Wednesday, November 19, 2014

Wiring a Stratocaster for Two Volumes and One Tone



My friend Adam was recently upgrading an Epiphone Strat copy (which we’ll be covering in the next blog post) and asked if I could help him with a somewhat unorthodox wiring idea. So, continuing on somewhat from the previous post about the Stratocaster 5-way switch, today we’re going to look at how to wire up a Strat so that it has two volume controls and one tone control.

More specifically, one of the volume pots will control both the neck pickup and the middle pickup, the second volume control would control the bridge pickup only, and the tone control will control all three pickups.

I couldn’t find much on Google about anyone else doing this, at least not without using a super switch, but I was pretty sure it could be done.

So this is what I came up with. Click on the image to enlarge it.



Here’s how it works:

In the bridge position, pin 1 (bridge) is connected to pin 0 (common) on both sides. The yellow wire from the bridge pickup goes to pin 1 and the signal then continues to pin 0 on the left side of the switch. This then connects to the bridge/middle volume control via the blue wire. Additionally, the purple wire from that volume control comes back to pins 3 and 1 on the right side of the switch and this then passes to pin 0 on that side since it is currently connected to pin 1. Pin 0 then connects to the tone control through the red wire and continues to the output jack.

In the middle position, pin 3 (middle) is connected to pin 0 (common) on both sides. The green wire from the middle pickup goes to pin 3 and the signal then continues to pin 0 on the left side of the switch. This then connects to the bridge/middle volume control via the blue wire as before. Additionally, the purple wire from the volume control comes back to pins 3 and 1 on the right side of the switch and this then passes to pin 0 on that side since it is currently connected to pin 3. Pin 0 then connects to the tone control through the red wire and continues to the output jack.

In the neck position, pin 5 (neck) is connected to pin 0 (common) on both sides. However, the neck pickup wiring is quite different from the other two pickups. The grey wire from the neck pickup goes directly to the neck volume control. It connects there no matter what position the switch is in, so you may wonder how that doesn’t affect the output even in the other switch positions, well, that’s because the pink wire coming OUT of the volume control connects to pin 5 of the switch and that doesn’t connect to anything unless the switch is in the neck position, at which time the signal can now continue to pin 0 on the right side of the switch. This then connects to the tone control through the red wire and continues to the output jack.

Wednesday, October 29, 2014

The Stratocaster 5-way Switch


Today we’re going to talk about the standard 5-way switch used in Fender Strat-style guitars—how it works, how to wire it up and variations of the switch itself.

Back when Strats were first made, they came with a 3-way switch (one position for each pickup), but some savvy guitarists soon realized that if they moved the switch into a position midway between two of the “official” positions, they could get two of the pickups to turn on at the same time, resulting in new sound options. This happened because the switch was what is known as a “make before break” switch, which means it touches the next contact before disconnecting from the previous one. It wasn’t easy to keep the switches in these in-between positions and guitarists often resorted to sticking matchsticks, etc., into the switch slot to hold them in position.

Here’s how the switch looks as more of an electrical diagram. As with all images, click to enlarge.

Seeing how customers were doing this, Fender eventually started installing 5-position switches. Note that these were still really 3-way switches, just with a couple of in-between positions added on so that matches were no longer required to hold the switch in those positions.

Also of note is that the switch is “dual pole”, which means that it is basically two switches in parallel that move at exactly the same time, without being electrically connected to each other.  If you take a good look at the switch below, you will see that there is a second row of contacts on the other side.



Here’s how THAT looks as more of an electrical diagram:

This allows for more wiring possibilities, which we’ll discuss later.

Looking at the photo of the switch a couple of images back, you can see that there are four contacts on the side facing us (and four on the other side that aren’t so easy to see). Of the four on this side, the left-most one is the “common” contact, which is to say that it is always connected. The three contacts to the right correspond with the three main switch positions (with the additional two positions being in-between 1 & 2 and 2 & 3 respectively). The other side of the switch has a similar setup.

Now given that there are only (normally) three pickups, and the switch has three contacts on each side (in addition to the common contact), you may be wondering why we need two sets of contacts in the first place. Well, this is so that you can have a bit more freedom when it comes to choosing how to control the volume and tone of each pickup. For example, with standard Strat wiring, the volume pot controls all three pickups, whereas the two tone pots control one pickup each (with the bridge pickup having no tone control at all). Older Strat versions had one of the tone pots controlling two of the pickups at the same time (and there are many more options too!)

Here’s how the switch would look from below. Rather than numbering the pins--which I think can be confusing given that there are 3 pins (not counting the common pins), but five positions—I’ve named them B (for bridge), M (for middle), N (for neck) and C (for common).

Again, remember that you also have two additional positions, as mentioned previously, in-between bridge and middle (so pins B and M would both be connected to C at the same time), and in-between middle and neck (so pins M and N would both be connected to C at the same time).

As for the other side of the switch, despite the fact that the pins appear to be in a different order, they still work the same way, so when the switch is in the Bridge position, the left-hand pin B is connected to the left-hand pin C, and the right-hand pin B is connected to the right-hand pin C.

I hope you’re still with us here. The above can be a bit of a brain melter, but once it clicks it makes a lot of sense.

In an effort to make this as simple as possible, here’s what a standard Strat’s wiring looks like just around the switch itself (remember that there are many, many ways to wire up a Strat and this is just one of the more common ones):
Without going into too much detail about how the tone controls actually work (that’s for another day), I’ll try to walk through how the switch works as clearly as I can.

When the switch is in the neck position, left-hand pin N (neck) is connected to left-hand pin C (common). This allows the signal from the neck pickup to pass to the common pin on this side of the switch. Since left-hand pin C is shorted to right-hand pin C, the signal from the neck pickup continues to right-hand pin C, where it then goes to the volume control. Additionally, right-hand pin C is currently connected to right-hand pin N, allowing the signal from the neck pickup to ALSO travel to the neck tone control.

When the switch is in the middle position, left-hand pin M (middle) is connected to left-hand pin C (common). This allows the signal from the middle pickup to pass to the common pin on this side of the switch. Since left-hand pin C is shorted to right-hand pin C, the signal from the middle pickup continues to right-hand pin C, where it then goes to the volume control. Additionally, right-hand pin C is currently connected to right-hand pin M, allowing the signal from the middle pickup to ALSO travel to the middle tone control.

When the switch is in the bridge position, left-hand pin B (bridge) is connected to left-hand pin C (common). This allows the signal from the bridge pickup to pass to the common pin on this side of the switch. Since left-hand pin C is shorted to right-hand pin C, the signal from the bridge pickup continues to right-hand pin C, where it then goes to the volume control. Additionally, right-hand pin C is currently connected to right-hand pin N, but right-hand pin N is not connected to anything else, the sound is unaffected by any tone control.

Remember that we also have those two additional in-between positions, but all that happens there is that everything is true for both positions either side of it, so for example in the in-between position between the neck and the middle pickup, everything I wrote about the neck position AND everything I wrote about the middle position is true.

Finally, in addition to a standard Stratocaster 5-way switch, you can also get import types, which look more like this:
Note that these are just wired up in the same way as the switch that I’ve already been describing, except that the pins are laid out a bit differently. In the above image, the pins are numbered (left to right) 3,2,1,0,0,3,2,1. These represent the following positions:

    3 – Bridge
    2 – Middle
    1 – Neck
    0 – Common
    0 – Common
    3 – Bridge
    2 – Middle
    1 – Neck


Finally, if you want to get all fancy with your wiring, you can get “super switches”, which have many more contacts, allowing you a much greater range of wiring options. Here’s an example of one below:



Thursday, August 7, 2014

Cheap and easy guitar nut lubricant



Yeah, that’s right, “nut lubricant”. Get all your giggling out of the way before we continue.

