BigDaddy's Tap Pickups

[BigDaddyPoo]

As we all know, tap instruments have different requirements than your average run of the mill ( read: boring ) guitars and basses. String spacing is usually comparable to a bass while string counts usually outnumber a guitar. It is almost impossible to find pickups for such an instrument. While some manufacturers make pickups wide enough, they will often have a single bar that picks up all strings instead of separate pole pieces for each string. And with so many strings each will have different diameters, thus different outputs. While this can be compensated for easily on a plucked instrument it is difficult to tap at the different strengths required to get each string to ring at the same volume.

In this thread I will chronicle my attempt to build a pickup that overcomes all of these issues. I am going to build a humbucking, stereo, 8 string pickup with adjustable pole pieces.

Wish me luck.

[BigDaddyPoo]

First, a little background info.

I picked up ( pun intended ) all of this knowledge from one book and three web sites.

The book: Building Electric Guitars by Martin Koch
The web sites: http://www.skguitar.com/
http://galileo.spaceports.com/~fishbake/index.html
http://www.ampage.com/

A pickup consists of 3 basic parts: the bobbin, the wire, and the pole pieces. The bobbin is like a thread bobbin. Instead of thread you wind it with wire. At the center of the bobbin are the pole pieces.

The bobbin can be made of wood, fiberboard, or plastic. I am going to use wood for my pickups since it looks cool to have a nice exotic wood pickup and also plastic tends to melt when you solder wire near it. My Chapman Stick had a bubinga pickup.

You have a few options for pole pieces. The simplest is to use round magnetic cylinders called bar magnets. The advantage is that assembly is simplified. The disadvantages are that the pole pieces are not adjustable and that it is easy to accidentally put one in backwards giving reverse polarity and dead spots between the strings. Bent notes will not pickup.

Another option, and the one I will go with, is using a single flat magnet, magnetized across its width which connects to soft steel pole pieces. These poles can be threaded to accept screws for hight adjustment. Though this approach can take a few more steps, I think adjustable poles will work better for a tapping instrument so you can adjust the output characteristics per string. My ( ancient ) Chapman Stick used adjustable poles and I liked this arrangement.
The wire is hair thin, made of copper and insulated with thin coating. The most common thickness is 42 AWG which is .0028” thick, though some use 43 and 44 AWG to get different tonality and output.

[BigDaddyPoo]

Factors Effecting Tone and Output

Windings: The higher the number of windings, the higher the output, but the deeper the tone. If you go too high with the number, you will end up with a muddy, dead sound. This can be counteracted to some extent by either using taller coils or different gage wire ( see below ). Most single coil pickups have between 7500 and 10000 turns of wire while each coil of a humbucker will usually have around half as many: 4000 to 5000 turns. I will base my first pickup on the Gibson PAF which I always liked the tone of. This pickup has 5000 turns of 42 AWG wire and screw pole pieces. Surprisingly, there is not much difference in the number of turns on a bass pickup.

Humbucker VS. Single Coil: It is well known that humbuckers reject unwanted RF noise. It does this by having two pickups wired in series that are of opposite magnetic polarity and the wiring is out of phase with each other. This cancels out unwanted hum that enter both coils but also cancels out certain harmonics. This gives more of a “scooped” sound, that is, it removes certain frequencies from the tonality. This gives humbuckers a meatier sound, while single coils have a clearer sound .

Scatter Winding VS. Ordered Winding: Scatter winding refers to the fact that a pickup was hand wound and thus the winds aren't evenly spaced and often overlap and cross at varied angles. Ordered winding gives consistent results where each pickup will sound almost exactly like the one manufactured by the same process months earlier, but the pickups will have a more sterile and often bright, brittle sound. Even though you can wind a scatter wound pickup to also have a bright sound, it will not be as brittle and will have more roundness to the tone. This is good news for those who want to roll their own: it's way easier to wind scatter style and requires less elaborate equipment.

Dimensions of the Coil: A tall thin pickup has a tighter, brighter sound than a short fat pickup with the same number of windings of the same gage wire.

Wire Thickness: The thinner the wire the higher the resistance. This gives less output and allows less highs to pass through. Thinner wire, however, allows more windings on the same bobbin. So you can actually have a higher output pickup with thin wire. Such pickups have less noise but a raspy sound.

Magnet Strength: The stronger the magnet the brighter the tone. Stronger magnets will also restrict the motion of the strings yielding less sustain.

Pickup Position: The closer to the bridge the pickups are, the brighter and thinner the sound. It is a common practice to place pickups at the position of pleasant harmonics. Often a neck pickup will be placed where the 24th fret would be and a bridge pickup, where the 43rd fret would be. Basically you can lightly tap between the bridge and the fretboard until a good sounding harmonic is produced and put your pickup there.

So, its all a balancing act. Output and noise ratio in balance with tone quality and clarity. From what I have been told, you can do all the math ( something I'm good at ) and planning you want, but finding the right mix boils down to trial and error.

[BigDaddyPoo]

Today I took a trip to Birmingham, AL, to get a few things I've been storing at friends' and relatives' houses since I went back to school two years ago for engineering. I recently transferred to MSU and moved into a bigger house so I get to reclaim some badly missed books, my bike, and my bass amp. Anyway, the reason I am telling you this is that Birmingham has tons of thrift stores where you can really score some good clothes, appliances, and recording gear ( my friend just bought some studio reference monitors that retail for $1200 each at an Alabama Thrift Store for only $20 for the pair ). I went in search of a sewing machine for my pickup winder, and found one for only $5.88. It is a White brand machine that looks like it was built in the 1950s. It smells like a musty old basement. It didn't work, though I could tell the motor was trying to turn despite the seized up inner workings of the machine.

You can use any electric motor to wind pickups. Most people use hand drills or drill presses. I chose to use a sewing machine motor because a sewing machine is controlled by a foot pedal. This is good not only for the fact that you don't have to drop the wire to stop the machine if something goes wrong, but also because you can use the pedal to control the RPMs of the machine. You could for instance start off slow and pick up speed ( pick up, get it? ) as you get comfortable in your winding rhythm.

The pickup bobbin will be mounted on to the motor and the wire will be fed onto it by hand. There is a way that you can use parts from an oscillating fan and a wire tensioner to do the winding hands-free, but that is too elaborate for my needs. Maybe when I'm filling 100 orders a week I will invest the time into such a rig, but until then...

I also plan to attach a bicycle speedometer/odometer to the motor to count my windings and RPMs. Schwinn makes a digital one for around $15 that allows you to tell it the size of your tires ( which effects the ratio of number of rotations required to travel 1 kilometer ), this way you don't have to use a calculator to find out the the actual number of turns you have made from the distance reading.

I arrived home from Alabama eager to take apart the dinosaur of a machine. Since I was a kid I have loved taking stuff apart and figuring out how it worked. This usually led to some bastardized RC car/Teddy Ruxpin combination, robotic hellspawn or something like that. For some reason the fix-it man side of me crushed my inquisitive kid side and I repaired sewing machine first, just to see if it worked. This took like 5 minutes. Finally, I sat down to rip the thing apart. I thought I would spend a good part of the evening in destructive bliss, but those damn efficient Japanese thought ahead some 50 years and made the motor and all of the corresponding electronic parts easily removable with only 5 screws! Genius engineers ( I shake my fist angrily in the air ). Total job time: 7 minutes, including conflicting repair and destruction.

The bliss was short lived like crack. And, as if addicted to such a drug, I wanted more. I wanted to take something else apart, so I spent the rest of the night ripping pickups off my guitar and 2 basses and measuring them ( and typing this long winded post ).

Next step: Laying out the plans for my machine's base and designing the contraption that will mount the pickup to the motor.

[BigDaddyPoo]

Here is the motor after removal. You may notice that the mounting hardwar is still attached, which will come in handy when putting the machine together. Notice the two outlet power box behind the pedal. I think I can plug anything into this, like a drill or any other electric motor to control its speed.

[rjgoos]

Big Daddy,

This is of great interest to me. Thanks for documenting this.


Jay

[cbowen4]

Originally posted by BigDaddyPoo
Notice the two outlet power box behind the pedal. I think I can plug anything into this, like a drill or any other electric motor to control its speed.

Older sewing machine generally have a resistive speed control. If you open the pedal you'll probably find a wiper arm moved by the pedal and a series of metal buttons, each separated by some resistive wire. This is designed to work with the relatively low power motor supplied with the machine. I wouldn't plug anything else into it, particularly a larger load like a drill, you'll probably burn it up and it would be a fire hazard.

[rockola]

Originally posted by BigDaddyPoo
I chose to use a sewing machine motor because a sewing machine is controlled by a foot pedal.There's a book by Jason Lollar (http://www.lollarguitars.com/) titled "Basic Pickup Winding, or, Complete Guide To Making Your Own Pickup Winder". The book deals with transforming a plain old sewing machine into a lean-and-mean pickup winder. Unfortunately it's no longer available, but there might be used copies floating around.

[BigDaddyPoo]

Sorry for the lack of updates folks.

Being a student I havn't been able to put the $20 together to order the magnets and pole screws I need to build my first pickup. Sad isn't it? I'm also waiting for a friend to visit me from nearby Birmingham, AL that has a part I need for my winding machine.

Anyway, this update is bought to us because of a link I have that some of you other builders might be interested in.

http://www.zacharyguitars.com/ZachAttack.htm

Zach is having custom pickups built by Kent Armstrong. These look alot like Barts only with adjustable pole pieces. This is done by machining a master design out of aluminum, creating a rubber mold, and basically filling it with electronics and epoxy. I have never seen a Bartalloni pickup out of an instrument, though I do have some Ibanez epoxy encased pickups. These Ibanez pickups are a plastic pickup cover filled with epoxy, but it sounds like the ZachAttacks are epoxy through and through.

Brenda, or some of you other folks who may have Bartallonis may be able to tell me if they are a filled cover or solid epoxy. I'm curious.

Some of you other builders with a bigger budget may be interested in talking to Kent about some custom pickups. It would be pretty cool to have your companies logo emblazoned on your pickups. How does "TraktorAttack" sound?

Hmm, sounds like something that might actual happen here in the south.

Overheard at a party at Mississippi State University: "Hey Dan, how'd yer cousin, Jebediah Pecan Pool, die?"

...

I, being poor, would have to build this for myself to have such cool pickups. Probably won't be able to machine a master pickup for my first design (see prior sentance about me being poor), but I think I do have access, when I get into my more advanced engineering classes, to some fancy CNC mills. So maybe in the future this will be doable.

[rockola]

Originally posted by BigDaddyPoo
I ... would have to build this for myself to have such cool pickups.Check out the book Animal Magnetism for Musicians (http://www.amazon.com/gp/product/9090018581/) by Erno Zwaan for a description of one approach to building custom epoxied pickups.

[BigDaddyPoo]

Very cool rockola. That sounds like the book I've been looking for. As the one and only reviewer on amazon put it: "Load of usefull information about creating pickup for bass."

Can't wait to check it ou...what the...

...crap, this costs as much as I need to spend on my magnets and pole screws.

Irony is a harsh mistress.

:D Just kidding. This is something I am definately going to have to add to my library.