A word on Internet Wisdom

Internet wisdom isn't always wise. I made a mistake and turned off my brain while creating my initial wiring diagram. Don't get me wrong, my diagram works perfectly, but my hopes for what it would provide were somewhat ill founded.

The "250k" for single coil and "500k" for humbucker internet wisdom is missing context. The best way to think of a passive guitar circuit is an alternating current source (the pickups), a voltage divider for volume (volume control) and frequency roll off (tone controls). The choice of resistance for the potentiometers only really matters for tone controls, as careful selection of capacitor and potentiometer define cutoff frequency and range. However, since my circuit has no tone controls, the resistance value for the volume is largely inconsequential.  

It has been many years since engineering school, but that is no excuse... Just be careful about turning off your brain. 

Initial Wiring Diagram

The plan for this guitar is to experiment with a few things, one of which is a wiring setup that isn't too crazy in its final form (may be crazy in intermediate steps) but can handle the tones that I want. This initial wiring diagram is intended to play with a few things, specifically, coil tapping and playing around with resistor values for the volume control. This particular wiring diagram contains no tone circuit, as I find I never use the tone knobs on any of my guitars. The mini switches and the five-way super switch are from AllParts. The volume pot is the 500k volume pot that was already in the guitar. The jack is the standard jack that came with the guitar.

With this setup, other than parallel wired single humbuckers, you can pretty much get all of the options that may end up being interesting to me. My goal was to get a few standard-ish tones:

• Strat neck tone: five-way switch in position 5, switch two in 'up' position
• 335 style neck tone: five-way switch in position 5, switch two in 'down' position
• Telecaster 'twang': five-way switch in positon 3, switch two in 'up' position
• SRV Strat-ish; five-way switch in position 4, switch two in 'down' position
• Mark Knopfler/Sultans of Swing: five-way siwtch in positon 2, switch two in 'down' position

The first switch (the resistor bypass) is based on 'internet wisdom' that you use 250k pots for single coil pickups and 500k pots for humbucker pickups. The switch enables/disables a parallel 500k ohm resistor to create an effective 250k ohm resistor. 

The little things are the hardest

I'm trying to turn my wiring diagrams into things like PDF files (so I can share them). It turns out, this is a real pain in the ass. The flow chart/diagraming software like Visio would be perfect, but I don't have it. Learning Illustrator or InDesign in order to do such a simple diagram is proving to be extremely frustrating.

Test fitting the pick guard

After drilling the holes for the neck pickup screws length, I test fit the pick guard. Only a couple of the holes line up. Bummer. I'll have to drill some new ones. Luckily none of the existing holes will be exposed. I don't care about the appearance too much right now, but I don't want it to be horrible if I can help it.

Preparing the Pickguard

I've mounted the pickups, five-way switch and two mini switches to the new pick guard.

There is a slight problem with the five way switch and the pick guard. The one and five position don't fully complete the connection. I'll have to file down the lever slot to ensure the switch can perform its full travel.

The shielding is quite evident. The volume control is not yet mounted on the pick guard.

Another problem has showed up. Since the Squire Strat is as cheaply produced as possible, the neck pickup position was routed for a humbucker (which is great), but there is no route for the long, spring loaded mounting screws. The picture below is of the body, the bridge pickup route contains two deep channels that are not visible on the neck pickup route.

 

Here is the long screw holding the pickup to the pick guard.

I ended up using an electric drill instead of a router to make the holes for the screws to fit. A simple enough solution.

Wiring it up should be straight forward. 

Positioning the Pickups

One thing the ES-335 style guitar and the Fender Stratocaster have in common with the neck pickup is the placement along the scale length. On the Strat, the neck pickup is placed at the 24th fret position, or specifically, one fourth of the scale length. On an ES-335 style guitar, the screw lug of the humbucker is placed at the 24th fret position.

Since my project guitar is a effectively a Fender Strat, choosing a pickguard that places the pickups in the proper location is the first key to trying to achieve the tones that I want.

This link: http://www.till.com/articles/PickupResponse/index.html provides tones of useful information on pickup placement.

I have purchased a 2 humbucker pickguard for a Strat from AllParts that appears to have the pickups in the proper locations. Since the Strat is a 25 and 1/2 inch scale length, I need the neck pickup to be 6 and 3/8 inches from the bridge.

What I think I want

With this guitar, my intent is to be able to capture the tones that I want in the form factor that I want.  I've picked out three tones that I definitely want with the flexibility of adding two more (with a typical 5 way switch).

I'm primarily looking for a Stratocaster neck pickup tone, an ES-335 style neck pickup tone and a Les Paul bridge tone.

This is a pretty tough combination to go after, especially since I tend to like the form factor of a Stratocaster. But for now, I'll just focus on electronics...

Mystery Pickups

I wanted to largely use parts that I already have for the first stab at the wiring arrangement that I want. Luckily I have a set of humbuckers sitting around and 500k pots to wire them up. There was just one small problem. The pickups contain no clear brand markings, only indicators which one is the neck and which one is the bridge pickup. Since pickup manufactures don't standardize on the wire colors, not to mention I have no idea the brand, I need to figure out the wires for myself.

http://www.neighborhost.com/scrapbook/pickup-id.html

Using the technique above, armed with my trusty multi-meter, I went to town.

The pickups have four wires. Each humbucker has two poles (north and south), with a pair of wires being the start and finish for each pole.

The first step is to determine which wires belong to each pole. Doing so is straight forward. Using the resistance (ohms) setting on the multi-meter. If a pair of wires has a measurable resistance (should be in the 5k - 15k ohms range), then they belong to the same pole. If the pair of wires has infinite resistance, they belong to different poles. Performing this test shows that the black and white wires belong to one pole and the red and green to the other. I was measuring ~12k Ohms per pole. Looks like they are hot pickups!

The second step is to determine which pair of wires belong specifically to the south pole and which pair belong to the north pole. With the multi-meter hooked up to the black and white wires, set in DC volts mode, tap a screw driver to each of the poles. If you see a spike on the multi-meter, then you have the wires for the pole in question. If you don't see a spike, or more likely, a much reduced spike when compared to the other pole, then the wire pair you are testing do not belong to the pole. Performing this test shows that the black and white wires belong to the south pole (the one with the visible screw lugs) and the red and green wires belong to the north pole.

The third and final step is to determine which direction is correct for a series wiring. Using the screw driver tap above, observe which direction the needle on the multi-meter moves as you tap. You want the south and north poles to move in the same direction. The article at the top of this posting seems pretty sure that the reading must be in the positive direction as you tap and negative as you pull away. I'm not sure it matters that much, but I'm going to use that convention and give it a shot.

After this whole procedure, I get the following wire assignments:

• South Pole (screw lug)
• White -
• Black +
• North Pole (covered lug)
• Green -
• Red +

If I perform a mapping to known pickups (say Seymour Duncan), commonly available wiring diagrams can then be applied to these pickups.

You may be asking, why use unknown pickups on a custom built guitar? At this stage I'm more interested if my unconventional wiring ideas are actually viable than the sound of the pickups. But that is a topic for another post...

First Upgrade

I performed the first upgrade to the guitar. I installed a set of Schaller locking tuners.

I would like the guitar in its finished form to have locking tuners and I had them sitting around (I was going to install them on a Strat, but changed my mind). In this case, the upgrade benefit is two fold: the stability of the tuning is way better and taking the strings off and putting them back on is much easier. The tuning stability is less of a concern right now, but the ease of taking strings off and putting them back on is a huge win as I'll be playing with the electronics quite a bit (I expect a fair amount of iteration).

The funny part is these tuners cost more than the guitar...

The One!

After two weeks of monitoring Craigslist, I found the first guitar that seems to fit the bill. An Affinity Squier Fat Strat for $50. Definitely what the doctor ordered. The story of the guitar is it belonged to a 12 year old guitar student who was interested in pretending to be a rock star more than practicing to be a rock star.

Due to the guitar's previous life, it is quite beat up, but played very little, an odd and acceptable combination. I was told the neck was straight, the joint is good and the electronics all work perfectly - except the top half of the lever switch was broken off. If I felt like using pliers for changing pickups, it all works. Perfect fit for my build philosophy. So I bought it...

As you can see, the broken switch in the center position. As it turns out, the fastest way to a low price on a guitar is to having something broken that limits the usefulness of the instrument, especially if it costs more to repair than the instrument is worth.

The guitar plays as well as expected. The tuners are poor, the pickups aren't that great, but the neck is decent, the action is low and the sustain is reasonable.

I am pleased.

Searching

I've been using CraigsList to track down my sacrificial guitar. All that I'm looking for at this point is something with a straight neck, good neck joint and minimal fret wear. Having the electronics work was secondary, but nice to have in order to keep with my "can play at any time" build philosophy.

It occurred to me that I really do want a bolt on neck, not just because it will be cheaper (I don't like to spend too much money on stuff I know I'm just going to throw away), but because it also allows me to build a body and a neck at separate times. It may seem like a crime to have a sweet body with a junk neck (or vice versa), but it does permit me to build at my leisure without having to go "all in".

Lots of searching appears to be pushing me towards a Squier Strat or Strat knock-off as my starting point. Probably not too much of a surprise.

Starting Out

I've always wanted to build an electric guitar. I've started the process. The goal here is to chronicle my (mis)adventure.

I've chosen a pragmatic build method that always gives me something to play at almost every stage of the build process to keep my interest high and have the build be part of my playing on a regular basis. My plan is to purchase a guitar as cheaply as possible and replace parts, one at a time, so I can not only play the instrument at any time, but really appreciate the individual change in isolation.

Before beginning all of this, I purchased the book "Build Your Own Electric Guitar" by Martin Oakham.

The book goes through many aspects of building a guitar from wood selection, fret placement, pickup placement, various neck joints, headstock styles. The details are light in some areas (particularly with techniques not used in the building of the sample guitar). All in all, this is an excellent starting point and makes it very clear what you are getting yourself into. My goal is to experiment, so having a survey is quite nice at this point. The section on finishing is a bit weak, but that is a long way off and I'll cross that bridge when I get there.

Time to search for the sacrificial guitar...