (green)
Loaded Resonant Peak (200K ohms & 470pF):
full: dV: 2.8dB f: 2.20kHz (red)
tapped: dV: 6.1dB f: 3.76kHz (gray)
Calculated C:
full: 131pF (141-10)
tapped: 463pF (473-10)
Gauss strength: 1100G at pole tops, AlNiCo 5
Seymour Duncan SSL-5T iI0ZNT 20141120
DC Resistance:
full: 13.59K
tapped: 6.56K
Inductance:
full: 6.015H
tapped: 1.817H
Resonant Peak:
full: dV: 16.3dB f: 5.24kHz (black)
tapped: dV: 17.4dB f: 5.54kHz (green)
Loaded Resonant Peak (200K ohms & 470pF):
full: dV: 4.4dB f: 2.38kHz (red)
tapped: dV: 9.3dB f: 3.89kHz (gray)
Calculated C:
full: 143pF (153-10)
tapped: 444pF (454-10)
Gauss strength: 1100G at pole tops, AlNiCo 5
Pics:
