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: