Results 1 to 25 of 25
Like Tree6Likes
  • 1 Post By Mark Hammer
  • 1 Post By Mike Sulzer
  • 3 Post By Mark Hammer
  • 1 Post By David Schwab

Thread: 30-year project almost done, but not quite - problem with neos?

  1. #1
    Senior Member
    Join Date
    May 2006
    Posts
    3,404

    30-year project almost done, but not quite - problem with neos?

    I bought a nice pre-war Kalamazoo KG-21 in 1985 or 86. It was desperately crying out for a neck pickup, but the lack of clearance between the strings and body (around 3.8") made finding a commercially available unit just about impossible. And I sure as hell wasn't going to cut a hole in it to install something, OR use a piezo bridge pickup as so many suggested.

    I had several unsuccessful attempts to wind myself a suitably-sized unit, but they fell apart. Finally, earlier this week, I finished a working pup. I used some very small neodymium buttons that I got from Lee Valley Tools, and some #43 green insulated wire from Elektrisola.

    The flatwork is very thin fibreglass PCB board, with the magnets glued with cyanoacrylate to the flatwork to form the bobbin. I was having a devil of a time gluing the magnets into place, since trying to glue additional magnets after the first one would always result in the additional magnets flipping out of place before the glue dried, because they were too close to the glued one/s. Forum regular David Schwab gave me a great tip to place the flatwork on top of my bench vice, so that the tug between mag and iron vice would be great enough to "convince" the button mags to stay where they were glued until the glue dried. Worked like a charm. The aperture for winding between upper and lower flatwork is around 7/32". Nudged up against neck, it sits level with the end of the fingerboard. The top and bottom are smooth copper, facing outward, so I can't see where the magnets are.

    With no particular tonal goal in mind, since the shape/size would not be like anything else, my goal was to simply wind until I couldn't fit any more wire on, and see where that got me. With the aperture for winding being so slender, there was no way I could use anything mechanical to wind without snagging the wire, unless I wanted to lay out for precision equipment, and that seemed a little extravagant for one pickup. So, I wound by entirely hand. Meh, it was something to do while sitting in the living room as my wife made her way through the shows she had PVR'd.

    The DCR of the resulting coil came out to be 1.9k, which will be compatible with the 100k thumbwheel volume pot I have planned to use. Normally, a 100k volume pot would load down a pickup, but since the intent is to magically transform me into Grant Green , loading is good. I potted it with candle wax, which in itself was kind of tricky. Wired it up, and taped it to the guitar top. Changed the strings over from bronze acoustic to some DR "zebra" electro-acoustics, and plugged in. Sounds alright, but here's the reason for the post: the B is too loud, and the high E is too quiet. I see on pictures of the "Charlie Christian" pickup on the ES-150 that the blade is lower under the B string than for the other 5 strings. So I'm guessing that I am not the first person to experience such a volume discrepancy. However, it's not just the louder B, but the quieter E.

    I tried repositioning the PU, thinking that perhaps not being able to see the magnets under the flatwork, I had erroneously misaligned the pickup and strings. But moving it around did not change things.

    So what I'm wondering is whether there is something amiss with the button mag used for the polepiece of the high E. After several failed attempts in past years, might I have stored it in a way that resulted in its' strength being diminished? If so, is it possible to "recharge" it with a stronger neo? Or are neos the sort of thing that remain stable over the long haul in spite of any sort of contaminating factors?

    Now that I've done it once, I'm not averse to trying again, and building a second unit (hopefully taking much less than 30 years), though the minimal clearance aspect makes accomplishing something like the differential proximity of the ES-150 pickup difficult to achieve. But I'm wondering if there is something I could do to achieve more uniform string levels.

  2. #2
    Supporting Member
    Join Date
    Sep 2007
    Posts
    2,756
    Mark, congratulations on getting the job done! It is very unlikely that a neo got demagnetized unless the plating got damaged and the material corroded, but you would have noticed that since it is not pretty. My only suggestion would be to leave the magnet on the high E as is and use smaller diameter buttons on the rest, varying as needed to make it work out. You might not hit it right on the next try, but I bet it will get a lot better. K&J Magnetics has hundreds of different sizes of buttons, if you have not checked them.

    Also, neo does come in a couple of grades. Is it possible you got one from the weaker grade and the rest are stronger? I kind of of doubt this, but you might be able to check it you have access to a gauss meter with a small probe.