So you know how sometimes you’re tuning up your guitar and you hear this pinging noise and the string suddenly “jumps” up in pitch? That’s caused by the string getting stuck (sometimes known as "binding") in the nut slots. You can also encounter it when using a tremolo.

My usual fix for this is to widen the nut slots slightly using nut files. However, today I’m going to show you another solution that can often work instead. We’re going to make a lubricant to put in the nut slots. This is especially useful for tremolo-equipped guitars.

Here's our patient for today. It's a late 80's Fernandes "Limited Edition" Strat. Beautiful guitar, but a terrible case of "pinging" at the nut.


We don’t need much for this, just some graphite (curtsey of a pencil lead) and something to hold the powder together (petroleum jelly). Some sandpaper and a little plastic knife or similar will be the only required tools.


First, start rubbing the pencil lead on fine sandpaper. Be careful not to start sanding away any wood, as we don’t really want this to get into the mix too. As it happens the pencil I’m using circumvents this issue anyway.




Once you’ve good a decent quantity of lead on there, take a small amount of petroleum jelly and dollop it right on top of the lead powder. Try to use as little as possible, while still being enough to “absorb” the pencil lead powder. Just keep mixing it around with the plastic knife until you feel that it’s mixed as well as it can be.





As you can see from the following image, that's some pretty nasty black greasy-looking stuff you've ended up with. Be careful not to get it on your clothing (or anything else you care about that's hard to clean for that matter).


Now move one of the strings to the side of its nut slot.


Carefully place a small amount of nut lubricant into the slot, then repeat for the next string.


Once all six string slots are done, place the strings back into position (you can use the strings to help scoop the lubricant into the slots).
Now wipe away as much surplus lubricant as you can (I’ve found that any surplus, especially extending past the fretboard end of the nut can deaden the sound of the string a little bit).


And we’re done. As mentioned at the start of the article, this particular guitar suffered from pretty severe pinging beforehand, but the lubricant completely cured it.

Sunday, March 30, 2014

Building a Noisy Cricket Mk II Amp and Mini Speaker Cabinet




I quite like the look of the Noisy Cricket Mk II amp from Beavis Audio (http://www.beavisaudio.com/projects/NoisyCricket/), and I happened to have a wooden box lying around that looked like it would work great as a 6” speaker cabinet, hence today’s project. (EDIT: Actually it turns out the Mk I and the MK II are the same. The only difference is the PCB design, and since I'm using veroboard, that's irrelevant.)

The Noisy Cricket is a little 1/2 Watt guitar amplifier that fits into a standard Hammond-like enclosure (such as the one I used here: http://diystrat.blogspot.com/2013/04/building-modified-ea-tremolo-pedal-on.html). It uses a MPF102 or a 2N5951 transistor as a preamp channel and an LM386 as the power amp. It’s also powered from a standard 9v guitar pedal power supply (or even a battery). What’s not to like?

As I usually do, I’m going to use Veroboard for this. A few people have already done layouts for it, and I decided to go with this one:



In addition to the Veroboard layout, this one has an additional tone switch, which lets you choose between the original 47nF tone capacitor, or the “improved bass” 100nF capacitor. In the end, I didn’t use a switch, electing instead to try both caps and choose whichever one I thought sounded best (in my case the 100nF).

Anyway, let’s get started. First we cut the veroboard to size:


You can see above that I have drilled a hole in the bottom right corner to match the one in the top left. That’s because I’m going to secure it inside the box (more on that later).

Now I cut the tracks in the appropriate locations:


And then give the copper a clean with a wire brush. This is to remove any tarnish from the copper, making it easier to solder.


Meanwhile, I’m also working on the box. First I work out where all of the controls/jacks will go:


Then I drill them out using a stepping drill bit:


After that I do a quick layout check to make sure everything is going to fit like I’d hoped:


I also glue in a couple of clips to hold the board in place once it’s done.


OK, let’s get soldering:


Here are all of the components in place (except for the chip itself, which I'll do as a last step):


Then the wires:


And then finally wired up to the pots, switches and jacks:


EDIT: I'm adding some extra information below about wiring up the box, since a couple of commenters so far have asked if I could share more details.

