Wednesday, May 26, 2010

the $20 homemade acoustic guitar pickup

How to make your own acoustic guitar pickup for cheap.  This way you can plug your guitar into a PA or an acoustic guitar amp.

Required tools:
soldering iron
electric drill
wire cutters
coping saw

Required parts:
buzzer piezo from Radio Shack (The Shack) $9
Switchcraft Nickel End Pin Jack $11
3M double-sided poster tape
1 foot of audio cable

Optional parts:
250k potentiometer
guitar wire

1.  Remove the strings and drill a 1/2 inch hole in the bottom of the guitar where the strap button is.  The nice thing about the Switchcraft jack is that it acts as a jack AND a strap button.  Be careful when drilling not to damage your guitar.

 2.  Take apart the buzzer.  This might require a coping saw to get through the plastic casing, careful not to damage the flat metal piezo.

3.  Solder one end of the audio cable to the piezo.  Positive is the top ring, negative (or ground) is the large bottom ring.   The two plates are separated by crystals, when given a current the produce a noise, when given a vibration they produce a current, we will be using the piezo for the latter.

4.  Solder the other end of the cable to your jack, positive is where the tip connects in the jack, negative is the sleeve or ground.

5.  By nature, the piezo is a very bright-sounding pickup for an acoustic, so we'll be using some 3M double-sided poster tape to attach this thing to the underside of the bridge.  Because it is made of thick foam it dampens some of the brightness.  Stick a piece of it to the top and bottom of the piezo.  Mount the bottom of the piezo to the underside of the bridge.  Then install the jack in the bottom of the guitar.

You could use the pickup just the way it is, but I chose to have a tone control to get a little warmer sound out of it.  Use the following wiring diagram to solder a tone control into your circuit (advanced skills required)

I chose not to drill another hole in my guitar for the tone control so I used some more of that poster tape on the back of the tone control and stuck it just out of sight in the sound hole, if I need to adjust tone at any point I can just do it with my fingertips through the sound hole.

Reinstall the strings and test it out!!

Thursday, May 13, 2010

What is 'scatter-winding' anyway??

Many high-end pickup manufacturers like to boast (myself included) that their pickups are "scatter-wound," but many people don't really understand what this term means.  In fact the whole art of winding pickups is quite foreign to a lot of people, even if they play guitar.  Quite simply, scatter winding is a method of making pickups that results in a unique and beautiful sound.  In this post I'll take a stab at trying to explain the principles of this method.

All electric guitar pickups use the same basic design, they are simply magnetic polepieces wrapped in very thin copper wire.  The polepieces generate a magnetic field that the string vibrates in, and the copper coils turn that vibration into an electric signal. 

In the '50s, electric guitars started getting extremely popular.  Humbuckers, used primarily in Gibson guitars, used a uniform wind made on a machine; and single-coils, used primarily in Fender guitars, used a scatter-wound coil made by hand.  Technically you could use either method for either type of pickup, but it is widely believed that single-coils sound better scatter-wound.  Tension also matters when winding a pickup, looser winds typically sound clearer and better.

When I first started winding pickups I didn't understand that the way in which you wind the pickups actually has an effect on the tone.  It made sense to me that the quality of wire you use, the number of turns, the quality of the magnets, and the strength of the magnets all played a part in the overall tone.  But I figured you would need some sort of ultra sensitive computer to hear if they were scatter-wound or not.  I made a couple of pickups by just guiding the wire back and fourth in a very even manner.  I made a couple variations of these and tested them, then I made a set of pickups using a scatter-winding technique.  The first thing I noticed was that the resistance (electrical output measured in ohms) of the pickup had dropped significantly.  When I installed them and tried them out I was amazed!  I was hearing details that I had never heard before, there was more treble and harmonics than I had heard from my earlier pickups.  The video below shows me scatter winding a pickup.  The wire is as thin as a human hair so you can't really see it, but you can see how my hand is moving to get an idea of how it's done.  It also helps to be blasting Pink Floyd while you're doing this for 15-20 minutes per coil.

When coils are wound on a machine, each consecutive wind is very close to the last wind.  when you scatter-wind a pickup the idea is to put lots of space between each consecutive wind, this lowers the distributed capacitance of a pickup so that more treble and detail get through.  Your tone control on your guitar has a capacitor on it, as you turn that control counter-cockwise it uses more and more of that capacitor to bleed off highs to the ground, and the result is you hear a darker guitar tone.  Scatter-winding does just the opposite, it gives the pickup more treble.  This sounds really good on single coils because they have a very open sound to begin with, extreme highs and extreme lows, a lot of the guitar's natural tone and character comes through.

When I'm scatter-winding a pickup, I try not to follow any sort of pattern and I move the wire randomly across the bobbin.  Machines are not good at this because they are programmed to do things very neatly.  I suppose you could program a robot to mimic the motion of the human hand, but that wouldn't exactly be cost-effective.  The human hand is a really good tool for this because it's hard for us to do things in a consecutive pattern.

Update 08/04/2010
You can also scatter-wind by simply guiding the wire back and fourth faster across the bobbin, thus putting more distance between each wind.

Scatter-wound pickups are more expensive because they have to be made by hand.  It also makes the pickup more unique because you can never exactly replicate what you did before, so each pickup has its own tonal character.  When Fender first started out as a company, all of their pickups were wound by hand, they are considered by many to be some of the best sounding pickups in the world.  Today they make thousands of guitars a year so naturally it doesn't make sense for them to hand-wind each pickup, but there are a few other winders out there like myself who still hand-wind every single pickup.