|
Post by antigua on Feb 15, 2018 2:15:01 GMT -5
Have you heard about pickup makers boasting "partially degaussed" AlNiCo for a more vintage tone? Well it's easy to do at home, and if the AlNiCo pole pieces are exposed, you don't even have to take the pickups out of the guitar to proceed. Why do this? The AlNiCo magnet is not a dead technology, though this type of magnet has been increasingly usurped by ceramic and rare earth magnets, which avoid several disadvantages associated with AlNiCo. One major disadvantage of AlNiCo is that physical shock, extreme heat changes, and exposure to stray magnetic fields can cause it to lose residual flux, or "strength". In the context of guitar pickups that contain AlNiCo magnets, degaussed magnets are valued by guitarists for either sounding "aged", or "mellow", or what have you. The effect of degaussing pole pieces is very similar to simply lowering pickups, so if you want to see if you will like the sound before hand, you can try simply lowering the pickups by three or four millimeters and then observing the difference. The advantage to degaussing the pole pieces as opposed to simply lowering the pickups is mostly in the fact that the pickups will not appear lowered by three or four millimeters. You can also degauss specific pole pieces, to make some of them produce a "lowered" sound, and others a "raised" sound. A fun thing to try is to degauss some pole pieces while leaving others full strength. The result could be similar to a Seymour Duncan "Five Two", where there are stronger AlNiCo 5 pole pieces under the wound string, and weaker AlNiCo 2 below the plain strings. I just gave this a try with my own Strat and the result is as you'd expect, the plain string sound mellowed out. How do you do it? Degaussing AlNiCo on purpose can be a little difficult, because you have to expose it to a magnetic field that is not so strong that re-polarizes the AlNiCo, nor so weak that it fails to weaken the AlNiCo at all, but there is a way to reliably degauss AlNiCo pole pieces to a very useful degree, and that is by using a standard AlNiCo 5 pole piece as the degaussing agent.
The trick is to take the pickup you want to partially degauss, then simply press a fully charged AlNiCo 5 pole piece into the tops of the pole piece(s) you want to degauss, so that they're "face against face", and trying to push away. Hold them in direct contact for about three to five seconds, then lift it away. This will reduce the flux density of an AlNiCo 5 pole piece by nearly half, or cut the flux density of AlNiCo 2, 3 or 4 by about 25%. AlNiCo pole pieces come in different lengths for staggered Strotcaster pickups, but as long as it's over 15mm in length, it will be strong enough to get the job done. I've found that holding the pole piece for a longer period of time, like twenty seconds, will further reduce the gauss another 10% to 15%, after which point there is no further change. Since both the target pole piece, and the "agent" pole piece you use for degaussing will mutually lose flux density, you'll have to recharge the "agent" pole piece using a neodymium magnet, for each pole piece that you degauss. It's very helpful to have a compass or a polarity tester on hand in order to know the polarity of the pickup and the other magnets, rather than simply noting whether they attract or repel. How does it work? The key ingredient is that the "H field" of the AlNiCo 5 pole piece is just strong enough, and the coercivity of AlNiCo low enough, that it will partially degauss other AlNiCo pole pieces. Unless you have a magnetometer, you won't know exactly where you started and where you end up, but you can use a small screw or a paperclip and gauge how much the magnetic attraction of the pole piece has changed. A fully charged AlNiCo pole piece will hold a paperclip rather tightly, where as a 50% degaussed AlNiCo 5 won't put up much of a fight. AlNiCo 2, 3 and 4 only produce about 50% of the flux density of AlNico 5 when fully charged, so this technique doesn't work as well with those alloys. A cheap analogue Annis magnetometer costs about $80 on eBay, while a better, digital "Hall Effect" magnetometer can be found for as little as $100, if you're willing to make a small investment. Note that if you only degauss the top of the pole piece, the strength at the bottom side will still be nearly full strength. Degaussing both the top and the bottom reduce the flux density at the top side by about another 50G. How much difference does it make? In my testing, which is pictured below, a fully charged AlNiCo 5 pole piece reduced the charge of other AlNiCo 5 pole pieces from around 1050 guass down to about 650 gauss. You might think half the magnetic strength means half the volume, but it doesn't work out that way. In fact, you have to degauss the pole piece by about this much in order to perceive a noticeable difference. Due to the instability of AlNiCo, some AlNiCo 5 pickups are received after having lost 20% of their charge through one mechanism or another, but with that small degree of loss, few people, if any, even notice. AlNiCo 3 pole pieces produce about 650 gauss at the pole tops when fully charged, while AlNiCo 2 and 4 are not much stronger. When running your guitar squeaky clean, you can perceive a bit of a volume drop, but with almost any amount of gain, the volume difference disappears, while the "softer" tonal qualities of degaussed pole pieces seems to remain. Supposing you have a pickup with AlNiCo 2, 3, or 4 pole pieces, I've found that if you try to degauss AlNiCo 2 with another AlNiCo 2 pole piece, you won't get much of a reduction in gauss. Starting out at 700G, an AlNiCo 2 pole pieces dropped to about 650G, not much of a difference. On the other hand, placing an AlNiCo 5 pole piece face against face to the AlNiCo 2 pole piece reduced it's strength from 700G down to 550G. Since AlNiCo 3 and 4 have a coercivity that is very close to that of AlNiCo 2, it's likely you would get similar results with those alloys. How do I undo this if I don't like it? In order to restore a pickup to stock condition, or to freshly charge a pole piece for this purpose, you'd want to get a neodymium magnet. Neodymium is so strong that even a small magnet as is seen in the pictures below will almost fully charge AlNiCo pole pieces, though you'd want to get one that is a bit wider and longer in order to fully charge and a pickup, or bar magnet along it's entire face at one time. If the neodyium is especially large and strong, like strong enough to crush your fingers, then it will be strong enough to charge the pickup without even making contact with the pole pieces, and so you can just waive it over the top of the pickup. You will definitely need a compass, or a polarity tester, in order to make sure that you recharge the AlNiCo pole pieces with the same polar orientation they started out with, in order to maintain the correct phase for the pickup. Incidentally, any pickup can be made into an RW/RP pickup by deliberately reversing the magnetic polarity, and then reversing the lead wires (the coil does not have to be literally "reverse wound"). In the case of a Telecaster neck pickup, you can degauss the pole pieces from the underside, but the AlNiCo will still be nearly full strength on the top side. Is there a downside? A caveat to doing this is that partially charged AlNiCo is always less stable than fully charged AlNiCo, so one you've reduced the flux density, the magnets will more easily lose charge over time, and it might become necessary to recharge the pole pieces to full strength again using a neodymium magnet, though you can partially degauss them once again, using the same technique described here. Also note that because AlNiCo 8 has a higher coercivity than lower AlNiCo grades, this procedure would probably bot degauss it to a useful degree, if at all. Pictures:Charging up an AlNiCo 5 pole piece to be used to degauss other pole pieces: The freshly charged AnNiCo 5 pole piece measures about 1250G: Unadulterated SSL-1 reading ~1050G: Pressing the AlNiCo 5 pole piece into the SSL-1's pole pieces: The SSL-1 now measures about 650G at the pole top. Here is a pickup with AlNiCo 2 pole pieces, measuring ~700G After pressing the AlNiCo 2 pole piece to the AlNiCo 2 pole pieces within the pickup, the overall drop is barely 50 gauss. However, recharging the AlNiCo 2 pickup, and then pressing the AlNiCo 5 pole pieces against the AlNiCo 2 pole pieces caused them to drop to about 550 gauss:
|
|
|
Post by pablogilberto on Jul 12, 2019 1:49:09 GMT -5
Hi Antigua! I have some questions: 1. How to determine if a magnet (say Alnino 5 or 2) is fully charged? Do you know the values (in Gauss)? 2. If I try to degauss an Alnico5 with an Alnico 5 (agent), how can I be sure that the non-agent will be degaussed instead of the agent? 3. Can I gauss/degauss Alnicos directly using neodymium? Thank you! Have you heard about pickup makers boasting "partially degaussed" AlNiCo for a more vintage tone? Well it's easy to do at home, and if the AlNiCo pole pieces are exposed, you don't even have to take the pickups out of the guitar to proceed. Why do this? The AlNiCo magnet is not a dead technology, though this type of magnet has been increasingly usurped by ceramic and rare earth magnets, which avoid several disadvantages associated with AlNiCo. One major disadvantage of AlNiCo is that physical shock, extreme heat changes, and exposure to stray magnetic fields can cause it to lose residual flux, or "strength". In the context of guitar pickups that contain AlNiCo magnets, degaussed magnets are valued by guitarists for either sounding "aged", or "mellow", or what have you. The effect of degaussing pole pieces is very similar to simply lowering pickups, so if you want to see if you will like the sound before hand, you can try simply lowering the pickups by three or four millimeters and then observing the difference. The advantage to degaussing the pole pieces as opposed to simply lowering the pickups is mostly in the fact that the pickups will not appear lowered by three or four millimeters. You can also degauss specific pole pieces, to make some of them produce a "lowered" sound, and others a "raised" sound. A fun thing to try is to degauss some pole pieces while leaving others full strength. The result could be similar to a Seymour Duncan "Five Two", where there are stronger AlNiCo 5 pole pieces under the wound string, and weaker AlNiCo 2 below the plain strings. I just gave this a try with my own Strat and the result is as you'd expect, the plain string sound mellowed out. How do you do it? Degaussing AlNiCo on purpose can be a little difficult, because you have to expose it to a magnetic field that is not so strong that re-polarizes the AlNiCo, nor so weak that it fails to weaken the AlNiCo at all, but there is a way to reliably degauss AlNiCo pole pieces to a very useful degree, and that is by using a standard AlNiCo 5 pole piece as the degaussing agent.
The trick is to take the pickup you want to partially degauss, then simply press a fully charged AlNiCo 5 pole piece into the tops of the pole piece(s) you want to degauss, so that they're "face against face", and trying to push away. Hold them in direct contact for about three to five seconds, then lift it away. This will reduce the flux density of an AlNiCo 5 pole piece by nearly half, or cut the flux density of AlNiCo 2, 3 or 4 by about 25%. AlNiCo pole pieces come in different lengths for staggered Strotcaster pickups, but as long as it's over 15mm in length, it will be strong enough to get the job done. I've found that holding the pole piece for a longer period of time, like twenty seconds, will further reduce the gauss another 10% to 15%, after which point there is no further change. Since both the target pole piece, and the "agent" pole piece you use for degaussing will mutually lose flux density, you'll have to recharge the "agent" pole piece using a neodymium magnet, for each pole piece that you degauss. It's very helpful to have a compass or a polarity tester on hand in order to know the polarity of the pickup and the other magnets, rather than simply noting whether they attract or repel. How does it work? The key ingredient is that the "H field" of the AlNiCo 5 pole piece is just strong enough, and the coercivity of AlNiCo low enough, that it will partially degauss other AlNiCo pole pieces. Unless you have a magnetometer, you won't know exactly where you started and where you end up, but you can use a small screw or a paperclip and gauge how much the magnetic attraction of the pole piece has changed. A fully charged AlNiCo pole piece will hold a paperclip rather tightly, where as a 50% degaussed AlNiCo 5 won't put up much of a fight. AlNiCo 2, 3 and 4 only produce about 50% of the flux density of AlNico 5 when fully charged, so this technique doesn't work as well with those alloys. A cheap analogue Annis magnetometer costs about $80 on eBay, while a better, digital "Hall Effect" magnetometer can be found for as little as $100, if you're willing to make a small investment. Note that if you only degauss the top of the pole piece, the strength at the bottom side will still be nearly full strength. Degaussing both the top and the bottom reduce the flux density at the top side by about another 50G. How much difference does it make? In my testing, which is pictured below, a fully charged AlNiCo 5 pole piece reduced the charge of other AlNiCo 5 pole pieces from around 1050 guass down to about 650 gauss. You might think half the magnetic strength means half the volume, but it doesn't work out that way. In fact, you have to degauss the pole piece by about this much in order to perceive a noticeable difference. Due to the instability of AlNiCo, some AlNiCo 5 pickups are received after having lost 20% of their charge through one mechanism or another, but with that small degree of loss, few people, if any, even notice. AlNiCo 3 pole pieces produce about 650 gauss at the pole tops when fully charged, while AlNiCo 2 and 4 are not much stronger. When running your guitar squeaky clean, you can perceive a bit of a volume drop, but with almost any amount of gain, the volume difference disappears, while the "softer" tonal qualities of degaussed pole pieces seems to remain. Supposing you have a pickup with AlNiCo 2, 3, or 4 pole pieces, I've found that if you try to degauss AlNiCo 2 with another AlNiCo 2 pole piece, you won't get much of a reduction in gauss. Starting out at 700G, an AlNiCo 2 pole pieces dropped to about 650G, not much of a difference. On the other hand, placing an AlNiCo 5 pole piece face against face to the AlNiCo 2 pole piece reduced it's strength from 700G down to 550G. Since AlNiCo 3 and 4 have a coercivity that is very close to that of AlNiCo 2, it's likely you would get similar results with those alloys. How do I undo this if I don't like it? In order to restore a pickup to stock condition, or to freshly charge a pole piece for this purpose, you'd want to get a neodymium magnet. Neodymium is so strong that even a small magnet as is seen in the pictures below will almost fully charge AlNiCo pole pieces, though you'd want to get one that is a bit wider and longer in order to fully charge and a pickup, or bar magnet along it's entire face at one time. If the neodyium is especially large and strong, like strong enough to crush your fingers, then it will be strong enough to charge the pickup without even making contact with the pole pieces, and so you can just waive it over the top of the pickup. You will definitely need a compass, or a polarity tester, in order to make sure that you recharge the AlNiCo pole pieces with the same polar orientation they started out with, in order to maintain the correct phase for the pickup. Incidentally, any pickup can be made into an RW/RP pickup by deliberately reversing the magnetic polarity, and then reversing the lead wires (the coil does not have to be literally "reverse wound"). In the case of a Telecaster neck pickup, you can degauss the pole pieces from the underside, but the AlNiCo will still be nearly full strength on the top side. Is there a downside? A caveat to doing this is that partially charged AlNiCo is always less stable than fully charged AlNiCo, so one you've reduced the flux density, the magnets will more easily lose charge over time, and it might become necessary to recharge the pole pieces to full strength again using a neodymium magnet, though you can partially degauss them once again, using the same technique described here. Also note that because AlNiCo 8 has a higher coercivity than lower AlNiCo grades, this procedure would probably bot degauss it to a useful degree, if at all. Pictures:Charging up an AlNiCo 5 pole piece to be used to degauss other pole pieces: The freshly charged AnNiCo 5 pole piece measures about 1250G: Unadulterated SSL-1 reading ~1050G: Pressing the AlNiCo 5 pole piece into the SSL-1's pole pieces: The SSL-1 now measures about 650G at the pole top. Here is a pickup with AlNiCo 2 pole pieces, measuring ~700G After pressing the AlNiCo 2 pole piece to the AlNiCo 2 pole pieces within the pickup, the overall drop is barely 50 gauss. However, recharging the AlNiCo 2 pickup, and then pressing the AlNiCo 5 pole pieces against the AlNiCo 2 pole pieces caused them to drop to about 550 gauss:
|
|
|
Post by antigua on Jul 12, 2019 18:08:25 GMT -5
Hi Antigua! I have some questions: 1. How to determine if a magnet (say Alnino 5 or 2) is fully charged? Do you know the values (in Gauss)? 2. If I try to degauss an Alnico5 with an Alnico 5 (agent), how can I be sure that the non-agent will be degaussed instead of the agent? 3. Can I gauss/degauss Alnicos directly using neodymium? Thank you! 1) if you have a Guassmeter on hand you can determine the full strength by saturating the AlNiCo with a neodymium, waiting about 15 minutes for it to settle, and then see what it reads. Strat pickup pole pieces usually max out around 1100G, but will read as high as 1300G immediately after a fresh charging with neodymium. The exact strength is dependent on the geometry of the magnet, shorter/wider AlNiCo will read weaker than taller/thinner AlNiCo due to the low coercivity of AlNiCo making it's strength very geometry dependent. 2) when you use AlNiCo 5 to degauss AlNiCo 5, both of them will be mutually degaussed, and that's part of what makes it work well, the agent loses strength, so the target is never fully de-saturated, either. 3) You can charge or gauss AlNiCo with neodymium, and that's how you would charge the agent AlNiCo, and/or fully charge the target pole pieces, if thats what you wanted to do. The problem the "agent" solves is that it's very difficult to partially degauss AlNiCo with a neodymium, because it's so powerful that it will entirely flip the polarity of the AlNiCo. Suppose you have AlNiCo 5 pole pieces that reads 1000 gauss and you want to reduce it to 500 gauss, using a second AlNiCo pole piece as an agent will take the target from 1000G down to 500G, but if you try it with neodymium, because it's so powerful, it will overshoot 500, and even 0, going from 1000G to -1000G, which is to say, it's polarity will reverse from north to south (or south to north), and it will still be fully charged. Does that make sense?
|
|
|
Post by pablogilberto on Jul 13, 2019 11:05:38 GMT -5
Hi Antigua! I have some questions: 1. How to determine if a magnet (say Alnino 5 or 2) is fully charged? Do you know the values (in Gauss)? 2. If I try to degauss an Alnico5 with an Alnico 5 (agent), how can I be sure that the non-agent will be degaussed instead of the agent? 3. Can I gauss/degauss Alnicos directly using neodymium? Thank you! 1) if you have a Guassmeter on hand you can determine the full strength by saturating the AlNiCo with a neodymium, waiting about 15 minutes for it to settle, and then see what it reads. Strat pickup pole pieces usually max out around 1100G, but will read as high as 1300G immediately after a fresh charging with neodymium. The exact strength is dependent on the geometry of the magnet, shorter/wider AlNiCo will read weaker than taller/thinner AlNiCo due to the low coercivity of AlNiCo making it's strength very geometry dependent. 2) when you use AlNiCo 5 to degauss AlNiCo 5, both of them will be mutually degaussed, and that's part of what makes it work well, the agent loses strength, so the target is never fully de-saturated, either. 3) You can charge or gauss AlNiCo with neodymium, and that's how you would charge the agent AlNiCo, and/or fully charge the target pole pieces, if thats what you wanted to do. The problem the "agent" solves is that it's very difficult to partially degauss AlNiCo with a neodymium, because it's so powerful that it will entirely flip the polarity of the AlNiCo. Suppose you have AlNiCo 5 pole pieces that reads 1000 gauss and you want to reduce it to 500 gauss, using a second AlNiCo pole piece as an agent will take the target from 1000G down to 500G, but if you try it with neodymium, because it's so powerful, it will overshoot 500, and even 0, going from 1000G to -1000G, which is to say, it's polarity will reverse from north to south (or south to north), and it will still be fully charged. Does that make sense? Thank you for your answers. This clarifies a lot of things to newbies like me. I have some follow-up questions: A. My mojotone pickup winder just arrived. It as a built-in Gauss meter. Do you have an idea if its well calibrated and accurate? B. I have seen some pickups advertised as “vintage output” which means lower level output, does this mean that the magnets used are partially degaussed? C. Based from what I have read, if I have 2 SC pickups with the same LRC values (esp Inductance which is directly affects the resonant frequency), they will sound 90% the same. (Please correct me if this is wrong). What will be the effect if this 2 pickups differ in Gauss values? Thanks in advance!
|
|
|
Post by antigua on Jul 14, 2019 2:33:11 GMT -5
1) if you have a Guassmeter on hand you can determine the full strength by saturating the AlNiCo with a neodymium, waiting about 15 minutes for it to settle, and then see what it reads. Strat pickup pole pieces usually max out around 1100G, but will read as high as 1300G immediately after a fresh charging with neodymium. The exact strength is dependent on the geometry of the magnet, shorter/wider AlNiCo will read weaker than taller/thinner AlNiCo due to the low coercivity of AlNiCo making it's strength very geometry dependent. 2) when you use AlNiCo 5 to degauss AlNiCo 5, both of them will be mutually degaussed, and that's part of what makes it work well, the agent loses strength, so the target is never fully de-saturated, either. 3) You can charge or gauss AlNiCo with neodymium, and that's how you would charge the agent AlNiCo, and/or fully charge the target pole pieces, if thats what you wanted to do. The problem the "agent" solves is that it's very difficult to partially degauss AlNiCo with a neodymium, because it's so powerful that it will entirely flip the polarity of the AlNiCo. Suppose you have AlNiCo 5 pole pieces that reads 1000 gauss and you want to reduce it to 500 gauss, using a second AlNiCo pole piece as an agent will take the target from 1000G down to 500G, but if you try it with neodymium, because it's so powerful, it will overshoot 500, and even 0, going from 1000G to -1000G, which is to say, it's polarity will reverse from north to south (or south to north), and it will still be fully charged. Does that make sense? Thank you for your answers. This clarifies a lot of things to newbies like me. I have some follow-up questions: A. My mojotone pickup winder just arrived. It as a built-in Gauss meter. Do you have an idea if its well calibrated and accurate? B. I have seen some pickups advertised as “vintage output” which means lower level output, does this mean that the magnets used are partially degaussed? C. Based from what I have read, if I have 2 SC pickups with the same LRC values (esp Inductance which is directly affects the resonant frequency), they will sound 90% the same. (Please correct me if this is wrong). What will be the effect if this 2 pickups differ in Gauss values? Thanks in advance! Im not sure how accurate the Mojotone gaussmeter is, but it doesn't have to be real accurate in order to be useful. A lot of people have this winder and I haven't seen complaints about the gaussmeter so I'd guess that it's fine. I don't use it because I already have a few others aside. I don't think there are any pickups on the market with intentionally degaussed magnets. It's not really easy to reliably degauss AlNiCo to a particular degree, especially not en mass. When AlNiCo is degaussed, it becomes less stable and more likely to degauss further, due to temperature change or physical shock, so it's not really a good idea to sell pickups with degaussed pickups, but as we do something ourselves at home, I think it's fine. If by chance the magnets become too weak, we can just recharge them with a neodymium magnet, but most guitarists out there wouldn't want to bother with such things. If two pickups with the same RLC values are the same but have different magnetic strengths, the difference in sound will be very similar to the difference you hear when you raise or lower pickups, because in either case the magnetic coupling between the coil and the guitar string is either made stronger or weaker. Weaker magnetic pull causes less interference with the vibrating string. Less magnetic pull means the string vibrates more like it would if there were no pickup there at all. A stronger magnetic pull interferes with the string, causing it to vibrate asymmetrically, because there is a pull on one side, but not the other. That asymmetry leads to an intermodulation as seen here guitarnuts2.proboards.com/thread/8002/analyzing-wolf-tone-effect-spectrogram . The subtle beating caused by the intermodulation is like a mild chorus-like effect. Magnetic pull also slightly changes the harmonic amplitudes, because the guitar string is divided into harmonic segments, and having the magnetic pull on one segment more than another shifts the kinetic energy from one harmonic level to another. I did experiments with this in this thread guitarnuts2.proboards.com/thread/7998/tonal-effect-pickup-height . What I found was that increased magnetic pull generally shifts energy into the higher harmonics (the narrower segments), leading to slightly more treble in the output. So, all together, more magnetic pull means you get a mild chorus effect, and an increase of treble. Keep in mind that when you have staggered pole pieces, like a vintage Strat pickup, since the G and D pole pieces are especially close to the strings already, they tend to become especially prominent in the overall output when the pickup is set close to the strings. Note that while inductance mostly determine the peak frequency, it's actually both inductance and capacitance, L and C, but because C is very small and L is very large, most the of the determination comes from L. See this equation: frequency = 1 / (2 * pi * sqrt(L * C)) The part that says "L * C" shows that L and C are equally important, it's only because a guitar coil has about 8,000 turns of wire that L becomes very large relative to C, and therefore becomes so prominent. If you intentionally put a 20nF capacitor across a pickup, then suddenly the capacitance is also very large and the resonant peak drops significantly.
|
|
|
Post by pablogilberto on Aug 8, 2019 4:02:02 GMT -5
Thank you so much for this info.
I am really learning a lot. It took me a while to digest everything. Apologies for the late reply.
Many thanks! Appreciate your help.
|
|
|
Post by aquin43 on Aug 16, 2019 8:17:13 GMT -5
I just rebalanced a Fender Noiseless N3 on an American Deluxe Strat by more or less demagnetising the B pole. The staggered pole pieces were intended to balance the volume of the strings but with a nickel wound set with a wound third, the second string was, nonetheless, always too loud. An earlier experiment with removing a pole from a Creamery pickup with screw in magnet poles had shown that complete removal of the pole left the string working but slightly weak, magnetised only by the leakage field from the adjacent magnets but with no pole to receive the signal flux. Demagnetising the pole while leaving it in place seems to do exactly what I required. I used a 30mm long stack of 4mm diameter, 3mm long neo magnets. The magnets in the pickup are long, so I would guess that the lower part retained some of the original magnetism while the neos were in contact. This was an uncontrolled experiment with no flux measurement, just the subjective result of the rebalancing.
Arthur
|
|
markm
Rookie Solder Flinger
Posts: 21
Likes: 2
|
Post by markm on Sept 10, 2019 0:45:22 GMT -5
I just wanted to add that I got a set of pickups a year or so ago with "aged" A2 poles. They had a very clear sort of Eric Johnson type sound, but were the weakest output by far from my other guitars. After swapping them out I did some measurements and saw that the inductance was actually quite high. I had a little epiphany and charged them up from some big neodymium disks. Today I tried them out again and had done of those fun little jams that make me shout when I'm done because I feel so pumped. #2 provides such a great inductance boost over #5, I think it may be my new favorite - but I like it fully charged for a great blues/rock sound. If you're looking for a really clean fingerpicking sound then maybe the degauss option would be appealing.
|
|
|
Post by antigua on Sept 10, 2019 18:46:30 GMT -5
I've subjectively observed that a high inductance pickup with a very weak magnetic coupling to the strings has a thin sound, more associated with a low inductance pickup. Experimental data has never really given any confirmation of this. I've done FFT analysis of pickup near and far to the strings and haven't seen any uniform obvious change in the curve, and this is more or less what I was looking for. What I thought I heard with my ears just didn't show up in a spectrogram. What did show up in the spectrogram was variation in harmonic intermodulation and beating as a result of the stronger magnetic pull causing asymmetrical in the guitar string. I didn't see any particular gutting of the lower mid range, or increase in the treble range.
It could possibly be attributed to Fletcher Munson curves, but I could turn the amp up and that wouldn't erase the effect. It could be perception based, though. Rather than say this as an effect science hasn't explain, we haven't even yet established that there is an effect there for science to explain.
|
|
mozz
Rookie Solder Flinger
Posts: 6
Likes: 1
|
Post by mozz on Nov 29, 2019 19:45:48 GMT -5
I have 2 different style degaussers used for erasing audio cassettes and another for demagnetizing reel to reel heads. I can measure before and after.
My question is, on a actual old strat, how much do these magnets actually lose if any? I thought i read after the initial magnetization, they only lose 1-2% over the course of 100 years.
I have also read Fender charged these with some sort of electromagnet that was hooked up to a car battery, the battery would discharge over time and would have to be recharged from time to time.
|
|
|
Post by antigua on Nov 30, 2019 0:03:53 GMT -5
I have 2 different style degaussers used for erasing audio cassettes and another for demagnetizing reel to reel heads. I can measure before and after.
My question is, on a actual old strat, how much do these magnets actually lose if any? I thought i read after the initial magnetization, they only lose 1-2% over the course of 100 years.
I have also read Fender charged these with some sort of electromagnet that was hooked up to a car battery, the battery would discharge over time and would have to be recharged from time to time.
I've never surveyed old pickups for Gauss strength, so I don't have any first hand direct data to work with. But as far as I can tell, nobody else does, either. A guitar shop in my city has a bunch of vintage Fenders, but I don't think they would let me go near them with a Gauss meter, they might worry that it would somehow ruin their twenty thousand dollar guitar. I know that AlNiCo loses about 10% of it's residual flux in the first few minutes after charging, and then is stable for a long time thereafter, provided it doesn't take shocks or heat changes, but that's the rub, a lot of vintage guitars probably did experience extreme heat changes, and they definitely got banged up.
|
|
yanyan
Meter Reader 1st Class
Posts: 52
Likes: 2
|
Post by yanyan on Dec 6, 2019 4:38:47 GMT -5
I apologize for being uninformed, but do ceramic magnets also degauss over time? Are they susceptible to shocks and temperature changes causing them to degauss?
|
|
|
Post by antigua on Dec 6, 2019 16:26:59 GMT -5
I apologize for being uninformed, but do ceramic magnets also degauss over time? Are they susceptible to shocks and temperature changes causing them to degauss? This chart shows how much magnetic "coercive force" is required H in order to achieve a permanent flux B, you can see how AlNiCo 5 requires little coercion in order to achieve a high permanent residual flux, which means it's a strong magnet but it's can also be demagnetized or have it's polarity reversed a lot easier than all of the other magnet types shown.
|
|
|
Post by b4nj0 on Dec 6, 2019 16:28:14 GMT -5
Entropy. Dust unto dust. Everything succumbs to the Second Law of Thermodynamics eventually (even radio active isotypes have a half life) and magnets are not immune whichever brew they're distilled from. If we look at it from a human perspective, it seems fair to guess that some magnet types would retain their strength for longer than others and I think that is what your question implies? I don't keep such league tables in my head but Google will no doubt assist there. As I think you suspected, knocks will speed up the process.
e&oe ...
|
|
|
Post by antigua on Dec 6, 2019 18:08:42 GMT -5
New idea for an experiment; subject AlNiCo pole pieces to various conditions and see what, if anything causes them to lose charge. My suspicion is that it would take extreme shock and temperature changes. AlNiCo was used industrial machinery, where heat changes and shock would be expected.
I've never seen direct evidence that old AlNiCo magnets lost charge, and even if it were observed, it could never be established that they were not fully saturated to begin with. Setting a guitar in front of loud speakers would not present enough H force to degauss the AlNiCo. You would have to place the pickups within an inch of so of the speaker's magnets, along their axis.
|
|
yanyan
Meter Reader 1st Class
Posts: 52
Likes: 2
|
Post by yanyan on Dec 8, 2019 7:41:25 GMT -5
This chart shows how much magnetic "coercive force" is required H in order to achieve a permanent flux B, you can see how AlNiCo 5 requires little coercion in order to achieve a high permanent residual flux, which means it's a strong magnet but it's can also be demagnetized or have it's polarity reversed a lot easier than all of the other magnet types shown.So, if i'm understanding this correctly (electronics idiot here), to "charge" a ceramic magnet to about 4000 gauss, it must be subject to a field of about 3000 oersteds? If more B is required, then H must simply be increased? How does this relate to aging of ceramic magnets causing them to degauss? Also, at the risk of going off-topic, i was worried about something that i did when i installed my pickups some 23 years ago. I didn't know better and i used a 100-watt Weller soldering gun. As far as i can remember, i didn't move the gun closer than about 2-3 inches to the pickups. To what kind of danger did i expose my new (at the time) pickups? Do you suppose there has been any lasting damage? They've sounded fine for 23 years, but i have no way to know if they're not actually sounding "at their best", as they would be if they weren't carelessly exposed to a soldering gun or other strong H source. Am i just overthinking?
|
|
|
Post by b4nj0 on Dec 8, 2019 13:50:04 GMT -5
I was left with no option than to use a Weller 100 Watt gun to change the gold cover in favour of a nickel one on a P90. When I reassembled it there was no audio output and you can guess what I first thought? However, I had approached it with the logic of a degausser which works by decaying hysterisis loops as you gradually move the magnetic field away from the head, so I held that gun stationary when I finished the soldering. In the end it turned out to be a switched amplifier input socket used on the guitar by the maker and the tab I really wanted was obscured from view beneath wood. It rang out OK but no sound <when plugged in> which really had me scratching my head. From my unrepresentative experience I would hazard a guess that you may be OK, but the general approach still ought to be one of avoiding soldering guns near magnets.
e&oe ...
|
|
|
Post by antigua on Dec 8, 2019 13:54:37 GMT -5
This chart shows how much magnetic "coercive force" is required H in order to achieve a permanent flux B, you can see how AlNiCo 5 requires little coercion in order to achieve a high permanent residual flux, which means it's a strong magnet but it's can also be demagnetized or have it's polarity reversed a lot easier than all of the other magnet types shown.So, if i'm understanding this correctly (electronics idiot here), to "charge" a ceramic magnet to about 4000 gauss, it must be subject to a field of about 3000 oersteds? If more B is required, then H must simply be increased? How does this relate to aging of ceramic magnets causing them to degauss? Also, at the risk of going off-topic, i was worried about something that i did when i installed my pickups some 23 years ago. I didn't know better and i used a 100-watt Weller soldering gun. As far as i can remember, i didn't move the gun closer than about 2-3 inches to the pickups. To what kind of danger did i expose my new (at the time) pickups? Do you suppose there has been any lasting damage? They've sounded fine for 23 years, but i have no way to know if they're not actually sounding "at their best", as they would be if they weren't carelessly exposed to a soldering gun or other strong H source. Am i just overthinking? I got that graph from here www.kjmagnetics.com/bhcurves.asp , I think it's just meant to be illustrative, the actual values needed are temperature dependent. They charge neodymium and ceramic magnets while they're still at a high temperature, and the magnetic particles are still free to move easily, then the material cools and the're locked into place with a particular magnetic orientation, and that temperature dependence is part of the reason they're so strong. AlNiCo, on the other hand, is much more heat resilient, because the way it maintains magnetic orientation is not as heat dependent, but the trade off is that they have different weaknesses, such as having a low coercivity, and being very brittle.
|
|
|
Post by gckelloch on May 24, 2021 2:38:08 GMT -5
Reviving this old thread with some info that may be useful. I'm thinking that part of the reason different AlNiCo grades produce a different note timbre with the same coil is that permeability differences cause the lines to vibrate through the coil differently depending on how much the lines are pulled toward the core i.e more magnetic flux toward the middle of the coil with AlNiCo II or III vs V. The angle of the lines moving through the coil may also cause some cancelations depending on pickup height? This recent blog entry by Scott Lawing may shed some light on the subject, and is worth the read none the less. I really like how he explains things simply and with a touch of good humor: lawingmusicalproducts.com/dr-lawings-blog/the-wide-range-humbucker-and-the-genius-of-seth-lover
|
|
|
Post by ms on May 24, 2021 6:46:14 GMT -5
Reviving this old thread with some info that may be useful. I'm thinking that part of the reason different AlNiCo grades produce a different note timbre with the same coil is that permeability differences cause the lines to vibrate through the coil differently depending on how much the lines are pulled toward the core i.e more magnetic flux toward the middle of the coil with AlNiCo II or III vs V. The angle of the lines moving through the coil may also cause some cancelations depending on pickup height? This recent blog entry by Scott Lawing may shed some light on the subject, and is worth the read none the less. I really like how he explains things simply and with a touch of good humor: lawingmusicalproducts.com/dr-lawings-blog/the-wide-range-humbucker-and-the-genius-of-seth-lover Yes, I think that Scot is performing a real public service with his explanations, especially the idea that it is the magnetization of the string, induced by the pickup permanent magnet, that counts. The implication is that the field of the permanent magnet matters only where the string is. For some reason this idea upsets a lot people. I like his quotes from Seth Lover that show that Seth understood these ideas, providing support from one of the "pickup gods". I think the most important effect of different permeability material is to change how much voltage the current in one loop of wire induces in the other loops. That is, it is altering the inductance, changing the resonant frequency, and thus the "filter function" applied to the signal from the string.
|
|
|
Post by antigua on May 24, 2021 12:07:01 GMT -5
Reviving this old thread with some info that may be useful. I'm thinking that part of the reason different AlNiCo grades produce a different note timbre with the same coil is that permeability differences cause the lines to vibrate through the coil differently depending on how much the lines are pulled toward the core i.e more magnetic flux toward the middle of the coil with AlNiCo II or III vs V. The angle of the lines moving through the coil may also cause some cancelations depending on pickup height? This recent blog entry by Scott Lawing may shed some light on the subject, and is worth the read none the less. I really like how he explains things simply and with a touch of good humor: lawingmusicalproducts.com/dr-lawings-blog/the-wide-range-humbucker-and-the-genius-of-seth-lover You mentioned the word timbre specifically, what differentiates timbre is relative amplitudes of harmonics, not merely the presence of harmonics. Some of the effects being discussed that relate to pickup geometry cause distortions, where it piles on higher harmonics, but it doesn't change the timbre much. Where the pickups is placed changes the timbre, because the string has nodes and anti-nodes and the location of the pickup intersects differently with them depending on where it's aligned, so the neck and bridge positions sound very different. I think what the magnet can do to affect the timbre is also related to the guitar string, and this has been demonstrated with spectrograms of recordings, if the magnet is stronger, it pulls on the string more, and it created asymmetry across the guitar string. That causes it's vibration pattern to become non-uniform, and the result is the creation of harmonics. Interestingly though, it doesn't increase harmonics uniformly, unless the string pull is towards the ends of the strings, it increases harmonics that correspond the pickup's position along the string, like a pinch harmonic, but much lighter. Since the increase in harmonics is non-uniform, and based on the positions of the magnets / pickup, the timbre will change slightly also. The harmonics caused by string pull could plausibly be an amplitude dependent effect, since when the string is first plucked and it displaces more, it comes closer to the strongest region of the magnetic field over the pole piece, but then the displacement shrinks as is loses energy and it's no longer coming in as close the strongest portion of the magnets field. So I think what happens with a weaker AlNiCo with a higher permeability is that the string pull is weaker, but the higher permeability causes the overall voltage output to be the same despite the decreased magnetic strength. And of course, the higher permeability increases the inductance, which in a Fender style single coil is a non-trivial increase. I think steel pole pickups follow the same pattern, but even more dramatically.
|
|
|
Post by gckelloch on May 24, 2021 19:38:25 GMT -5
Thanks for replying, guys. Lover's WRH is a marked improvement over the imbalanced and high impedance core of the PAF design.
Yes, I now understand how the asymmetry produces artificial harmonics.
In another of Dr. Lawing's simulations the outer flux lines coming from the strings turn back up more in the coil with a lower permeability core. I'm thinking the difference in polarity of the lines going through the outer vs inner part of the coil, in conjuction with how they interact with the field eminating from the core, may create some cancelation at certain frequencies.
Regarding note timbre at given coil height, one only need lower the coil height and then raise the pole screws to equalize the magnetic force in the strings on a P90 (or the Nd-Microcoils) to hear a relative loss of lower harmonic "warmth". I doubt it has much to do with a change in the window aperture, but that could be a factor. I adjust pickup and pole screw heights to less than 1/8 a screw turn in some cases. The difference in note timbre and transient character is audible and can significantly alter how I feel about a pickup.
Incidentely, I recently found an old post on TDPRI by the late Bill Lawrence in which he mentioned that vacuum (sintered?) AlNiCO II is essentially like AlNiCu III, albiet more stable. That may be common knowledge by now, but I see no reason anymore to use AlNiCO V poles considering the drawbacks.
|
|
|
Post by antigua on May 25, 2021 0:03:02 GMT -5
Thanks for replying, guys. Lover's WRH is a marked improvement over the imbalanced and high impedance core of the PAF design. Yes, I now understand how the asymmetry produces artificial harmonics. In another of Dr. Lawing's simulations the outer flux lines coming from the strings turn back up more in the coil with a lower permeability core. I'm thinking the difference in polarity of the lines going through the outer vs inner part of the coil, in conjuction with how they interact with the field eminating from the core, may create some cancelation at certain frequencies. Regarding note timbre at given coil height, one only need lower the coil height and then raise the pole screws to equalize the magnetic force in the strings on a P90 (or the Nd-Microcoils) to hear a relative loss of lower harmonic "warmth". I doubt it has much to do with a change in the window aperture, but that could be a factor. I adjust pickup and pole screw heights to less than 1/8 a screw turn in some cases. The difference in note timbre and transient character is audible and can significantly alter how I feel about a pickup. Incidentely, I recently found an old post on TDPRI by the late Bill Lawrence in which he mentioned that vacuum (sintered?) AlNiCO II is essentially like AlNiCu III, albiet more stable. That may be common knowledge by now, but I see no reason anymore to use AlNiCO V poles considering the drawbacks. I think the especially strong magnetic pull of the AlNiCo 5 plays a part in their distinctive sound. In fact, AlNiCo 5 is the only common style of pole piece that is strong enough to actually cause string "warble" if you get it too close to the strings. All other pickups, including Strat pickups with AlNiCo 2 and 3, of of the variety that is incapable of doing that. And this one of those times where I don't have to say I "think" it makes a difference, the difference can be seen in a spectrogram. I like the sound of Strat pickup s with AlNiCo 2 or 3 that are under-wound enough do where the inductance remains close to 2.4 henries, despite the higher permeability of the core, but they still don't have the bite of a pickup with AlNiCo 5 pole pieces. As far as cancellations due to how the magnetized string intersects with the coil, you'd have to have a situation where the coil was enclosing more of the return path than the primary path, but because the magnetizing agent itself is in the core of the coil, the string isn't going to magnetize in such a way that allows that to happen.
|
|
|
Post by gckelloch on May 27, 2021 16:05:56 GMT -5
That’s a good point about more bite, but I find the stronger intermodulations and harsh attack of the AlNiCo V pole pickups I’ve used to be too much at the pickup heights I like. More bite can be achieved with a hard sharp pick.
I just got some Bog Street “Ultem-Tak” picks on recommendation from R.J. Ronquillo (awesome R&B/soul style session player on YT). They offer 3 model sizes at 3 thicknesses with a “Textured” bevel option on the 0.6-2mm “Medium” thickness which excites more high harmonics for more bite without the intermodulations. I got the “Axe Blade” size textured option because the larger “Axe Cut” model might feel clunky. What I like about these picks is the hole in the center with the embossed grip allows me to relax my grip. I also like the sharper geometry than the Dunlop Ultex Triangle picks, and the 0.6mm rounded side is great for rhythm playing. It’s a really well-engineered pick, and not expensive considering what you get. Two sharp sides is like an extra pick for the money. I’m not trying to push a product, but I thought it relevant to the discussion...and ya’know: new picks!
|
|