First, let’s look at the power switch. You need to connect your DC-in jack (the middle pin) to one leg of the power switch (let’s go with the middle pin). The bottom leg of the switch connects to the 9V wire on the board. Make sure the negative pin of the DC-in jack connects to “ground”.

Here's a close-up of the power switch:




Actually, a point about “ground”. What I usually end up doing is choosing a fairly solid patch of metal to connect all the grounds to. In this case, I used one of the ground tabs on one of the ¼” jacks (doesn’t matter which jack since they’re connected electrically through the metal enclosure [this approach won’t work if it’s not in a metal enclosure, but simply hooking up the other 1/4" jack's ground to this same point too will keep you right]).


You can see that there are a few ground wires all connecting the right-hand jack in the image below.
 


The wire labeled “LED+” goes to the long leg of the power LED (the other leg should then also be connected to ground.

“Grit 1” and “Grit 2” connect to the middle leg and bottom leg of the grit switch (doesn’t matter which way around). If you buy a DPDT switch (six legs), then you can use the other column of pins to give power to an LED that will indicate when the grit switch is turned on. To do so, connect the middle leg in the other column of that switch to ground. Connect the end leg of the switch in that column to a 1k resistor and connect the other end of the resistor to the short leg of the grit LED. Finally connect the long leg of the LED to 9V ON THE BOARD (not straight to the DC-in jack).


Here's how my switch looks:



OK, that’s the switches and LEDs. Now let's look at the pots.


I’ve attached a photo that sort of shows the pot wiring. Basically as you look at that picture, the pin on the right of each pot is pin one, middle is pin two, and the left one is pin 3. Same for all three pots. If you mix up pins one and three, it’ll still work, but everything will work in reverse (turning up will actually reduce the volume, for example).
 


So, for example, “Vol 3” refers to pin 3 on the volume pot.



Some more points:
  • Gain pins 1 and 2 are connected together. You can’t really see it in the photo, unfortunately.
  • Tone pins 2 and 3 are connected together too.
  • “Output” goes to the tip pin of the output/speaker jack (the other pin goes to ground of course). 
  • Many speakers will be marked + and -. Theoretically, “-“ should go to ground, but it doesn’t really matter that much.

Here’s how it looks all closed up:


Now remember I mentioned that box? Well here it is beside a lovely 6” speaker I picked up:


We’ll need to cut a big circular hole, so let’s make sure we get the centre in the right place:


Then we measure the diameter of the speaker:


I’m using this adjustable spinning blade of death to cut the hole. Believe me when I tell you that this particular tool deserves all of your respect and then some. It will happily remove some of your body parts if you are not careful.


But for all of its scariness, it does do a great job:


A few more small holes for the securing screws and here’s the speaker attached (I'll add a grill to this later):


Now we need to wire up a jack. Unfortunately the thickness of the wood is more than the length of the thread on the jack, so I’m having to get a little creative with the solution.

I use another boring bit to scribe a line a few mm down into the wood. This will act as a guide for the next step, both for the depth and the outer diameter.



I then use a flat-bottomed drill bit (really, it’s a routing bit) and very carefully lower the depth of the wood within the confines of the outer circle I’ve just cut:


I also cut a little lip in there to match the lip that’s on the jack itself:



Here’s the jack in place:



I wanted to make some sort of handle, but also use the handle to hold the amp in place. However, I’d like to be able to remove the amp at any stage to use with a different speaker, or even use a different amp with THIS speaker.

So I attached a piece of leather like so:




Now the jack gets wired up to the speaker:


And I used a couple of metal fasteners to hold the back cover on:


After a bit of a search, I found a suitably-sized grill to protect the speaker:


And here it is holding the Noisy Cricket in place:





Finally here is a quick, dirty and extremely amateur demo of the amp. I probably should have planned what I was going to play before I started the camera rolling, but hopefully it will at the very least give you an idea what the amp sounds like.