    Speaking of corrosion, I have noticed that guitar players are not good for neodymium magnets; they should be protected as yours seems to be since they are between two pieces of board. But it might not be a bad idea to wax pot it for long life as well.

    Quote Originally Posted by Mark Hammer View Post
    I bought a nice pre-war Kalamazoo KG-21 in 1985 or 86. It was desperately crying out for a neck pickup, but the lack of clearance between the strings and body (around 3.8") made finding a commercially available unit just about impossible. And I sure as hell wasn't going to cut a hole in it to install something, OR use a piezo bridge pickup as so many suggested.

    I had several unsuccessful attempts to wind myself a suitably-sized unit, but they fell apart. Finally, earlier this week, I finished a working pup. I used some very small neodymium buttons that I got from Lee Valley Tools, and some #43 green insulated wire from Elektrisola.

    The flatwork is very thin fibreglass PCB board, with the magnets glued with cyanoacrylate to the flatwork to form the bobbin. I was having a devil of a time gluing the magnets into place, since trying to glue additional magnets after the first one would always result in the additional magnets flipping out of place before the glue dried, because they were too close to the glued one/s. Forum regular David Schwab gave me a great tip to place the flatwork on top of my bench vice, so that the tug between mag and iron vice would be great enough to "convince" the button mags to stay where they were glued until the glue dried. Worked like a charm. The aperture for winding between upper and lower flatwork is around 7/32". Nudged up against neck, it sits level with the end of the fingerboard. The top and bottom are smooth copper, facing outward, so I can't see where the magnets are.

    With no particular tonal goal in mind, since the shape/size would not be like anything else, my goal was to simply wind until I couldn't fit any more wire on, and see where that got me. With the aperture for winding being so slender, there was no way I could use anything mechanical to wind without snagging the wire, unless I wanted to lay out for precision equipment, and that seemed a little extravagant for one pickup. So, I wound by entirely hand. Meh, it was something to do while sitting in the living room as my wife made her way through the shows she had PVR'd.

    The DCR of the resulting coil came out to be 1.9k, which will be compatible with the 100k thumbwheel volume pot I have planned to use. Normally, a 100k volume pot would load down a pickup, but since the intent is to magically transform me into Grant Green , loading is good. I potted it with candle wax, which in itself was kind of tricky. Wired it up, and taped it to the guitar top. Changed the strings over from bronze acoustic to some DR "zebra" electro-acoustics, and plugged in. Sounds alright, but here's the reason for the post: the B is too loud, and the high E is too quiet. I see on pictures of the "Charlie Christian" pickup on the ES-150 that the blade is lower under the B string than for the other 5 strings. So I'm guessing that I am not the first person to experience such a volume discrepancy. However, it's not just the louder B, but the quieter E.

    I tried repositioning the PU, thinking that perhaps not being able to see the magnets under the flatwork, I had erroneously misaligned the pickup and strings. But moving it around did not change things.

    So what I'm wondering is whether there is something amiss with the button mag used for the polepiece of the high E. After several failed attempts in past years, might I have stored it in a way that resulted in its' strength being diminished? If so, is it possible to "recharge" it with a stronger neo? Or are neos the sort of thing that remain stable over the long haul in spite of any sort of contaminating factors?

    Now that I've done it once, I'm not averse to trying again, and building a second unit (hopefully taking much less than 30 years), though the minimal clearance aspect makes accomplishing something like the differential proximity of the ES-150 pickup difficult to achieve. But I'm wondering if there is something I could do to achieve more uniform string levels.

  3. #3
    Senior Member
    Join Date
    May 2006
    Posts
    3,404
    Thanks for your reply and encouragement Mike. Much appreciated.

    I source my magnets locally, since getting anything over the border often becomes onerous with various surprise brokerage fees. But I'll check into K&J. The limitation created by sourcing locally is that diameter and thickness tend to be highly correlated; getting something a little wider in diameter is unlikely to be available with the same thickness. What I was sort of wondering was whether there might be any sort of material I might be able to get in thin sheet form, that would allow me to place a thin piece on top of the B-string magnets to reduce its sensitivity. Can one get/use mu-metal or something similar?

    Alternatively can one degauss one of those little buttons for use under the B?

  4. #4
    Supporting Member
    Join Date
    Sep 2007
    Posts
    2,756
    I do not think you have enough space to do shielding. Controlled degaussing would be very difficult and might not be stable with other magnets around. These things are so small and cheap there must be some way you can get them!

    Quote Originally Posted by Mark Hammer View Post
    Thanks for your reply and encouragement Mike. Much appreciated.

    I source my magnets locally, since getting anything over the border often becomes onerous with various surprise brokerage fees. But I'll check into K&J. The limitation created by sourcing locally is that diameter and thickness tend to be highly correlated; getting something a little wider in diameter is unlikely to be available with the same thickness. What I was sort of wondering was whether there might be any sort of material I might be able to get in thin sheet form, that would allow me to place a thin piece on top of the B-string magnets to reduce its sensitivity. Can one get/use mu-metal or something similar?

    Alternatively can one degauss one of those little buttons for use under the B?

  5. #5
    Senior Member
    Join Date
    May 2006
    Posts
    3,404
    What I was thinking of was just a small slip of mu-metal foil over the B-string magnet (and I might be misunderstanding the way that magnetic shielding works, so go easy on me) that would not occupy enough space to radically change the height/thickness of the pickup.

  6. #6
    Senior Member
    Join Date
    Jan 2009
    Posts
    577
    Quote Originally Posted by Mark Hammer View Post
    What I was thinking of was just a small slip of mu-metal foil over the B-string magnet (and I might be misunderstanding the way that magnetic shielding works, so go easy on me) that would not occupy enough space to radically change the height/thickness of the pickup.
    Hi
    A good way to alter the strength of the magnet is to slip a reversed polarity magnet near to the magnet that is too loud. You will find the nearer you move the reverse polarized magnet to the offending magnet the more the the volume drops. There is a guy called Elmar Flatpup history here in Vienna who makes flat thin humbuckers and uses this technique to great effect, (hats off to him)

    Cheers

    Andrew

  7. #7
    rjb
    rjb is offline
    Old Timer
    Join Date
    Feb 2010
    Location
    Somewhere near Bawlmer, Merlin
    Posts
    1,771
    I have a Harmony Patrician with similar neck clearance- which I outfitted with a thin, modified & pickguard-mounted DeArmond soundhole pickup. Not quite happy with the sound, I've also been considering DIY alternatives for "a while" - although not quite 30 years. Since I haven't actually gotten around to building anything, all of the following is speculation.

    • The "reversed polarity magnet trick" works- if you have enough clearance for another magnet on top of your pickup.
      You may be able to balance the string volumes by using a fatter E string, and a slip of thin steel (no need for exotic mu metal) over the B string magnet.
      The K&J Steel Plate Thickness Calculator may help visualize the shielding effect. (If not, it's still kinda fun to play with.)
      https://www.kjmagnetics.com/thickness.calculator.asp
      |
    • You could avoid the "jumping magnets" problem by making your bottom flange of mild steel (probably about 0.030" thick for maximum "stickitivity".)
      Again, see the K&J steel plate thickness calculator.
      DeArmond used this method in their thin "gold foil" and other pickups.
      |
    • Elmar's "Flatpup" design is also interesting- and has the advantage of being humbucking.


    Have fun,
    -rb

  8. #8
    Senior Member
    Join Date
    May 2006
    Posts
    3,404
    Holy mackeral! Just for the heck of it, based on your suggestion, I took a small X-acto knife blade I had, and laid it over top of the B-string magnet. Instant volume reduction. Next, I slid it over a bit so that it waslying on top of the B and E string magnets, but not the others, and it not only tamed the B sring, but also evened out the volume between B and E.

    I wouldn't have believed it until hearing with my own ears. Wonderful! So now I have to pick up some more magnets tomorrow, make some wider flatwork to accommodate a bigger coil, and straddle the B and E magnets with a little slip of steel.

    Thanks for the idea!!
    kayakerca likes this.

  9. #9
    rjb
    rjb is offline
    Old Timer
    Join Date
    Feb 2010
    Location
    Somewhere near Bawlmer, Merlin
    Posts
    1,771
    Quote Originally Posted by Mark Hammer View Post
    Holy mackeral!
    |
    Thanks for the idea!!
    You're welcome. I'm glad it worked. Boy, was that a lucky guess!
    When I do get around to making a pickup for the Patrician, I'll have to remember "the X-acto blade trick"!
    Last edited by rjb; 02-25-2017 at 03:50 AM.

  10. #10
    Supporting Member
    Join Date
    Sep 2007
    Posts
    2,756
    Maybe the two magnets are different and this evens them out. It is hard to see how one string could get louder and the other softer otherwise.

  11. #11
    rjb
    rjb is offline
    Old Timer
    Join Date
    Feb 2010
    Location
    Somewhere near Bawlmer, Merlin
    Posts
    1,771
    Quote Originally Posted by Mike Sulzer View Post
    It is hard to see how one string could get louder and the other softer otherwise.
    Errm, uh, edge effects?

    Just out of curiosity, what are the dimensions of the neo buttons?
    According to this article (which I've only skimmed), a magnet which has been above its max operating temperature suffers irreversible magnetisation loss. The MaxOpTemp is lower for thinner magnets. In example 3, a 1/16" thick magnet potted at 60C (140F) would be just barely safe; at 80C(176F) it would permanently lose some strength. Holy moly, I just realized that.
    https://www.kjmagnetics.com/blog.asp...dymium-magnets

    On another note, I forgot to mention that making the bottom flange of mild steel would theoretically "fatten" the tone by raising inductance and directing more magnetic field upward. Plus that "eddy current" jazz. But you guys know that stuff anyhow.
    Last edited by rjb; 02-25-2017 at 02:29 PM.

  12. #12
    Supporting Member
    Join Date
    Sep 2007
    Posts
    2,756
    Errm, uh, edge effects with Neodymium? Sure, although I have not observed them. I would not expect this to be a big effect. Neodymium is non permeable, and therefore the fields from neighbring magnets simply add. The field from a magnet on the next string is looping around and therfore points in the opposite direction as the field from the magnet below. An interior string should see reduction from both neighbors, while an end string should see it only from one, and therefore the field should be higher on the ends strings, but not by so much. This is the opposite of what Mark observed.


    However, you are right to urge caution with temperature, especially potting. Maybe you could use this effect to control the degaussing fof special effects, but I would not expect it to be so easy to control.
    rjb likes this.

  13. #13
    Senior Member
    Join Date
    May 2006
    Posts
    3,404
    The mags are 1/10" x 1/4". Just went to the store and bought some more.

  14. #14
    Old Timer tedmich's Avatar
    Join Date
    Apr 2008
    Location
    Sonoma CA
    Posts
    3,045
    pictures please!!!


  15. #15
    rjb
    rjb is offline
    Old Timer
    Join Date
    Feb 2010
    Location
    Somewhere near Bawlmer, Merlin
    Posts
    1,771
    Quote Originally Posted by Mike Sulzer View Post
    Errm, uh, edge effects with Neodymium?
    I had meant that to be a throw-away line, but I'm glad I made it.
    Thanks to your explanation, I now kinda understand what "edge effects" means.

    Quote Originally Posted by tedmich View Post
    pictures please!!!

    Huzzah. I'm not visualizing how you get a 7/32" aperture with those magnets.

    But my main point was to be careful with hot wax and small neos.

    -rb

  16. #16
    Senior Member
    Join Date
    May 2006
    Posts
    3,404
    Apologies for the delay. Here you go:
    img_20170301_191004.jpg
    img_20170301_191019.jpg
    img_20170301_191107.jpg
    img_20170301_191202.jpg
    img_20170301_191211.jpg
    David Schwab, John_H and kayakerca like this.

  17. #17
    rjb
    rjb is offline
    Old Timer
    Join Date
    Feb 2010
    Location
    Somewhere near Bawlmer, Merlin
    Posts
    1,771
    Quote Originally Posted by Mark Hammer View Post
    Apologies for the delay. Here you go:
    Aw, man- no step-by-step assembly gut shots?
    Final product does look good!
    Last edited by rjb; 03-02-2017 at 01:52 PM.

  18. #18
    Senior Member
    Join Date
    May 2006
    Posts
    3,404
    If I work up the gumption to make another with a wider coil, I'll take pics.

  19. #19
    Pickup Maker David Schwab's Avatar
    Join Date
    May 2006
    Location
    Staten Island, NY
    Posts
    10,919
    So, I made a very similar pickup, which I assume is what I talked to Mark about (don't actually remember!), and I also ran into a similar problem. This was for a 5 string Moses Graphite bass, and the pickup was cast in a mold of the original pickup (After belt sanding the top off the original pickup to determine how it was made). After it was done the G string was way too quiet.

    I figured that after the pickup was wound and encapsulated, the G string magnet came loose and moved closer to the D string.

    So for the next pickup, I made a wooden core to hold the magnets in place.

    Here you see the original pickup, made on thin PCB, the spacer, and the second pickup which I made with fiberboard.
    Attached Thumbnails Attached Thumbnails img_4250.jpg   img_6483.jpg   img_6864.jpg  
    Jason Rodgers likes this.
    It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. Albert Einstein

    www.sgd-lutherie.com
    www.soundcloud.com/davidravenmoon
    SGD Lutherie Facebook page

  20. #20
    Senior Member
    Join Date
    May 2006
    Posts
    3,404
    Yours is a whole lot prettier than mine, Dave.

  21. #21
    Pickup Maker David Schwab's Avatar
    Join Date
    May 2006
    Location
    Staten Island, NY
    Posts
    10,919
    Thanks Mark. It's ironic since it got embedded in epoxy, never to be seen again!

  22. #22
    Senior Member SpareRibs's Avatar
    Join Date
    Feb 2011
    Location
    PNW
    Posts
    423
    Hello,
    Some of those earlier pickups were made with the type of magnetic material refrigerator magnets are made from. That could be used for the bottom flat work.

  23. #23
    Pickup Maker David Schwab's Avatar
    Join Date
    May 2006
    Location
    Staten Island, NY
    Posts
    10,919
    Quote Originally Posted by SpareRibs View Post
    Hello,
    Some of those earlier pickups were made with the type of magnetic material refrigerator magnets are made from. That could be used for the bottom flat work.
    Rubber magnets are too flexible to use as flatwork. The kind used for refrigerator magnets don't have a regular N & S pole... they are in alternating strips. So they aren't suitable for pickups. Rickenbacker uses rubber magnets. They are very weak and create muddy sounding pickups. For such a shallow pickup, thin neos are perfect.
    It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. Albert Einstein

    www.sgd-lutherie.com
    www.soundcloud.com/davidravenmoon
    SGD Lutherie Facebook page

  24. #24
    rjb
    rjb is offline
    Old Timer
    Join Date
    Feb 2010
    Location
    Somewhere near Bawlmer, Merlin
    Posts
    1,771
    Quote Originally Posted by David Schwab View Post
    Rubber magnets are too flexible to use as flatwork. The kind used for refrigerator magnets don't have a regular N & S pole... they are in alternating strips. So they aren't suitable for pickups. Rickenbacker uses rubber magnets. They are very weak and create muddy sounding pickups. For such a shallow pickup, thin neos are perfect.
    Some DeArmond pickups used a rubber magnet glued to a steel backplate. The backplate was the lower flange; the upper flange was two sheets of plastic (similar to that used for acoustic guitar pickguards) laminated and glued on top of the magnet.

    -rb

  25. #25
    Pickup Maker David Schwab's Avatar
    Join Date
    May 2006
    Location
    Staten Island, NY
    Posts
    10,919
    Quote Originally Posted by rjb View Post
    Some DeArmond pickups used a rubber magnet glued to a steel backplate. The backplate was the lower flange; the upper flange was two sheets of plastic (similar to that used for acoustic guitar pickguards) laminated and glued on top of the magnet.

    -rb
    Yeah, a number of pickups did. But those aren't the same as refrigerator magnets. I'd just use a standard ceramic in that case. When I replaced the rubber magnet on a Rickenbacker neck pickup with small neos, the pickup sounded a lot better. It wasn't as dark, and had a nice open top end.
    It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. Albert Einstein

    www.sgd-lutherie.com
    www.soundcloud.com/davidravenmoon
    SGD Lutherie Facebook page

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Can you Re-orient Alnico magnets with Neos?
    By Will_White in forum Beginner/ Hobbyist
    Replies: 5
    Last Post: 06-10-2015, 07:06 PM
  2. Kalamazoo Bass 30 project (first post)
    By aab0mb in forum Vintage Amps
    Replies: 59
    Last Post: 12-11-2013, 01:54 PM
  3. Replies: 9
    Last Post: 06-24-2013, 06:13 AM
  4. Neos
    By automan in forum Pickup Makers
    Replies: 38
    Last Post: 02-03-2010, 08:07 PM
  5. jensen 10" neos
    By old_picker in forum Guitar Amps
    Replies: 1
    Last Post: 02-17-2009, 06:13 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •