Thursday, October 22, 2009

Installing an under-saddle pickup on an acoustic guitar

This beautiful guitar needs an under-saddle pickup. This is a kind of 4-step process, as follows:

1. Drill a 12mm (or 12.5mm) hole where the endpin used to be, to install the endpin jack.
2. Drill a hole through the bridge to allow the pickup wire to pass through.
3. Sand down the bottom of the old saddle, taking off the same amount as the height of the pickup that will now sit under it.
4. Solder the wire from the pickup to the endpin jack.

OK, let the adventure begin!

Firstly, before drilling a hole for the endpin jack, the old endpin needs to be removed. As this is tapered in shape, it should be easy to just yank it out. Get a good firm grip with your fingers and give it a tug. If you’re lucky, it’ll pull right out. In my case it did.

Now you’re left with a hole that is too small for the endpin jack. As you are not drilling a new hole, but rather expanding one that already exists, the traditional method is to use a reamer.

The problem with this method, however, is that a reamer leaves you with a tapered hole (unless you get a specialised one just for this job), so by the time you open the hole out to 12 mm at one end, it is still too small at the other end. To rectify this, you need to use a round file to file out the rest. I’ve done this before and it took a lot of time.

So instead, I decided to try a different approach this time. It just so happens I have a stepping drill bit whose largest diameter is exactly 12 mm. As it is a stepping drill bit, it behaves in a similar way to a reamer, in that it enlarges holes as it goes through, rather than making one huge 12mm hole in one go. This makes it a nice safe way to drill the endpin jack hole without having to worry about splitting or chipping wood. I wasn’t quite sure how this method was going to work out for me, but it worked perfectly. Note that this will only work if the largest diameter of your stepping drill bit is 12mm.

Most under-saddle pickups require you to drill a hole straight down through the bridge (under the saddle), but this particular pickup required the hole to be drilled at 45°. This was quite risky, as it was very difficult to avoid the bracing inside the guitar. If you are ever doing this, have a good feel inside the guitar to try to locate the closest bracing, in the hope that you can somehow avoid it (whatever you do, don’t have your hand in there while you are drilling the hole). Luckily in this case it was possible to avoid the brace by about the width of a human hair (no kidding).

The hole needs to be smoothed out with a small round needle file, so that there are no rough edges. For this particular type of pickup, it is also necessary to round off the 45° angle, so that the pickup/lead doesn't get a kink in it.

The pickup lead now needs to be fed through the hole and the pickup then placed in the saddle slot.

Now you need to sand the same amount off the bottom of the saddle as the height of the pickup. Use a Vernier caliper to measure the thickness of the pickup, then mark this on the bottom of the saddle. Simply rub the saddle against sandpaper taped to a very flat surface (it’s extremely important to get a flat surface on the bottom of the saddle, so do it right) until you have sanded off the correct amount.

The last thing you need to do before stringing up the guitar is to solder the pickup lead to the endpin jack. Make sure that before you do this, you slide any endpin jack covers, nuts, washers, etc., up the lead, as you won’t be able to do this once it’s soldered. You can slide these parts up the cable from inside the guitar, then pass the lead through the endpin jack hole to do the soldering outside the guitar. It’s a good idea to protect the finish on your guitar with rags or something while doing the soldering.

Here's what the endpin jack looks like before soldering:

Once soldered, push the endpin jack into the hole. Feed the washer and nut down the lead and onto the endpin jack (inside the guitar – yes, it’s fiddly). Tighten the endpin jack nut, making sure that it is nice and tight, as it will have a tendency to work loose otherwise. If there is some sort of endpin jack cover, fit this now.

Here's the endpin jack installed:

Now place the saddle in the saddle slot and string up the guitar.

Here's the finished product. She's a beauty, isn't she? Sounds great too.

Tuesday, July 28, 2009

How to upgrade guitar tuners

A very common guitar upgrade is to swap out crappy, cheapo, open-backed (or “stamped”) tuners and replace them with better, enclosed die-cast tuners. I’d like to show you how to do that, and point out a few potential dangers along the way. The example shown uses an acoustic guitar with 3-a-side tuners, but you could follow the same process for an electric, be it 3-a-side or 6-in-line.

