Part 3 - Humming

Opposites attract. That well known saying is true in the case of Humbucker pickups. As mentioned in the last part a Humbucker pickup does exactly that, stops the hum.

A magnet has a north and south and if you can remember back to your school days, those of you that weren’t sagging off, or, reading a comic under the desk, this is what makes a compass work as the magnet will always point to North. When a string vibrates it goes on forever just like ripples in water after you have thrown a stone in. This vibration whizzes round the pickup coil faster and faster creating a hum that gets to the point of destruction (feedback) as the string and coil vibrations bounce back and forth against each other.

Part of this can be stopped by setting the pickup coil in wax, put in hot and allowed to cool. This process is called ‘Potting’

The Dreaded Hum caused so many problems for years that it looked liked the end for the electric guitar until, one day a Luthier at the Gibson guitar factory, Seth Lover, remembered his science lesson in school. He remembered it very well as that was the day he forgot his comic and had to pay attention to the lesson. The answer was simple, join two pickups together. But the clever part is magnet one faces north to south and magnet two faces south to north. This way they cancel the Hum

You might say well hang on a mo, a Fender Stratocaster has three single coil pickups and that doesn’t hum, simple; Pickup 1 is N/S pickup 2 is S/N and number 3 is N/S, to use a racing term the middle pickup is an each way bet, cancelling the other two.

Set Up and the Neck of A Guitar

Now the most important part of the guitar is the neck and how it is ‘set up’.

Hands up all you Twangers, who have bought a new guitar and just started playing it as it is and have done so for years and years?

Quite a few me thinks! I even know a very well known Mersey beat guitarist who kept a set of strings on for nearly twenty years!!!!

Strings I’ll come back to but lets start with the neck.

The new Eric Clapton -Hank Marvin- Jack the lad goes in to Frank Hessys Music store* (Editors Note: Uhuuum Bassman, Frank's Dead!!!), picks up a shinning lump of plastic ,strums E,A, and B7th and then - yes we ALL do it, looks down the neck. ‘Yup straight as an arrow’ then buys it. Wrong. The perfect neck for playing should NOT be straight, What? I can hear the masses scream, Let me explain. A string is held tight at the Tailpiece and at the other end by the machine head. When plucked it vibrates but not equally along its length. The middle of the string moves up and down more than the two fixed ends so, the neck need a slight bow at this point to stop the string from hitting it. This is called ‘relief’ and is measured in thousandths of an inch but it still has to be there for the neck to function correctly. This is done by adjusting the truss rod. Most mass produced guitars are only’ set up’ to a mean average that’s why a lot of guitars have a high action, they have no Relief!!

Next time we will go through how to set up your guitar correctly and the ‘secrets’ of the Stars on how theirs are set up .

 * Hessys Music Centre was the famous music shop in Liverpool where the Beatles, Gerry and many other Liverpool bands bought their first guitars. Unfortunately it's now a coffee shop or something.

Part 4 Setting Up The Guitar