Tweet
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.
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.
Comment