Click on any of the images to see bigger versions.

Here’s the patient.

The guitar itself plays well and sounds pretty good, but the tuners have become almost impossible to turn, so it’s time for a change. Although these may look like enclosed tuners, they are simply open-backed tuners, with nothing more than a back cover, which doesn’t even stop dust from getting in.

Decent enclosed tuners can be had very cheap these days. This particular guitar didn’t really warrant Schaller or Grover tuners, but the replacement no-name tuners it is about to receive are a huge improvement over what was there before. I should mention here that if you have a very expensive or collectible guitar, you should probably try to replace your tuners with exact matches if at all possible.

First thing to do is remove the strings. After that, these tuners are removed very simply by unscrewing the little retaining screws, as shown here.

The bushings (also known as ferrules) also need to be removed from the front. The trick here is to stick something like a screwdriver into the hole and then gently roll it around so that the bushing slowly works its way out.

Time for a little cleaning.

Now we’re ready to start the work required for the upgrade.

Unfortunately, enclosed tuners generally require larger holes than open-backed ones. The holes on this guitar appear to be a little over 7mm, but as you can see below, the new tuners in this case will require a 10mm hole.

I got this handy hole-sizing gauge with my drill bit set.

As you can see below, it also measures the enclosed tuner at 10mm.

This is one of the two tools required for enlarging the holes. It’s called a reamer and it really is the perfect tool for enlarging already-existing holes.

I put the reamer through the same 10mm hole on the gauge and mark it with correction fluid. Alternatively, you could mark with a pen, or tape, or whatever you like.

We ream out the hole until the mark meets the wood, then stop. In fact, I would advise you to go just a little bit farther, but not much. The reasoning here is that if you make the opening of the holes a little bit bigger here, you are less likely to chip the finish during the filing process described later.

We do the same to all 6 holes, then repeat the process from the other side of the peg head.

We now have a situation where the opening of the holes on both sides of the peg head are 10mm, but since the reamer is tapered, the hole is not 10mm the whole way through, so we need to do a bit of filing to correct this. Although this photo shows the file being inserted from the back of the peg head, I advise you to insert it from the front. That way it is less likely you will chip any of the veneer off the front of the peg head. If anything chips off the back, it is a lot easier to hide it under the tuner, although in fact, chips from the back are less likely anyway.

Once all 6 holes have been filed, and you have checked them all to make sure the tuners fit, it’s time to screw the tuners into place. Line up something straight, like a ruler, against three of the tuners and make a mark in the holes for the retaining screws. Then do the same for the other 3 tuners.

You could use a drill to make pilot holes for the retaining screws, but I prefer one of these. It’s much easier to control and less likely to accidentally go right through the peg head (and believe me, you really don’t want to do that). It’s called a pin vice (or vise, depending on where you come from).

Whichever method you use, remember that these are just pilot holes, so should be thinner than the screws themselves. Don’t be tempted to just screw in the screws without the pilot holes. There’s a very slim chance you’ll split some wood, but there’s a very BIG chance some of the screws will actually snap on the way in. Last thing to remember is that you should mark the drill bit beforehand so that you know when it has gone deep enough for the screws, but not so deep that it goes right through the peg head.

I recommend that you screw in the retaining screws, but not too tight, then screw on the bushings from the front of the peg head, using a socket (in my case, 10mm). Finally, tighten up the retaining screws. You may even want to use your ruler again while you’re doing this.

Anyway, here’s the finished result (the new tuners got switched from gold ones to silver ones at the last minute, before you ask). As you can see, the back isn’t pretty, but it’s functional, which is all that was required in this case. A set of machine heads with offset retaining screw holes would’ve hidden the footprint of the previous tuners a bit better, so that’s something you may want to keep in mind if appearances matter to you.

Monday, June 29, 2009

Making an Ebony Nut and Saddle

I may have mentioned a while back that a friend of mine generously donated a couple of nut and saddle blanks – one set in Corian and one set in ebony. I already used the Corian nut blank to make a raised nut for playing slide guitar (as seen HERE). Now it was time to put the ebony to use.

My acoustic only came with a plastic nut and saddle, so I was keen to see what sort of a difference this would make (to be discussed later).

The ebony blanks:

The first thing I should mention here is that ebony is a very difficult wood to work with. The only thing I can compare it to is frozen chocolate. It’s extremely hard, but it’s still possible to chip bits off the edge quite easily, so you have to be very careful, patient, and have very sharp tools.

First thing to do was to remove the old nut and saddle to use as a template.

These were then traced around on the nut and saddle blanks.

Let’s look at the process of making the saddle first.

The tracing:

Cutting to length:

Initial, quite rough, shaping, using a file (shown below):

Then final shaping and smoothing using fairly smooth sandpaper, to give the finished saddle shown here:

And finally, fitted to the guitar:

Now the nut


Again, rough shaping, only this time starting with a little plane (shown below), then a file, then sandpaper:

Despite taking care, a bit chipped off, as shown below. No problem, I need to add a curve anyway:

The nut also needed to be thinned to fit into the nut slot. This was done in the same way as the Corian nut HERE.

With the slots cut:

Finally, fitted to the guitar:

The sound is definitely different. The wound strings appear to have more depth and seem to have more sustain too, whereas I was a little disappointed with the unwound strings initially, though they seem to have come to life now. Overall I like the sound, though I would like to also try bone, so don’t be surprised if you see another similar post somewhere down the road.

Thursday, June 25, 2009

How to wire up a Stomp Box / Effects Pedal

Today we're going to talk about how to wire up a stompbox.

Apart from the effects circuit itself, there are three things that have to be thought about when wiring up a stompbox, which are the stomp switch, the stereo input jack and the DC-in connector.

I’ll be referring to this image throughout the explanation (as with all images on here, click to enlarge):

1. The Switch

To try to make this easy to follow, consider the left-hand column of the switch to be the input column, the middle column to be the LED column, and the right-hand column to be the output column. If for any reason you only have a 6-pin switch, you can still use it, just without the LED column.

Off position

In the OFF position, pin 4 is connected to pin 7, pin 5 is connected to pin 8, and pin 6 is connected to pin 9 (in my diagram at least – you may have a switch with different numbers written on it, though often they have none at all).

Looking at just the left and right columns, the input comes in from the input jack via the yellow wire connected to pin 4, is directed downwards to pin 7, which is shorted to pin 9 via the jumper wire, then this is redirected up to pin 6 which is connected to the output jack. In other words, a bypass is in operation. As the effects circuit itself is completely disconnected, it cannot influence the signal, so this is true bypass.

As for the middle column, there is not much going on there. The ground/earth wire is connected to pin 5, but it is not redirected anywhere, so nothing happens, and the LED does not light up.

On position

In the ON position, pin 4 is connected to pin 1, pin 5 is connected to pin 2 and pin 6 is connected to pin 3.

Again, looking at just the left and right columns, the input again comes in from the input jack via the yellow wire connected to pin 4, is directed upwards to pin 1, which then goes to the input of the effects circuit. The output of the effects circuit goes to pin 3, and this is redirected down to pin 6 which is connected to the output jack.

As for the middle column, the ground/earth wire is connected to pin 5, which is redirected up to pin 2 and fed to the negative terminal of the LED, allowing it to light up.

OK, that’s the switch explained, but there’s more going on here.

2. The Stereo Input Jack

You may be wondering why a stereo input jack is required, when you are only using a mono signal. Well, that’s because the third connector (pin 3) on the input jack is used to control the power supply to the circuit.

Let’s assume for a moment that you are using a battery. Instead of the negative of the battery being connected straight to the negative of the effects circuit, which would mean the battery is in use ALWAYS (even when the circuit appears to be switched off), the negative of the battery is instead connected to the third connector (pin 3) of the stereo input jack. That way, when nothing is plugged into the stomp box, the third connector is not connected to anything and the battery is not being used. When you plug in a mono jack plug, it shorts the third connector to the shield/sleeve connector (pin 1) of the socket, which in turn connects it to earth/ground, powering the effects circuit.

You may wonder why you don’t just power up the battery at the same time as switching on the effects circuit. Without going into too many details, this is because the sudden surge of power leads to a loud popping noise, which no-one wants to hear.

3. The DC-in Connector

Lastly, we have the (5.5 x 2.1mm) DC-in connector. This also has three connectors and can sometimes cause confusion, since instead of having a positive inner (centre pin/tip), which would be the norm for most electronic items, it actually has a negative inner. I’ve numbered the pins in the diagram for clarity, as follows: pin 1 is the (negative) inner/pin/tip and is connected to the negative of the battery, pin 2 is the outer (sleeve) and is connected to the positive (+9v) of the effects circuit, and finally in a similar way to the stereo input jack, pin 3 is the 3rd, extra, pin and is connected to the positive terminal of the battery.

(The difference between this and the input jack is that in this case, pins 2 and 3 are normally shorted UNTIL you plug in a power supply, at which time pin 3 becomes disconnected.)

When nothing is plugged in, the positive terminal of the battery, which is connected to pin 3, is shorted to pin 2, and continues on its way to the positive of the effects circuit. When the power supply is plugged in, however, pin 3 (and therefore the positive of the battery) is disconnected, and the positive voltage from the power supply goes directly to the effects circuit via pin 2.

One more thing to note is that since the DC-in socket has a positive outer, it should be one with a plastic surround, so that the outer does not make electrical contact with the enclosure (which is grounded/earthed).

Something like this (below) is fine:

Whereas something like this (below) is NOT suitable:


Additional information

With thanks to CheopisIV ( and bugg over at the mylespaul forums for clearing this up, it is a wise idea to ground the input of the circuit itself when not in use (in other words, while it is being bypassed). Without a grounded input, the input signal can float all over the place and by the time it gets amplified through the circuit, there can be quite a large uncontrolled signal in there. Now theoretically this wouldn't be connected to the output socket, since the circuit is being bypassed, but the noise can be picked up by other means, and so it is safer to just avoid it if possible. 

So we simply add one extra jumper wire from the leg of the switch that goes to the circuit input and the unused leg on the LED column. The resulting wiring would look like so:
While the circuit is bypassed, the circuit input is connected to the ground wire going into the centre pin (pin 5) of the switch. When the switch is engaged, this connection is broken and the circuit just works as previously described.

Finally here are a couple more circuits for people who want to take out either the battery or the DC-in jack:

Wednesday, June 24, 2009

Under the stairs

I’m really behind on the updates, sorry. I’ve been doing some real-world stuff that didn’t leave much time for much DIY guitar-related fun. I am happy to report that one of the reasons I haven’t had as much time to tinker is that I’ve actually been playing the guitar a bit.

One of the things that took up some of my time was sorting out a new property back home, which required a rather long return flight, not helped by the fact that the airline forgot to load the headphones for the entertainment system on the way there, and I hadn’t brought my own for the first time ever.

While I was back home, I rifled through some stuff that I had left at a friend’s house and stumbled across a stomp box I made just after finishing the DIY Strat. I had totally forgotten about it, and even if I had remembered I would have been sure it had been thrown out.

Anyway, for the very few that may be interested, here it is. Note the professional enclosure (not)! What a great colour (grey primer covered by lacquer, which was all I had at the time).

The circuit is one of Aron Nelson’s designs (if you don’t know who Aron Nelson is, but are interested in DIY stomp boxes, then Google his name now). This particular circuit is “The Hornet” and the circuit diagram can be found here: (scroll down a bit to find it)

Unfortunately when I made this, I didn’t really understand how to do the switching, so I ended up wiring it up like this:

I mean, it works (sort of), but it’s not a good way to wire it up for a couple of reasons.
Firstly, this is why it works...

The switch has 4 legs. In one position, legs 1 and 2 are shorted. In the other position legs 3 and 4 are shorted.

When poles 1 and 2 are shorted, power is sent to the circuit.

When poles 3 and 4 are shorted, power is disconnected from the circuit, but the input is shorted to the output, creating a bypass.

However, here’s why it’s not a good way to wire it up...

1. Even when no power is applied, and a bypass is in operation, the circuit still manages to affect the sound, for example by creating some sort of a path from the signal to earth.

2. When the switch is pressed, the circuit is activated at the same time as power is applied, and a loud popping noise is heard.

For those that are interested, in the next blog post, I’ll show you the correct way to wire up a switch in a stomp box: