Tuesday, May 24, 2011

Project 8 String Single Coil -- part 1

Project 8 string humbucker...

I have to make a single coil pickup to match a set of green BKP 8 string humbuckers for a custom guitar. I had the customer ship a sacrificial humbucker that matches the set. My plan is to extend the height of the slug side bobbin, install some A5 rod magnets, wind it to about 8-9k and make a new baseplate.

I was not impressed with my first look at a Bare Knuckle pickup. Honestly they are not built any better than any other major manufacturer pickup. The parts are not better than what you can get from Mojotone in my opinion. The sacrificial humbucker has several tool marks and digs in the top. The bobbins have a satin look to them. And of course there is a visible seam in each of the bobbins.

The baseplate has the name engraved in it.

Enough looks lets take this thing apart. You can see the #2 brass screws are really long compared to normal PAFs (makes sense to hold everything together.. vibration == microphonics).

The rough cast A5 looks like a sensmag (nice quality regardless). The bobbins have a visible seam. It looks like they cut down 2 six string bobbins and glued them together. You can even see the seam from the top (I am not a fan).

The baseplate looks like a plain piece of stainless steel. The tabs have serious rough edges, one have thought they would have cleaned them up with a file or something. I was surprised to see that they used what looks like scraps as the wood filler.

Last look at the top of the bobbin and its defects.

Looks like a normal PAF so far.

I strapped it to the winder to try and count the winds to try and get a better guesstimate on what it would take to get to 8 or 9k. The coil read about 4 ohms or so. I would say that the coil was wound a bit messy but the wax potting was exceptional and went all the way to the center of the bobbin.

In the end I got tired of trying to unwind it and cut the coil off. The wax potting was so good it made the wire break as I tried to unwind it.

A look at the clean bobbin.

Here is the test bobbin. I cut it in half with a razor saw and glued a piece of pickgaurd material in the middle with pvc glue. You can see it next to a standard HB bobbin in the second picture.

Time to cut the green bobbin. I need to cut this as square as possible with minimal material loss. So I squared the top of my wood vise before hand to give a good surface to work from. Then I clamp my favorite razor saw in the vice were the teeth just kiss the middle of the bobbin. Gradually I raise the saw a little each time until I am done. Resting the bobbin on the square surface keeps the cut square and clamping the saw keeps it from flexing providing a straight cut.

Here we glue the thing back together with the pickguard extension in the middle. I use 2 .187 drill bits to align the bobbin while the glue dries. Clamp and wait.

Out of the clamps. I used a small triangle file with safe edges to clean up the middle of the pickup.

Baseplate finished.


  1. This is some great info here. With all the talk about BK pickups, Ive found myself falling into the hype. Its nice to see an inside-out of one of them. I know the bottom line is performance but for those prices Id like to see quality through an through. Thanks for sharing this!

  2. You are welcome.

    I don't think there is anything wrong with BKPs. I just don't see where the hype is coming from. Hand wound pickups (aka scatterwound) have a distinct sound to them however there are times when a machine wound coil is preferred.

    I will try to get my hands on a 6 string version and see about checking them out.

    Quality 6 string parts are easier to source in quantity. So I will be interested to see the differences.


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